Online Damage Detection on Metal and Composite Space Structures by Active and Passive Acoustic Methods

NASA Astrophysics Data System (ADS)

Scheerer, M.; Cardone, T.; Rapisarda, A.; Ottaviano, S.; Ftancesconi, D.

2012-07-01

In the frame of ESA funded programme Future Launcher Preparatory Programme Period 1 “Preparatory Activities on M&S”, Aerospace & Advanced Composites and Thales Alenia Space-Italia, have conceived and tested a structural health monitoring approach based on integrated Acoustic Emission - Active Ultrasound Damage Identification. The monitoring methods implemented in the study are both passive and active methods and the purpose is to cover large areas with a sufficient damage size detection capability. Two representative space sub-structures have been built and tested: a composite overwrapped pressure vessel (COPV) and a curved, stiffened Al-Li panel. In each structure, typical critical damages have been introduced: delaminations caused by impacts in the COPV and a crack in the stiffener of the Al-Li panel which was grown during a fatigue test campaign. The location and severity of both types of damages have been successfully assessed online using two commercially available systems: one 6 channel AE system from Vallen and one 64 channel AU system from Acellent.

Spiral Bevel Gear Damage Detection Using Decision Fusion Analysis

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Handschuh, Robert F.; Afjeh, Abdollah A.

2002-01-01

A diagnostic tool for detecting damage to spiral bevel gears was developed. Two different monitoring technologies, oil debris analysis and vibration, were integrated using data fusion into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual monitoring technologies. This diagnostic tool was evaluated by collecting vibration and oil debris data from fatigue tests performed in the NASA Glenn Spiral Bevel Gear Fatigue Rigs. Data was collected during experiments performed in this test rig when pitting damage occurred. Results show that combining the vibration and oil debris measurement technologies improves the detection of pitting damage on spiral bevel gears.

Structural damage detection based on stochastic subspace identification and statistical pattern recognition: I. Theory

NASA Astrophysics Data System (ADS)

Ren, W. X.; Lin, Y. Q.; Fang, S. E.

2011-11-01

One of the key issues in vibration-based structural health monitoring is to extract the damage-sensitive but environment-insensitive features from sampled dynamic response measurements and to carry out the statistical analysis of these features for structural damage detection. A new damage feature is proposed in this paper by using the system matrices of the forward innovation model based on the covariance-driven stochastic subspace identification of a vibrating system. To overcome the variations of the system matrices, a non-singularity transposition matrix is introduced so that the system matrices are normalized to their standard forms. For reducing the effects of modeling errors, noise and environmental variations on measured structural responses, a statistical pattern recognition paradigm is incorporated into the proposed method. The Mahalanobis and Euclidean distance decision functions of the damage feature vector are adopted by defining a statistics-based damage index. The proposed structural damage detection method is verified against one numerical signal and two numerical beams. It is demonstrated that the proposed statistics-based damage index is sensitive to damage and shows some robustness to the noise and false estimation of the system ranks. The method is capable of locating damage of the beam structures under different types of excitations. The robustness of the proposed damage detection method to the variations in environmental temperature is further validated in a companion paper by a reinforced concrete beam tested in the laboratory and a full-scale arch bridge tested in the field.

Laser-Induced Damage Threshold and Certification Procedures for Optical Materials

NASA Technical Reports Server (NTRS)

1997-01-01

This document provides instructions for performing laser-induced-damage-threshold tests and pass-fail certification tests on optical materials used in pulsed-laser systems. The optical materials to which these procedures apply include coated and uncoated optical substrates, laser crystals, Q-switches, polarizers, and other optical components employed in pulsed-laser systems.

Design of a pulsatile flow facility to evaluate thrombogenic potential of implantable cardiac devices.

PubMed

Arjunon, Sivakkumar; Ardana, Pablo Hidalgo; Saikrishnan, Neelakantan; Madhani, Shalv; Foster, Brent; Glezer, Ari; Yoganathan, Ajit P

2015-04-01

Due to expensive nature of clinical trials, implantable cardiac devices should first be extensively characterized in vitro. Prosthetic heart valves (PHVs), an important class of these devices, have been shown to be associated with thromboembolic complications. Although various in vitro systems have been designed to quantify blood-cell damage and platelet activation caused by nonphysiological hemodynamic shear stresses in these PHVs, very few systems attempt to characterize both blood damage and fluid dynamics aspects of PHVs in the same test system. Various numerical modeling methodologies are also evolving to simulate the structural mechanics, fluid mechanics, and blood damage aspects of these devices. This article presents a completely hemocompatible small-volume test-platform that can be used for thrombogenicity studies and experimental fluid mechanics characterization. Using a programmable piston pump to drive freshly drawn human blood inside a cylindrical column, the presented system can simulate various physiological and pathophysiological conditions in testing PHVs. The system includes a modular device-mounting chamber, and in this presented case, a 23 mm St. Jude Medical (SJM) Regents® mechanical heart valve (MHV) in aortic position was used as the test device. The system was validated for its capability to quantify blood damage by measuring blood damage induced by the tester itself (using freshly drawn whole human blood). Blood damage levels were ascertained through clinically relevant assays on human blood while fluid dynamics were characterized using time-resolved particle image velocimetry (PIV) using a blood-mimicking fluid. Blood damage induced by the tester itself, assessed through Thrombin-anti-Thrombin (TAT), Prothrombin factor 1.2 (PF1.2), and hemolysis (Drabkins assay), was within clinically accepted levels. The hydrodynamic performance of the tester showed consistent, repeatable physiological pressure and flow conditions. In addition, the system contains proximity sensors to accurately capture leaflet motion during the entire cardiac cycle. The PIV results showed skewing of the leakage jet, caused by the asymmetric closing of the two leaflets. All these results are critical to characterizing the blood damage and fluid dynamics characteristics of the SJM Regents® MHV, proving the utility of this tester as a precise system for assessing the hemodynamics and thrombogenicity for various PHVs.

Tests of Fire Suppression Effectiveness of Damaged Water Mist Systems

DTIC Science & Technology

2014-05-01

essure the damage pi essure is installed in the test compa Damage pipe no essur Pipe 7 104.9 12.9 31.0 22.0 132.5...pipe is installed in the test compartment, see Figure 68 Damage pipe no. Total [L/ Pr no [ba r u [ba v r [b a ea [L flow min] essure at rth...nozzle r] P so essure at th nozzle r] A p erage essure ar] C l lculated k flow /min] Pipe 4 104 35 23 29 66.9 .6 .8 .7 .5

Condition Assessment of Foundation Piles and Utility Poles Based on Guided Wave Propagation Using a Network of Tactile Transducers and Support Vector Machines

PubMed Central

Yu, Yang; Niederleithinger, Ernst; Li, Jianchun; Wiggenhauser, Herbert

2017-01-01

This paper presents a novel non-destructive testing and health monitoring system using a network of tactile transducers and accelerometers for the condition assessment and damage classification of foundation piles and utility poles. While in traditional pile integrity testing an impact hammer with broadband frequency excitation is typically used, the proposed testing system utilizes an innovative excitation system based on a network of tactile transducers to induce controlled narrow-band frequency stress waves. Thereby, the simultaneous excitation of multiple stress wave types and modes is avoided (or at least reduced), and targeted wave forms can be generated. The new testing system enables the testing and monitoring of foundation piles and utility poles where the top is inaccessible, making the new testing system suitable, for example, for the condition assessment of pile structures with obstructed heads and of poles with live wires. For system validation, the new system was experimentally tested on nine timber and concrete poles that were inflicted with several types of damage. The tactile transducers were excited with continuous sine wave signals of 1 kHz frequency. Support vector machines were employed together with advanced signal processing algorithms to distinguish recorded stress wave signals from pole structures with different types of damage. The results show that using fast Fourier transform signals, combined with principal component analysis as the input feature vector for support vector machine (SVM) classifiers with different kernel functions, can achieve damage classification with accuracies of 92.5% ± 7.5%. PMID:29258274

Multiple damage identification on a wind turbine blade using a structural neural system

NASA Astrophysics Data System (ADS)

Kirikera, Goutham R.; Schulz, Mark J.; Sundaresan, Mannur J.

2007-04-01

A large number of sensors are required to perform real-time structural health monitoring (SHM) to detect acoustic emissions (AE) produced by damage growth on large complicated structures. This requires a large number of high sampling rate data acquisition channels to analyze high frequency signals. To overcome the cost and complexity of having such a large data acquisition system, a structural neural system (SNS) was developed. The SNS reduces the required number of data acquisition channels and predicts the location of damage within a sensor grid. The sensor grid uses interconnected sensor nodes to form continuous sensors. The combination of continuous sensors and the biomimetic parallel processing of the SNS tremendously reduce the complexity of SHM. A wave simulation algorithm (WSA) was developed to understand the flexural wave propagation in composite structures and to utilize the code for developing the SNS. Simulation of AE responses in a plate and comparison with experimental results are shown in the paper. The SNS was recently tested by a team of researchers from University of Cincinnati and North Carolina A&T State University during a quasi-static proof test of a 9 meter long wind turbine blade at the National Renewable Energy Laboratory (NREL) test facility in Golden, Colorado. Twelve piezoelectric sensor nodes were used to form four continuous sensors to monitor the condition of the blade during the test. The four continuous sensors are used as inputs to the SNS. There are only two analog output channels of the SNS, and these signals are digitized and analyzed in a computer to detect damage. In the test of the wind turbine blade, multiple damages were identified and later verified by sectioning of the blade. The results of damage identification using the SNS during this proof test will be shown in this paper. Overall, the SNS is very sensitive and can detect damage on complex structures with ribs, joints, and different materials, and the system relatively inexpensive and simple to implement on large structures.

Investigation of Spiral Bevel Gear Condition Indicator Validation via AC-29-2C Combining Test Rig Damage Progression Data with Fielded Rotorcraft Data

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.

2015-01-01

This is the final of three reports published on the results of this project. In the first report, results were presented on nineteen tests performed in the NASA Glenn Spiral Bevel Gear Fatigue Test Rig on spiral bevel gear sets designed to simulate helicopter fielded failures. In the second report, fielded helicopter HUMS data from forty helicopters were processed with the same techniques that were applied to spiral bevel rig test data. Twenty of the forty helicopters experienced damage to the spiral bevel gears, while the other twenty helicopters had no known anomalies within the time frame of the datasets. In this report, results from the rig and helicopter data analysis will be compared for differences and similarities in condition indicator (CI) response. Observations and findings using sub-scale rig failure progression tests to validate helicopter gear condition indicators will be presented. In the helicopter, gear health monitoring data was measured when damage occurred and after the gear sets were replaced at two helicopter regimes. For the helicopters or tails, data was taken in the flat pitch ground 101 rotor speed (FPG101) regime. For nine tails, data was also taken at 120 knots true airspeed (120KTA) regime. In the test rig, gear sets were tested until damage initiated and progressed while gear health monitoring data and operational parameters were measured and tooth damage progression documented. For the rig tests, the gear speed was maintained at 3500RPM, a one hour run-in was performed at 4000 in-lb gear torque, than the torque was increased to 8000 in-lbs. The HUMS gear condition indicator data evaluated included Figure of Merit 4 (FM4), Root Mean Square (RMS) or Diagnostic Algorithm 1(DA1), + 3 Sideband Index (SI3) and + 1 Sideband Index (SI1). These were selected based on their sensitivity in detecting contact fatigue damage modes from analytical, experimental and historical helicopter data. For this report, the helicopter dataset was reduced to fourteen tails and the test rig data set was reduced to eight tested gear sets. The damage modes compared were separated into three cases. For case one, both the gear and pinion showed signs of contact fatigue or scuffing damage. For case two, only the pinion showed signs of contact fatigue damage or scuffing. Case three was limited to the gear tests when scuffing occurred immediately after the gear run-in. Results of this investigation highlighted the importance of understanding the complete monitored systems, for both the helicopter and test rig, before interpreting health monitoring data. Further work is required to better define these two systems that include better state awareness of the fielded systems, new sensing technologies, new experimental methods or models that quantify the effect of system design on CI response and new methods for setting thresholds that take into consideration the variance of each system.

Investigation of Time Series Representations and Similarity Measures for Structural Damage Pattern Recognition

PubMed Central

Swartz, R. Andrew

2013-01-01

This paper investigates the time series representation methods and similarity measures for sensor data feature extraction and structural damage pattern recognition. Both model-based time series representation and dimensionality reduction methods are studied to compare the effectiveness of feature extraction for damage pattern recognition. The evaluation of feature extraction methods is performed by examining the separation of feature vectors among different damage patterns and the pattern recognition success rate. In addition, the impact of similarity measures on the pattern recognition success rate and the metrics for damage localization are also investigated. The test data used in this study are from the System Identification to Monitor Civil Engineering Structures (SIMCES) Z24 Bridge damage detection tests, a rigorous instrumentation campaign that recorded the dynamic performance of a concrete box-girder bridge under progressively increasing damage scenarios. A number of progressive damage test case datasets and damage test data with different damage modalities are used. The simulation results show that both time series representation methods and similarity measures have significant impact on the pattern recognition success rate. PMID:24191136

Seismic damage identification for steel structures using distributed fiber optics.

PubMed

Hou, Shuang; Cai, C S; Ou, Jinping

2009-08-01

A distributed fiber optic monitoring methodology based on optic time domain reflectometry technology is developed for seismic damage identification of steel structures. Epoxy with a strength closely associated to a specified structure damage state is used for bonding zigzagged configured optic fibers on the surfaces of the structure. Sensing the local deformation of the structure, the epoxy modulates the signal change within the optic fiber in response to the damage state of the structure. A monotonic loading test is conducted on a steel specimen installed with the proposed sensing system using selected epoxy that will crack at the designated strain level, which indicates the damage of the steel structure. Then, using the selected epoxy, a varying degree of cyclic loading amplitudes, which is associated with different damage states, is applied on a second specimen. The test results show that the specimen's damage can be identified by the optic sensors, and its maximum local deformation can be recorded by the sensing system; moreover, the damage evolution can also be identified.

Creation of backdoors in quantum communications via laser damage

NASA Astrophysics Data System (ADS)

Makarov, Vadim; Bourgoin, Jean-Philippe; Chaiwongkhot, Poompong; Gagné, Mathieu; Jennewein, Thomas; Kaiser, Sarah; Kashyap, Raman; Legré, Matthieu; Minshull, Carter; Sajeed, Shihan

2016-09-01

Practical quantum communication (QC) protocols are assumed to be secure provided implemented devices are properly characterized and all known side channels are closed. We show that this is not always true. We demonstrate a laser-damage attack capable of modifying device behavior on demand. We test it on two practical QC systems for key distribution and coin tossing, and show that newly created deviations lead to side channels. This reveals that laser damage is a potential security risk to existing QC systems, and necessitates their testing to guarantee security.

Post Test Evaluation of HSCT Nozzle Acoustic Liner Subcomponents Subjected to a Hot Acoustic Durability Test

NASA Technical Reports Server (NTRS)

Verrilli, Michael J.; Lee, Kuan

2008-01-01

The acoustic liner system designed for use in the High Speed Civil Transport (HSCT) was tested in a thermal-acoustic environment. Five ceramic matrix composite (CMC) acoustic tile configurations, five bulk acoustic absorbers, and one thermal protection system design were tested. The CMC acoustic tiles were subjected to two 2 3/4 hr ambient temperature acoustic exposures to measure their dynamic response. One exposure was conducted on the tiles alone and the second exposure included the tiles and the T-foam bulk absorber. The measured tile RMS strains were small. With or without the T-foam absorber, the dynamic strains were below strain levels that would cause damage during fatigue loading. After the ambient exposure, a 75-hr durability test of the entire acoustic liner system was conducted using a thermal-acoustic cycle that approximated the anticipated service cycle. Acoustic loads up to 139 dB/Hz and temperatures up to 1670 F (910 C) were employed during this 60 cycle test. During the durability test, the CMC tiles were exposed to temperatures up to 1780 F and a transient through thickness gradient up to 490 F. The TPS peak temperatures on the hot side of the panels ranged from 750 to 1000 F during the 60 cycles. The through thickness delta T ranged from 450 to 650 F, varying with TPS location and cycle number. No damage, such as cracks or chipping, was observed in the CMC tiles after completion of the testing. However, on tile warped during the durability test and was replaced after 43 or 60 cycles. No externally observed damage was found in this tile. No failure of the CMC fasteners occurred, but damage was observed. Cracks and missing material occurred, only in the fastener head region. No indication of damage was observed in the T-foam acoustic absorbers. The SiC foam acoustic absorber experienced damage after about 43 cycles. Cracking in the TPS occurred around the attachment holes and under a vent. In spite of the development of damage, the TPS maintained its insulative capability throughout the durability test. The durability test results demonstrate damage-tolerant CMC tile, CMC fastener, TPS, and T-foam absorber designs for the combined thermal and acoustic engine nozzle environment.

Transmission Bearing Damage Detection Using Decision Fusion Analysis

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Lewicki, David G.; Decker, Harry J.

2004-01-01

A diagnostic tool was developed for detecting fatigue damage to rolling element bearings in an OH-58 main rotor transmission. Two different monitoring technologies, oil debris analysis and vibration, were integrated using data fusion into a health monitoring system for detecting bearing surface fatigue pitting damage. This integrated system showed improved detection and decision-making capabilities as compared to using individual monitoring technologies. This diagnostic tool was evaluated by collecting vibration and oil debris data from tests performed in the NASA Glenn 500 hp Helicopter Transmission Test Stand. Data was collected during experiments performed in this test rig when two unanticipated bearing failures occurred. Results show that combining the vibration and oil debris measurement technologies improves the detection of pitting damage on spiral bevel gears duplex ball bearings and spiral bevel pinion triplex ball bearings in a main rotor transmission.

Design, testing, and damage tolerance study of bonded stiffened composite wing cover panels

NASA Technical Reports Server (NTRS)

Madan, Ram C.; Sutton, Jason O.

1988-01-01

Results are presented from the application of damage tolerance criteria for composite panels to multistringer composite wing cover panels developed under NASA's Composite Transport Wing Technology Development contract. This conceptual wing design integrated aeroelastic stiffness constraints with an enhanced damage tolerance material system, in order to yield optimized producibility and structural performance. Damage tolerance was demonstrated in a test program using full-sized cover panel subcomponents; panel skins were impacted at midbay between stiffeners, directly over a stiffener, and over the stiffener flange edge. None of the impacts produced visible damage. NASTRAN analyses were performed to simulate NDI-detected invisible damage.

LSP Composite Susbtrate Destructive Evaluation Test Assessment Manual

NASA Technical Reports Server (NTRS)

Kovach, Daniel J.; Erickson, Grant J.

2013-01-01

This document specifies the processes to perform post-strike destructive damage evaluation of tested CFRP panels.It is recognized that many factors besides lightning damage protection are involved in the selection of an appropriate Lightning Strike Protection (LSP) for a particular system (e.g., cost, weight, corrosion resistance, shielding effectiveness, etc.). This document strives primarily to address the standardized generation of damage protection performance data.

The Effects of Foam Thermal Protection System on the Damage Tolerance Characteristics of Composite Sandwich Structures for Launch Vehicles

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Hodge, A. J.; Jackson, J. R.

2011-01-01

For any structure composed of laminated composite materials, impact damage is one of the greatest risks and therefore most widely tested responses. Typically, impact damage testing and analysis assumes that a solid object comes into contact with the bare surface of the laminate (the outer ply). However, most launch vehicle structures will have a thermal protection system (TPS) covering the structure for the majority of its life. Thus, the impact response of the material with the TPS covering is the impact scenario of interest. In this study, laminates representative of the composite interstage structure for the Ares I launch vehicle were impact tested with and without the planned TPS covering, which consists of polyurethane foam. Response variables examined include maximum load of impact, damage size as detected by nondestructive evaluation techniques, and damage morphology and compression after impact strength. Results show that there is little difference between TPS covered and bare specimens, except the residual strength data is higher for TPS covered specimens.

Stress Distribution and Damage Mode of Ceramic-Dentin Bilayer Systems

NASA Astrophysics Data System (ADS)

Kurtoglu, Cem; Demiroz, S. Suna; Mehmetov, Emirullah; Uysal, Hakan

The aim of this study was to evaluate the damage modes of ceramic systems bonded to dentin under Hertzian indentation. Single-cycle Hertzian contact test over 150-850 N load range was applied randomly to 210 ceramic-dentin bilayer disc specimens of zirconia or IPS Empress II -1 mm, -1.5 mm and of feldspathic porcelain -1 mm, -1.5 mm, -2 mm. Optical microscopy was employed for the identification of quasiplastic mode and radial cracks. Finite element analysis was used to analyze the stress distribution. Our results showed that the degree of damage in both modes evolved progressively and the origin changed with contact load. Stress location and value were consistent with the mechanical test results. It was concluded that microstructure and thickness of the material have a significant effect on the damage modes of ceramic layer systems.

Survivability characteristics of composite compression structure

NASA Technical Reports Server (NTRS)

Avery, John G.; Allen, M. R.; Sawdy, D.; Avery, S.

1990-01-01

Test and evaluation was performed to determine the compression residual capability of graphite reinforced composite panels following perforation by high-velocity fragments representative of combat threats. Assessments were made of the size of the ballistic damage, the effect of applied compression load at impact, damage growth during cyclic loading and residual static strength. Several fiber/matrix systems were investigated including high-strain fibers, tough epoxies, and APC-2 thermoplastic. Additionally, several laminate configurations were evaluated including hard and soft laminates and the incorporation of buffer strips and stitching for improved damage resistance of tolerance. Both panels (12 x 20-inches) and full scale box-beam components were tested to assure scalability of results. The evaluation generally showed small differences in the responses of the material systems tested. The soft laminate configurations with concentrated reinforcement exhibited the highest residual strength. Ballistic damage did not grow or increase in severity as a result of cyclic loading, and the effects of applied load at impact were not significant under the conditions tested.

Effect of resin on impact damage tolerance of graphite/epoxy laminates

NASA Technical Reports Server (NTRS)

Williams, J. G.; Rhodes, M. D.

1982-01-01

Twenty-four different epoxy resin systems were evaluated by a variety of test techniques to identify materials that exhibited improved impact damage tolerance in graphite/epoxy composite laminates. Forty-eight-ply composite panels of five of the material systems were able to sustain 100 m/s impact by a 1.27-cm-diameter aluminum projectile while statically loaded to strains of 0.005. Of the five materials with the highest tolerance to impact, two had elastomeric additives, two had thermoplastic additives, and one had a vinyl modifier; all the five systems used bisphenol A as the base resin. An evaluation of test results shows that the laminate damage tolerance is largely determined by the resin tensile properties, and that improvements in laminate damage tolerance are not necessarily made at the expense of room-temperature mechanical properties. The results also suggest that a resin volume fraction of 40 percent or greater may be required to permit the plastic flow between fibers necessary for improved damage tolerance.

Damage detection of structures identified with deterministic-stochastic models using seismic data.

PubMed

Huang, Ming-Chih; Wang, Yen-Po; Chang, Ming-Lian

2014-01-01

A deterministic-stochastic subspace identification method is adopted and experimentally verified in this study to identify the equivalent single-input-multiple-output system parameters of the discrete-time state equation. The method of damage locating vector (DLV) is then considered for damage detection. A series of shaking table tests using a five-storey steel frame has been conducted. Both single and multiple damage conditions at various locations have been considered. In the system identification analysis, either full or partial observation conditions have been taken into account. It has been shown that the damaged stories can be identified from global responses of the structure to earthquakes if sufficiently observed. In addition to detecting damage(s) with respect to the intact structure, identification of new or extended damages of the as-damaged counterpart has also been studied. This study gives further insights into the scheme in terms of effectiveness, robustness, and limitation for damage localization of frame systems.

An Experimental Investigation of Damaged Arresting Gear Tapes for the Langley Aircraft Landing Dynamics Facility

NASA Technical Reports Server (NTRS)

Mason, Angela J.

1999-01-01

An experimental investigation was performed on damaged arresting gear tapes at the Langley Aircraft Landing Dynamics Facility. The arrestment system uses five pairs of tapes to bring the test carriage to a halt. The procedure used to determine when to replace the tapes consists of a close evaluation of each of the 10 tapes after each run. During this evaluation, each tape is examined thoroughly and any damage observed on the tape is recorded. If the damaged tape does not pass the inspection, the tape is replaced with a new one. For the past 13 years, the most commonly seen damage types are edge fray damage and transverse damage. Tests were conducted to determine the maximum tensile strength of a damaged arresting gear tape specimen. The data indicate that tapes exhibiting transverse damage can withstand higher loads than tapes with edge fray damage.

Mitochondrial DNA damage is associated with damage accrual and disease duration in patients with Systemic Lupus Erythematosus

PubMed Central

López-López, Linnette; Nieves-Plaza, Mariely; Castro, María del R.; Font, Yvonne M.; Torres-Ramos, Carlos; Vilá, Luis M.; Ayala-Peña, Sylvette

2014-01-01

Objective To determine the extent of mitochondrial DNA (mtDNA) damage in systemic lupus erythematosus (SLE) patients compared to healthy subjects and to determine the factors associated with mtDNA damage among SLE patients. Methods A cross-sectional study was performed in 86 SLE patients (per American College of Rheumatology classification criteria) and 86 healthy individuals matched for age and gender. Peripheral blood mononuclear cells (PBMCs) were collected from subjects to assess the relative amounts of mtDNA damage. Quantitative polymerase chain reaction assay was used to measure the frequency of mtDNA lesions and mtDNA abundance. Socioeconomic-demographic features, clinical manifestations, pharmacologic treatment, disease activity, and damage accrual were determined. Statistical analyses were performed using t test, pairwise correlation, and Pearson’s chi-square test (or Fisher’s exact test) as appropriate. Results Among SLE patients, 93.0% were women. The mean (SD) age was 38.0 (10.4) years and the mean (SD) disease duration was 8.7 (7.5) years. SLE patients exhibited increased levels of mtDNA damage as shown by higher levels of mtDNA lesions and decreased mtDNA abundance as compared to healthy individuals. There was a negative correlation between disease damage and mtDNA abundance and a positive correlation between mtDNA lesions and disease duration. No association was found between disease activity and mtDNA damage. Conclusion PBMCs from SLE patients exhibited more mtDNA damage compared to healthy subjects. Higher levels of mtDNA damage were observed among SLE patients with major organ involvement and damage accrual. These results suggest that mtDNA damage have a potential role in the pathogenesis of SLE. PMID:24899636

Mitochondrial DNA damage is associated with damage accrual and disease duration in patients with systemic lupus erythematosus.

PubMed

López-López, L; Nieves-Plaza, M; Castro, M del R; Font, Y M; Torres-Ramos, C A; Vilá, L M; Ayala-Peña, S

2014-10-01

To determine the extent of mitochondrial DNA (mtDNA) damage in systemic lupus erythematosus (SLE) patients compared to healthy subjects and to determine the factors associated with mtDNA damage among SLE patients. A cross-sectional study was performed in 86 SLE patients (per American College of Rheumatology classification criteria) and 86 healthy individuals matched for age and gender. Peripheral blood mononuclear cells (PBMCs) were collected from subjects to assess the relative amounts of mtDNA damage. Quantitative polymerase chain reaction assay was used to measure the frequency of mtDNA lesions and mtDNA abundance. Socioeconomic-demographic features, clinical manifestations, pharmacologic treatment, disease activity, and damage accrual were determined. Statistical analyses were performed using t test, pairwise correlation, and Pearson's chi-square test (or Fisher's exact test) as appropriate. Among SLE patients, 93.0% were women. The mean (SD) age was 38.0 (10.4) years and the mean (SD) disease duration was 8.7 (7.5) years. SLE patients exhibited increased levels of mtDNA damage as shown by higher levels of mtDNA lesions and decreased mtDNA abundance as compared to healthy individuals. There was a negative correlation between disease damage and mtDNA abundance and a positive correlation between mtDNA lesions and disease duration. No association was found between disease activity and mtDNA damage. PBMCs from SLE patients exhibited more mtDNA damage compared to healthy subjects. Higher levels of mtDNA damage were observed among SLE patients with major organ involvement and damage accrual. These results suggest that mtDNA damage have a potential role in the pathogenesis of SLE. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

TPS In-Flight Health Monitoring Project Progress Report

NASA Technical Reports Server (NTRS)

Kostyk, Chris; Richards, Lance; Hudston, Larry; Prosser, William

2007-01-01

Progress in the development of new thermal protection systems (TPS) is reported. New approaches use embedded lightweight, sensitive, fiber optic strain and temperature sensors within the TPS. Goals of the program are to develop and demonstrate a prototype TPS health monitoring system, develop a thermal-based damage detection algorithm, characterize limits of sensor/system performance, and develop ea methodology transferable to new designs of TPS health monitoring systems. Tasks completed during the project helped establish confidence in understanding of both test setup and the model and validated system/sensor performance in a simple TPS structure. Other progress included complete initial system testing, commencement of the algorithm development effort, generation of a damaged thermal response characteristics database, initial development of a test plan for integration testing of proven FBG sensors in simple TPS structure, and development of partnerships to apply the technology.

Damage suppression system using embedded SMA (shape memory alloy) foils in CFRP laminate structures

NASA Astrophysics Data System (ADS)

Ogisu, Toshimichi; Shimanuki, Masakazu; Kiyoshima, Satoshi; Takaki, Junji; Takeda, Nobuo

2003-08-01

This paper presents an overview of the demonstrator program with respect to the damage growth suppression effects using embedded SMA foils in CFRP laminates. The damage growth suppression effects were demonstrated for the technical verification in order to apply to aircraft structure. In our previous studies, the authors already confirmed the damage growth suppression effects of CFRP laminates with embedded pre-strained SMA foils through both coupon and structural element tests. It was founded that these effects were obtained by the suppression of the strain energy release rate based on the suppression of the crack opening displacement due to the recovery stress of SMA foils through the detail observation of the damage behavior. In this study, these results were verified using the demonstrator test article, which was 1/3-scaled model of commercial airliner fuselage structure. For the demonstration of damage growth suppression effects, the evaluation area was located in the lower panel, which was dominated in tension load during demonstration. The evaluation area is the integrated stiffened panel including both "smart area" (CFRP laminate with embedded pre-strained SMA foils) and "conventional area" (standard CFRP laminate) for the direct comparison. The demonstration was conducted at 80 degree Celsius in smart area and room temperature (RT) in conventional area during quasi-static load-unload test method. As the test results, the demonstrator test article presented that the damage onset strain in the smart area was improved by 30% for compared with the conventional area. Therefore, the successful technical verification of the damage onset/growth suppression effect using the demonstrator presented the feasibility of the application of smart material and structural system to aircraft structures.

A prototype tap test imaging system: Initial field test results

NASA Astrophysics Data System (ADS)

Peters, J. J.; Barnard, D. J.; Hudelson, N. A.; Simpson, T. S.; Hsu, D. K.

2000-05-01

This paper describes a simple, field-worthy tap test imaging system that gives quantitative information about the size, shape, and severity of defects and damages. The system consists of an accelerometer, electronic circuits for conditioning the signal and measuring the impact duration, a laptop PC and data acquisition and processing software. The images are generated manually by tapping on a grid printed on a plastic sheet laid over the part's surface. A mechanized scanner is currently under development. The prototype has produced images for a variety of aircraft composite and metal honeycomb structures containing flaws, damages, and repairs. Images of the local contact stiffness, deduced from the impact duration using a spring model, revealed quantitatively the stiffness reduction due to flaws and damages, as well as the stiffness enhancement due to substructures. The system has been field tested on commercial and military aircraft as well as rotor blades and engine decks on helicopters. Field test results will be shown and the operation of the system will be demonstrated.—This material is based upon work supported by the Federal Aviation Administration under Contract #DTFA03-98-D-00008, Delivery Order No. IA016 and performed at Iowa State University's Center for NDE as part of the Center for Aviation Systems Reliability program.

Adapter assembly prevents damage to tubing during high pressure tests

NASA Technical Reports Server (NTRS)

Stinett, L. L.

1965-01-01

Portable adapter assembly prevents damage to tubing and injury to personnel when pressurizing a system or during high pressure tests. The assembly is capable of withstanding high pressure. It is securely attached to the tubing stub end and may be removed without brazing, cutting or cleaning the tube.

CMO YAG laser damage test facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hue, J.; Dijon, J.; Lyan, P.

1996-12-31

The CMO YAG laser damage test facility, which is equipped with a 30Hz laser, is presented in this paper. The main points are described below: (1) The characteristics of the laser beam and the in situ damage detection technique (a scattered light measurement system) are perfectly suited to work up to the frequency of the laser. They are monitored in real time, and work at three wavelengths: 1064 nm, 532 nm, 355 nm. (2) With this same shutter, it is possible to automatically stop the laser on the pulse which induces the first damages. These automatic capabilities enable the samplesmore » to be tested quickly. (3) A Nomarski microscope supplied with a 16-bit CCD camera enables the test sites to be photographed before and after the laser interaction. Image processing enables the authors to extract the first damages. before and after the laser interaction. Image processing enables them to extract the first damages. (4) Six pulse widths are available (between 3ns and 13ns). Therefore, with all these characterization tools, many kinds of laser tests may be considered. These different features are illustrated by experimental results (1-on-1 test or R-on-1 test).« less

Autoregressive statistical pattern recognition algorithms for damage detection in civil structures

NASA Astrophysics Data System (ADS)

Yao, Ruigen; Pakzad, Shamim N.

2012-08-01

Statistical pattern recognition has recently emerged as a promising set of complementary methods to system identification for automatic structural damage assessment. Its essence is to use well-known concepts in statistics for boundary definition of different pattern classes, such as those for damaged and undamaged structures. In this paper, several statistical pattern recognition algorithms using autoregressive models, including statistical control charts and hypothesis testing, are reviewed as potentially competitive damage detection techniques. To enhance the performance of statistical methods, new feature extraction techniques using model spectra and residual autocorrelation, together with resampling-based threshold construction methods, are proposed. Subsequently, simulated acceleration data from a multi degree-of-freedom system is generated to test and compare the efficiency of the existing and proposed algorithms. Data from laboratory experiments conducted on a truss and a large-scale bridge slab model are then used to further validate the damage detection methods and demonstrate the superior performance of proposed algorithms.

Determination of ultra-short laser induced damage threshold of KH{sub 2}PO{sub 4} crystal: Numerical calculation and experimental verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Jian; Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210; Chen, Mingjun, E-mail: chenmj@hit.edu.cn, E-mail: chowdhury.24@osu.edu

Rapid growth and ultra-precision machining of large-size KDP (KH{sub 2}PO{sub 4}) crystals with high laser damage resistance are tough challenges in the development of large laser systems. It is of high interest and practical significance to have theoretical models for scientists and manufacturers to determine the laser-induced damage threshold (LIDT) of actually prepared KDP optics. Here, we numerically and experimentally investigate the laser-induced damage on KDP crystals in ultra-short pulse laser regime. On basis of the rate equation for free electron generation, a model dedicated to predicting the LIDT is developed by considering the synergistic effect of photoionization, impact ionizationmore » and decay of electrons. Laser damage tests are performed to measure the single-pulse LIDT with several testing protocols. The testing results combined with previously reported experimental data agree well with those calculated by the model. By taking the light intensification into consideration, the model is successfully applied to quantitatively evaluate the effect of surface flaws inevitably introduced in the preparation processes on the laser damage resistance of KDP crystals. This work can not only contribute to further understanding of the laser damage mechanisms of optical materials, but also provide available models for evaluating the laser damage resistance of exquisitely prepared optical components used in high power laser systems.« less

Laser Paint Stripping

DTIC Science & Technology

1991-06-01

of this laser system to remove paint from metals, including aluminum, and from carbon fiber reinforced composites cleanly and without damage to the...The tests perpendicular to fiber direction in the unidirectional composite were selected as most sensitive indicators of damage. Flexural tests on the... Composite Flexural Strength Tests 10 2.2.11 Composite Compressive Strength Tests 11 2.2.12 Turbine Blade Cleaning 11 2.2.13 Residual Carbon 11 2.2.14

Characterization and damage evaluation of advanced materials

NASA Astrophysics Data System (ADS)

Mitrovic, Milan

Mechanical characterization of advanced materials, namely magnetostrictive and graphite/epoxy composite materials, is studied in this dissertation, with an emphasis on damage evaluation of composite materials. Consequently, the work in this dissertation is divided into two parts, with the first part focusing on characterization of the magneto-elastic response of magnetostrictlve materials, while the second part of this dissertation describes methods for evaluating the fatigue damage in composite materials. The objective of the first part of this dissertation is to evaluate a nonlinear constitutive relation which more closely depict the magneto-elastic response of magnetostrictive materials. Correlation between experimental and theoretical values indicate that the model adequately predicts the nonlinear strain/field relations in specific regimes, and that the currently employed linear approaches are inappropriate for modeling the response of this material in a structure. The objective of the second part of this dissertation is to unravel the complexities associated with damage events associated with polymeric composite materials. The intent is to characterize and understand the influence of impact and fatigue induced damage on the residual thermo-mechanical properties and compressive strength of composite systems. The influence of fatigue generated matrix cracking and micro-delaminations on thermal expansion coefficient (TEC) and compressive strength is investigated for woven graphite/epoxy composite system. Experimental results indicate that a strong correlation exists between TEC and compressive strength measurements, indicating that TEC measurements can be used as a damage metric for this material systems. The influence of delaminations on the natural frequencies and mode shapes of a composite laminate is also investigated. Based on the changes of these parameters as a function of damage, a methodology for determining the size and location of damage is suggested. Finally, the influence of loading parameters on impact damage growth is investigated experimentally though constant amplitude and spectrum loading fatigue tests. Based on observed impact damage growth during these tests it is suggested that the low load levels can be deleted from the standardized test sequence without significant influence on impact damage propagation.

Extracting the distribution of laser damage precursors on fused silica surfaces for 351 nm, 3 ns laser pulses at high fluences (20-150 J/cm2).

PubMed

Laurence, Ted A; Bude, Jeff D; Ly, Sonny; Shen, Nan; Feit, Michael D

2012-05-07

Surface laser damage limits the lifetime of optics for systems guiding high fluence pulses, particularly damage in silica optics used for inertial confinement fusion-class lasers (nanosecond-scale high energy pulses at 355 nm/3.5 eV). The density of damage precursors at low fluence has been measured using large beams (1-3 cm); higher fluences cannot be measured easily since the high density of resulting damage initiation sites results in clustering. We developed automated experiments and analysis that allow us to damage test thousands of sites with small beams (10-30 µm), and automatically image the test sites to determine if laser damage occurred. We developed an analysis method that provides a rigorous connection between these small beam damage test results of damage probability versus laser pulse energy and the large beam damage results of damage precursor densities versus fluence. We find that for uncoated and coated fused silica samples, the distribution of precursors nearly flattens at very high fluences, up to 150 J/cm2, providing important constraints on the physical distribution and nature of these precursors.

Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elhadj, S.; Steele, W. A.; VanBlarcom, D. S.

Here, we investigate an approach for the recycling of laser-damaged large-aperture deuterated potassium dihydrogen phosphate (DKDP) crystals used for optical switching (KDP) and for frequency conversion (DKDP) in megajoule-class high-power laser systems. The approach consists of micromachining the surface laser damage sites (mitigation), combined with multiple soaks and ultrasonication steps in a coating solvent to remove, synergistically, both the highly adherent machining debris and the laser-damage-affected antireflection coating. We then identify features of the laser-damage-affected coating, such as the “solvent-persistent” coating and the “burned-in” coating, that are difficult to remove by conventional approaches without damaging the surface. We also providemore » a solution to the erosion problem identified in this work when colloidal coatings are processed during ultrasonication. Finally, we provide a proof of principle of the approach by testing the full process that includes laser damage mitigation of DKDP test parts, coat stripping, reapplication of a new antireflective coat, and a laser damage test demonstrating performance up to at least 12 J/cm 2 at UV wavelengths, which is well above current requirements. Our approach ultimately provides a potential path to a scalable recycling loop for the management of optics in large, high-power laser systems that can reduce cost and extend lifetime of highly valuable and difficult to grow large DKDP crystals.« less

Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating

DOE PAGES

Elhadj, S.; Steele, W. A.; VanBlarcom, D. S.; ...

2017-03-07

Here, we investigate an approach for the recycling of laser-damaged large-aperture deuterated potassium dihydrogen phosphate (DKDP) crystals used for optical switching (KDP) and for frequency conversion (DKDP) in megajoule-class high-power laser systems. The approach consists of micromachining the surface laser damage sites (mitigation), combined with multiple soaks and ultrasonication steps in a coating solvent to remove, synergistically, both the highly adherent machining debris and the laser-damage-affected antireflection coating. We then identify features of the laser-damage-affected coating, such as the “solvent-persistent” coating and the “burned-in” coating, that are difficult to remove by conventional approaches without damaging the surface. We also providemore » a solution to the erosion problem identified in this work when colloidal coatings are processed during ultrasonication. Finally, we provide a proof of principle of the approach by testing the full process that includes laser damage mitigation of DKDP test parts, coat stripping, reapplication of a new antireflective coat, and a laser damage test demonstrating performance up to at least 12 J/cm 2 at UV wavelengths, which is well above current requirements. Our approach ultimately provides a potential path to a scalable recycling loop for the management of optics in large, high-power laser systems that can reduce cost and extend lifetime of highly valuable and difficult to grow large DKDP crystals.« less

U.S. National Committee proposed revision to the ISO Laser Damage Standard

NASA Astrophysics Data System (ADS)

Arenberg, Jonathan W.; Howland, Donna; Thomas, Michael; Turner, Trey; Bellum, John; Field, Ella; Carr, C. Wren; Shaffer, Gary; Brophy, Matthew; Krisiloff, Allen

2017-11-01

This paper reports on the fundamental idea behind a US National Committee, The Optics and Electro-Optics Standards Council (OEOSC) Task Force (TF) 7, proposal for a so-called Type 1 laser damage test procedure. A Type 1 test is designed to give a simple binary, pass or fail, result. Such tests are intended for the transactional type of damage testing typical of acceptance and quality control testing. As such is it intended for bulk of certification of optics for the ability to survive a given fluence, useful for manufacturers of optics and their customers, the system builders. At the root of the proposed method is the probability that an optic of area A will have R or less damage occurrences with a user specified probability P at test fluence Φ. This assessment is made by a survey of area and the observation of n events. The paper presents the derivation of probability of N or less damage sites on A given n events observed in area a. The paper concludes with the remaining steps to development of a useful test procedure based on the idea presented.

Cavitation damage prediction for spallation target vessels by assessment of acoustic vibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Futakawa, Masatoshi; Kogawa, Hiroyuki; Hasegawa, Shoichi

2008-01-01

Liquid-mercury target systems for MW-class spallation neutron sources are being developed around the world. Proton beams are used to induce the spallation reaction. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. In order to estimate the cavitation erosion, i.e. the pitting damage formed by the collapse of cavitation bubbles, off-beam tests were performed by using an electric magnetic impact testing machine (MIMTM), which can impose equivalentmore » pressure pulses in mercury. The damage potential was defined based on the relationship between the pitting damage and the time-integrated acoustic vibration induced by impact due to the bubble collapses. Additionally, the damage potential was measured in on-beam tests carried out by using the proton beam at WNR (Weapons Neutron Research) facility in Los Alamos Neutron Science Center (LANSCE). In this paper, the concept of the damage potential, the relationship between the pitting damage formation and the damage potential both in off-beam and on-beam tests is shown.« less

Boulder damage symposium annual thin film laser damage competition

DOE PAGES

Stolz, Christopher J.

2012-11-28

Optical instruments and laser systems are often fluence-limited by multilayer thin films deposited on the optical surfaces. When comparing publications within the laser damage literature, there can be confusing and conflicting laser damage results. This is due to differences in testing protocols between research groups studying very different applications. In this series of competitions, samples from multiple vendors are compared under identical testing parameters and a single testing service. Unlike a typical study where a hypothesis is tested within a well-controlled experiment with isolated variables, this competition isolates the laser damage testing variables so that trends can be observed betweenmore » different deposition processes, coating materials, cleaning techniques, and multiple coating suppliers. The resulting series of damage competitions has also been designed to observe general trends of damage morphologies and mechanisms over a wide range of coating types (high reflector and antireflector), wavelengths (193 to 1064 nm), and pulse lengths (180 fs to 13 ns). A double blind test assured sample and submitter anonymity were used in each of the competitions so only a summary of the deposition process, coating materials, layer count and spectral results are presented. Laser resistance was strongly affected by substrate cleaning, coating deposition method, and coating material selection whereas layer count and spectral properties had minimal impact.« less

Initial stages of cavitation damage and erosion on copper and brass tested in a rotating disk device

NASA Technical Reports Server (NTRS)

Rao, P. V.; Rao, B. C. S.; Rao, N. S. L.

1982-01-01

In view of the differences in flow and experimental conditions, there has been a continuing debate as to whether or not the ultrasonic method of producing cavitation damage is similar to the damage occurring in cavitating flow systems, namely, venturi and rotating disk devices. In this paper, the progress of cavitation damage during incubation periods on polycrystalline copper and brass tested in a rotating disk device is presented. The results indicate several similarities and differences in the damage mechanism encountered in a rotating disk device (which simulates field rotary devices) and a magnetostriction apparatus. The macroscopic erosion appears similar to that in the vibratory device except for nonuniform erosion and apparent plastic flow during the initial damage phase.

Experimental Modal Analysis and Dynaic Strain Fiber Bragg Gratings for Structural Health Monitoring of Composite Aerospace Structures

NASA Astrophysics Data System (ADS)

Panopoulou, A.; Fransen, S.; Gomez Molinero, V.; Kostopoulos, V.

2012-07-01

The objective of this work is to develop a new structural health monitoring system for composite aerospace structures based on dynamic response strain measurements and experimental modal analysis techniques. Fibre Bragg Grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The structural dynamic behaviour has been numerically simulated and experimentally verified by means of vibration testing. The hypothesis of all vibration tests was that actual damage in composites reduces their stiffness and produces the same result as mass increase produces. Thus, damage was simulated by slightly varying locally the mass of the structure at different zones. Experimental modal analysis based on the strain responses was conducted and the extracted strain mode shapes were the input for the damage detection expert system. A feed-forward back propagation neural network was the core of the damage detection system. The features-input to the neural network consisted of the strain mode shapes, extracted from the experimental modal analysis. Dedicated training and validation activities were carried out based on the experimental results. The system showed high reliability, confirmed by the ability of the neural network to recognize the size and the position of damage on the structure. The experiments were performed on a real structure i.e. a lightweight antenna sub- reflector, manufactured and tested at EADS CASA ESPACIO. An integrated FBG sensor network, based on the advantage of multiplexing, was mounted on the structure with optimum topology. Numerical simulation of both structures was used as a support tool at all the steps of the work. Potential applications for the proposed system are during ground qualification extensive tests of space structures and during the mission as modal analysis tool on board, being able via the FBG responses to identify a potential failure.

Low Velocity Impact Damage to Carbon/Epoxy Laminates

NASA Technical Reports Server (NTRS)

Nettles, Alan T.

2011-01-01

Impact damage tends to be more detrimental to a laminate's compression strength as compared to tensile strength. Proper use of Non Destructive Evaluation (NDE) Techniques can remove conservatism (weight) from many structures. Test largest components economically feasible as coupons. If damage tolerance is a driver, then consider different resin systems. Do not use a single knockdown factor to account for damage.

Is Your Child at Risk for Lead Poisoning?

ERIC Educational Resources Information Center

Berg, Nancy

1992-01-01

Lead poisoning is the number one environmental threat to children. At low levels it harms development, damages blood cells, and lowers IQ. At higher levels, it damages the nervous system, kidneys, reproductive system, and mental development. The article examines risk factors and discusses contamination, testing for lead, and prevention. (SM)

Damage Detection Sensor System for Aerospace and Multiple Applications

NASA Technical Reports Server (NTRS)

Williams, Martha; Lewis, Mark; Gibson, Tracy L.; Lane, John; Medelius, Pedro

2017-01-01

NASA has identified structural health monitoring and damage detection and verification as critical needs in multiple technology roadmaps. The sensor systems can be customized for detecting location, damage size, and depth, with velocity options and can be designed for particular environments for monitoring of impact or physical damage to a structure. The damage detection system has been successfully demonstrated in a harsh environment and remote integration tested over 1000 miles apart. Multiple applications includes: Spacecraft and Aircraft; Inflatable, Deployable and Expandable Structures; Space Debris Monitoring; Space Habitats; Military Shelters; Solar Arrays, Smart Garments and Wearables, Extravehicular activity (EVA) suits; Critical Hardware Enclosures; Embedded Composite Structures; and Flexible Hybrid Printed Electronics and Systems. For better implementation and infusion into more flexible architectures, important and improved designs in advancing embedded software and GUI interface, and increasing flexibility, modularity, and configurable capabilities of the system are currently being carried out.

Changes in motor function, cognition, and emotion-related behavior after right hemispheric intracerebral hemorrhage in various brain regions of mouse.

PubMed

Zhu, Wei; Gao, Yufeng; Wan, Jieru; Lan, Xi; Han, Xiaoning; Zhu, Shanshan; Zang, Weidong; Chen, Xuemei; Ziai, Wendy; Hanley, Daniel F; Russo, Scott J; Jorge, Ricardo E; Wang, Jian

2018-03-01

Intracerebral hemorrhage (ICH) is a detrimental type of stroke. Mouse models of ICH, induced by collagenase or blood infusion, commonly target striatum, but not other brain sites such as ventricular system, cortex, and hippocampus. Few studies have systemically investigated brain damage and neurobehavioral deficits that develop in animal models of ICH in these areas of the right hemisphere. Therefore, we evaluated the brain damage and neurobehavioral dysfunction associated with right hemispheric ICH in ventricle, cortex, hippocampus, and striatum. The ICH model was induced by autologous whole blood or collagenase VII-S (0.075 units in 0.5 µl saline) injection. At different time points after ICH induction, mice were assessed for brain tissue damage and neurobehavioral deficits. Sham control mice were used for comparison. We found that ICH location influenced features of brain damage, microglia/macrophage activation, and behavioral deficits. Furthermore, the 24-point neurologic deficit scoring system was most sensitive for evaluating locomotor abnormalities in all four models, especially on days 1, 3, and 7 post-ICH. The wire-hanging test was useful for evaluating locomotor abnormalities in models of striatal, intraventricular, and cortical ICH. The cylinder test identified locomotor abnormalities only in the striatal ICH model. The novel object recognition test was effective for evaluating recognition memory dysfunction in all models except for striatal ICH. The tail suspension test, forced swim test, and sucrose preference test were effective for evaluating emotional abnormality in all four models but did not correlate with severity of brain damage. These results will help to inform future preclinical studies of ICH outcomes. Copyright © 2018 Elsevier Inc. All rights reserved.

The Evaluation of Damage Effects on MgO Added Concrete with Slag Cement Exposed to Calcium Chloride Deicing Salt.

PubMed

Jang, Jae-Kyeong; Kim, Hong-Gi; Kim, Jun-Hyeong; Ryou, Jae-Suk

2018-05-14

Concrete systems exposed to deicers are damaged in physical and chemical ways. In mitigating the damage from CaCl₂ deicers, the usage of ground slag cement and MgO are investigated. Ordinary Portland cement (OPC) and slag cement are used in different proportions as the binding material, and MgO in doses of 0%, 5%, 7%, and 10% are added to the systems. After 28 days of water-curing, the specimens are immersed in 30% CaCl₂ solution by mass for 180 days. Compressive strength test, carbonation test, chloride penetration test, chloride content test, XRD analysis, and SEM-EDAX analysis are conducted to evaluate the damage effects of the deicing solution. Up to 28 days, plain specimens with increasing MgO show a decrease in compressive strength, an increase in carbonation resistance, and a decrease in chloride penetration resistance, whereas the S30- and S50- specimens show a slight increase in compressive strength, an increase in carbonation resistance, and a slight increase in chloride penetration resistance. After 180 days of immersion in deicing solution, specimens with MgO retain their compressive strength longer and show improved durability. Furthermore, the addition of MgO to concrete systems with slag cement induces the formation of magnesium silicate hydrate (M-S-H) phases.

Advanced information processing system - Status report. [for fault tolerant and damage tolerant data processing for aerospace vehicles

NASA Technical Reports Server (NTRS)

Brock, L. D.; Lala, J.

1986-01-01

The Advanced Information Processing System (AIPS) is designed to provide a fault tolerant and damage tolerant data processing architecture for a broad range of aerospace vehicles. The AIPS architecture also has attributes to enhance system effectiveness such as graceful degradation, growth and change tolerance, integrability, etc. Two key building blocks being developed by the AIPS program are a fault and damage tolerant processor and communication network. A proof-of-concept system is now being built and will be tested to demonstrate the validity and performance of the AIPS concepts.

Hierarchical structural health monitoring system combining a fiber optic spinal cord network and distributed nerve cell devices

NASA Astrophysics Data System (ADS)

Minakuchi, Shu; Tsukamoto, Haruka; Takeda, Nobuo

2009-03-01

This study proposes novel hierarchical sensing concept for detecting damages in composite structures. In the hierarchical system, numerous three-dimensionally structured sensor devices are distributed throughout the whole structural area and connected with the optical fiber network through transducing mechanisms. The distributed "sensory nerve cell" devices detect the damage, and the fiber optic "spinal cord" network gathers damage signals and transmits the information to a measuring instrument. This study began by discussing the basic concept of the hierarchical sensing system thorough comparison with existing fiber optic based systems and nerve systems in the animal kingdom. Then, in order to validate the proposed sensing concept, impact damage detection system for the composite structure was proposed. The sensor devices were developed based on Comparative Vacuum Monitoring (CVM) system and the Brillouin based distributed strain sensing was utilized to gather the damage signals from the distributed devices. Finally a verification test was conducted using prototype devices. Occurrence of barely visible impact damage was successfully detected and it was clearly indicated that the hierarchical system has better repairability, higher robustness, and wider monitorable area compared to existing systems utilizing embedded optical fiber sensors.

Next generation control system for reflexive aerostructures

NASA Astrophysics Data System (ADS)

Maddux, Michael R.; Meents, Elizabeth P.; Barnell, Thomas J.; Cable, Kristin M.; Hemmelgarn, Christopher; Margraf, Thomas W.; Havens, Ernie

2010-04-01

Cornerstone Research Group Inc. (CRG) has developed and demonstrated a composite structural solution called reflexive composites for aerospace applications featuring CRG's healable shape memory polymer (SMP) matrix. In reflexive composites, an integrated structural health monitoring (SHM) system autonomously monitors the structural health of composite aerospace structures, while integrated intelligent controls monitor data from the SHM system to characterize damage and initiate healing when damage is detected. Development of next generation intelligent controls for reflexive composites were initiated for the purpose of integrating prognostic health monitoring capabilities into the reflexive composite structural solution. Initial efforts involved data generation through physical inspections and mechanical testing. Compression after impact (CAI) testing was conducted on composite-reinforced shape memory polymer samples to induce damage and investigate the effectiveness of matrix healing on mechanical performance. Non-destructive evaluation (NDE) techniques were employed to observe and characterize material damage. Restoration of mechanical performance was demonstrated through healing, while NDE data showed location and size of damage and verified mitigation of damage post-healing. Data generated was used in the development of next generation reflexive controls software. Data output from the intelligent controls could serve as input to Integrated Vehicle Health Management (IVHM) systems and Integrated Resilient Aircraft Controls (IRAC). Reflexive composite technology has the ability to reduce maintenance required on composite structures through healing, offering potential to significantly extend service life of aerospace vehicles and reduce operating and lifecycle costs.

UV Radiation Damage and Bacterial DNA Repair Systems

ERIC Educational Resources Information Center

Zion, Michal; Guy, Daniel; Yarom, Ruth; Slesak, Michaela

2006-01-01

This paper reports on a simple hands-on laboratory procedure for high school students in studying both radiation damage and DNA repair systems in bacteria. The sensitivity to ultra-violet (UV) radiation of both "Escherichia coli" and "Serratia marcescens" is tested by radiating them for varying time periods. Two growth temperatures are used in…

Real-time sensing of fatigue crack damage for information-based decision and control

NASA Astrophysics Data System (ADS)

Keller, Eric Evans

Information-based decision and control for structures that are subject to failure by fatigue cracking is based on the following notion: Maintenance, usage scheduling, and control parameter tuning can be optimized through real time knowledge of the current state of fatigue crack damage. Additionally, if the material properties of a mechanical structure can be identified within a smaller range, then the remaining life prediction of that structure will be substantially more accurate. Information-based decision systems can rely one physical models, estimation of material properties, exact knowledge of usage history, and sensor data to synthesize an accurate snapshot of the current state of damage and the likely remaining life of a structure under given assumed loading. The work outlined in this thesis is structured to enhance the development of information-based decision and control systems. This is achieved by constructing a test facility for laboratory experiments on real-time damage sensing. This test facility makes use of a methodology that has been formulated for fatigue crack model parameter estimation and significantly improves the quality of predictions of remaining life. Specifically, the thesis focuses on development of an on-line fatigue crack damage sensing and life prediction system that is built upon the disciplines of Systems Sciences and Mechanics of Materials. A major part of the research effort has been expended to design and fabricate a test apparatus which allows: (i) measurement and recording of statistical data for fatigue crack growth in metallic materials via different sensing techniques; and (ii) identification of stochastic model parameters for prediction of fatigue crack damage. To this end, this thesis describes the test apparatus and the associated instrumentation based on four different sensing techniques, namely, traveling optical microscopy, ultrasonic flaw detection, Alternating Current Potential Drop (ACPD), and fiber-optic extensometry-based compliance, for crack length measurements.

Recent Total Ionizing Dose and Displacement Damage Compendium of Candidate Electronics for NASA Space Systems

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; Boutte, Alvin J.; Campola, Michael J.; Carts, Martin A.; Casey, Megan C.; Chen, Dakai; LaBel, Kenneth A.; Ladbury, Raymond L.; Lauenstein, Jean-Marie; Marshall, Cheryl J.;

The Evaluation of Damage Effects on MgO Added Concrete with Slag Cement Exposed to Calcium Chloride Deicing Salt

PubMed Central

Jang, Jae-Kyeong; Kim, Hong-Gi; Kim, Jun-Hyeong

2018-01-01

Concrete systems exposed to deicers are damaged in physical and chemical ways. In mitigating the damage from CaCl2 deicers, the usage of ground slag cement and MgO are investigated. Ordinary Portland cement (OPC) and slag cement are used in different proportions as the binding material, and MgO in doses of 0%, 5%, 7%, and 10% are added to the systems. After 28 days of water-curing, the specimens are immersed in 30% CaCl2 solution by mass for 180 days. Compressive strength test, carbonation test, chloride penetration test, chloride content test, XRD analysis, and SEM-EDAX analysis are conducted to evaluate the damage effects of the deicing solution. Up to 28 days, plain specimens with increasing MgO show a decrease in compressive strength, an increase in carbonation resistance, and a decrease in chloride penetration resistance, whereas the S30- and S50- specimens show a slight increase in compressive strength, an increase in carbonation resistance, and a slight increase in chloride penetration resistance. After 180 days of immersion in deicing solution, specimens with MgO retain their compressive strength longer and show improved durability. Furthermore, the addition of MgO to concrete systems with slag cement induces the formation of magnesium silicate hydrate (M-S-H) phases. PMID:29758008

Experimental Aerothermodynamics In Support Of The Columbia Accident Investigation

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.

2004-01-01

The technical foundation for the most probable damage scenario reported in the Columbia Accident Investigation Board's final report was largely derived from synergistic aerodynamic/aerothermodynamic wind tunnel measurements and inviscid predictions made at NASA Langley Research Center and later corroborated with engineering analysis, high fidelity numerical viscous simulations, and foam impact testing near the close of the investigation. This report provides an overview of the hypersonic aerothermodynamic wind tunnel program conducted at NASA Langley and illustrates how the ground-based heating measurements provided early insight that guided the direction and utilization of agency resources in support of the investigation. Global surface heat transfer mappings, surface streamline patterns, and shock shapes were measured on 0.0075 scale models of the Orbiter configuration with and without postulated damage to the thermal protection system. Test parametrics include angle of attack from 38 to 42 degs, sideslip angles of 38 to 42 degs, sideslip angles of plus or minus 1 deg, Reynolds numbers based upon model length from 0.05 x 10(exp 6) to 6.5 x 10(exp 6), and normal shock density ratios of 5 (Mach 6 Air) and 12 (Mach 6 CF4). The primary objective of the testing was to provide surface heating characteristics on scaled Orbiter models with outer mold line perturbations to simulate various forms of localized surface damage to the thermal protection system. Initial experimental testing conducted within two weeks of the accident simulated a broad spectrum of thermal protection system damage to the Orbiter windward surface and was used to refute several hypothesized forms of thermal protection system damage, which included gouges in the windward thermal protection system tiles, breaches through the wing new the main landing gear door, and protuberances along the wing leading edge that produced asymmetric boundary layer transition. As the forensic phase of the investigation developed and the condition of recovered debris was examined, increasing emphasis was placed on identifying wing leading edge damage (partially and fully missing reinforced carbon-carbon panels, and eventually holes in the wing leading edge with venting to the wing upper surface) that produced off-nominal heating trends consistent with extracted Orbiter flight recorder temperature data.

Orbital Debris Impact Damage to Reusable Launch Vehicles

NASA Technical Reports Server (NTRS)

Robinson, Jennifer H.

1998-01-01

In an effort by the National Aeronautics and Space Administration (NASA), hypervelocity impact tests were performed on thermal protection systems (TPS) applied on the external surfaces of reusable launch vehicles (RLV) to determine the potential damage from orbital debris impacts. Three TPS types were tested, bonded to composite structures representing RLV fuel tank walls. The three heat shield materials tested were Alumina-Enhanced Thermal Barrier-12 (AETB-12), Flexible Reusable Surface Insulation (FRSI), and Advanced Flexible Reusable Surface Insulation (AFRSI). Using this test data, predictor equations were developed for the entry hole diameters in the three TPS materials, with correlation coefficients ranging from 0.69 to 0.86. Possible methods are proposed for approximating damage occurring at expected orbital impact velocities higher than tested, with references to other published work.

Design and testing of integrated Bragg grating sensor systems for advanced grid structure

NASA Astrophysics Data System (ADS)

Amano, Masataro; Mizutani, Tadahito; Okabe, Yoji; Takeda, Nobuo; Ozaki, Tsuyoshi

2006-03-01

In this research, the authors target on the construction of structural health monitoring system of Advanced Grid Structure (AGS) made of Carbon fiber reinforced plastic (CFRP). AGS has often been applied to aerospace structures because of the following advantages: (1) Since ribs carry only axial forces, the weakness in the transverse direction of the CFRP unidirectional laminates is negligible. (2) AGS has damage tolerance because the fracture of a rib hardly affects other ribs, namely AGS is a fail-safe structure. In this research, in order to detect existence and regions of rib fractures in AGS, we embedded multiplexed fiber Bragg grating (FBG) sensors into AGS in rib longitudinal directions for measurement of strains. Monitoring of the change in rib longitudinal strains is the most effective SHM system for AGS. In order to confirm our proposal, we carried out following discussions. First, we analytically revealed that the change in rib longitudinal strains was the most sensitive signal for damage detection because of AGS's structural redundancy. Then, we introduced a statistical outlier analysis technique into the SHM system for damage recognition. Finally, we established AGS with the SHM system and verified experimentally. The result of the test showed that damage existence and regions in AGS could be detected with the proposed SHM system.

Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications

NASA Technical Reports Server (NTRS)

Szatkowski, George N.; Dudley, Kenneth L.; Smith, Laura J.; Wang, Chuantong; Ticatch, Larry A.

2014-01-01

Traditional methods to protect composite aircraft from lightning strike damage rely on a conductive layer embedded on or within the surface of the aircraft composite skin. This method is effective at preventing major direct effect damage and minimizes indirect effects to aircraft systems from lightning strike attachment, but provides no additional benefit for the added parasitic weight from the conductive layer. When a known lightning strike occurs, the points of attachment and detachment on the aircraft surface are visually inspected and checked for damage by maintenance personnel to ensure continued safe flight operations. A new multi-functional lightning strike protection (LSP) method has been developed to provide aircraft lightning strike protection, damage detection and diagnosis for composite aircraft surfaces. The method incorporates a SansEC sensor array on the aircraft exterior surfaces forming a "Smart skin" surface for aircraft lightning zones certified to withstand strikes up to 100 kiloamperes peak current. SansEC sensors are open-circuit devices comprised of conductive trace spiral patterns sans (without) electrical connections. The SansEC sensor is an electromagnetic resonator having specific resonant parameters (frequency, amplitude, bandwidth & phase) which when electromagnetically coupled with a composite substrate will indicate the electrical impedance of the composite through a change in its resonant response. Any measureable shift in the resonant characteristics can be an indication of damage to the composite caused by a lightning strike or from other means. The SansEC sensor method is intended to diagnose damage for both in-situ health monitoring or ground inspections. In this paper, the theoretical mathematical framework is established for the use of open circuit sensors to perform damage detection and diagnosis on carbon fiber composites. Both computational and experimental analyses were conducted to validate this new method and system for aircraft composite damage detection and diagnosis. Experimental test results on seeded fault damage coupons and computational modeling simulation results are presented. This paper also presents the shielding effectiveness along with the lightning direct effect test results from several different SansEC LSP and baseline protected and unprotected carbon fiber reinforced polymer (CFRP) test panels struck at 40 and 100 kiloamperes following a universal common practice test procedure to enable damage comparisons between SansEC LSP configurations and common practice copper mesh LSP approaches. The SansEC test panels were mounted in a LSP test bed during the lightning test. Electrical, mechanical and thermal parameters were measured during lightning attachment and are presented with post test nondestructive inspection comparisons. The paper provides correlational results between the SansEC sensors computed electric field distribution and the location of the lightning attachment on the sensor trace and visual observations showing the SansEC sensor's affinity for dispersing the lightning attachment.

Lamb wave propagation in Z-pin reinforced co-cured composite pi-joints

NASA Astrophysics Data System (ADS)

Swenson, Eric D.; Soni, Som R.; Kapoor, Hitesh

2010-04-01

This paper presents an initial study on Lamb wave propagation characteristics in z-pin reinforced, co-cured composite pi-joints for the purposes of structural health monitoring (SHM). Pi-joint test articles were designed and created to replicate a co-cured, all composite skin-spar joint found within a typical aircraft wing structure. Because pi-joints exhibit various complex damage modes, formal studies are required if SHM systems are to be developed to monitor these types of joints for potential damage. Experiments were conducted on a undamaged (healthy) and damaged test articles where Lamb waves were excited using one lead zirconate titanate (PZT) transducer. A three-dimensional (3D) scanning laser Doppler vibrometer (LDV) was used to collect high-density scans of both the in-plane and out-of-plane velocity measurements. In the damaged test article, where delamination, matrix cracking, and fiber breakage can clearly be seen, changes in both the fundamental antisymmetric A0 and symmetric S0 Lamb wave modes are apparent. In both test articles, the effects of narrow geometry, discontinuity due to the attachment of the web, and thickness has detectable effects on Lamb wave propagation. From the comparisons between Lamb waves propagating through the undamaged and damaged test articles, it is clear that damage can be detected using Lamb waves in z-pin reinforced, co-cured composite pi-joints for this case of extensive damage.

Enhanced Damage-Resistant Optics for Spaceflight Laser Systems: Workshop findings and recommendations

NASA Technical Reports Server (NTRS)

Schulze, Norman; Cimolino, Marc; Guenther, Arthur; Mcminn, Ted; Rainer, Frank; Schmid, Ansgar; Seitel, Steven C.; Soileau, M. J.; Theon, John S.; Walz, William

1991-01-01

NASA has defined a program to address critical laser-induced damage issues peculiar to its remote sensing systems. The Langley Research Center (LaRC), with input from the Goddard Space Flight Center (GSFC), has developed a program plan focusing on the certification of optical materials for spaceflight applications and the development of techniques to determine the reliability of such materials under extended laser exposures. This plan involves cooperative efforts between NASA and optics manufacturers to quantify the performance of optical materials for NASA systems and to ensure NASA's continued application of the highest quality optics possible for enhanced system reliability. A review panel was organized to assess NASA's optical damage concerns and to evaluate the effectiveness of the LaRC proposed program plan. This panel consisted of experts in the areas of laser-induced damage, optical coating manufacture, and the design and development of laser systems for space. The panel was presented information on NASA's current and planned laser remote sensing programs, laser-induced damage problems already encountered in NASA systems, and the proposed program plan to address these issues. Additionally, technical presentations were made on the state of the art in damage mechanisms, optical materials testing, and issues of coating manufacture germane to laser damage.

Live fire testing requirements - Assessing the impact

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Bryon, J.F.

1992-08-01

Full-up live-fire testing (LFT) of aircraft configured for combat is evaluated in terms of the practical implications of the technique. LFT legislation requires the testing of tactical fighters, helicopters, and other aircraft when they are loaded with the flammables and explosives associated with combat. LFT permits the study of damage mechanisms and battle-damage repair techniques during the design phase, and probability-of-kill estimates and novel systems designs can be developed based on LFT data.

On impact damage detection and quantification for CFRP laminates using structural response data only

NASA Astrophysics Data System (ADS)

Sultan, M. T. H.; Worden, K.; Pierce, S. G.; Hickey, D.; Staszewski, W. J.; Dulieu-Barton, J. M.; Hodzic, A.

2011-11-01

The overall purpose of the research is to detect and attempt to quantify impact damage in structures made from composite materials. A study that uses simplified coupon specimens made from a Carbon Fibre-Reinforced Polymer (CFRP) prepreg with 11, 12 and 13 plies is presented. PZT sensors were placed at three separate locations in each test specimen to record the responses from impact events. To perform damaging impact tests, an instrumented drop-test machine was used and the impact energy was set to cover a range of 0.37-41.72 J. The response signals captured from each sensor were recorded by a data acquisition system for subsequent evaluation. The impacted specimens were examined with an X-ray technique to determine the extent of the damaged areas and it was found that the apparent damaged area grew monotonically with impact energy. A number of simple univariate and multivariate features were extracted from the sensor signals recorded during impact by computing their spectra and calculating frequency centroids. The concept of discordancy from the statistical discipline of outlier analysis is employed in order to separate the responses from non-damaging and damaging impacts. The results show that the potential damage indices introduced here provide a means of identifying damaging impacts from the response data alone.

Experimental Evaluation of Fatigue Damage Progression in Postbuckled Single Stringer Composite Specimens

NASA Technical Reports Server (NTRS)

Bisagni, Chiara; Davila, Carlos G.; Rose, Cheryl A.; Zalameda, Joseph N.

2014-01-01

The durability and damage tolerance of postbuckled composite structures are not yet completely understood, and remain difficult to predict due to the nonlinearity of the geometric response and its interaction with local damage modes. A research effort was conducted to investigate experimentally the quasi-static and fatigue damage progression in a single-stringer compression (SSC) specimen. Three specimens were manufactured with a hat-stiffener, and an initial defect was introduced with a Teflon film embedded between one flange of the stringer and the skin. One of the specimens was tested under quasi-static compressive loading, while the remaining two specimens were tested by cycling in postbuckling. The tests were performed at the NASA Langley Research Center under controlled conditions and with instrumentation that allows a precise evaluation of the postbuckling response and of the damage modes. Three-dimensional digital image correlation VIC-3D systems were used to provide full field displacements and strains on the skin and the stringer. Passive thermal monitoring was conducted during the fatigue tests using an infrared camera that showed the location of the delamination front while the specimen was being cycled. The live information from the thermography was used to stop the fatigue tests at critical stages of the damage evolution to allow detailed ultrasonic scans.

Flight Test Comparison of Different Adaptive Augmentations for Fault Tolerant Control Laws for a Modified F-15 Aircraft

NASA Technical Reports Server (NTRS)

Burken, John J.; Hanson, Curtis E.; Lee, James A.; Kaneshige, John T.

2009-01-01

This report describes the improvements and enhancements to a neural network based approach for directly adapting to aerodynamic changes resulting from damage or failures. This research is a follow-on effort to flight tests performed on the NASA F-15 aircraft as part of the Intelligent Flight Control System research effort. Previous flight test results demonstrated the potential for performance improvement under destabilizing damage conditions. Little or no improvement was provided under simulated control surface failures, however, and the adaptive system was prone to pilot-induced oscillations. An improved controller was designed to reduce the occurrence of pilot-induced oscillations and increase robustness to failures in general. This report presents an analysis of the neural networks used in the previous flight test, the improved adaptive controller, and the baseline case with no adaptation. Flight test results demonstrate significant improvement in performance by using the new adaptive controller compared with the previous adaptive system and the baseline system for control surface failures.

Evaluation of sonic IR for NDE at Lawrence Livermore National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, W O

2001-02-01

Sonic IR was evaluated as an NDE technique at LLNL using a commercial ThermoSoniX system from Indigo Systems Corp. The main effort was to detect small cracks in aluminum oxide, a dense stiff ceramic. Test coupons were made containing 0.2-mm cracks by surface grinding, 1-mm cracks by compression with a Vickers bit, and 4-mm cracks by 3-point bending. Only the 3-point bend cracks produced thermal images. Several parts shattered during testing, perhaps by being forced at resonance by the 20-kHz acoustic probe. Tests on damaged carbon composite coupons produced thermal images that were in excellent agreement with ultrasonic inspection. Themore » composite results also showed some dependence on contact location of the acoustic probe, and on the method of support. Tests on glass with surface damage produced weak images at the pits. Tests on metal ballistic targets produced thermal images at the impact sites. Modal analyses suggest that the input frequency should be matched to the desired response, and also that forced resonance damaged some parts.« less

Nonlinear imaging (NIM) of barely visible impact damage (BVID) in composite panels using a semi and full air-coupled linear and nonlinear ultrasound technique

NASA Astrophysics Data System (ADS)

Malfense Fierro, Gian Piero; Meo, Michele

2018-03-01

Two non-contact methods were evaluated to address the reliability and reproducibility concerns affecting industry adoption of nonlinear ultrasound techniques for non-destructive testing and evaluation (NDT/E) purposes. A semi and a fully air-coupled linear and nonlinear ultrasound method was evaluated by testing for barely visible impact damage (BVID) in composite materials. Air coupled systems provide various advantages over contact driven systems; such as: ease of inspection, no contact and lubrication issues and a great potential for non-uniform geometry evaluation. The semi air-coupled setup used a suction attached piezoelectric transducer to excite the sample and an array of low-cost microphones to capture the signal over the inspection area, while the second method focused on a purely air-coupled setup, using an air-coupled transducer to excite the structure and capture the signal. One of the issues facing nonlinear and any air-coupled systems is transferring enough energy to stimulate wave propagation and in the case of nonlinear ultrasound; damage regions. Results for both methods provided nonlinear imaging (NIM) of damage regions using a sweep excitation methodology, with the semi aircoupled system providing clearer results.

Flight Test of an Adaptive Controller and Simulated Failure/Damage on the NASA NF-15B

NASA Technical Reports Server (NTRS)

Buschbacher, Mark; Maliska, Heather

2006-01-01

The method of flight-testing the Intelligent Flight Control System (IFCS) Second Generation (Gen-2) project on the NASA NF-15B is herein described. The Gen-2 project objective includes flight-testing a dynamic inversion controller augmented by a direct adaptive neural network to demonstrate performance improvements in the presence of simulated failure/damage. The Gen-2 objectives as implemented on the NASA NF-15B created challenges for software design, structural loading limitations, and flight test operations. Simulated failure/damage is introduced by modifying control surface commands, therefore requiring structural loads measurements. Flight-testing began with the validation of a structural loads model. Flight-testing of the Gen-2 controller continued, using test maneuvers designed in a sequenced approach. Success would clear the new controller with respect to dynamic response, simulated failure/damage, and with adaptation on and off. A handling qualities evaluation was conducted on the capability of the Gen-2 controller to restore aircraft response in the presence of a simulated failure/damage. Control room monitoring of loads sensors, flight dynamics, and controller adaptation, in addition to postflight data comparison to the simulation, ensured a safe methodology of buildup testing. Flight-testing continued without major incident to accomplish the project objectives, successfully uncovering strengths and weaknesses of the Gen-2 control approach in flight.

Finite element implementation of a thermo-damage-viscoelastic constitutive model for hydroxyl-terminated polybutadiene composite propellant

NASA Astrophysics Data System (ADS)

Xu, Jinsheng; Han, Long; Zheng, Jian; Chen, Xiong; Zhou, Changsheng

2017-11-01

A thermo-damage-viscoelastic model for hydroxyl-terminated polybutadiene (HTPB) composite propellant with consideration for the effect of temperature was implemented in ABAQUS. The damage evolution law of the model has the same form as the crack growth equation for viscoelastic materials, and only a single damage variable S is considered. The HTPB propellant was considered as an isotropic material, and the deviatoric and volumetric strain-stress relations are decoupled and described by the bulk and shear relaxation moduli, respectively. The stress update equations were expressed by the principal stresses σ_{ii}R and the rotation tensor M, the Jacobian matrix in the global coordinate system J_{ijkl} was obtained according to the fourth-order tensor transformation rules. Two models having complex stress states were used to verify the accuracy of the constitutive model. The test results showed good agreement with the strain responses of characteristic points measured by a contactless optical deformation test system, which illustrates that the thermo-damage-viscoelastic model perform well at describing the mechanical properties of an HTPB propellant.

355-nm, nanosecond laser mirror thin film damage competition

NASA Astrophysics Data System (ADS)

Negres, Raluca A.; Stolz, Christopher J.; Thomas, Michael D.; Caputo, Mark

2017-11-01

This competition aimed to survey state-of-the-art UV high reflectors. The requirements of the coatings are a minimum reflection of 99.5% at 45 degrees incidence angle for P-polarized light at 355-nm. The choice of coating materials, design, and deposition method were left to the participants. Laser damage testing was performed at a single testing facility using the raster scan method with a 5-ns pulse length laser system operating at 10 Hz in a single longitudinal mode. A double blind test assured sample and submitter anonymity. In addition to the laser damage resistance results, details of the deposition processes, cleaning method, coating materials and layer count are also shared.

Innovations in dynamic test restraint systems

NASA Technical Reports Server (NTRS)

Fuld, Christopher J.

1990-01-01

Recent launch system development programs have led to a new generation of large scale dynamic tests. The variety of test scenarios share one common requirement: restrain and capture massive high velocity flight hardware with no structural damage. The Space Systems Lab of McDonnell Douglas developed a remarkably simple and cost effective approach to such testing using ripstitch energy absorbers adapted from the sport of technical rockclimbing. The proven system reliability of the capture system concept has led to a wide variety of applications in test system design and in aerospace hardware design.

Analytical and experimental vibration analysis of a faulty gear system

NASA Astrophysics Data System (ADS)

Choy, F. K.; Braun, M. J.; Polyshchuk, V.; Zakrajsek, J. J.; Townsend, D. P.; Handschuh, R. F.

1994-10-01

A comprehensive analytical procedure was developed for predicting faults in gear transmission systems under normal operating conditions. A gear tooth fault model is developed to simulate the effects of pitting and wear on the vibration signal under normal operating conditions. The model uses changes in the gear mesh stiffness to simulate the effects of gear tooth faults. The overall dynamics of the gear transmission system is evaluated by coupling the dynamics of each individual gear-rotor system through gear mesh forces generated between each gear-rotor system and the bearing forces generated between the rotor and the gearbox structures. The predicted results were compared with experimental results obtained from a spiral bevel gear fatigue test rig at NASA Lewis Research Center. The Wigner-Ville Distribution (WVD) was used to give a comprehensive comparison of the predicted and experimental results. The WVD method applied to the experimental results were also compared to other fault detection techniques to verify the WVD's ability to detect the pitting damage, and to determine its relative performance. Overall results show good correlation between the experimental vibration data of the damaged test gear and the predicted vibration from the model with simulated gear tooth pitting damage. Results also verified that the WVD method can successfully detect and locate gear tooth wear and pitting damage.

Analytical and experimental vibration analysis of a faulty gear system

NASA Astrophysics Data System (ADS)

Choy, F. K.; Braun, M. J.; Polyshchuk, V.; Zakrajsek, J. J.; Townsend, D. P.; Handschuh, R. F.

1994-10-01

A comprehensive analytical procedure was developed for predicting faults in gear transmission systems under normal operating conditions. A gear tooth fault model is developed to simulate the effects of pitting and wear on the vibration signal under normal operating conditions. The model uses changes in the gear mesh stiffness to simulate the effects of gear tooth faults. The overall dynamics of the gear transmission system is evaluated by coupling the dynamics of each individual gear-rotor system through gear mesh forces generated between each gear-rotor system and the bearing forces generated between the rotor and the gearbox structure. The predicted results were compared with experimental results obtained from a spiral bevel gear fatigue test rig at NASA Lewis Research Center. The Wigner-Ville distribution (WVD) was used to give a comprehensive comparison of the predicted and experimental results. The WVD method applied to the experimental results were also compared to other fault detection techniques to verify the WVD's ability to detect the pitting damage, and to determine its relative performance. Overall results show good correlation between the experimental vibration data of the damaged test gear and the predicted vibration from the model with simulated gear tooth pitting damage. Results also verified that the WVD method can successfully detect and locate gear tooth wear and pitting damage.

Analytical and Experimental Vibration Analysis of a Faulty Gear System

NASA Technical Reports Server (NTRS)

Choy, F. K.; Braun, M. J.; Polyshchuk, V.; Zakrajsek, J. J.; Townsend, D. P.; Handschuh, R. F.

1994-01-01

A comprehensive analytical procedure was developed for predicting faults in gear transmission systems under normal operating conditions. A gear tooth fault model is developed to simulate the effects of pitting and wear on the vibration signal under normal operating conditions. The model uses changes in the gear mesh stiffness to simulate the effects of gear tooth faults. The overall dynamics of the gear transmission system is evaluated by coupling the dynamics of each individual gear-rotor system through gear mesh forces generated between each gear-rotor system and the bearing forces generated between the rotor and the gearbox structure. The predicted results were compared with experimental results obtained from a spiral bevel gear fatigue test rig at NASA Lewis Research Center. The Wigner-Ville distribution (WVD) was used to give a comprehensive comparison of the predicted and experimental results. The WVD method applied to the experimental results were also compared to other fault detection techniques to verify the WVD's ability to detect the pitting damage, and to determine its relative performance. Overall results show good correlation between the experimental vibration data of the damaged test gear and the predicted vibration from the model with simulated gear tooth pitting damage. Results also verified that the WVD method can successfully detect and locate gear tooth wear and pitting damage.

CW laser damage testing of RAR nano-textured fused silica and YAG

NASA Astrophysics Data System (ADS)

MacLeod, Bruce D.; Hobbs, Douglas S.; Manni, Anthony D.; Sabatino, Ernest; Bernot, David M.; DeFrances, Sage; Randi, Joseph A.; Thomas, Jeffrey

2017-11-01

A study of the continuous wave (CW) laser induced damage threshold (LiDT) of fused silica and yttrium aluminum garnet (YAG) optics was conducted to further illustrate the enhanced survivability within high power laser systems of an anti-reflection (AR) treatment consisting of randomly distributed surface relief nanostructures (RAR). A series of three CW LiDT tests using the 1070nm wavelength, 16 KW fiber laser test bed at Penn State Electro-Optic Center (PSEOC) were designed and completed, with improvements in the testing protocol, areal coverage, and maximum exposure intensities implemented between test cycles. Initial results for accumulated power, stationary site exposures of RAR nano-textured optics showed no damage and low surface temperatures similar to the control optics with no AR treatment. In contrast, optics with thin-film AR coatings showed high surface temperatures consistent with absorption by the film layers. Surface discriminating absorption measurements made using the Photothermal Common-path Interferometry (PCI) method, showed zero added surface absorption for the RAR nanotextured optics, and absorption levels in the 2-5 part per million range for thin-film AR coated optics. In addition, the surface absorption of thin-film AR coatings was also found to have localized absorption spikes that are likely pre-cursors for damage. Subsequent CW LiDT testing protocol included raster scanning an increased intensity focused beam over the test optic surface where it was found that thin-film AR coated optics damaged at intensities in the 2 to 5 MW/cm2 range with surface temperatures over 250C during the long-duration exposures. Significantly, none of the 10 RAR nano-textured fused silica optics tested could be damaged up to the maximum system intensity of 15.5 MW/cm2, and surface temperatures remained low. YAG optics tested during the final cycle exhibited a similar result with RAR nano-textured surfaces surviving intensities over 3 times higher than thin-film AR coated surfaces. This result was correlated with PCI measurements that also show zero-added surface absorption for the RAR nano-textured YAG optics.

Detection of Ballast Damage by In-Situ Vibration Measurement of Sleepers

NASA Astrophysics Data System (ADS)

Lam, H. F.; Wong, M. T.; Keefe, R. M.

2010-05-01

Ballasted track is one of the most important elements of railway transportation systems worldwide. Owing to its importance in railway safety, many monitoring and evaluation methods have been developed. Current railway track monitoring systems are comprehensive, fast and efficient in testing railway track level and alignment, rail gauge, rail corrugation, etc. However, the monitoring of ballast condition still relies very much on visual inspection and core tests. Although extensive research has been carried out in the development of non-destructive methods for ballast condition evaluation, a commonly accepted and cost-effective method is still in demand. In Hong Kong practice, if abnormal train vibration is reported by the train operator or passengers, permanent way inspectors will locate the problem area by track geometry measurement. It must be pointed out that visual inspection can only identify ballast damage on the track surface, the track geometry deficiencies and rail twists can be detected using a track gauge. Ballast damage under the sleeper loading area and the ballast shoulder, which are the main factors affecting track stability and ride quality, are extremely difficult if not impossible to be detected by visual inspection. Core test is a destructive test, which is expensive, time consuming and may be disruptive to traffic. A fast real-time ballast damage detection method that can be implemented by permanent way inspectors with simple equipment can certainly provide valuable information for engineers in assessing the safety and riding quality of ballasted track systems. The main objective of this paper is to study the feasibility in using the vibration characteristics of sleepers in quantifying the ballast condition under the sleepers, and so as to explore the possibility in developing a handy method for the detection of ballast damage based on the measured vibration of sleepers.

Results of the AFRSI rewaterproofing systems screening test in the NASA/Ames Research Center (ARC) 2 x 2-foot transonic wind tunnel

NASA Technical Reports Server (NTRS)

Marroquin, J.; Kingsland, R. B.

1985-01-01

An experimental investigation was conducted in the NASA/Ames Research Center 2x2-foot Transonic Wind Tunnel to evaluate two AFRSI rewaterproofing systems and to investigate films as a means of reducing blanket joint distortion. The wind tunnel wall slot configuration influenced on the flow field over the test panel was investigated; primarily using oil flow data, and resulted in a closed slot configuration to provide a satisfactory screening environment flow field for the test. Sixteen AFRSI test panels, configured to represent the test system or film, were subjected to this screening environment (a flow field of separated and reattached flow at a freestream Mach numnber of 0.65 and q = 650 or 900 psf). Each condition was held until damage to the test article was observed or 55 minutes if no damage was incurred. All objectives related to AFRSI rewaterproofing and to the use of films to stiffen the blanket fibers were achieved.

Method of Fault Detection and Rerouting

NASA Technical Reports Server (NTRS)

Gibson, Tracy L. (Inventor); Medelius, Pedro J. (Inventor); Lewis, Mark E. (Inventor)

2013-01-01

A system and method for detecting damage in an electrical wire, including delivering at least one test electrical signal to an outer electrically conductive material in a continuous or non-continuous layer covering an electrically insulative material layer that covers an electrically conductive wire core. Detecting the test electrical signals in the outer conductive material layer to obtain data that is processed to identify damage in the outer electrically conductive material layer.

Quantitative nondestructive evaluation of materials and structures

NASA Technical Reports Server (NTRS)

Smith, Barry T.

1991-01-01

An experimental investigation was undertaken to quantify damage tolerance and resistance in composite materials impacted using the drop-weight method. Tests were conducted on laminates of several different carbon-fiber composite systems, such as epoxies, modified epoxies, and amorphous and semicrystalline thermoplastics. Impacted composite specimens were examined using destructive and non-destructive techniques to establish the characteristic damage states. Specifically, optical microscopy, ultrasonic, and scanning electron microscopy techniques were used to identify impact induced damage mechanisms. Damage propagation during post impact compression was also studied.

Final Report: Posttest Analysis of Omega II Optical Specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newlander, C D; Fisher, J H

Preliminary posttest analyses have been completed on optical specimens exposed during the Omega II test series conducted on 14 July 2006. The Omega Facility, located at the Laboratory for Laser Energetics (LLE) at the University of Rochester was used to produce X-ray environments through the interaction of intense pulsed laser radiation upon germanium-loaded silica aerogels. The optical specimen testing was supported by GH Systems through experiment design, pre- and post-test analyses, specimen acquisition, and overall technical experience. The test specimens were fabricated and characterized by Surface Optics Corporation (SOC), San Diego, CA and were simple protected gold coatings on silicamore » substrates. Six test specimens were exposed, five filtered with thin beryllium foil filters, and one unfiltered which was exposed directly to the raw environment. The experimental objectives were: (1) demonstrate that tests of optical specimens could be performed at the Omega facility; (2) evaluate the use and survivability of beryllium foil filters as a function of thickness; (3) obtain damage data on optical specimens which ranged from no damage to damage; (4) correlate existing thermal response models with the damage data; (5) evaluate the use of the direct raw environment upon the specimen response and the ability/desirability to conduct sensitive optical specimen tests using the raw environment; and (6) initiate the development of a protocol for performing optical coatings/mirror tests. This report documents the activities performed by GH Systems in evaluating and using the environments provided by LLNL, the PUFFTFT analyses performed using those environments, and the calculated results compared to the observed and measured posttest data.« less

Analyzing the dynamic response of rotating blades in small-scale wind turbines

NASA Astrophysics Data System (ADS)

Hsiung, Wan-Ying; Huang, Yu-Ting; Loh, Chin-Hsiung; Loh, Kenneth J.; Kamisky, Robert J.; Nip, Danny; van Dam, Cornelis

2014-03-01

The objective of this study was to validate modal analysis, system identification and damage detection of small-scale rotating wind turbine blades in the laboratory and in the field. Here, wind turbine blades were instrumented with accelerometers and strain gages, and data acquisition was achieved using a prototype wireless sensing system. In the first portion of this study conducted in the laboratory, sensors were installed onto metallic structural elements that were fabricated to be representative of an actual wind blade. In order to control the excitation (rotation of the wind blade), a motor was used to spin the blades at controlled angular velocities. The wind turbine was installed on a shaking table for testing under rotation of turbine blades. Data measured by the sensors were recorded while the blade was operated at different speeds. On the other hand, the second part of this study utilized a small-scale wind turbine system mounted on the rooftop of a building. The main difference, as compared to the lab tests, was that the field tests relied on actual wind excitations (as opposed to a controlled motor). The raw data from both tests were analyzed using signal processing and system identification techniques for deriving the model response of the blades. The multivariate singular spectrum analysis (MSSA) and covariance-driven stochastic subspace identification method (SSI-COV) were used to identify the dynamic characteristics of the system. Damage of one turbine blade (loose bolts connection) in the lab test was also conducted. The extracted modal properties for both undamaged and damage cases under different ambient or forced excitations (earthquake loading) were compared. These tests confirmed that dynamic characterization of rotating wind turbines was feasible, and the results will guide future monitoring studies planned for larger-scale systems.

Application of higher order SVD to vibration-based system identification and damage detection

NASA Astrophysics Data System (ADS)

Chao, Shu-Hsien; Loh, Chin-Hsiung; Weng, Jian-Huang

2012-04-01

Singular value decomposition (SVD) is a powerful linear algebra tool. It is widely used in many different signal processing methods, such principal component analysis (PCA), singular spectrum analysis (SSA), frequency domain decomposition (FDD), subspace identification and stochastic subspace identification method ( SI and SSI ). In each case, the data is arranged appropriately in matrix form and SVD is used to extract the feature of the data set. In this study three different algorithms on signal processing and system identification are proposed: SSA, SSI-COV and SSI-DATA. Based on the extracted subspace and null-space from SVD of data matrix, damage detection algorithms can be developed. The proposed algorithm is used to process the shaking table test data of the 6-story steel frame. Features contained in the vibration data are extracted by the proposed method. Damage detection can then be investigated from the test data of the frame structure through subspace-based and nullspace-based damage indices.

Low-Cost, Class D Testing of Spacecraft Photovoltaic Systems Can Reduce Risk

NASA Technical Reports Server (NTRS)

Forgione, Joshua B.; Kojima, Gilbert K.; Hanel, Robert; Mallinson, Mark V.

2014-01-01

The end-to-end verification of a spacecraft photovoltaic power generation system requires light! Specifically, the standard practice for doing so is the Large Area Pulsed Solar Simulation (LAPSS). A LAPSS test can characterize a photovoltaic system's efficiency via its response to rapidly applied impulses of simulated sunlight. However, a Class D program on a constrained budget and schedule may not have the resources to ship an entire satellite for a LAPSS test alone. Such was the case with the Lunar Atmospheric and Dust Environment Explorer (LADEE) program, which was also averse to the risk of hardware damage during shipment. When the Electrical Power System (EPS) team was denied a spacecraft-level LAPSS test, the lack of an end-to-end power generation test elevated to a project-level technical risk. The team pulled together very limited resources to not only eliminate the risk, but build a process to monitor the health of the system through mission operations. We discuss a process for performing a low-cost, end-to-end test of the LADEE photovoltaic system. The approach combines system-level functional test, panel-level performance results, and periodic inspection (and repair) up until launch. Following launch, mission operations tools are utilized to assess system performance based on a scant amount of data. The process starts in manufacturing at the subcontractor. The panel manufacturer provides functional test and LAPSS data on each individual panel. We apply an initial assumption that the per-panel performance is sufficient to meet the power generation requirements. The manufacturer's data is also carried as the performance allocation for each panel during EPS system modeling and initial mission operations. During integration and test, a high-power, professional theater lamp system provides simulated sunlight to each panel on the spacecraft, thereby permitting a true end-to-end system test. A passing test results in a step response to nearly full-rated current at the appropriate solar array switch in the power system. A metal-halide bulb, infrared imagers, and onboard spacecraft measurements are utilized to minimize risk of thermal damage during test. Data is provided to support test results for both passing and marginal panels. Prior to encapsulation in the launch vehicle, each panel is inspected for damage by the panel manufacturer. Cracked cells or other damage is amended on-site. Because the photovoltaic test system is inexpensive and portable, each repaired panel can be re-verified immediately. Post-launch, the photovoltaic system is again characterized for per-panel deviations from the manufacturer's performance test. This proved especially tricky as the LADEE spacecraft performs only one current measurement on the entire array. The algorithm for Matlab tools to assess panel performance based on spacecraft attitude is discussed. While not as precise and comprehensive as LAPSS, the LADEE approach leverages minimal resources into an ongoing assessment program that can be applied through numerous stages of the mission. The project takes a true Class D approach in assessing the technical value of a spacecraft level performance test versus the programmatic risk of shipping the spacecraft to another facility. The resources required are a fraction of that for a LAPSS test, and is easy to repeat. Further, the test equipment can be handed down to future projects without building an on-site facility.

Early detection of subclinical visual damage after blast-mediated TBI enables prevention of chronic visual deficit by treatment with P7C3-S243.

PubMed

Dutca, Laura M; Stasheff, Steven F; Hedberg-Buenz, Adam; Rudd, Danielle S; Batra, Nikhil; Blodi, Frederick R; Yorek, Matthew S; Yin, Terry; Shankar, Malini; Herlein, Judith A; Naidoo, Jacinth; Morlock, Lorraine; Williams, Noelle; Kardon, Randy H; Anderson, Michael G; Pieper, Andrew A; Harper, Matthew M

2014-12-02

Traumatic brain injury (TBI) frequently leads to chronic visual dysfunction. The purpose of this study was to investigate the effect of TBI on retinal ganglion cells (RGCs), and to test whether treatment with the novel neuroprotective compound P7C3-S243 could prevent in vivo functional deficits in the visual system. Blast-mediated TBI was modeled using an enclosed over-pressure blast chamber. The RGC physiology was evaluated using a multielectrode array and pattern electroretinogram (PERG). Histological analysis of RGC dendritic field and cell number were evaluated at the end of the study. Visual outcome measures also were evaluated based on treatment of mice with P7C3-S243 or vehicle control. We show that deficits in neutral position PERG after blast-mediated TBI occur in a temporally bimodal fashion, with temporary recovery 4 weeks after injury followed by chronically persistent dysfunction 12 weeks later. This later time point is associated with development of dendritic abnormalities and irreversible death of RGCs. We also demonstrate that ongoing pathologic processes during the temporary recovery latent period (including abnormalities of RGC physiology) lead to future dysfunction of the visual system. We report that modification of PERG to provocative postural tilt testing elicits changes in PERG measurements that correlate with a key in vitro measures of damage: the spontaneous and light-evoked activity of RGCs. Treatment with P7C3-S243 immediately after injury and throughout the temporary recovery latent period protects mice from developing chronic visual system dysfunction. Provocative PERG testing serves as a noninvasive test in the living organism to identify early damage to the visual system, which may reflect corresponding damage in the brain that is not otherwise detectable by noninvasive means. This provides the basis for developing an earlier diagnostic test to identify patients at risk for developing chronic CNS and visual system damage after TBI at an earlier stage when treatments may be more effective in preventing these sequelae. In addition, treatment with the neuroprotective agent P7C3-S243 after TBI protects from visual system dysfunction after TBI. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Early Detection of Subclinical Visual Damage After Blast-Mediated TBI Enables Prevention of Chronic Visual Deficit by Treatment With P7C3-S243

PubMed Central

Dutca, Laura M.; Stasheff, Steven F.; Hedberg-Buenz, Adam; Rudd, Danielle S.; Batra, Nikhil; Blodi, Frederick R.; Yorek, Matthew S.; Yin, Terry; Shankar, Malini; Herlein, Judith A.; Naidoo, Jacinth; Morlock, Lorraine; Williams, Noelle; Kardon, Randy H.; Anderson, Michael G.; Pieper, Andrew A.; Harper, Matthew M.

2014-01-01

Purpose. Traumatic brain injury (TBI) frequently leads to chronic visual dysfunction. The purpose of this study was to investigate the effect of TBI on retinal ganglion cells (RGCs), and to test whether treatment with the novel neuroprotective compound P7C3-S243 could prevent in vivo functional deficits in the visual system. Methods. Blast-mediated TBI was modeled using an enclosed over-pressure blast chamber. The RGC physiology was evaluated using a multielectrode array and pattern electroretinogram (PERG). Histological analysis of RGC dendritic field and cell number were evaluated at the end of the study. Visual outcome measures also were evaluated based on treatment of mice with P7C3-S243 or vehicle control. Results. We show that deficits in neutral position PERG after blast-mediated TBI occur in a temporally bimodal fashion, with temporary recovery 4 weeks after injury followed by chronically persistent dysfunction 12 weeks later. This later time point is associated with development of dendritic abnormalities and irreversible death of RGCs. We also demonstrate that ongoing pathologic processes during the temporary recovery latent period (including abnormalities of RGC physiology) lead to future dysfunction of the visual system. We report that modification of PERG to provocative postural tilt testing elicits changes in PERG measurements that correlate with a key in vitro measures of damage: the spontaneous and light-evoked activity of RGCs. Treatment with P7C3-S243 immediately after injury and throughout the temporary recovery latent period protects mice from developing chronic visual system dysfunction. Conclusions. Provocative PERG testing serves as a noninvasive test in the living organism to identify early damage to the visual system, which may reflect corresponding damage in the brain that is not otherwise detectable by noninvasive means. This provides the basis for developing an earlier diagnostic test to identify patients at risk for developing chronic CNS and visual system damage after TBI at an earlier stage when treatments may be more effective in preventing these sequelae. In addition, treatment with the neuroprotective agent P7C3-S243 after TBI protects from visual system dysfunction after TBI. PMID:25468886

Distributed Impact Detector System (DIDS) Health Monitoring System Evaluation

NASA Technical Reports Server (NTRS)

Prosser, William H.; Madaras, Eric I.

2010-01-01

Damage due to impacts from micrometeoroids and orbital debris is one of the most significant on-orbit hazards for spacecraft. Impacts to thermal protection systems must be detected and the damage evaluated to determine if repairs are needed to allow safe re-entry. To address this issue for the International Space Station Program, Langley Research Center and Johnson Space Center technologists have been working to develop and implement advanced methods for detecting impacts and resultant leaks. LaRC funded a Small Business Innovative Research contract to Invocon, Inc. to develop special wireless sensor systems that are compact, light weight, and have long battery lifetimes to enable applications to long duration space structures. These sensor systems are known as distributed impact detection systems (DIDS). In an assessment, the NASA Engineering and Safety Center procured two prototype DIDS sensor units to evaluate their capabilities in laboratory testing and field testing in an ISS Node 1 structural test article. This document contains the findings of the assessment.

355-nm, nanosecond laser mirror thin film damage competition

DOE PAGES

Negres, Raluca A.; Stolz, Christopher J.; Thomas, Michael D.; ...

2017-11-23

Here, this competition aimed to survey state-of-the-art UV high reflectors. The requirements of the coatings are a minimum reflection of 99.5% at 45 degrees incidence angle for P-polarized light at 355-nm. The choice of coating materials, design, and deposition method were left to the participants. Laser damage testing was performed at a single testing facility using the raster scan method with a 5-ns pulse length laser system operating at 10 Hz in a single longitudinal mode. A double blind test assured sample and submitter anonymity. Finally, in addition to the laser damage resistance results, details of the deposition processes, cleaningmore » method, coating materials and layer count are also shared.« less

3-ω damage threshold evaluation of final optics components using Beamlet Mule and off-line testing

NASA Astrophysics Data System (ADS)

Kozlowski, Mark R.; Maricle, Stephen M.; Mouser, Ron P.; Schwartz, Sheldon; Wegner, Paul J.; Weiland, Timothy L.

1999-07-01

A statistics-based model is being develop to predict the laser-damage-limited lifetime of UV optical components on the NIF laser. In order to provide data for the mode, laser damage experiments were performed on the Beamlet laser system at LLNL. An early protoype NIF focus lens was exposed to twenty 351 nm pulses at an average fluence of 5 J/cm2, 3ns. Using a high resolution optic inspection inspection system a total of 353 damage sites was detected within the 1160 cm2 beam aperture. Through inspections of the lens before, after and, in some cases, during the campaign, pulse to pulse damage growth rates were measured for damage initiating both on the surface and at bulk inclusions. Growth rates as high as 79 micrometers /pulse were observed for damage initiating at pre-existing scratches in the surface. For most damage sites on the optic, both on the surface and at bulk inclusions. Growth rates as high as 79 micrometers /pulse were observed for damage initiating at per- existing scratches in the surface. For most damage sites on the optic, both surface and bulk, the damage growth rate was approximately 10(Mu) m/pulse.

Efficient generation of receiver operating characteristics for the evaluation of damage detection in practical structural health monitoring applications.

PubMed

Liu, Chang; Dobson, Jacob; Cawley, Peter

2017-03-01

Permanently installed guided wave monitoring systems are attractive for monitoring large structures. By frequently interrogating the test structure over a long period of time, such systems have the potential to detect defects much earlier than with conventional one-off inspection, and reduce the time and labour cost involved. However, for the systems to be accepted under real operational conditions, their damage detection performance needs to be evaluated in these practical settings. The receiver operating characteristic (ROC) is an established performance metric for one-off inspections, but the generation of the ROC requires many test structures with realistic damage growth at different locations and different environmental conditions, and this is often impractical. In this paper, we propose an evaluation framework using experimental data collected over multiple environmental cycles on an undamaged structure with synthetic damage signatures added by superposition. Recent advances in computation power enable examples covering a wide range of practical scenarios to be generated, and for multiple cases of each scenario to be tested so that the statistics of the performance can be evaluated. The proposed methodology has been demonstrated using data collected from a laboratory pipe specimen over many temperature cycles, superposed with damage signatures predicted for a flat-bottom hole growing at different rates at various locations. Three damage detection schemes, conventional baseline subtraction, singular value decomposition (SVD) and independent component analysis (ICA), have been evaluated. It has been shown that in all cases, the component methods perform significantly better than the residual method, with ICA generally the better of the two. The results have been validated using experimental data monitoring a pipe in which a flat-bottom hole was drilled and enlarged over successive temperature cycles. The methodology can be used to evaluate the performance of an installed monitoring system and to show whether it is capable of detecting particular damage growth at any given location. It will enable monitoring results to be evaluated rigorously and will be valuable in the development of safety cases.

Efficient generation of receiver operating characteristics for the evaluation of damage detection in practical structural health monitoring applications

PubMed Central

Dobson, Jacob; Cawley, Peter

2017-01-01

Permanently installed guided wave monitoring systems are attractive for monitoring large structures. By frequently interrogating the test structure over a long period of time, such systems have the potential to detect defects much earlier than with conventional one-off inspection, and reduce the time and labour cost involved. However, for the systems to be accepted under real operational conditions, their damage detection performance needs to be evaluated in these practical settings. The receiver operating characteristic (ROC) is an established performance metric for one-off inspections, but the generation of the ROC requires many test structures with realistic damage growth at different locations and different environmental conditions, and this is often impractical. In this paper, we propose an evaluation framework using experimental data collected over multiple environmental cycles on an undamaged structure with synthetic damage signatures added by superposition. Recent advances in computation power enable examples covering a wide range of practical scenarios to be generated, and for multiple cases of each scenario to be tested so that the statistics of the performance can be evaluated. The proposed methodology has been demonstrated using data collected from a laboratory pipe specimen over many temperature cycles, superposed with damage signatures predicted for a flat-bottom hole growing at different rates at various locations. Three damage detection schemes, conventional baseline subtraction, singular value decomposition (SVD) and independent component analysis (ICA), have been evaluated. It has been shown that in all cases, the component methods perform significantly better than the residual method, with ICA generally the better of the two. The results have been validated using experimental data monitoring a pipe in which a flat-bottom hole was drilled and enlarged over successive temperature cycles. The methodology can be used to evaluate the performance of an installed monitoring system and to show whether it is capable of detecting particular damage growth at any given location. It will enable monitoring results to be evaluated rigorously and will be valuable in the development of safety cases. PMID:28413339

Value contamination avoidance devices

NASA Technical Reports Server (NTRS)

Endicott, D. L.

1975-01-01

Mechanical redesign methods were used to minimize contamination damage of conventional fluid components and a contamination separator device was developed for long term reusable space vehicles. These were incorporated into an existing 50.8 mm poppet valve and tested for damage tolerance in a full size open loop flow system with gaseous and liquid nitrogen. Cyclic and steady flow conditions were tested with particles of 125 to 420 micrometers aluminum oxide dispersed in the test fluids. Nonflow life tests (100,000 cycles) were made with two valve configurations in gaseous hydrogen. The redesigned valve had an acceptable cycle life and improved tolerance to contamination damage when the primary sealing surfaces were coated with thin coatings of hard plastic (Teflon S and Kynar). Analytical studies and flow testing were completed of four different versions of the separator. overall separation efficiencies in the 55-90% range were measured with these non-optimum configurations.

An Assessment of the Common Carrier Shipping Environment

DTIC Science & Technology

1979-01-01

resistance to ’damage of the, item to be protected or packaged, and (3) a knowledge of the performance i/ Maintained at Madison, Wis., in cOoperation...the damage attributed to shippers, while rough handling accounted for 80 percent of the damage attributed to carriers. Results of surveys of this tyre ...vibration environment in tractor trailers. Tests were conducted to determine the effect of suspension system (conventioaal steel spring, rubber isolator

Experimental research on femto-second laser damaging array CCD cameras

NASA Astrophysics Data System (ADS)

Shao, Junfeng; Guo, Jin; Wang, Ting-feng; Wang, Ming

2013-05-01

Charged Coupled Devices (CCD) are widely used in military and security applications, such as airborne and ship based surveillance, satellite reconnaissance and so on. Homeland security requires effective means to negate these advanced overseeing systems. Researches show that CCD based EO systems can be significantly dazzled or even damaged by high-repetition rate pulsed lasers. Here, we report femto - second laser interaction with CCD camera, which is probable of great importance in future. Femto - second laser is quite fresh new lasers, which has unique characteristics, such as extremely short pulse width (1 fs = 10-15 s), extremely high peak power (1 TW = 1012W), and especially its unique features when interacting with matters. Researches in femto second laser interaction with materials (metals, dielectrics) clearly indicate non-thermal effect dominates the process, which is of vast difference from that of long pulses interaction with matters. Firstly, the damage threshold test are performed with femto second laser acting on the CCD camera. An 800nm, 500μJ, 100fs laser pulse is used to irradiate interline CCD solid-state image sensor in the experiment. In order to focus laser energy onto tiny CCD active cells, an optical system of F/5.6 is used. A Sony production CCDs are chose as typical targets. The damage threshold is evaluated with multiple test data. Point damage, line damage and full array damage were observed when the irradiated pulse energy continuously increase during the experiment. The point damage threshold is found 151.2 mJ/cm2.The line damage threshold is found 508.2 mJ/cm2.The full-array damage threshold is found to be 5.91 J/cm2. Although the phenomenon is almost the same as that of nano laser interaction with CCD, these damage thresholds are substantially lower than that of data obtained from nano second laser interaction with CCD. Then at the same time, the electric features after different degrees of damage are tested with electronic multi meter. The resistance values between clock signal lines are measured. Contrasting the resistance values of the CCD before and after damage, it is found that the resistances decrease significantly between the vertical transfer clock signal lines values. The same results are found between the vertical transfer clock signal line and the earth electrode (ground).At last, the damage position and the damage mechanism were analyzed with above results and SEM morphological experiments. The point damage results in the laser destroying material, which shows no macro electro influence. The line damage is quite different from that of point damage, which shows deeper material corroding effect. More importantly, short circuits are found between vertical clock lines. The full array damage is even more severe than that of line damage starring with SEM, while no obvious different electrical features than that of line damage are found. Further researches are anticipated in femto second laser caused CCD damage mechanism with more advanced tools. This research is valuable in EO countermeasure and/or laser shielding applications.

Synthesis of Sine-on-Random vibration profiles for accelerated life tests based on fatigue damage spectrum equivalence

NASA Astrophysics Data System (ADS)

Angeli, Andrea; Cornelis, Bram; Troncossi, Marco

2018-03-01

In many real life environments, mechanical and electronic systems are subjected to vibrations that may induce dynamic loads and potentially lead to an early failure due to fatigue damage. Thus, qualification tests by means of shakers are advisable for the most critical components in order to verify their durability throughout the entire life cycle. Nowadays the trend is to tailor the qualification tests according to the specific application of the tested component, considering the measured field data as reference to set up the experimental campaign, for example through the so called "Mission Synthesis" methodology. One of the main issues is to define the excitation profiles for the tests, that must have, besides the (potentially scaled) frequency content, also the same damage potential of the field data despite being applied for a limited duration. With this target, the current procedures generally provide the test profile as a stationary random vibration specified by a Power Spectral Density (PSD). In certain applications this output may prove inadequate to represent the nature of the reference signal, and the procedure could result in an unrealistic qualification test. For instance when a rotating part is present in the system the component under analysis may be subjected to Sine-on-Random (SoR) vibrations, namely excitations composed of sinusoidal contributions superimposed to random vibrations. In this case, the synthesized test profile should preserve not only the induced fatigue damage but also the deterministic components of the environmental vibration. In this work, the potential advantages of a novel procedure to synthesize SoR profiles instead of PSDs for qualification tests are presented and supported by the results of an experimental campaign.

Rapid Damage Assessment. Volume II. Development and Testing of Rapid Damage Assessment System.

DTIC Science & Technology

1981-02-01

pixels/s Camera Line Rate 732.4 lines/s Pixels per Line 1728 video 314 blank 4 line number (binary) 2 run number (BCD) 2048 total Pixel Resolution 8 bits...sists of an LSI-ll microprocessor, a VDI -200 video display processor, an FD-2 dual floppy diskette subsystem, an FT-I function key-trackball module...COMPONENT LIST FOR IMAGE PROCESSOR SYSTEM IMAGE PROCESSOR SYSTEM VIEWS I VDI -200 Display Processor Racks, Table FD-2 Dual Floppy Diskette Subsystem FT-l

Retinal nerve fiber layer thickness and neuropsychiatric manifestations in systemic lupus erythematosus.

PubMed

Shulman, S; Shorer, R; Wollman, J; Dotan, G; Paran, D

2017-11-01

Background Cognitive impairment is frequent in systemic lupus erythematosus. Atrophy of the corpus callosum and hippocampus have been reported in patients with systemic lupus erythematosus, and diffusion tensor imaging studies have shown impaired white matter integrity, suggesting that white matter damage in systemic lupus erythematosus may underlie the cognitive impairment as well as other neuropsychiatric systemic lupus erythematosus manifestations. Retinal nerve fiber layer thickness, as assessed by optical coherence tomography, has been suggested as a biomarker for white matter damage in neurologic disorders such as multiple sclerosis, Alzheimer's disease and Parkinson's disease. Retinal nerve fiber layer thinning may occur early, even in patients with mild clinical symptoms. Aim The objective of this study was to assess the association of retinal nerve fiber layer thickness, as a biomarker of white matter damage in systemic lupus erythematosus patients, with neuropsychiatric systemic lupus erythematosus manifestations, including cognitive impairment. Methods Twenty-one consecutive patients with systemic lupus erythematosus underwent neuropsychological testing using a validated computerized battery of tests as well as the Rey-Auditory verbal learning test. All 21 patients, as well as 11 healthy, age matched controls, underwent optical coherence tomography testing to assess retinal nerve fiber layer thickness. Correlations between retinal nerve fiber layer thickness and results in eight cognitive domains assessed by the computerized battery of tests as well as the Rey-Auditory verbal learning test were assessed in patients with systemic lupus erythematosus, with and without neuropsychiatric systemic lupus erythematosus, and compared to retinal nerve fiber layer thickness in healthy controls. Results No statistically significant correlation was found between retinal nerve fiber layer thickness in patients with systemic lupus erythematosus as compared to healthy controls. When evaluating by subgroups, no correlation was found between patients with or without neuropsychiatric systemic lupus erythematosus or cognitive impairment and retinal nerve fiber layer thickness. Conclusion Retinal nerve fiber layer thickness of systemic lupus erythematosus patients was not found to be statistically different compared to controls. Within systemic lupus erythematosus patients there was no correlation between retinal nerve fiber layer thickness and cognitive impairment or other neuropsychiatric systemic lupus erythematosus manifestations.

Radiation Effects on Optoelectronic Devices in Space Missions

NASA Technical Reports Server (NTRS)

Johnston, Allan H.

2006-01-01

Radiation degradation of optoelectronic devices is discussed, including effects on optical emitters, detectors and optocouplers. The importance of displacement damage is emphasized, including the limitations of non-ionizing energy loss (NIEL) in normalizing damage. Failures of optoelectronics in fielded space systems are discussed, along with testing and qualification methods.

Flip-Flop Recovery System for sounding rocket payloads

NASA Technical Reports Server (NTRS)

Flores, A., Jr.

1986-01-01

The design, development, and testing of the Flip-Flop Recovery System, which protects sensitive forward-mounted instruments from ground impact during sounding rocket payload recovery operations, are discussed. The system was originally developed to reduce the impact damage to the expensive gold-plated forward-mounted spectrometers in two existing Taurus-Orion rocket payloads. The concept of the recovery system is simple: the payload is flipped over end-for-end at a predetermined time just after parachute deployment, thus minimizing the risk of damage to the sensitive forward portion of the payload from ground impact.

Development of integrated damage detection system for international America's Cup class yacht structures using a fiber optic distributed sensor

NASA Astrophysics Data System (ADS)

Akiyoshi, Shimada; Naruse, Hiroshi; Uzawa, Kyoshi; Murayama, Hideaki; Kageyama, Kazuro

2000-06-01

We constructed a new health monitoring system to detect damage using a fiber optic distributed sensor, namely a Brillouin optical time domain reflectometer (BOTDR), and installed it in International America's Cup Class (IACC) yachts, the Japanese entry in America's Cup 2000. IACC yachts are designed to be as fast as possible, so it is essential that they are lightweight and encounter minimum water resistance. Advanced composite sandwich structures, made with carbon fiber reinforced plastic (CFRP) skins and a honeycomb core, are used to achieve the lightweight structure. Yacht structure designs push the strength of the materials to their limit and so it is important to detect highly stressed or damaged regions that might cause a catastrophic fracture. The BOTDR measures changes in the Brillouin frequency shift caused by distributed strain along one optical fiber. We undertook two experiments: a pulling test and a four point bending test on a composite beam. The former showed that no slippage occurred between the optical fiber glass and its coating. The latter confirmed that a debonding between the skin and the core of 300 mm length could be found with the BOTDR. Next we examined the effectiveness with which this system can assess the structural integrity of IACC yachts. The results show that our system has the potential for use as a damage detection system for smart structures.

Identification of characteristic frequencies of damaged railway tracks using field hammer test measurements

NASA Astrophysics Data System (ADS)

Oregui, M.; Li, Z.; Dollevoet, R.

2015-03-01

In this paper, the feasibility of the Frequency Response Function (FRF)-based statistical method to identify the characteristic frequencies of railway track defects is studied. The method compares a damaged track state to a healthy state based on non-destructive field hammer test measurements. First, a study is carried out to investigate the repeatability of hammer tests in railway tracks. By changing the excitation and measurement locations it is shown that the variability introduced by the test process is negligible. Second, following the concepts of control charts employed in process monitoring, a method to define an approximate healthy state is introduced by using hammer test measurements at locations without visual damage. Then, the feasibility study includes an investigation into squats (i.e. a major type of rail surface defect) of varying severity. The identified frequency ranges related to squats agree with those found in an extensively validated vehicle-borne detection system. Therefore, the FRF-based statistical method in combination with the non-destructive hammer test measurements has the potential to be employed to identify the characteristic frequencies of damaged conditions in railway tracks in the frequency range of 300-3000 Hz.

X ray attenuation measurements for high-temperature materials characterization and in-situ monitoring of damage accumulation. Ph.D. Thesis - Cleveland State Univ., 1991

NASA Technical Reports Server (NTRS)

Baaklini, George Y.

1992-01-01

The scope of this dissertation is to develop and apply x ray attenuation measurement systems that are capable of: (1) characterizing density variations in high-temperature materials, e.g., monolithic ceramics, ceramic and intermetallic matrix composites, and (2) noninvasively monitoring damage accumulation and failure sequences in ceramic matrix composites under room temperature tensile testing. This dissertation results in the development of: (1) a point scan digital radiography system, and (2) an in-situ x ray material testing system. Radiographic evaluation before, during, and after loading shows the effect of preexisting volume flaws on the fracture behavior of composites. Results show that x ray film radiography can monitor damage accumulation during tensile loading. Matrix cracking, fiber matrix debonding, fiber bridging, and fiber pullout are imaged throughout the tensile loading of the specimens. Further in-situ radiography is found to be a practical technique for estimating interfacial shear strength between the silicon carbide fibers and the reaction bonded silicon nitride matrix. It is concluded that pretest, in-situ, and post test x ray imaging can provide for greater understanding of ceramic matrix composite mechanical behavior.

Integrating Oil Debris and Vibration Measurements for Intelligent Machine Health Monitoring. Degree awarded by Toledo Univ., May 2002

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.

2003-01-01

A diagnostic tool for detecting damage to gears was developed. Two different measurement technologies, oil debris analysis and vibration were integrated into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual measurement technologies. This diagnostic tool was developed and evaluated experimentally by collecting vibration and oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig. An oil debris sensor and the two vibration algorithms were adapted as the diagnostic tools. An inductance type oil debris sensor was selected for the oil analysis measurement technology. Gear damage data for this type of sensor was limited to data collected in the NASA Glenn test rigs. For this reason, this analysis included development of a parameter for detecting gear pitting damage using this type of sensor. The vibration data was used to calculate two previously available gear vibration diagnostic algorithms. The two vibration algorithms were selected based on their maturity and published success in detecting damage to gears. Oil debris and vibration features were then developed using fuzzy logic analysis techniques, then input into a multi sensor data fusion process. Results show combining the vibration and oil debris measurement technologies improves the detection of pitting damage on spur gears. As a result of this research, this new diagnostic tool has significantly improved detection of gear damage in the NASA Glenn Spur Gear Fatigue Rigs. This research also resulted in several other findings that will improve the development of future health monitoring systems. Oil debris analysis was found to be more reliable than vibration analysis for detecting pitting fatigue failure of gears and is capable of indicating damage progression. Also, some vibration algorithms are as sensitive to operational effects as they are to damage. Another finding was that clear threshold limits must be established for diagnostic tools. Based on additional experimental data obtained from the NASA Glenn Spiral Bevel Gear Fatigue Rig, the methodology developed in this study can be successfully implemented on other geared systems.

Numerical analysis of PZT rebar active sensing system for structural health monitoring of RC structure

NASA Astrophysics Data System (ADS)

Wu, F.; Yi, J.; Li, W. J.

2014-03-01

An active sensing diagnostic system for reinforced concrete SHM has been under investigation. Test results show that the system can detect the damage of the structure. To fundamentally understand the damage algorithm and therefore to establish a robust diagnostic method, accurate Finite Element Analysis (FEA) for the system becomes essential. For the system, a rebar with surface bonded PZT under a transient wave load was simulated and analyzed using commercial FEA software. A detailed 2D axi-symmetric model for a rebar attaching PZT was first established. The model simulates the rebar with wedges, an epoxy adhesive layer, as well as a PZT layer. PZT material parameter transformation with high order tensors was discussed due to the format differences between IEEE Standard and ANSYS. The selection of material properties such as Raleigh damping coefficients was discussed. The direct coupled-field analysis type was selected during simulation. The results from simulation matched well with the experimental data. Further simulation for debonding damage detection for concrete beam with the PZT rebar has been performed. And the numerical results have been validated with test results too. The good consistency between two proves that the numerical models were reasonably accurate. Further system optimization has been performed based on these models. By changing PZT layout and size, the output signals could be increased with magnitudes. And the damage detection signals have been found to be increased exponentially with the debonding size of the rebar.

In-Space Repair and Refurbishment of Thermal Protection System Structures for Reusable Launch Vehicles

NASA Technical Reports Server (NTRS)

Singh, M.

2007-01-01

Advanced repair and refurbishment technologies are critically needed for the thermal protection system of current space transportation systems as well as for future launch and crew return vehicles. There is a history of damage to these systems from impact during ground handling or ice during launch. In addition, there exists the potential for in-orbit damage from micrometeoroid and orbital debris impact as well as different factors (weather, launch acoustics, shearing, etc.) during launch and re-entry. The GRC developed GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair) material has shown multiuse capability for repair of small cracks and damage in reinforced carbon-carbon (RCC) material. The concept consists of preparing an adhesive paste of desired ceramic with appropriate additives and then applying the paste to the damaged/cracked area of the RCC composites with an adhesive delivery system. The adhesive paste cures at 100-120 C and transforms into a high temperature ceramic during reentry conditions. A number of plasma torch and ArcJet tests were carried out to evaluate the crack repair capability of GRABER materials for Reinforced Carbon-Carbon (RCC) composites. For the large area repair applications, Integrated Systems for Tile and Leading Edge Repair (InSTALER) have been developed and evaluated under various ArcJet testing conditions. In this presentation, performance of the repair materials as applied to RCC is discussed. Additionally, critical in-space repair needs and technical challenges are reviewed.

High Performance COPVs for In-Space Storage of High Pressure Cryogenic Fuels

NASA Technical Reports Server (NTRS)

Schneider, Judy; Dyess, Mark; Hastings, Chad; Wang, Jun

2008-01-01

Polymeric composite overwrapped pressure vessels (COPVs) provide an attractive material system to support developing commercial launch business and alternate fuel ventures. However to be able to design with these materials, the mechanical behavior of the materials must be understood with regards to processing, performance, damage tolerance, and environment. For the storage of cryogenic propellants, it is important to evaluate the materials performance and impact damage resistance at cryogenic temperatures in order to minimize weight and to ensure safety and reliability. As part of this study, material tests of candidate fiber and resin systems were used as the basis for the selection of the material combinations for evaluation in a COPV at cryogenic conditions. This comprehensive approach has also been expanded to address issues with impact damage tolerance and material degradation due to environmental factors. KEY WORDS: Cryogenic testing, evaluation and applications for pressure vessels, COPVs, tanks, or storage vessels.

Acoustic emission monitoring of low velocity impact damage in graphite/epoxy laminates during tensile loading

NASA Technical Reports Server (NTRS)

Parker, Bradford H.

1992-01-01

An acoustic emission (AE) system was set up in a linear location data acquisition mode to monitor the tensile loading of eight-ply quasi-isotropic graphite/epoxy specimens containing low velocity impact damage. The impact damage was induced using an instrumented drop weight tower. During impact, specimens were supported by either an aluminum plate or a membrane configuration. Cross-sectional examinations revealed that the aluminum plate configuration resulted in primarily matrix cracking and back surface fiber failure. The membrane support resulted in only matrix cracking and delamination damage. Penetrant enhanced radiography and immersion ultrasonics were used in order to assess the amount of impact damage in each tensile specimen. During tensile loading, AE reliably detected and located the damage sites which included fiber failure. All specimens with areas of fiber breakage ultimately failed at the impact site. AE did not reliably locate damage which consisted of only delaminations and matrix cracking. Specimens with this type of damage did not ultimately fail at the impact site. In summary, AE demonstrated the ability to increase the reliability of structural proof tests; however, the successful use of this technique requires extensive baseline testing.

Experimental Hypersonic Aerodynamic Characteristics of the Space Shuttle Orbiter for a Range of Damage Scenarios

NASA Technical Reports Server (NTRS)

Brauckmann, Gregory J.; Scallion, William I.

2004-01-01

Aerodynamic tests in support of the Columbia accident investigation were conducted in two hypersonic wind tunnels at the NASA Langley Research Center, the 20-Inch Mach 6 Air Tunnel and the 20-Inch CF4 Tunnel. The primary purpose of these tests was to measure the forces and moments generated by a variety of outer mold line alterations (damage scenarios) using 0.0075-scale models of the Space Shuttle Orbiter. Simultaneously acquired global heat transfer mappings were obtained for a majority of the configurations tested. Test parametrics included angles of attack from 38 to 42 deg, unit Reynolds numbers from 0.3 x 10(exp 6) to 3.0 x 10(exp 6) per foot, and normal shock density ratios of 5 (Mach 6 air) and 12 (CF4). The damage scenarios evaluated included asymmetric boundary layer transition, gouges in the windward surface thermal protection system tiles, wing leading edge damage (partially and fully missing reinforced carbon-carbon (RCC) panels), deformation of the wing windward surface, and main landing gear and/or door deployment. The measured aerodynamic increments for the damage scenarios examined were generally small in magnitude, as were the flight-derived values during most of the entry prior to loss of communication. A progressive damage scenario is presented that qualitatively matches the flight observations for the STS-107 entry.

Inelastic response of metal matrix composites under biaxial loading

NASA Technical Reports Server (NTRS)

Lissenden, C. J.; Mirzadeh, F.; Pindera, M.-J.; Herakovich, C. T.

1991-01-01

Theoretical predictions and experimental results were obtained for inelastic response of unidirectional and angle ply composite tubes subjected to axial and torsional loading. The composite material consist of silicon carbide fibers in a titanium alloy matrix. This material is known to be susceptible to fiber matrix interfacial damage. A method to distinguish between matrix yielding and fiber matrix interfacial damage is suggested. Biaxial tests were conducted on the two different layup configurations using an MTS Axial/Torsional load frame with a PC based data acquisition system. The experimentally determined elastic moduli of the SiC/Ti system are compared with those predicted by a micromechanics model. The test results indicate that fiber matrix interfacial damage occurs at relatively low load levels and is a local phenomenon. The micromechanics model used is the method of cells originally proposed by Aboudi. Finite element models using the ABACUS finite element program were used to study end effects and fixture specimen interactions. The results to date have shown good correlation between theory and experiment for response prior to damage initiation.

Application of Laser Based Ultrasound for NDE of Damage in Thick Stitched Composites

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Friedman, Adam D.; Hinders, Mark K.; Madaras, Eric I.

1997-01-01

As design engineers implement new composite systems such as thick, load bearing composite structures, they must have certifiable confidence in structure s durability and worthiness. This confidence builds from understanding the structural response and failure characteristics of simple components loaded in testing machines to tests on full scale sections. Nondestructive evaluation is an important element which can provide quantitative information on the damage initiation, propagation, and final failure modes for the composite structural components. Although ultrasound is generally accepted as a test method, the use of conventional ultrasound for in-situ monitoring of damage during tests of large structures is not practical. The use of lasers to both generate and detect ultrasound extends the application of ultrasound to in- situ sensing of damage in a deformed structure remotely and in a non-contact manner. The goal of the present research is to utilize this technology to monitor damage progression during testing. The present paper describes the application of laser based ultrasound to quantify damage in thick stitched composite structural elements to demonstrate the method. This method involves using a Q-switched laser to generate a rapid, local linear thermal strain on the surface of the structure. This local strain causes the generation of ultrasonic waves into the material. A second laser used with a Fabry-Perot interferometer detects the surface deflections. The use of fiber optics provides for eye safety and a convenient method of delivering the laser over long distances to the specimens. The material for these structural elements is composed of several stacks of composite material assembled together by stitching through the laminate thickness that ranging from 0.5 to 0.8 inches. The specimens used for these nondestructive evaluation studies had either impact damage or skin/stiffener interlaminar failure. Although little or no visible surface damage existed, internal damage was detected by laser based ultrasound.

Environmental Barrier Coating Fracture, Fatigue and High-Heat-Flux Durability Modeling and Stochastic Progressive Damage Simulation

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Nemeth, Noel N.

2017-01-01

Advanced environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect emerging light-weight SiC/SiC ceramic matrix composite (CMC) engine components, further raising engine operating temperatures and performance. Because the environmental barrier coating systems are critical to the performance, reliability and durability of these hot-section ceramic engine components, a prime-reliant coating system along with established life design methodology are required for the hot-section ceramic component insertion into engine service. In this paper, we have first summarized some observations of high temperature, high-heat-flux environmental degradation and failure mechanisms of environmental barrier coating systems in laboratory simulated engine environment tests. In particular, the coating surface cracking morphologies and associated subsequent delamination mechanisms under the engine level high-heat-flux, combustion steam, and mechanical creep and fatigue loading conditions will be discussed. The EBC compostion and archtechture improvements based on advanced high heat flux environmental testing, and the modeling advances based on the integrated Finite Element Analysis Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program will also be highlighted. The stochastic progressive damage simulation successfully predicts mud flat damage pattern in EBCs on coated 3-D specimens, and a 2-D model of through-the-thickness cross-section. A 2-parameter Weibull distribution was assumed in characterizing the coating layer stochastic strength response and the formation of damage was therefore modeled. The damage initiation and coalescence into progressively smaller mudflat crack cells was demonstrated. A coating life prediction framework may be realized by examining the surface crack initiation and delamination propagation in conjunction with environmental degradation under high-heat-flux and environment load test conditions.

The influence of image sensor irradiation damage on the tracking and pointing accuracy of optical communication system

NASA Astrophysics Data System (ADS)

Li, Xiaoliang; Luo, Lei; Li, Pengwei; Yu, Qingkui

2018-03-01

The image sensor in satellite optical communication system may generate noise due to space irradiation damage, leading to deviation for the determination of the light spot centroid. Based on the irradiation test data of CMOS devices, simulated defect spots in different sizes have been used for calculating the centroid deviation value by grey-level centroid algorithm. The impact on tracking & pointing accuracy of the system has been analyzed. The results show that both the amount and the position of irradiation-induced defect pixels contribute to spot centroid deviation. And the larger spot has less deviation. At last, considering the space radiation damage, suggestions are made for the constraints of spot size selection.

Theoretical neutron damage calculations in industrial robotic manipulators used for non-destructive imaging applications

DOE PAGES

Hashem, Joseph; Schneider, Erich; Pryor, Mitch; ...

2017-01-01

Our paper describes how to use MCNP to evaluate the rate of material damage in a robot incurred by exposure to a neutron flux. The example used in this work is that of a robotic manipulator installed in a high intensity, fast, and collimated neutron radiography beam port at the University of Texas at Austin's TRIGA Mark II research reactor. Our effort includes taking robotic technologies and using them to automate non-destructive imaging tasks in nuclear facilities where the robotic manipulator acts as the motion control system for neutron imaging tasks. Simulated radiation tests are used to analyze the radiationmore » damage to the robot. Once the neutron damage is calculated using MCNP, several possible shielding materials are analyzed to determine the most effective way of minimizing the neutron damage. Furthermore, neutron damage predictions provide users the means to simulate geometrical and material changes, thus saving time, money, and energy in determining the optimal setup for a robotic system installed in a radiation environment.« less

Theoretical neutron damage calculations in industrial robotic manipulators used for non-destructive imaging applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashem, Joseph; Schneider, Erich; Pryor, Mitch

Our paper describes how to use MCNP to evaluate the rate of material damage in a robot incurred by exposure to a neutron flux. The example used in this work is that of a robotic manipulator installed in a high intensity, fast, and collimated neutron radiography beam port at the University of Texas at Austin's TRIGA Mark II research reactor. Our effort includes taking robotic technologies and using them to automate non-destructive imaging tasks in nuclear facilities where the robotic manipulator acts as the motion control system for neutron imaging tasks. Simulated radiation tests are used to analyze the radiationmore » damage to the robot. Once the neutron damage is calculated using MCNP, several possible shielding materials are analyzed to determine the most effective way of minimizing the neutron damage. Furthermore, neutron damage predictions provide users the means to simulate geometrical and material changes, thus saving time, money, and energy in determining the optimal setup for a robotic system installed in a radiation environment.« less

Computational Modeling and Experimental Validation of Shock Induced Damage in Woven E-Glass/Vinylester Laminates

NASA Astrophysics Data System (ADS)

Hufner, D. R.; Augustine, M. R.

2018-05-01

A novel experimental method was developed to simulate underwater explosion pressure pulses within a laboratory environment. An impact-based experimental apparatus was constructed; capable of generating pressure pulses with basic character similar to underwater explosions, while also allowing the pulse to be tuned to different intensities. Having the capability to vary the shock impulse was considered essential to producing various levels of shock-induced damage without the need to modify the fixture. The experimental apparatus and test method are considered ideal for investigating the shock response of composite material systems and/or experimental validation of new material models. One such test program is presented herein, in which a series of E-glass/Vinylester laminates were subjected to a range of shock pulses that induced varying degrees of damage. Analysis-test correlations were performed using a rate-dependent constitutive model capable of representing anisotropic damage and ultimate yarn failure. Agreement between analytical predictions and experimental results was considered acceptable.

Analytical and Experimental Vibration Analysis of a Faulty Gear System.

DTIC Science & Technology

1994-10-01

Wigner - Ville Distribution ( WVD ) was used to give a comprehensive comparison of the predicted and...experimental results. The WVD method applied to the experimental results were also compared to other fault detection techniques to verify the WVD’s ability to...of the damaged test gear and the predicted vibration from the model with simulated gear tooth pitting damage. Results also verified that the WVD method can successfully detect and locate gear tooth wear and pitting damage.

Investigation of Spiral Bevel Gear Condition Indicator Validation Via AC-29-2C Using Damage Progression Tests

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.

2014-01-01

This report documents the results of spiral bevel gear rig tests performed under a NASA Space Act Agreement with the Federal Aviation Administration (FAA) to support validation and demonstration of rotorcraft Health and Usage Monitoring Systems (HUMS) for maintenance credits via FAA Advisory Circular (AC) 29-2C, Section MG-15, Airworthiness Approval of Rotorcraft (HUMS) (Ref. 1). The overarching goal of this work was to determine a method to validate condition indicators in the lab that better represent their response to faults in the field. Using existing in-service helicopter HUMS flight data from faulted spiral bevel gears as a "Case Study," to better understand the differences between both systems, and the availability of the NASA Glenn Spiral Bevel Gear Fatigue Rig, a plan was put in place to design, fabricate and test comparable gear sets with comparable failure modes within the constraints of the test rig. The research objectives of the rig tests were to evaluate the capability of detecting gear surface pitting fatigue and other generated failure modes on spiral bevel gear teeth using gear condition indicators currently used in fielded HUMS. Nineteen final design gear sets were tested. Tables were generated for each test, summarizing the failure modes observed on the gear teeth for each test during each inspection interval and color coded based on damage mode per inspection photos. Gear condition indicators (CI) Figure of Merit 4 (FM4), Root Mean Square (RMS), +/- 1 Sideband Index (SI1) and +/- 3 Sideband Index (SI3) were plotted along with rig operational parameters. Statistical tables of the means and standard deviations were calculated within inspection intervals for each CI. As testing progressed, it became clear that certain condition indicators were more sensitive to a specific component and failure mode. These tests were clustered together for further analysis. Maintenance actions during testing were also documented. Correlation coefficients were calculated between each CI, component, damage state and torque. Results found test rig and gear design, type of fault and data acquisition can affect CI performance. Results found FM4, SI1 and SI3 can be used to detect macro pitting on two more gear or pinion teeth as long as it is detected prior to progressing to other components or transitioning to another failure mode. The sensitivity of RMS to system and operational conditions limit its reliability for systems that are not maintained at steady state. Failure modes that occurred due to scuffing or fretting were challenging to detect with current gear diagnostic tools, since the damage is distributed across all the gear and pinion teeth, smearing the impacting signatures typically used to differentiate between a healthy and damaged tooth contact. This is one of three final reports published on the results of this project. In the second report, damage modes experienced in the field will be mapped to the failure modes created in the test rig. The helicopter CI data will then be re-processed with the same analysis techniques applied to spiral bevel rig test data. In the third report, results from the rig and helicopter data analysis will be correlated. Observations, findings and lessons learned using sub-scale rig failure progression tests to validate helicopter gear condition indicators will be presented.

In vitro studies on chemoprotective effect of Purnark against benzo(a)pyrene-induced chromosomal damage in human lymphocytes.

PubMed

Ghaisas, S D; Bhide, S V

1994-01-01

Human lymphocytes were used as an assay system to test chemopreventive activity of natural products. Purnark, a mixture of extracts of turmeric, betel leaf and catechu, was tested for its chemoprotective activity against BP induced DNA damage. Sister chromatid exchange and micronuclei were used as markers to assess the protective activity of Purnark. Purnark gave 50-60% protection against BP induced SCEs and micronuclei. Purnark at 100 micrograms dose did not show any genotoxicity.

Displacement Damage Effects in Solar Cells: Mining Damage From the Microelectronics and Photonics Test Bed Space Experiment

NASA Technical Reports Server (NTRS)

Hardage, Donna (Technical Monitor); Walters, R. J.; Morton, T. L.; Messenger, S. R.

2004-01-01

The objective is to develop an improved space solar cell radiation response analysis capability and to produce a computer modeling tool which implements the analysis. This was accomplished through analysis of solar cell flight data taken on the Microelectronics and Photonics Test Bed experiment. This effort specifically addresses issues related to rapid technological change in the area of solar cells for space applications in order to enhance system performance, decrease risk, and reduce cost for future missions.

Damage to Candida albicans Hyphae and Pseudohyphae by the Myeloperoxidase System and Oxidative Products of Neutrophil Metabolism In Vitro

PubMed Central

Diamond, Richard D.; Clark, Robert A.; Haudenschild, Christian C.

1980-01-01

In previous studies, we noted that Candida hyphae and pseudohyphae could be damaged and probably killed by neutrophils, primarily by oxygen-dependent nonphagocytic mechanisms. In extending these studies, amount of damage to hyphae again was measured by inhibition of [14C]cytosine uptake. Neutrophils from only one of four patients with chronic granulomatous disease damaged hyphae at all, and neutrophils from this single patient damaged hyphae far less efficiently than simultaneously tested neutrophils from normal control subjects. Neutrophils from neither of two subjects with hereditary myeloperoxidase deficiency damaged the hyphae. This confirmed the importance of oxidative mechanisms in general and myeloperoxidase-mediated systems in particular in damaging Candida hyphae. Several potentially fungicidal oxidative intermediates are produced by metabolic pathways of normal neutrophils, but their relative toxicity for Candida hyphae was previously unknown. To help determine this, cell-free in vitro systems were used to generate these potentially microbicidal products. Myeloperoxidase with hydrogen peroxide, iodide, and chloride resulted in 91.2% damage to hyphal inocula in 11 experiments. There was less damage when either chloride or iodide was omitted, and no damage when myeloperoxidase was omitted or inactivated by heating. Azide, cyanide, and catalase (but not heated catalase) inhibited the damage. Systems for generation of hydrogen peroxide could replace reagent hydrogen peroxide in the myeloperoxidase system. These included glucose oxidase, in the presence of glucose, and xanthine oxidase, in the presence of either hypoxanthine or acetaldehyde. In the presence of myeloperoxidase and a halide, the toxicity of the xanthine oxidase system was not inhibited by superoxide dismutase and, under some conditions, was marginally increased by this enzyme. This suggested that superoxide radical did not damage hyphae directly but served primarily as an intermediate in the production of hydrogen peroxide. The possible damage to hyphae by singlet oxygen was examined using photoactivation of rose bengal. This dye damaged hyphae in the presence of light and oxygen. The effect was almost completely inhibited by putative quenchers of singlet oxygen: histidine, tryptophan, and 1,4-diazobicyclo[2.2.2]octane. These agents also inhibited damage to hyphae by myeloperoxidase, halide, and either hydrogen peroxide or a peroxide source (xanthine oxidase plus acetaldehyde). Myeloperoxidase-mediated damage to hyphae was also inhibited by dimethyl sulfoxide, an antioxidant and scavenger of the hydroxyl radical. These data support the involvement of oxidative mechanisms and the myeloperoxidase-H2O2-halide system, in particular in damaging hyphae in vitro and perhaps in vivo as well. Images PMID:6253527

Reinforced Carbon-Carbon Subcomponent Flat Plate Impact Testing for Space Shuttle Orbiter Return to Flight

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Brand, Jeremy H.; Pereira, J. Michael; Revilock, Duane M.

2007-01-01

Following the tragedy of the Space Shuttle Columbia on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the Space Shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize Reinforced Carbon-Carbon (RCC) and various debris materials which could potentially shed on ascent and impact the Orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS DYNA to predict damage by potential and actual impact events on the Orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: fundamental tests to obtain independent static and dynamic material model properties of materials of interest, sub-component impact tests to provide highly controlled impact test data for the correlation and validation of the models, and full-scale impact tests to establish the final level of confidence for the analysis methodology. This paper discusses the second level subcomponent test program in detail and its application to the LS DYNA model validation process. The level two testing consisted of over one hundred impact tests in the NASA Glenn Research Center Ballistic Impact Lab on 6 by 6 in. and 6 by 12 in. flat plates of RCC and evaluated three types of debris projectiles: BX 265 External Tank foam, ice, and PDL 1034 External Tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile. The information obtained from this testing validated the LS DYNA damage prediction models and provided a certain level of confidence to begin performing analysis for full-size RCC test articles for returning NASA to flight with STS 114 and beyond.

Semi-Automated Air-Coupled Impact-Echo Method for Large-Scale Parkade Structure.

PubMed

Epp, Tyler; Svecova, Dagmar; Cha, Young-Jin

2018-03-29

Structural Health Monitoring (SHM) has moved to data-dense systems, utilizing numerous sensor types to monitor infrastructure, such as bridges and dams, more regularly. One of the issues faced in this endeavour is the scale of the inspected structures and the time it takes to carry out testing. Installing automated systems that can provide measurements in a timely manner is one way of overcoming these obstacles. This study proposes an Artificial Neural Network (ANN) application that determines intact and damaged locations from a small training sample of impact-echo data, using air-coupled microphones from a reinforced concrete beam in lab conditions and data collected from a field experiment in a parking garage. The impact-echo testing in the field is carried out in a semi-autonomous manner to expedite the front end of the in situ damage detection testing. The use of an ANN removes the need for a user-defined cutoff value for the classification of intact and damaged locations when a least-square distance approach is used. It is postulated that this may contribute significantly to testing time reduction when monitoring large-scale civil Reinforced Concrete (RC) structures.

Semi-Automated Air-Coupled Impact-Echo Method for Large-Scale Parkade Structure

PubMed Central

Epp, Tyler; Svecova, Dagmar; Cha, Young-Jin

2018-01-01

Structural Health Monitoring (SHM) has moved to data-dense systems, utilizing numerous sensor types to monitor infrastructure, such as bridges and dams, more regularly. One of the issues faced in this endeavour is the scale of the inspected structures and the time it takes to carry out testing. Installing automated systems that can provide measurements in a timely manner is one way of overcoming these obstacles. This study proposes an Artificial Neural Network (ANN) application that determines intact and damaged locations from a small training sample of impact-echo data, using air-coupled microphones from a reinforced concrete beam in lab conditions and data collected from a field experiment in a parking garage. The impact-echo testing in the field is carried out in a semi-autonomous manner to expedite the front end of the in situ damage detection testing. The use of an ANN removes the need for a user-defined cutoff value for the classification of intact and damaged locations when a least-square distance approach is used. It is postulated that this may contribute significantly to testing time reduction when monitoring large-scale civil Reinforced Concrete (RC) structures. PMID:29596332

Crack identification for reinforced concrete using PZT based smart rebar active sensing diagnostic network

NASA Astrophysics Data System (ADS)

Song, N. N.; Wu, F.

2016-04-01

An active sensing diagnostic system using PZT based smart rebar for SHM of RC structure has been currently under investigation. Previous test results showed that the system could detect the de-bond of concrete from reinforcement, and the diagnostic signals were increased exponentially with the de-bonding size. Previous study also showed that the smart rebar could function well like regular reinforcement to undertake tension stresses. In this study, a smart rebar network has been used to detect the crack damage of concrete based on guided waves. Experimental test has been carried out for the study. In the test, concrete beams with 2 reinforcements have been built. 8 sets of PZT elements were mounted onto the reinforcement bars in an optimized way to form an active sensing diagnostic system. A 90 kHz 5-cycle Hanning-windowed tone burst was used as input. Multiple cracks have been generated on the concrete structures. Through the guided bulk waves propagating in the structures from actuators and sensors mounted from different bars, crack damage could be detected clearly. Cases for both single and multiple cracks were tested. Different crack depths from the surface and different crack numbers have been studied. Test result shows that the amplitude of sensor output signals is deceased linearly with a propagating crack, and is decreased exponentially with increased crack numbers. From the study, the active sensing diagnostic system using PZT based smart rebar network shows a promising way to provide concrete crack damage information through the "talk" among sensors.

Results of tests of Insta-Foam Thermal Protection System (TPS) material for protection of equipment inside the SRB aft skirt

NASA Technical Reports Server (NTRS)

Dean, W. G.

1982-01-01

The objective of these tests was to determine whether Insta-Foam can be used successfully to protect items inside the solid rocket booster aft skirt during reentry. On some of the early Space Shuttle flights the aft skirt heat shield curtain failed during reentry. This allowed the hot gases to damage some of the equipment, etc., inside the skirt. For example, some of the propellant lines were overheated and ruptured and some of the NSI (nozzle severance) cables were damaged. It was suggested that the Insta-Foam thermal protection system be sprayed over these lines, etc., to protect them during future flights in case of a curtain failure. The tests presented were devised and run to check out the feasibility of this idea.

Lightning Protection System for Space Shuttle

NASA Technical Reports Server (NTRS)

1977-01-01

The suitability and cost effectiveness of using a lightning mast for the shuttle service and access tower (SSAT) similar to the type used for the Apollo Soyuz Test Project (ASTP) mobile launcher (ML) was evaluated. Topics covered include: (1) ASTP launch damage to mast, mast supports, grounded overhead wires, and the instrumentation system; (2) modifications required to permit reusing the ASTP mast on the SSAT; (3) comparative costing factors per launch over a 10 year period in repetitive maintenance and refurbishment of the existing and modified masts, mast supports, grounded overhead wires, and ground instrumentation required to sustain mechanical and electrical integrity of the masts; (4) effects of blast testing samples of the ASTP ML type mast (corrosion and electrical flashover); (5) comparison of damages from ASTP launch and from blast testing.

Adaptable Holders for Arc-Jet Screening Candidate Thermal Protection System Repair Materials

NASA Technical Reports Server (NTRS)

Riccio, Joe; Milhoan, Jim D.

2010-01-01

Reusable holders have been devised for evaluating high-temperature, plasma-resistant re-entry materials, especially fabrics. Typical material samples tested support thermal-protection-system damage repair requiring evaluation prior to re-entry into terrestrial atmosphere. These tests allow evaluation of each material to withstand the most severe predicted re-entry conditions.

Evaluation of Fatigue Crack Growth and Fracture Properties of Cryogenic Model Materials

NASA Technical Reports Server (NTRS)

Newman, John A.; Forth, Scott C.; Everett, Richard A., Jr.; Newman, James C., Jr.; Kimmel, William M.

2002-01-01

The criteria used to prevent failure of wind-tunnel models and support hardware were revised as part of a project to enhance the capabilities of cryogenic wind tunnel testing at NASA Langley Research Center. Specifically, damage-tolerance fatigue life prediction methods are now required for critical components, and material selection criteria are more general and based on laboratory test data. The suitability of two candidate model alloys (AerMet 100 and C-250 steel) was investigated by obtaining the fatigue crack growth and fracture data required for a damage-tolerance fatigue life analysis. Finally, an example is presented to illustrate the newly implemented damage tolerance analyses required of wind-tunnel model system components.

Normalized spectral damage of a linear system over different spectral loading patterns

NASA Astrophysics Data System (ADS)

Kim, Chan-Jung

2017-08-01

Spectral fatigue damage is affected by different loading patterns; the damage may be accumulated in a different manner because the spectral pattern has an influence on stresses or strains. The normalization of spectral damage with respect to spectral loading acceleration is a novel solution to compare the accumulated fatigue damage over different spectral loading patterns. To evaluate the sensitivity of fatigue damage over different spectral loading cases, a simple notched specimen is used to conduct a uniaxial vibration test for two representative spectral patterns-random and harmonic-between 30 and 3000 Hz. The fatigue damage to the simple specimen is analyzed for different spectral loading cases using the normalized spectral damage from the measured response data for both acceleration and strain. The influence of spectral loading patterns is discussed based on these analyses.

International SAMPE Symposium and Exhibition, 35th, Anaheim, CA, Apr. 2-5, 1990, Proceedings. Books 1 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janicki, G.; Bailey, V.; Schjelderup, H.

The present conference discusses topics in the fields of ultralightweight structures, producibility of thermoplastic composites, innovation in sandwich structures, composite failure processes, toughened materials, metal-matrix composites, advanced materials for future naval systems, thermoplastic polymers, automated composites manufacturers, advanced adhesives, emerging processes for aerospace component fabrication, and modified resin systems. Also discussed are matrix behavior for damage tolerance, composite materials repair, testing for damage tolerance, composite strength analyses, materials workplace health and safety, cost-conscious composites, bismaleimide systems, and issues facing advanced composite materials suppliers.

Investigation of Gearbox Vibration Transmission Paths on Gear Condition Indicator Performance

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Islam, AKM Anwarul; Feldman, Jason; Larsen, Chris

2013-01-01

Helicopter health monitoring systems use vibration signatures generated from damaged components to identify transmission faults. For damaged gears, these signatures relate to changes in dynamics due to the meshing of the damaged tooth. These signatures, referred to as condition indicators (CI), can perform differently when measured on different systems, such as a component test rig, or a full-scale transmission test stand, or an aircraft. These differences can result from dissimilarities in systems design and environment under dynamic operating conditions. The static structure can also filter the response between the vibration source and the accelerometer, when the accelerometer is installed on the housing. To assess the utility of static vibration transfer paths for predicting gear CI performance, measurements were taken on the NASA Glenn Spiral Bevel Gear Fatigue Test Rig. The vibration measurements were taken to determine the effect of torque, accelerometer location and gearbox design on accelerometer response. Measurements were taken at the housing and compared while impacting the gear set near mesh. These impacts were made at gear mesh to simulate gear meshing dynamics. Data measured on a helicopter gearbox installed in a static fixture were also compared to the test rig. The behavior of the structure under static conditions was also compared to CI values calculated under dynamic conditions. Results indicate that static vibration transfer path measurements can provide some insight into spiral bevel gear CI performance by identifying structural characteristics unique to each system that can affect specific CI response.

The Application of Voltage Transformer Simulator in Electrical Test Training

NASA Astrophysics Data System (ADS)

Li, Nan; Zhang, Jun; Chai, Ziqi; Wang, Jingpeng; Yang, Baowei

2018-02-01

The voltage transformer test is an important means to monitor its operating state. The accuracy and reliability of the test data is directly related to the test skill level of the operator. However, the risk of test instruments damage, equipment being tested damage and electric shock in operator is caused by improper operation when training the transformer test. In this paper, a simulation device of voltage transformer is set up, and a simulation model is built for the most common 500kV capacitor voltage transformer (CVT), the simulation model can realize several test items of CVT by combing with teaching guidance platform, simulation instrument, complete set of system software and auxiliary equipment in Changchun. Many successful applications show that the simulation device has good practical value and wide application prospect.

A computer vision system for the recognition of trees in aerial photographs

NASA Technical Reports Server (NTRS)

Pinz, Axel J.

1991-01-01

Increasing problems of forest damage in Central Europe set the demand for an appropriate forest damage assessment tool. The Vision Expert System (VES) is presented which is capable of finding trees in color infrared aerial photographs. Concept and architecture of VES are discussed briefly. The system is applied to a multisource test data set. The processing of this multisource data set leads to a multiple interpretation result for one scene. An integration of these results will provide a better scene description by the vision system. This is achieved by an implementation of Steven's correlation algorithm.

Experimental apparatus to test air trap valves

NASA Astrophysics Data System (ADS)

Lemos De Lucca, Y. de F.; de Aquino, G. A.; Filho, J. G. D.

2010-08-01

It is known that the presence of trapped air within water distribution pipes can lead to irregular operation or even damage to the distribution systems and their components. The presence of trapped air may occur while the pipes are being filled with water, or while the pumping systems are in operation. The formation of large air pockets can produce the water hammer phenomenon, the instability and the loss of pressure in the water distribution networks. As a result, it can overload the pumps, increase the consumption of electricity, and damage the pumping system. In order to avoid its formation, all of the trapped air should be removed through "air trap valves". In Brazil, manufacturers frequently have unreliable sizing charts, which cause malfunctioning of the "air trap valves". The result of these malfunctions causes accidents of substantial damage. The construction of a test facility will provide a foundation of technical information that will be used to help make decisions when designing a system of pipelines where "air trap valves" are used. To achieve this, all of the valve characteristics (geometric, mechanic, hydraulic and dynamic) should be determined. This paper aims to describe and analyze the experimental apparatus and test procedure to be used to test "air trap valves". The experimental apparatus and test facility will be located at the University of Campinas, Brazil at the College of Civil Engineering, Architecture, and Urbanism in the Hydraulics and Fluid Mechanics laboratory. The experimental apparatus will be comprised of various components (pumps, steel pipes, butterfly valves to control the discharge, flow meter and reservoirs) and instrumentation (pressure transducers, anemometer and proximity sensor). It should be emphasized that all theoretical and experimental procedures should be defined while taking into consideration flow parameters and fluid properties that influence the tests.

Application of outlier analysis for baseline-free damage diagnosis

NASA Astrophysics Data System (ADS)

Kim, Seung Dae; In, Chi Won; Cronin, Kelly E.; Sohn, Hoon; Harries, Kent

2006-03-01

As carbon fiber-reinforced polymer (CFRP) laminates have been widely accepted as valuable materials for retrofitting civil infrastructure systems, an appropriate assessment of bonding conditions between host structures and CFRP laminates becomes a critical issue to guarantee the performance of CFRP strengthened structures. This study attempts to develop a continuous performance monitoring system for CFRP strengthened structures by autonomously inspecting the bonding conditions between the CFRP layers and the host structure. The uniqueness of this study is to develop a new concept and theoretical framework of nondestructive testing (NDT), in which debonding is detected "without using past baseline data." The proposed baseline-free damage diagnosis is achieved in two stages. In the first step, features sensitive to debonding of the CFPR layers but insensitive to loading conditions are extracted based on a concept referred to as a time reversal process. This time reversal process allows extracting damage-sensitive features without direct comparison with past baseline data. Then, a statistical damage classifier will be developed in the second step to make a decision regarding the bonding condition of the CFRP layers. The threshold necessary for decision making will be adaptively determined without predetermined threshold values. Monotonic and fatigue load tests of full-scale CFRP strengthened RC beams are conducted to demonstrate the potential of the proposed reference-free debonding monitoring system.

In-Space Repair of Reinforced Carbon-Carbon (RCC) Thermal Protection System Structures

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay

2005-01-01

Advanced repair and refurbishment technologies are critically needed for the RCC-based thermal protection system of current space transportation system as well as for future Crew Exploration Vehicles (CEV). The damage to these components could be caused by impact during ground handling or due to falling of ice or other objects during launch. In addition, in-orbit damage includes micrometeoroid and orbital debris impact as well as different factors (weather, launch acoustics, shearing, etc.) during launch and re-entry. The GRC developed GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair) material has shown multiuse capability for repair of small cracks and damage in reinforced carbon-carbon (RCC) material. The concept consists of preparing an adhesive paste of desired ceramic with appropriate adhesives and then applying the paste to the damaged/cracked area of the RCC composites with adhesive delivery system. The adhesive paste cures at 100-120 C and transforms into a high temperature ceramic during simulated entry conditions. A number of plasma torch and ArcJet tests were carried out to evaluate the crack repair capability of GRABER materials for Reinforced Carbon-Carbon (RCC) composites. For the large area repair applications, PLASTER (Patch Laminates and Sealant Technology for Exterior Repair) based systems have been developed. In this presentation, critical in-space repair needs and technical challenges as well as various issues and complexities will be discussed along with the plasma performance and post test characterization of repaired RCC materials.

In-Space Repair of Reinforced Carbon-Carbon Thermal Protection System Structures

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay

2006-01-01

Advanced repair and refurbishment technologies are critically needed for the thermal protection system of current space transportation system as well as for future Crew Exploration Vehicles (CEV). The damage to these components could be caused by impact during ground handling or due to falling of ice or other objects during launch. In addition, in-orbit damage includes micrometeoroid and orbital debris impact as well as different factors (weather, launch acoustics, shearing, etc.) during launch and re-entry. The GRC developed GRABER (Glenn Refractory Adhesive for Bonding and Exterior Repair) material has shown multiuse capability for repair of small cracks and damage in reinforced carbon-carbon (RCC) material. The concept consists of preparing an adhesive paste of desired ceramic with appropriate additives and then applying the paste to the damaged/cracked area of the RCC composites with adhesive delivery system. The adhesive paste cures at 100-120 C and transforms into a high temperature ceramic during simulated entry conditions. A number of plasma torch and ArcJet tests were carried out to evaluate the crack repair capability of GRABER materials for Reinforced Carbon-Carbon (RCC) composites. For the large area repair applications, integrated system for tile and leading edge repair (InSTALER) have been developed. In this presentation, critical in-space repair needs and technical challenges as well as various issues and complexities will be discussed along with the plasma performance and post test characterization of repaired RCC materials.

UV-B affects the immune system and promotes nuclear abnormalities in pigmented and non-pigmented bullfrog tadpoles.

PubMed

Franco-Belussi, Lilian; Fanali, Lara Zácari; De Oliveira, Classius

2018-03-01

Ultra-Violet (UV) radiation is a stressor of the immune system and causes DNA damage. Leukocytes can change in response to environmental changes in anurans, making them an important biomarker of stressful situations. The initial barrier against UV in ectothermic animals is melanin-containing cells in skin and in their internal organs. Here, we tested the effects of UV exposure on immune cells and DNA integrity in pigmented and non-pigmented tadpoles of Lithobates catesbeianus. We used an inflammation model with lipopolysaccharide (LPS) of Escherichia coli to test synergic effects of UV and LPS. We tested the following hypotheses: 1) DNA damage caused by UV will be more pronounced in non-pigmented than in pigmented animals; 2) LPS increases leukocytes in both pigmented and non-pigmented animals by systemic inflammation; 3) The combined LPS and UV exposure will decrease the number of leukocytes. We found that the frequency of immune cells differed between pigmented and non-pigmented tadpoles. UV exposure increased mast cells and DNA damage in erythrocytes in both pigmented and non-pigmented tadpoles, while leukocytes decreased after UV exposure. Non-pigmented tadpoles experienced DNA damage and a lower lymphocyte count earlier than pigmented tadpoles. UV altered immune cells likely as a consequence of local and systemic inflammation. These alterations were less severe in pigmented than in non-pigmented animals. UV and LPS increased internal melanin in pigmented tadpoles, which were correlated with DNA damage and leukocytes. Here, we described for the first time the effects of UV and LPS in immune cells of pigmented and non-pigmented tadpoles. In addition, we demonstrated that internal melanin in tadpoles help in these defenses, since leukocyte responses were faster in non-pigmented animals, supporting the hypothesis that melanin is involved in the initial innate immune response. Copyright © 2018 Elsevier B.V. All rights reserved.

Damage Simulation in Composite Materials: Why It Matters and What Is Happening Currently at NASA in This Area

NASA Technical Reports Server (NTRS)

McElroy, Mack; de Carvalho, Nelson; Estes, Ashley; Lin, Shih-yung

2017-01-01

Use of lightweight composite materials in space and aircraft structure designs is often challenging due to high costs associated with structural certification. Of primary concern in the use of composite structures is durability and damage tolerance. This concern is due to the inherent susceptibility of composite materials to both fabrication and service induced flaws. Due to a lack of general industry accepted analysis tools applicable to composites damage simulation, a certification procedure relies almost entirely on testing. It is this reliance on testing, especially compared to structures comprised of legacy metallic materials where damage simulation tools are available, that can drive costs for using composite materials in aerospace structures. The observation that use of composites can be expensive due to testing requirements is not new and as such, research on analysis tools for simulating damage in composite structures has been occurring for several decades. A convenient approach many researchers/model-developers in this area have taken is to select a specific problem relevant to aerospace structural certification and develop a model that is accurate within that scope. Some examples are open hole tension tests, compression after impact tests, low-velocity impact, damage tolerance of an embedded flaw, and fatigue crack growth to name a few. Based on the premise that running analyses is cheaper than running tests, one motivation that many researchers in this area have is that if generally applicable and reliable damage simulation tools were available the dependence on certification testing could be lessened thereby reducing overall design cost. It is generally accepted that simulation tools if applied in this manner would still need to be thoroughly validated and that composite testing will never be completely replaced by analysis. Research and development is currently occurring at NASA to create numerical damage simulation tools applicable to damage in composites. The Advanced Composites Project (ACP) at NASA Langley has supported the development of composites damage simulation tools in a consortium of aerospace companies with a goal of reducing the certification time of a commercial aircraft by 30%. And while the scope of ACP does not include spacecraft, much of the methodology and simulation capabilities can apply to spacecraft certification in the Space Launch System and Orion programs as well. Some specific applications of composite damage simulation models in a certification program are (1) evaluation of damage during service when maintenance may be difficult or impossible, (2) a tool for early design iterations, (3) gaining insight into a particular damage process and applying this insight towards a test coupon or structural design, and (4) analysis of damage scenarios that are difficult or impossible to recreate in a test. As analysis capabilities improve, these applications and more will become realized resulting in a reduction in cost for use of composites in aerospace vehicles. NASA is engaged in this process from both research and application perspectives. In addition to the background information discussed previously, this presentation covers a look at recent research at NASA in this area and some current/potential applications in the Orion program.

Sandwich Structure Risk Reduction in Support of the Payload Adapter Fitting

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Jackson, J. R.; Guin, W. E.

2018-01-01

Reducing risk for utilizing honeycomb sandwich structure for the Space Launch System payload adapter fitting includes determining what parameters need to be tested for damage tolerance to ensure a safe structure. Specimen size and boundary conditions are the most practical parameters to use in damage tolerance inspection. The effect of impact over core splices and foreign object debris between the facesheet and core is assessed. Effects of enhanced damage tolerance by applying an outer layer of carbon fiber woven cloth is examined. A simple repair technique for barely visible impact damage that restores all compression strength is presented.

Impact Testing of Orbiter Thermal Protection System Materials

NASA Technical Reports Server (NTRS)

Kerr, Justin

2006-01-01

This viewgraph presentation reviews the impact testing of the materials used in designing the shuttle orbiter thermal protection system (TPS). Pursuant to the Columbia Accident Investigation Board recommendations a testing program of the TPS system was instituted. This involved using various types of impactors in different sizes shot from various sizes and strengths guns to impact the TPS tiles and the Leading Edge Structural Subsystem (LESS). The observed damage is shown, and the resultant lessons learned are reviewed.

Round window administration of gentamicin: a new method for the study of ototoxicity of cochlear hair cells.

PubMed

Husmann, K R; Morgan, A S; Girod, D A; Durham, D

1998-11-01

Damage to inner ear sensory hair cells after systemic administration of ototoxic drugs has been documented in humans and animals. Birds have the ability to regenerate new hair cells to replace those damaged by drugs or noise. Unfortunately, the systemic administration of gentamicin damages both ears in a variable fashion with potentially confounding systemic drug effects. We developed a method of direct application of gentamicin to one cochlea of hatchling chickens, allowing the other ear to serve as a within-animal control. We tested variables including the vehicle for application, location of application, dosage, and duration of gentamicin exposure. After 5 or 28 days survival, the percent length damage to the cochlea and regeneration of hair cells was evaluated using scanning electron microscopy. Controls consisted of the opposite unexposed cochlea and additional animals which received saline instead of gentamicin. Excellent damage was achieved using gentamicin-soaked Gelfoam pledgets applied to the round window membrane. The percent length damage could be varied from 15 to 100% by changing the dosage of gentamicin, with exposures as short as 30 min. No damage was observed in control animals. Regeneration of hair cells was observed in both the base and apex by 28 days survival.

Experimental investigation and damage assessment in a post tensioned concrete beam

NASA Astrophysics Data System (ADS)

Limongelli, Maria; Siegert, Dominique; Merliot, Erick; Waeytens, Julien; Bourquin, Frederic; Vidal, Roland; Le Corvec, Veronique; Guegen, Ivan; Cottineau, Louis-Marie

2017-04-01

This paper presents the results of an experimental campaign carried out on a prestressed concrete beam in the realm of the project SIPRIS (Systèmes Intelligents pour la Prévention des Risques Structurels), aimed to develop intelligent systems for the prevention of structural risk related to the aging of large infrastructures. The specimen was tested in several configurations aimed to re-produce several different phases of the 'life' of the beam: in the original undamaged state, under an increasing loss of tension in the cables, during and after cracking induced by a point load, after a strengthening intervention, after new cracking of the 'repaired' beam. Damage was introduced in a controlled way by means of three-point static bending tests. The transverse point loads were ap-plied at several different sections along the beam axis. Before and after each static test, the dy-namical response of the beam was measured under sine-sweep and impact tests by an extensive set of accelerometers deployed along the beam axis. The availability of both static and dynamic tests allows to investigate and compare their effectiveness to detect damages in the tensioned beam and to reliably identify the evolution of damage. The paper discusses the tests program and some results relevant to the dynamic characterization of the beam in the different phases.

Fiber-Optic Defect and Damage Locator System for Wind Turbine Blades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dr. Vahid Sotoudeh; Dr. Richard J. Black; Dr. Behzad Moslehi

2010-10-30

IFOS in collaboration with Auburn University demonstrated the feasibility of a Fiber Bragg Grating (FBG) integrated sensor system capable of providing real time in-situ defect detection, localization and quantification of damage. In addition, the system is capable of validating wind turbine blade structural models, using recent advances in non-contact, non-destructive dynamic testing of composite structures. This new generation method makes it possible to analyze wind turbine blades not only non-destructively, but also without physically contacting or implanting intrusive electrical elements and transducers into the structure. Phase I successfully demonstrated the feasibility of the technology with the construction of a 1.5more » kHz sensor interrogator and preliminary instrumentation and testing of both composite material coupons and a wind turbine blade.« less

A high accuracy femto-/picosecond laser damage test facility dedicated to the study of optical thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mangote, B.; Gallais, L.; Zerrad, M.

2012-01-15

A laser damage test facility delivering pulses from 100 fs to 3 ps and designed to operate at 1030 nm is presented. The different details of its implementation and performances are given. The originality of this system relies the online damage detection system based on Nomarski microscopy and the use of a non-conventional energy detection method based on the utilization of a cooled CCD that offers the possibility to obtain the laser induced damage threshold (LIDT) with high accuracy. Applications of this instrument to study thin films under laser irradiation are presented. Particularly the deterministic behavior of the sub-picosecond damagemore » is investigated in the case of fused silica and oxide films. It is demonstrated that the transition of 0-1 damage probability is very sharp and the LIDT is perfectly deterministic at few hundreds of femtoseconds. The damage process in dielectric materials being the results of electronic processes, specific information such as the material bandgap is needed for the interpretation of results and applications of scaling laws. A review of the different approaches for the estimation of the absorption gap of optical dielectric coatings is conducted and the results given by the different methods are compared and discussed. The LIDT and gap of several oxide materials are then measured with the presented instrument: Al{sub 2}O{sub 3}, Nb{sub 2}O{sub 5}, HfO{sub 2}, SiO{sub 2}, Ta{sub 2}O{sub 5}, and ZrO{sub 2}. The obtained relation between the LIDT and gap at 1030 nm confirms the linear evolution of the threshold with the bandgap that exists at 800 nm, and our work expands the number of tested materials.« less

Nanotechnology

NASA Technical Reports Server (NTRS)

Biaggi-Labiosa, Azlin

2016-01-01

Present an overview of the Nanotechnology Project at NASA's Game Changing Technology Industry Day. Mature and demonstrate flight readiness of CNT reinforced composites for future NASA mission applications?Sounding rocket test in a multiexperiment payload?Integrate into cold gas thruster system as propellant storage?The technology would provide the means for reduced COPV mass and improved damage tolerance and flight qualify CNT reinforced composites. PROBLEM/NEED BEING ADDRESSED:?Reduce weight and enhance the performance and damage tolerance of aerospace structuresGAME-CHANGING SOLUTION:?Improve mechanical properties of CNTs to eventually replace CFRP –lighter and stronger?First flight-testing of a CNT reinforced composite structural component as part of an operational flight systemUNIQUENESS:?CNT manufacturing methods developed?Flight qualify CNT reinforced composites

Development of an Opto-Acoustic Recanalization System Final Report CRADA No. 1314-96

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, L. D.; Adam, H. R.

The objective of the project was to develop an ischemic stroke treatient system that restores blood flow to the brain by removing occlusions using acoustic energy created by fiber optic delivery of laser light, a process called Opto Acoustic Recanalization (OAR). The key tasks of the project were to select a laser system, quantify temperature, pressure and particle size distribution, and develop a prototype device incorporating a feedback mechanism. System parameters were developed to cause emulsification while attempting to minimize particle size and collateral damage. The prototype system was tested in animal models and resulted in no visible collateral damage.

Ultrasonic scanning system for imaging flaw growth in composites

NASA Technical Reports Server (NTRS)

Kiraly, L. J.; Meyn, E. H.

1982-01-01

A system for measuring and visually representing damage in composite specimens while they are being loaded was demonstrated. It uses a hobbiest grade microcomputer system to control data taking and image processing. The system scans operator selected regions of the specimen while it is under load in a tensile test machine and measures internal damage by the attenuation of a 2.5 MHz ultrasonic beam passed through the specimen. The microcomputer dynamically controls the position of ultrasonic transducers mounted on a two axis motor driven carriage. As many as 65,536 samples can be taken and filed on a floppy disk system in less than four minutes.

Multiple pulse nanosecond laser induced damage threshold on hybrid mirrors

NASA Astrophysics Data System (ADS)

Vanda, Jan; Muresan, Mihai-George; Bilek, Vojtech; Sebek, Matej; Hanus, Martin; Lucianetti, Antonio; Rostohar, Danijela; Mocek, Tomas; Škoda, Václav

2017-11-01

So-called hybrid mirrors, consisting of broadband metallic surface coated with dielectric reflector designed for specific wavelength, becoming more important with progressing development of broadband mid-IR sources realized using parametric down conversion system. Multiple pulse nanosecond laser induced damage on such mirrors was tested by method s-on-1, where s stands for various numbers of pulses. We show difference in damage threshold between common protected silver mirrors and hybrid silver mirrors prepared by PVD technique and their variants prepared by IAD. Keywords: LIDT,

An embedded fibre optic sensor for impact damage detection in composite materials

NASA Astrophysics Data System (ADS)

Glossop, Neil David William

1989-09-01

A structurally embedded fiber optic damage detection sensor for composite materials is described. The system is designed specifically for the detection of barely visible damage resulting from low velocity impacts in Kevlar-epoxy laminates. By monitoring the light transmission properties of optical fiber embedded in the composite, it was shown that the integrity of the material can be accurately determined. The effect of several parameters on the sensitivity of the system was investigated, including the effect of the optical fiber orientation and depth of embedding within the composite. A novel surface was also developed for the optical fibers to ensure they will fracture at the requisite damage level. The influence of the optical fiber sensors on the tensile and compressive material properties and on the impact resistance of the laminate was also studied. Extensive experimental results from impact tests are reported and a numerical model of the impact event is presented which is able to predict and model the damage mechanism and sensor system. A new and powerful method of nondestructive evaluation for translucent composite materials based on image enhanced backlighting is also described.

The Ex Vivo Eye Irritation Test as an alternative test method for serious eye damage/eye irritation.

PubMed

Spöler, Felix; Kray, Oya; Kray, Stefan; Panfil, Claudia; Schrage, Norbert F

2015-07-01

Ocular irritation testing is a common requirement for the classification, labelling and packaging of chemicals (substances and mixtures). The in vivo Draize rabbit eye test (OECD Test Guideline 405) is considered to be the regulatory reference method for the classification of chemicals according to their potential to induce eye injury. In the Draize test, chemicals are applied to rabbit eyes in vivo, and changes are monitored over time. If no damage is observed, the chemical is not categorised. Otherwise, the classification depends on the severity and reversibility of the damage. Alternative test methods have to be designed to match the classifications from the in vivo reference method. However, observation of damage reversibility is usually not possible in vitro. Within the present study, a new organotypic method based on rabbit corneas obtained from food production is demonstrated to close this gap. The Ex Vivo Eye Irritation Test (EVEIT) retains the full biochemical activity of the corneal epithelium, epithelial stem cells and endothelium. This permits the in-depth analysis of ocular chemical trauma beyond that achievable by using established in vitro methods. In particular, the EVEIT is the first test to permit the direct monitoring of recovery of all corneal layers after damage. To develop a prediction model for the EVEIT that is comparable to the GHS system, 37 reference chemicals were analysed. The experimental data were used to derive a three-level potency ranking of eye irritation and corrosion that best fits the GHS categorisation. In vivo data available in the literature were used for comparison. When compared with GHS classification predictions, the overall accuracy of the three-level potency ranking was 78%. The classification of chemicals as irritating versus non-irritating resulted in 96% sensitivity, 91% specificity and 95% accuracy. 2015 FRAME.

Estimation of corrosion damage in steel reinforced mortar using waveguides

NASA Astrophysics Data System (ADS)

Reis, Henrique; Ervin, Benjamin L.; Kuchma, Daniel A.; Bernhard, Jennifer

2005-05-01

Corrosion of reinforced concrete is a chronic infrastructure problem, particularly in areas with deicing salt and marine exposure. To maintain structural integrity, a testing method is needed to identify areas of corroding reinforcement. For purposes of rehabilitation, the method must also be able to evaluate the degree, rate and location of damage. Towards the development of a wireless embedded sensor system to monitor and assess corrosion damage in reinforced concrete, reinforced mortar specimens were manufactured with seeded defects to simulate corrosion damage. Taking advantage of waveguide effects of the reinforcing bars, these specimens were then tested using an ultrasonic approach. Using the same ultrasonic approach, specimens without seeded defects were also monitored during accelerated corrosion tests. Both the ultrasonic sending and the receiving transducers were mounted on the steel rebar. Advantage was taken of the lower frequency (<250 kHz) fundamental flexural propagation mode because of its relatively large displacements at the interface between the reinforcing steel and the surrounding concrete. Waveform energy (indicative of attenuation) is presented and discussed in terms of corrosion damage. Current results indicate that the loss of bond strength between the reinforcing steel and the surrounding concrete can be detected and evaluated.

Effects of weld damage on the dynamics of energy-absorbing lanyards.

PubMed

Katona, David N; Bennett, Charlie R; McKoryk, Michael; Brisson, Andre L; Sparrey, Carolyn J

2017-12-01

Manufacturers recommend removing fall protection system components from service for any indication of weld spatter or tool damage; however, little is known about the specific effects of lanyard damage on fall arrest dynamics. Thirty-two energy-absorbing lanyards were drop tested after being damaged with weld spatter, plasma torches and cutting tools and compared with new, undamaged lanyards. Two lanyards damaged with a plasma torch failed completely without deploying the energy absorber while weld spatter damage and tool cuts, up to two-thirds through the width of the webbing, had no effect on fall arrest dynamics. The results highlight the catastrophic implications of high-temperature damage to lanyard webbing resulting from plasma torches - which require immediate removal from service. In addition, the integrated energy absorber design in bungee-style lanyards makes them more susceptible to damage anywhere along the length. We therefore recommended against bungee lanyards for ironworkers and welders.

Integrating Condition Indicators and Usage Parameters for Improved Spiral Bevel Gear Health Monitoring

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Handschuh, Robert F.; Delgado, Irebert R.

2013-01-01

The objective of this study was to illustrate the importance of combining Health Usage Monitoring Systems (HUMS) data with usage monitoring system data when detecting rotorcraft transmission health. Six gear sets were tested in the NASA Glenn Spiral Bevel Gear Fatigue Rig. Damage was initiated and progressed on the gear and pinion teeth. Damage progression was measured by debris generation and documented with inspection photos at varying torque values. A contact fatigue analysis was applied to the gear design indicating the effect temperature, load and reliability had on gear life. Results of this study illustrated the benefits of combining HUMS data and actual usage data to indicate progression of damage for spiral bevel gears.

Integrating Condition Indicators and Usage Parameters for Improved Spiral Bevel Gear Health Monitoring

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Handschuh, Robert F.; Delgado, Irebert, R.

2013-01-01

The objective of this study was to illustrate the importance of combining Health Usage Monitoring Systems (HUMS) data with usage monitoring system data when detecting rotorcraft transmission health. Three gear sets were tested in the NASA Glenn Spiral Bevel Gear Fatigue Rig. Damage was initiated and progressed on the gear and pinion teeth. Damage progression was measured by debris generation and documented with inspection photos at varying torque values. A contact fatigue analysis was applied to the gear design indicating the effect temperature, load and reliability had on gear life. Results of this study illustrated the benefits of combining HUMS data and actual usage data to indicate progression of damage for spiral bevel gears.

Damage detection of an in-service condensation pipeline joint

NASA Astrophysics Data System (ADS)

Briand, Julie; Rezaei, Davood; Taheri, Farid

2010-04-01

The early detection of damage in structural or mechanical systems is of vital importance. With early detection, the damage may be repaired before the integrity of the system is jeopardized, resulting in monetary losses, loss of life or limb, and environmental impacts. Among the various types of structural health monitoring techniques, vibration-based methods are of significant interest since the damage location does not need to be known beforehand, making it a more versatile approach. The non-destructive damage detection method used for the experiments herein is a novel vibration-based method which uses an index called the EMD Energy Damage Index, developed with the aim of providing improved qualitative results compared to those methods currently available. As part of an effort to establish the integrity and limitation of this novel damage detection method, field testing was completed on a mechanical pipe joint on a condensation line, located in the physical plant of Dalhousie University. Piezoceramic sensors, placed at various locations around the joint were used to monitor the free vibration of the pipe imposed through the use of an impulse hammer. Multiple damage progression scenarios were completed, each having a healthy state and multiple damage cases. Subsequently, the recorded signals from the healthy and damaged joint were processed through the EMD Energy Damage Index developed in-house in an effort to detect the inflicted damage. The proposed methodology successfully detected the inflicted damages. In this paper, the effects of impact location, sensor location, frequency bandwidth, intrinsic mode functions, and boundary conditions are discussed.

Investigation of the Leak Response of a Carbon-Fiber Laminate Loaded in Biaxial Tension

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Ratcliffe, James G.

2013-01-01

Designers of pressurized structures have been reluctant to use composite materials because of concerns over leakage. Biaxial stress states are expected to be the worst-case loading condition for allowing leakage to occur through microcracks. To investigate the leakage behavior under in-plane biaxial loading, a cruciform composite specimen was designed that would have a relatively large test section with a uniform 1:1 biaxial loading ratio. A 7.6-cm-square test section was desired for future investigations of the leakage response as a result of impact damage. Many iterations of the cruciform specimen were evaluated using finite element analysis to reduce stress concentrations and maximize the size of the uniform biaxial strain field. The final design allowed the specimen to go to relatively high biaxial strain levels without incurring damage away from the test section. The specimen was designed and manufactured using carbon/epoxy fabric with a four-ply-thick, quasi-isotropic, central test section. Initial validation and testing were performed on a specimen without impact damage. The specimen was tested to maximum biaxial strains of approximately 4500micro epsilon without apparent damage. A leak measurement system containing a pressurized cavity was clamped to the test section and used to measure the flow rate through the specimen. The leakage behavior of the specimen was investigated for pressure differences up to 172 kPa

Remtech SSME nozzle design TPS

NASA Technical Reports Server (NTRS)

Bancroft, Steven A.; Engel, Carl D.; Pond, John E.

1990-01-01

Thermal damage to the Space Shuttle Main Engine (SSME) aft manifold Thermal Protection System (TPS) has been observed for flights STS-8 through STS-13. This damaged area is located on the ME2 and ME3 and extends over a region of approximately one square foot. Total failure or burn-through of the TPS could lead to severe thermal damage of the SSME manifold and loss of an engine nozzle necessitating nozzle replacement causing significant schedule delays and cost increases. Thermal damage to the manifold can be defined as a situation where the manifold temperature becomes greater than 1300 F; thereby causing loss of heat treatment in the nozzle. Results of Orbiter/nozzle wind tunnel tests and Hot Gas Facility tests of the TPS are presented. Aerothermal and thermal analysis models for the SSME aft manifold are discussed along with the flight predictions, design trajectory and design environment. Finally, the TPS design concept and TPS thermal response are addressed.

Fukunaga-Koontz feature transformation for statistical structural damage detection and hierarchical neuro-fuzzy damage localisation

NASA Astrophysics Data System (ADS)

Hoell, Simon; Omenzetter, Piotr

2017-07-01

Considering jointly damage sensitive features (DSFs) of signals recorded by multiple sensors, applying advanced transformations to these DSFs and assessing systematically their contribution to damage detectability and localisation can significantly enhance the performance of structural health monitoring systems. This philosophy is explored here for partial autocorrelation coefficients (PACCs) of acceleration responses. They are interrogated with the help of the linear discriminant analysis based on the Fukunaga-Koontz transformation using datasets of the healthy and selected reference damage states. Then, a simple but efficient fast forward selection procedure is applied to rank the DSF components with respect to statistical distance measures specialised for either damage detection or localisation. For the damage detection task, the optimal feature subsets are identified based on the statistical hypothesis testing. For damage localisation, a hierarchical neuro-fuzzy tool is developed that uses the DSF ranking to establish its own optimal architecture. The proposed approaches are evaluated experimentally on data from non-destructively simulated damage in a laboratory scale wind turbine blade. The results support our claim of being able to enhance damage detectability and localisation performance by transforming and optimally selecting DSFs. It is demonstrated that the optimally selected PACCs from multiple sensors or their Fukunaga-Koontz transformed versions can not only improve the detectability of damage via statistical hypothesis testing but also increase the accuracy of damage localisation when used as inputs into a hierarchical neuro-fuzzy network. Furthermore, the computational effort of employing these advanced soft computing models for damage localisation can be significantly reduced by using transformed DSFs.

Testing and modeling of PBX-9591 shock initiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lam, Kim; Foley, Timothy; Novak, Alan

2010-01-01

This paper describes an ongoing effort to develop a detonation sensitivity test for PBX-9501 that is suitable for studying pristine and damaged HE. The approach involves testing and comparing the sensitivities of HE pressed to various densities and those of pre-damaged samples with similar porosities. The ultimate objectives are to understand the response of pre-damaged HE to shock impacts and to develop practical computational models for use in system analysis codes for HE safety studies. Computer simulation with the CTH shock physics code is used to aid the experimental design and analyze the test results. In the calculations, initiation andmore » growth or failure of detonation are modeled with the empirical HVRB model. The historical LANL SSGT and LSGT were reviewed and it was determined that a new, modified gap test be developed to satisfy the current requirements. In the new test, the donor/spacer/acceptor assembly is placed in a holder that is designed to work with fixtures for pre-damaging the acceptor sample. CTH simulations were made of the gap test with PBX-9501 samples pressed to three different densities. The calculated sensitivities were validated by test observations. The agreement between the computed and experimental critical gap thicknesses, ranging from 9 to 21 mm under various test conditions, is well within 1 mm. These results show that the numerical modeling is a valuable complement to the experimental efforts in studying and understanding shock initiation of PBX-9501.« less

The potential dysfunction of otolith organs in patients after mumps infection

PubMed Central

Tian, Liang; Han, Zhao; Wang, Jing; Chi, Fang-Lu

2017-01-01

Objective To investigate the relationship between mumps and the extent of hearing impairment and otolith organ damage. Methods A total of 27 patients with unilateral hearing impairment following mumps were enrolled. The degrees of hearing loss and otolith organ damage were confirmed by audiometric and vestibular evoked myogenic potential [VEMP] tests. All the results were compared and analyzed using Stata 13.0 software for Windows. Results The VEMP thresholds of the affected ears were significantly higher than those of the unaffected ears in both tests (cervical VEMP [cVEMP] test and ocular VEMP [oVEMP] test; p = 0.000 and 0.001, respectively). The mean cVEMP and oVEMP threshold values of the affected ears with hearing impairment for ≤10 years were significantly lower than those of affected ears with hearing impairment for >10 years [p = 0.009 and 0.004, respectively]. Conclusions Deafness resulting from mumps is usually profound and permanent, which indicates severe damage to the cochlea due to the disease. The functions of otolith organs in the vestibular system are also impaired. Over time, the function of the otolith organs or their neural pathway may suffer secondary damage. PMID:28746415

Vibration Testing of an Operating Stirling Convertor

NASA Technical Reports Server (NTRS)

Hughes, William O.; McNelis, Mark E.; Goodnight, Thomas W.

2000-01-01

The NASA John H. Glenn Research Center and the U.S. Department of Energy are currently developing a Stirling convertor for use as an advanced spacecraft power system for future NASA deep-space missions. As part of this development, a Stirling Technology Demonstrator Convertor (TDC) was recently tested to verify its survivability and capability of withstanding its expected launch random vibration environment. The TDC was fully operational (producing power) during the random vibration testing. The output power of the convertor was measured during the testing, and these results are discussed in this paper. Numerous accelerometers and force gauges were also present which provided information on the dynamic characteristics of the TDC and an indication of any possible damage due to vibration. These measurements will also be discussed in this paper. The vibration testing of the Stirling TDC was extremely successful. The TDC survived all its vibration testing with no structural damage or functional performance degradation. As a result of this testing, the Stirling convertor's capability to withstand vibration has been demonstrated, enabling its usage in future spacecraft power systems.

Repair of Budd Pioneer Coach car crush zones

DOT National Transportation Integrated Search

2007-05-01

The research team conducted a project to repair cars for use in a full-scale train-to-train collision test with crash energy management systems. The two cars had been damaged in previous dynamic tests. Several components required replacement, and som...

Response analysis of an automobile shipping container

NASA Technical Reports Server (NTRS)

Hua, L.; Lee, S. H.; Johnstone, B.

1973-01-01

The design and development of automobile shipping containers to reduce enroute damage are discussed. Vibration tests were conducted to determine the system structural integrity. A dynamic analysis was made using NASTRAN and the results of the test and the analysis are compared.

HLH Drive System

DTIC Science & Technology

1977-09-01

Material Comparison ....... .. 359 D-16 Comparison Chart - Rotor Brake Designs, Boeing Vertol, HLH ........... 360 D-17 Conventional Steel Disk Dynamic ...engines off. 0 In the event of a rotor brake caliper or disc failure, the system shall preclude damage to critical dynamic components. * The rotor brake... Dynamic System Test Rig (DSTR) shown in Figure. .8 provided a means for integrating and testing the aft and conbiner trans- missions, the aft rotor , thr’ee

A polarization sensitive hyperspectral imaging system for detection of differences in tissue properties

NASA Astrophysics Data System (ADS)

Peller, Joseph A.; Ceja, Nancy K.; Wawak, Amanda J.; Trammell, Susan R.

2018-02-01

Polarized light imaging and optical spectroscopy can be used to distinguish between healthy and diseased tissue. In this study, the design and testing of a single-pixel hyperspectral imaging system that uses differences in the polarization of light reflected from tissue to differentiate between healthy and thermally damaged tissue is discussed. Thermal lesions were created in porcine skin (n = 8) samples using an IR laser. The damaged regions were clearly visible in the polarized light hyperspectral images. Reflectance hyperspectral and white light imaging was also obtained for all tissue samples. Sizes of the thermally damaged regions as measured via polarized light hyperspectral imaging are compared to sizes of these regions as measured in the reflectance hyperspectral images and white light images. Good agreement between the sizes measured by all three imaging modalities was found. Hyperspectral polarized light imaging can differentiate between healthy and damaged tissue. Possible applications of this imaging system include determination of tumor margins during cancer surgery or pre-surgical biopsy.

Genetic fuzzy system for online structural health monitoring of composite helicopter rotor blades

NASA Astrophysics Data System (ADS)

Pawar, Prashant M.; Ganguli, Ranjan

2007-07-01

A structural health monitoring (SHM) methodology is developed for composite rotor blades. An aeroelastic analysis of composite rotor blades based on the finite element method in space and time and with implanted matrix cracking and debonding/delamination damage is used to obtain measurable system parameters such as blade response, loads and strains. A rotor blade with a two-cell airfoil section and [0/±45/90]s family of laminates is used for numerical simulations. The model based measurements are contaminated with noise to simulate real data. Genetic fuzzy systems (GFS) are developed for global online damage detection using displacement and force-based measurement deviations between damaged and undamaged conditions and for local online damage detection using strains. It is observed that the success rate of the GFS depends on number of measurements, type of measurements and training and testing noise level. The GFS work quite well with noisy data and is recommended for online SHM of composite helicopter rotor blades.

Evaluation of DNA damage and cytotoxicity of polyurethane-based nano- and microparticles as promising biomaterials for drug delivery systems

NASA Astrophysics Data System (ADS)

Caon, Thiago; Zanetti-Ramos, Betina Giehl; Lemos-Senna, Elenara; Cloutet, Eric; Cramail, Henri; Borsali, Redouane; Soldi, Valdir; Simões, Cláudia Maria Oliveira

2010-06-01

The in vitro cytotoxicity and DNA damage evaluation of biodegradable polyurethane-based micro- and nanoparticles were carried out on animal fibroblasts. For cytotoxicity measurement and primary DNA damage evaluation, MTT and Comet assays were used, respectively. Different formulations were tested to evaluate the influence of chemical composition and physicochemical characteristics of particles on cell toxicity. No inhibition of cells growth surrounding the polyurethane particles was observed. On the other hand, a decrease of cell viability was verified when the anionic surfactant sodium dodecyl sulfate (SDS) was used as droplets stabilizer of monomeric phase. Polyurethane nanoparticles stabilized with Tween 80 and Pluronic F68 caused minor cytotoxic effects. These results indicated that the surface charge plays an important role on cytotoxicity. Particles synthesized from MDI displayed a higher cytotoxicity than those synthesized from IPDI. Size and physicochemical properties of the particles may explain the higher degree of DNA damage produced by two tested formulations. In this way, a rational choice of particles' constituents based on their cytotoxicity and genotoxicity could be very useful for conceiving biomaterials to be used as drug delivering systems.

Structural Testing of a Stitched/Resin Film Infused Graphite-Epoxy Wing Box

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Bush, Harold G.

2001-01-01

The results of a series of tests conducted at the NASA Langley Research Center to evaluate the behavior of an all-composite full-scale wing box are presented. The wing box is representative of a section of a 220-passenger commercial transport aircraft wing box and was designed and constructed by The Boeing Company as part of the NASA Advanced Subsonics Technology (AST) program. The semi-span wing was fabricated from a graphite-epoxy material system with cover panels and spars held together using Kevlar stitches through the thickness. No mechanical fasteners were used to hold the stiffeners to the skin of the cover panels. Tests were conducted with and without low-speed impact damage, discrete source damage and repairs. Up-bending, down-bending and brake roll loading conditions were applied. The structure with non-visible impact damage carried 97% of Design Ultimate Load prior to failure through a lower cover panel access hole.

Effect of Electrostatic Discharge on Electrical Characteristics of Discrete Electronic Components

NASA Technical Reports Server (NTRS)

Wysocki, Phil; Vashchenko, Vladislav; Celaya, Jose; Saha, Sankalita; Goebel, Kai

2009-01-01

This article reports on preliminary results of a study conducted to examine how temporary electrical overstress seed fault conditions in discrete power electronic components that cannot be detected with reliability tests but impact longevity of the device. These defects do not result in formal parametric failures per datasheet specifications, but result in substantial change in the electrical characteristics when compared with pristine device parameters. Tests were carried out on commercially available 600V IGBT devices using transmission line pulse (TLP) and system level ESD stress. It was hypothesized that the ESD causes local damage during the ESD discharge which may greatly accelerate degradation mechanisms and thus reduce the life of the components. This hypothesis was explored in simulation studies where different types of damage were imposed to different parts of the device. Experimental results agree qualitatively with the simulation for a number of tests which will motivate more in-depth modeling of the damage.

Characterization of total ionizing dose damage in COTS pinned photodiode CMOS image sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zujun, E-mail: wangzujun@nint.ac.cn; Ma, Wuying; Huang, Shaoyan

The characterization of total ionizing dose (TID) damage in COTS pinned photodiode (PPD) CMOS image sensors (CISs) is investigated. The radiation experiments are carried out at a {sup 60}Co γ-ray source. The CISs are produced by 0.18-μm CMOS technology and the pixel architecture is 8T global shutter pixel with correlated double sampling (CDS) based on a 4T PPD front end. The parameters of CISs such as temporal domain, spatial domain, and spectral domain are measured at the CIS test system as the EMVA 1288 standard before and after irradiation. The dark current, random noise, dark signal non-uniformity (DSNU), photo responsemore » non-uniformity (PRNU), overall system gain, saturation output, dynamic range (DR), signal to noise ratio (SNR), quantum efficiency (QE), and responsivity versus the TID are reported. The behaviors of the tested CISs show remarkable degradations after radiation. The degradation mechanisms of CISs induced by TID damage are also analyzed.« less

Characterization of total ionizing dose damage in COTS pinned photodiode CMOS image sensors

NASA Astrophysics Data System (ADS)

Wang, Zujun; Ma, Wuying; Huang, Shaoyan; Yao, Zhibin; Liu, Minbo; He, Baoping; Liu, Jing; Sheng, Jiangkun; Xue, Yuan

2016-03-01

The characterization of total ionizing dose (TID) damage in COTS pinned photodiode (PPD) CMOS image sensors (CISs) is investigated. The radiation experiments are carried out at a 60Co γ-ray source. The CISs are produced by 0.18-μm CMOS technology and the pixel architecture is 8T global shutter pixel with correlated double sampling (CDS) based on a 4T PPD front end. The parameters of CISs such as temporal domain, spatial domain, and spectral domain are measured at the CIS test system as the EMVA 1288 standard before and after irradiation. The dark current, random noise, dark signal non-uniformity (DSNU), photo response non-uniformity (PRNU), overall system gain, saturation output, dynamic range (DR), signal to noise ratio (SNR), quantum efficiency (QE), and responsivity versus the TID are reported. The behaviors of the tested CISs show remarkable degradations after radiation. The degradation mechanisms of CISs induced by TID damage are also analyzed.

Limited Associations between Keel Bone Damage and Bone Properties Measured with Computer Tomography, Three-Point Bending Test, and Analysis of Minerals in Swiss Laying Hens

PubMed Central

Gebhardt-Henrich, Sabine G.; Pfulg, Andreas; Fröhlich, Ernst K. F.; Käppeli, Susanna; Guggisberg, Dominik; Liesegang, Annette; Stoffel, Michael H.

2017-01-01

Keel bone damage is a wide-spread welfare problem in laying hens. It is unclear so far whether bone quality relates to keel bone damage. The goal of the present study was to detect possible associations between keel bone damage and bone properties of intact and damaged keel bones and of tibias in end-of-lay hens raised in loose housing systems. Bones were palpated and examined by peripheral quantitative computer tomography (PQCT), a three-point bending test, and analyses of bone ash. Contrary to our expectations, PQCT revealed higher cortical and trabecular contents in fractured than in intact keel bones. This might be due to structural bone repair after fractures. Density measurements of cortical and trabecular tissues of keel bones did not differ between individuals with and without fractures. In the three-point bending test of the tibias, ultimate shear strength was significantly higher in birds with intact vs. fractured keel bones. Likewise, birds with intact or slightly deviated keel bones had higher mineral and calcium contents of the keel bone than birds with fractured keel bones. Calcium content in keel bones was correlated with calcium content in tibias. Although there were some associations between bone traits related to bone strength and keel bone damage, other factors such as stochastic events related to housing such as falls and collisions seem to be at least as important for the prevalence of keel bone damage. PMID:28848740

High Voltage Solar Array ARC Testing for a Direct Drive Hall Effect Thruster System

NASA Technical Reports Server (NTRS)

Schneider, T.; Vaughn, J.; Carruth, M. R.; Mikellides, I. G.; Jongeward, G. A.; Peterson, T.; Kerslake, T. W.; Snyder, D.; Ferguson, D.; Hoskins, A.

2003-01-01

The deleterious effects of spacecraft charging are well known, particularly when the charging leads to arc events. The damage that results from arcing can severely reduce system lifetime and even cause critical system failures. On a primary spacecraft system such as a solar array, there is very little tolerance for arcing. Motivated by these concerns, an experimental investigation was undertaken to determine arc thresholds for a high voltage (200-500 V) solar array in a plasma environment. The investigation was in support of a NASA program to develop a Direct Drive Hall-Effect Thruster (112HET) system. By directly coupling the solar array to a Hall-effect thruster, the D2HET program seeks to reduce mass, cost and complexity commonly associated with the power processing in conventional power systems. In the investigation, multiple solar array technologies and configurations were tested. The cell samples were biased to a negative voltage, with an applied potential difference between them, to imitate possible scenarios in solar array strings that could lead to damaging arcs. The samples were tested in an environment that emulated a low-energy, HET-induced plasma. Short duration "trigger" arcs as well as long duration "sustained" arcs were generated. Typical current and voltage waveforms associated with the arc events are presented. Arc thresholds are also defined in terms of vo!tage, (current and power. The data will be used to propose a new, high-voltage (>300 V) solar array design for which the likelihood of damage from arcing is minimal.

High Voltage Solar Array Arc Testing for a Direct Drive Hall Effect Thruster System

NASA Technical Reports Server (NTRS)

Schneider, Todd; Carruth, M. R., Jr.; Vaughn, J. A.; Jongeward, G. A.; Mikellides, I. G.; Ferguson, D.; Kerslake, T. W.; Peterson, T.; Snyder, D.; Hoskins, A.

2004-01-01

The deleterious effects of spacecraft charging are well known, particularly when the charging leads to arc events. The damage that results from arcing can severely reduce system lifetime and even cause critical system failures. On a primary spacecraft system such as a solar array, there is very little tolerance for arcing. Motivated by these concerns, an experimental investigation was undertaken to determine arc thresholds for a high voltage (200-500 V) solar array in a plasma environment. The investigation was in support of a NASA program to develop a Direct Drive Hall-Effect Thruster (D2HET) system. By directly coupling the solar array to a Hall-effect thruster, the D2HET program seeks to reduce mass, cost and complexity commonly associated with the power processing in conventional power systems. In the investigation, multiple solar array technologies and configurations were tested. The cell samples were biased to a negative voltage, with an applied potential difference between them, to imitate possible scenarios in solar array strings that could lead to damaging arcs. The samples were tested in an environment that emulated a low-energy, HET-induced plasma. Short duration trigger arcs as well as long duration sustained arcs were generated. Typical current and voltage waveforms associated with the arc events are presented. Arc thresholds are also defined in terms of voltage, current and power. The data will be used to propose a new, high-voltage (greater than 300 V) solar array design for which the likelihood of damage from arcing is minimal.

Quantification of Gear Tooth Damage by Optimal Tracking of Vibration Signatures

NASA Technical Reports Server (NTRS)

Choy, F. K.; Veillette, R. J.; Polyshchuk, V.; Braun, M. J.; Hendricks, R. C.

1996-01-01

This paper presents a technique for quantifying the wear or damage of gear teeth in a transmission system. The procedure developed in this study can be applied as a part of either an onboard machine health-monitoring system or a health diagnostic system used during regular maintenance. As the developed methodology is based on analysis of gearbox vibration under normal operating conditions, no shutdown or special modification of operating parameters is required during the diagnostic process. The process of quantifying the wear or damage of gear teeth requires a set of measured vibration data and a model of the gear mesh dynamics. An optimization problem is formulated to determine the profile of a time-varying mesh stiffness parameter for which the model output approximates the measured data. The resulting stiffness profile is then related to the level of gear tooth wear or damage. The procedure was applied to a data set generated artificially and to another obtained experimentally from a spiral bevel gear test rig. The results demonstrate the utility of the procedure as part of an overall health-monitoring system.

Plant genotoxicity: a molecular cytogenetic approach in plant bioassays.

PubMed

Maluszynska, Jolanta; Juchimiuk, Jolanta

2005-06-01

It is important for the prevention of DNA changes caused by environment to understand the biological consequences of DNA damages and their molecular modes of action that lead to repair or alterations of the genetic material. Numerous genotoxicity assay systems have been developed to identify DNA reactive compounds. The available data show that plant bioassays are important tests in the detection of genotoxic contamination in the environment and the establishment of controlling systems. Plant system can detect a wide range of genetic damage, including gene mutations and chromosome aberrations. Recently introduced molecular cytogenetic methods allow analysis of genotoxicity, both at the chromosomal and DNA level. FISH gives a new possibility of the detection and analysis of chromosomal rearrangements in a great detail. DNA fragmentation can be estimated using the TUNEL test and the single cell gel electrophoresis (Comet assay).

Evaluating Post-Earthquake Building Safety Using Economical MEMS Seismometers

PubMed Central

Yin, Ren-Cheng

2018-01-01

The earthquake early warning (EEW)-research group at National Taiwan University has been developing a microelectromechanical system-based accelerometer called “P-Alert”, designed for issuing EEWs. The main advantage of P-Alert is that it is a relatively economical seismometer. However, because of the expensive nature of commercial hardware for structural health monitoring (SHM) systems, the application of SHM to buildings remains limited. To determine the performance of P-Alert for evaluating post-earthquake building safety, we conducted a series of steel-frame shaking table tests with incremental damage. We used the fragility curves of different damage levels and the interstory drift ratios (calculated by the measured acceleration of each story using double integration and a filter) to gauge the potential damage levels. We concluded that the acceptable detection of damage for an entire building is possible. With improvements to the synchronization of the P-Alert sensors, we also anticipate a damage localization feature for the stories of a building. PMID:29734736

Evaluating Post-Earthquake Building Safety Using Economical MEMS Seismometers.

PubMed

Hsu, Ting-Yu; Yin, Ren-Cheng; Wu, Yih-Min

2018-05-05

The earthquake early warning (EEW)-research group at National Taiwan University has been developing a microelectromechanical system-based accelerometer called “P-Alert”, designed for issuing EEWs. The main advantage of P-Alert is that it is a relatively economical seismometer. However, because of the expensive nature of commercial hardware for structural health monitoring (SHM) systems, the application of SHM to buildings remains limited. To determine the performance of P-Alert for evaluating post-earthquake building safety, we conducted a series of steel-frame shaking table tests with incremental damage. We used the fragility curves of different damage levels and the interstory drift ratios (calculated by the measured acceleration of each story using double integration and a filter) to gauge the potential damage levels. We concluded that the acceptable detection of damage for an entire building is possible. With improvements to the synchronization of the P-Alert sensors, we also anticipate a damage localization feature for the stories of a building.

A comparative evaluation of piezoelectric sensors for acoustic emission-based impact location estimation and damage classification in composite structures

NASA Astrophysics Data System (ADS)

Uprety, Bibhisha; Kim, Sungwon; Mathews, V. John; Adams, Daniel O.

2015-03-01

Acoustic Emission (AE) based Structural Health Monitoring (SHM) is of great interest for detecting impact damage in composite structures. Within the aerospace industry the need to detect and locate these events, even when no visible damage is present, is important both from the maintenance and design perspectives. In this investigation, four commercially available piezoelectric sensors were evaluated for usage in an AE-based SHM system. Of particular interest was comparing the acoustic response of the candidate piezoelectric sensors for impact location estimations as well as damage classification resulting from the impact in fiber-reinforced composite structures. Sensor assessment was performed based on response signal characterization and performance for active testing at 300 kHz and steel-ball drop testing using both aluminum and carbon/epoxy composite plates. Wave mode velocities calculated from the measured arrival times were found to be in good agreement with predictions obtained using both the Disperse code and finite element analysis. Differences in the relative strength of the received wave modes, the overall signal strengths and signal-to-noise ratios were observed through the use of both active testing as well as passive steel-ball drop testing. Further comparative is focusing on assessing AE sensor performance for use in impact location estimation algorithms as well as detecting and classifying damage produced in composite structures due to impact events.

Development of a molecular method for testing the effectiveness of UV systems on-site.

PubMed

Nizri, Limor; Vaizel-Ohayon, Dalit; Ben-Amram, Hila; Sharaby, Yehonatan; Halpern, Malka; Mamane, Hadas

2017-12-15

We established a molecular method for quantifying ultraviolet (UV) disinfection efficacy using total bacterial DNA in a water sample. To evaluate UV damage to the DNA, we developed the "DNA damage" factor, which is a novel cultivation-independent approach that reveals UV-exposure efficiency by applying a simple PCR amplification method. The study's goal was to prove the feasibility of this method for demonstrating the efficiency of UV systems in the field using flow-through UV reactors. In laboratory-based experiments using seeded bacteria, the DNA damage tests demonstrated a good correlation between PCR products and UV dose. In the field, natural groundwater sampled before and after being subjected to the full-scale UV reactors was filtered, and the DNA extracted from the filtrate was subjected to PCR amplification for a 900-bp fragment of the 16S rRNA gene with initial DNA concentrations of 0.1 and 1 ng/μL. In both cases, the UV dose predicted and explained a significant proportion of the variance in the log inactivation ratio and DNA damage factor. Log inactivation ratio was very low, as expected in groundwater due to low initial bacterial counts, whereas the DNA damage factor was within the range of values obtained in the laboratory-based experiments. Consequently, the DNA damage factor reflected the true performance of the full-scale UV system during operational water flow by using the indigenous bacterial array present in a water sample. By applying this method, we were able to predict with high confidence, the UV reactor inactivation potential. For method validation, laboratory and field iterations are required to create a practical field calibration curve that can be used to determine the expected efficiency of the full-scale UV system in the field under actual operation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Damage Characterization of EBC-SiCSiC Ceramic Matrix Composites Under Imposed Thermal Gradient Testing

NASA Technical Reports Server (NTRS)

Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

2014-01-01

Due to their high temperature capabilities, Ceramic Matrix Composite (CMC) components are being developed for use in hot-section aerospace engine applications. Harsh engine environments have led to the development of Environmental Barrier Coatings (EBCs) for silicon-based CMCs to further increase thermal and environmental capabilities. This study aims at understanding the damage mechanisms associated with these materials under simulated operating conditions. A high heat-flux laser testing rig capable of imposing large through-thickness thermal gradients by means of controlled laser beam heating and back-side air cooling is used. Tests are performed on uncoated composites, as well as CMC substrates that have been coated with state-of-the-art ceramic EBC systems. Results show that the use of the EBCs may help increase temperature capability and creep resistance by reducing the effects of stressed oxidation and environmental degradation. Also, the ability of electrical resistance (ER) and acoustic emission (AE) measurements to monitor material condition and damage state during high temperature testing is shown; suggesting their usefulness as a valuable health monitoring technique. Micromechanics models are used to describe the localized stress state of the composite system, which is utilized along with ER modeling concepts to develop an electromechanical model capable of characterizing material behavior.

Fatigue Damage Spectrum calculation in a Mission Synthesis procedure for Sine-on-Random excitations

NASA Astrophysics Data System (ADS)

Angeli, Andrea; Cornelis, Bram; Troncossi, Marco

2016-09-01

In many real-life environments, certain mechanical and electronic components may be subjected to Sine-on-Random vibrations, i.e. excitations composed of random vibrations superimposed on deterministic (sinusoidal) contributions, in particular sine tones due to some rotating parts of the system (e.g. helicopters, engine-mounted components,...). These components must be designed to withstand the fatigue damage induced by the “composed” vibration environment, and qualification tests are advisable for the most critical ones. In the case of an accelerated qualification test, a proper test tailoring which starts from the real environment (measured vibration signals) and which preserves not only the accumulated fatigue damage but also the “nature” of the excitation (i.e. sinusoidal components plus random process) is important to obtain reliable results. In this paper, the classic time domain approach is taken as a reference for the comparison of different methods for the Fatigue Damage Spectrum (FDS) calculation in case of Sine-on-Random vibration environments. Then, a methodology to compute a Sine-on-Random specification based on a mission FDS is proposed.

Teeth: Among Nature's Most Durable Biocomposites

NASA Astrophysics Data System (ADS)

Lawn, Brian R.; Lee, James J.-W.; Chai, Herzl

2010-08-01

This paper addresses the durability of natural teeth from a materials perspective. Teeth are depicted as smart biocomposites, highly resistant to cumulative deformation and fracture. Favorable morphological features of teeth at both macroscopic and microscopic levels contribute to an innate damage tolerance. Damage modes are activated readily within the brittle enamel coat but are contained from spreading catastrophically into the vulnerable tooth interior in sustained occlusal loading. Although tooth enamel contains a multitude of microstructural defects that can act as sources of fracture, substantial overloads are required to drive any developing cracks to ultimate failure—nature's strategy is to contain damage rather than avoid it. Tests on model glass-shell systems simulating the basic elements of the tooth enamel/dentin layer structure help to identify important damage modes. Fracture and deformation mechanics provide a basis for analyzing critical conditions for each mode, in terms of characteristic tooth dimensions and materials properties. Comparative tests on extracted human and animal teeth confirm the validity of the model test approach and point to new research directions. Implications in biomechanics, especially as they relate to dentistry and anthropology, are outlined.

Correlate Life Predictions and Condition Indicators in Helicopter Tail Gearbox Bearings

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Bolander, Nathan; Haynes, Chris; Branning, Jeremy; Wade, Daniel R.

2010-01-01

Research to correlate bearing remaining useful life (RUL) predictions with Helicopter Health Usage Monitoring Systems (HUMS) condition indicators (CI) to indicate the damage state of a transmission component has been developed. Condition indicators were monitored and recorded on UH-60M (Black Hawk) tail gearbox output shaft thrust bearings, which had been removed from helicopters and installed in a bearing spall propagation test rig. Condition indicators monitoring the tail gearbox output shaft thrust bearings in UH-60M helicopters were also recorded from an on-board HUMS. The spal-lpropagation data collected in the test rig was used to generate condition indicators for bearing fault detection. A damage progression model was also developed from this data. Determining the RUL of this component in a helicopter requires the CI response to be mapped to the damage state. The data from helicopters and a test rig were analyzed to determine if bearing remaining useful life predictions could be correlated with HUMS condition indicators (CI). Results indicate data fusion analysis techniques can be used to map the CI response to the damage levels.

Air launch wireless sensor nodes (ALSN) for battle damage assessment (BDA)

NASA Astrophysics Data System (ADS)

Back, Jason M.; Beck, Steven D.; Frank, Mark A.; Hoenes, Eric

2006-05-01

This paper summarizes the Defense Threat Reduction Agency (DTRA) sponsored development and demonstration of an Air Launched Sensor Node (ALSN) system designed to fill DTRA's immediate need to support the Global Strike requirement of weapon-borne deliverable sensors for Battle Damage Assessment (BDA). Unattended ground sensors were integrated into a CBU-103 Tactical Munitions Dispenser (TMD), and flight test demonstrated with the 46 th Test Wing at Eglin AFB, FL. The objectives of the ALSN program were to repackage an existing multi-sensor node system to conform to the payload envelope and deployment configuration design; to integrate this payload into the CBU-103 TMD; and to conduct a combined payload flight test demonstration. The final sensor node included multiple sensors a microphone, a geophone, and multiple directional Passive Infrared (PIR) detectors with processing electronics, a low power wireless communications 802.15.4 mesh network, GPS (Global Positioning System), and power integrated into a form-fit BLU-97 munitions deployable package. This paper will present and discuss the flight test, results, and ALSN performance.

Imaging tools to measure treatment response in gout.

PubMed

Dalbeth, Nicola; Doyle, Anthony J

2018-01-01

Imaging tests are in clinical use for diagnosis, assessment of disease severity and as a marker of treatment response in people with gout. Various imaging tests have differing properties for assessing the three key disease domains in gout: urate deposition (including tophus burden), joint inflammation and structural joint damage. Dual-energy CT allows measurement of urate deposition and bone damage, and ultrasonography allows assessment of all three domains. Scoring systems have been described that allow radiological quantification of disease severity and these scoring systems may play a role in assessing the response to treatment in gout. This article reviews the properties of imaging tests, describes the available scoring systems for quantification of disease severity and discusses the challenges and controversies regarding the use of imaging tools to measure treatment response in gout. © The Author 2018. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Analysis of Carbon Fiber Reinforced PEEK Hinge Mechanism Articulation Components in a Rotating Hinge Knee Design: A Comparison of In Vitro and Retrieval Findings.

PubMed

Schierjott, Ronja A; Giurea, Alexander; Neuhaus, Hans-Joachim; Schwiesau, Jens; Pfaff, Andreas M; Utzschneider, Sandra; Tozzi, Gianluca; Grupp, Thomas M

2016-01-01

Carbon fiber reinforced poly-ether-ether-ketone (CFR-PEEK) represents a promising alternative material for bushings in total knee replacements, after early clinical failures of polyethylene in this application. The objective of the present study was to evaluate the damage modes and the extent of damage observed on CFR-PEEK hinge mechanism articulation components after in vivo service in a rotating hinge knee (RHK) system and to compare the results with corresponding components subjected to in vitro wear tests. Key question was if there were any similarities or differences between in vivo and in vitro damage characteristics. Twelve retrieved RHK systems after an average of 34.9 months in vivo underwent wear damage analysis with focus on the four integrated CFR-PEEK components and distinction between different damage modes and classification with a scoring system. The analysis included visual examination, scanning electron microscopy, and energy dispersive X-ray spectroscopy, as well as surface roughness and profile measurements. The main wear damage modes were comparable between retrieved and in vitro specimens ( n = 3), whereby the size of affected area on the retrieved components showed a higher variation. Overall, the retrieved specimens seemed to be slightly heavier damaged which was probably attributable to the more complex loading and kinematic conditions in vivo.

Experimental Investigations on Effect of Damage on Vibration Characteristics of a Reinforced Concrete Beam

NASA Astrophysics Data System (ADS)

Srinivas, V.; Jeyasehar, C. Antony; Ramanjaneyulu, K.; Sasmal, Saptarshi

2012-02-01

Need for developing efficient non-destructive damage assessment procedures for civil engineering structures is growing rapidly towards structural health assessment and management of existing structures. Damage assessment of structures by monitoring changes in the dynamic properties or response of the structure has received considerable attention in recent years. In the present study, damage assessment studies have been carried out on a reinforced concrete beam by evaluating the changes in vibration characteristics with the changes in damage levels. Structural damage is introduced by static load applied through a hydraulic jack. After each stage of damage, vibration testing is performed and system parameters were evaluated from the measured acceleration and displacement responses. Reduction in fundamental frequencies in first three modes is observed for different levels of damage. It is found that a consistent decrease in fundamental frequency with increase in damage magnitude is noted. The beam is numerically simulated and found that the vibration characteristics obtained from the measured data are in close agreement with the numerical data.

Imparting Barely Visible Impact Damage to a Stitched Composite Large-Scale Pressure Box

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Przekop, Adam

2016-01-01

The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is a concept that was developed by The Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body (HWB) aircraft configuration, which has been a focus of the NASA Environmentally Responsible Aviation Project. The NASA-Boeing structural development for the HWB aircraft culminated in testing of the multi-bay box, which is an 80%-scale representation of the pressurized center-body section. This structure was tested in the NASA Langley Research Center Combined Loads Test System facility. As part of this testing, barely visible impact damage was imparted to the interior and exterior of the test article to demonstrate compliance with a condition representative of the requirements for Category 1 damaged composite structure as defined by the Federal Aviation Regulations. Interior impacts were imparted using an existing spring-loaded impactor, while the exterior impacts were imparted using a newly designed, gravity-driven impactor. This paper describes the impacts to the test article, and the design of the gravitydriven guided-weight impactor. The guided-weight impactor proved to be a very reliable method to impart barely visible impact damage in locations which are not easily accessible for a traditional drop-weight impactor, while at the same time having the capability to be highly configurable for use on other aircraft structures.

Identification of explosives and drugs and inspection of material defects with THz radiation

NASA Astrophysics Data System (ADS)

Zhang, Cunlin; Mu, Kaijun; Jiang, Xue; Jiao, Yueying; Zhang, Liangliang; Zhou, Qingli; Zhang, Yan; Shen, Jingling; Zhao, Guoshong; Zhang, X.-C.

2008-03-01

We report the sensing of explosive materials and illicit drugs by using terahertz time-domain spectroscopy (THz-TDS) and imaging. Several explosive materials, such as γ-HNIW, RDX, 2,4-DNT, TNT, Nitro-aniline, and illicit drugs, such as methamphetamine (MA) etc were researched here. Non-destructive testing, as one of the major applications of THz imaging, can be applied to an area of critical need: the testing of aerospace materials. Composite materials such as carbon fiber are widely used in this industry. The nature of their use requires technologies that are able to differentiate between safe and unsafe materials, due to either manufacturing tolerance or damage acquired while in use. In this paper, we discuss the applicability of terahertz (THz) imaging systems to this purpose, focusing on graphite fiber composite materials, carbon silicon composite materials and so on. We applied THz imaging technology to evaluate the fire damage to a variety of carbon fiber composite samples. Major carbon fiber materials have polarization-dependent reflectivity in THz frequency range, and we show how the polarization dependence changes versus the burned damage level. Additionally, time domain information acquired through a THz time-domain spectroscopy (TDS) system provides further information with which to characterize the damage. We also detect fuel tank insulation foam panel defects with pulse and continuous-wave (CW) terahertz system.

Characterizing fretting damage in different test media for cardiovascular device durability testing.

PubMed

Weaver, J D; Ramirez, L; Sivan, S; Di Prima, M

2018-06-01

In vitro durability tests of cardiovascular devices are often used to evaluate the potential for fretting damage during clinical use. Evaluation of fretting damage is important because severe fretting can concentrate stress and lead to the loss of structural integrity. Most international standards call for the use of phosphate buffered saline (PBS) for such tests although there has been little evidence to date that the use of PBS is appropriate in terms of predicting the amount of fretting damage that would occur in vivo. In order to determine an appropriate test media for in vitro durability tests where fretting damage is being evaluated, we utilized an in vitro test that is relevant to cardiovascular devices both in terms of dimensions and materials (nitinol, cobalt-chromium, and stainless steel) to characterize fretting damage in PBS, deionized water (DIW), and heparinized porcine blood. Overall, tests conducted in blood were found to have increased levels of fretting damage over tests in DIW or PBS, although the magnitude of this difference was smaller than the variability for each test media. Tests conducted in DIW and PBS led to mostly similar amounts of fretting damage with the exception of one material combination where DIW had greatly reduced damage compared to PBS and blood. Differences in fretting damage among materials were also observed with nitinol having less fretting damage than stainless steel or cobalt-chromium. In general, evaluating fretting damage in PBS or DIW may be appropriate although caution should be used when selecting test media and interpreting results given some of the differences observed across different materials. Published by Elsevier Ltd.

Shockless spalling damage of alumina ceramic

NASA Astrophysics Data System (ADS)

Erzar, B.; Buzaud, E.

2012-05-01

Ceramic materials are commonly used to build multi-layer armour. However reliable test data is needed to identify correctly models and to be able to perform accurate numerical simulation of the dynamic response of armour systems. In this work, isentropic loading waves have been applied to alumina samples to induce spalling damage. The technique employed allows assessing carefully the strain-rate at failure and the dynamic strength. Moreover, specimens have been recovered and analysed using SEM. In a damaged but unbroken specimen, interactions between cracks has been highlighted illustrating the fragmentation process.

Collateral Damage: How High-Stakes Testing Corrupts America's Schools

ERIC Educational Resources Information Center

Nichols, Sharon L.; Berliner, David C.

2007-01-01

Drawing on their extensive research, Nichols and Berliner document and categorize the ways that high-stakes testing threatens the purposes and ideals of the American education system. For more than a decade, the debate over high-stakes testing has dominated the field of education. This passionate and provocative book provides a fresh perspective…

Design of a piezoelectric-based structural health monitoring system for damage detection in composite materials

NASA Astrophysics Data System (ADS)

Kessler, Seth S.; Spearing, S. Mark

2002-07-01

Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents the conclusions of an experimental and analytical survey of candidate methods for in-situ damage detection in composite structures. Experimental results are presented for the application of modal analysis and Lamb wave techniques to quasi-isotropic graphite/epoxy test specimens containing representative damage. Piezoelectric patches were used as actuators and sensors for both sets of experiments. Modal analysis methods were reliable for detecting small amounts of global damage in a simple composite structure. By comparison, Lamb wave methods were sensitive to all types of local damage present between the sensor and actuator, provided useful information about damage presence and severity, and present the possibility of estimating damage type and location. Analogous experiments were also performed for more complex built-up structures. These techniques are suitable for structural health monitoring applications since they can be applied with low power conformable sensors and can provide useful information about the state of a structure during operation. Piezoelectric patches could also be used as multipurpose sensors to detect damage by a variety of methods such as modal analysis, Lamb wave, acoustic emission and strain based methods simultaneously, by altering driving frequencies and sampling rates. This paper present guidelines and recommendations drawn from this research to assist in the design of a structural health monitoring system for a vehicle. These systems will be an important component in future designs of air and spacecraft to increase the feasibility of their missions.

A new qualitative acoustic emission parameter based on Shannon's entropy for damage monitoring

NASA Astrophysics Data System (ADS)

Chai, Mengyu; Zhang, Zaoxiao; Duan, Quan

2018-02-01

An important objective of acoustic emission (AE) non-destructive monitoring is to accurately identify approaching critical damage and to avoid premature failure by means of the evolutions of AE parameters. One major drawback of most parameters such as count and rise time is that they are strongly dependent on the threshold and other settings employed in AE data acquisition system. This may hinder the correct reflection of original waveform generated from AE sources and consequently bring difficulty for the accurate identification of the critical damage and early failure. In this investigation, a new qualitative AE parameter based on Shannon's entropy, i.e. AE entropy is proposed for damage monitoring. Since it derives from the uncertainty of amplitude distribution of each AE waveform, it is independent of the threshold and other time-driven parameters and can characterize the original micro-structural deformations. Fatigue crack growth test on CrMoV steel and three point bending test on a ductile material are conducted to validate the feasibility and effectiveness of the proposed parameter. The results show that the new parameter, compared to AE amplitude, is more effective in discriminating the different damage stages and identifying the critical damage.

The effect of the impactor diameter and temperature on low velocity impact behavior of CFRP laminates

NASA Astrophysics Data System (ADS)

Evci, C.; Uyandıran, I.

2017-02-01

Impact damage is one of the major concerns that should be taken into account with the new aircraft and spacecraft structures which employ ever-growing use of composite materials. Considering the thermal loads encountered at different altitudes, both low and high temperatures can affect the properties and impact behavior of composite materials. This study aims to investigate the effect of temperature and impactor diameter on the impact behavior and damage development in balanced and symmetrical CFRP laminates which were manufactured by employing vacuum bagging process with autoclave cure. Instrumented drop-weight impact testing system is used to perform the low velocity impact tests in a range of temperatures ranged from 60 down to -50 °C. Impact tests for each temperature level were conducted using three different hemispherical impactor diameters varying from 10 to 20 mm. Energy profile method is employed to determine the impact threshold energies for damage evolution. The level of impact damage is determined from the dent depth on the impacted face and delamination damage detected using ultrasonic C-Scan technique. Test results reveal that the threshold of penetration energy, main failure force and delamination area increase with impactor diameter at all temperature levels. No clear influence of temperature on the critical force thresholds could be derived. However, penetration threshold energy decreased as the temperature was lowered. Drop in the penetration threshold was more obvious with quite low temperatures. Delamination damage area increased while the temperature decreased from +60 °C to -50 °C.

Correlation of scanning microwave interferometry and digital X-ray images for damage detection in ceramic composite armor

NASA Astrophysics Data System (ADS)

Schmidt, Karl F.; Goitia, Ryan M.; Ellingson, William A.; Green, William

2012-05-01

Application of non-contact, scanning, microwave interferometry for inspection of ceramic-based composite armor facilitates detection of defects which may occur in manufacturing or in service. Non-contact, one-side access permits inspection of panels while on the vehicle. The method was applied as a base line inspection and post-damage inspection of composite ceramic armor containing artificial defects, fiduciaries, and actual damage. Detection, sizing, and depth location capabilities were compared using microwave interferometry system and micro-focus digital x-ray imaging. The data demonstrates corroboration of microwave interference scanning detection of cracks and laminar features. The authors present details of the system operation, descriptions of the test samples used, and recent results obtained.

Detection, location, and quantification of structural damage by neural-net-processed moiré profilometry

NASA Astrophysics Data System (ADS)

Grossman, Barry G.; Gonzalez, Frank S.; Blatt, Joel H.; Hooker, Jeffery A.

1992-03-01

The development of efficient high speed techniques to recognize, locate, and quantify damage is vitally important for successful automated inspection systems such as ones used for the inspection of undersea pipelines. Two critical problems must be solved to achieve these goals: the reduction of nonuseful information present in the video image and automatic recognition and quantification of extent and location of damage. Artificial neural network processed moire profilometry appears to be a promising technique to accomplish this. Real time video moire techniques have been developed which clearly distinguish damaged and undamaged areas on structures, thus reducing the amount of extraneous information input into an inspection system. Artificial neural networks have demonstrated advantages for image processing, since they can learn the desired response to a given input and are inherently fast when implemented in hardware due to their parallel computing architecture. Video moire images of pipes with dents of different depths were used to train a neural network, with the desired output being the location and severity of the damage. The system was then successfully tested with a second series of moire images. The techniques employed and the results obtained are discussed.

Thermomechanical testing of high-temperature composites - Thermomechanical fatigue (TMF) behavior of SiC(SCS-6)/Ti-15-3

NASA Technical Reports Server (NTRS)

Castelli, Michael G.; Bartolotta, Paul; Ellis, John R.

1992-01-01

Thermomechanical testing techniques recently developed for monolithic structural alloys were successfully extended to continuous fiber reinforced composite materials in plate form. The success of this adaptation was verified on a model metal matrix composite (MMC) material, namely SiC(SCS-6)/Ti-15V-3Cr-3Al-3Sn. Effects of heating system type and specimen preparation are also addressed. Cyclic lives determined under full thermomechanical conditions were shown to be significantly reduced from those obtained under comparable isothermal and in-phase bi-thermal conditions. Fractography and metallography from specimens subjected to isothermal, out-of-phase and in-phase conditions reveal distinct differences in damage-failure modes. Isothermal metallography revealed extensive matrix cracking associated with fiber damage throughout the entire cross-section of the specimen. Out-of-phase metallography revealed extensive matrix damage associated with minimal (if any) fiber cracking. However, the damage was located exclusively at surface and near-surface locations. In-phase conditions produced extensive fiber cracking throughout the entire cross-section, associated with minimal (if any) matrix damage.

Thermomechanical testing techniques for high-temparature composites: TMF behavior of SiC(SCS-6)/Ti-15-3

NASA Technical Reports Server (NTRS)

Castelli, Michael G.; Ellis, J. Rodney; Bartolotta, Paul A.

1990-01-01

Thermomechanical testing techniques recently developed for monolithic structural alloys were successfully extended to continuous fiber reinforced composite materials in plate form. The success of this adaptation was verified on a model metal matrix composite (MMC) material, namely SiC(SCS-6)/Ti-15V-3Cr-3Al-3Sn. Effects of heating system type and specimen preparation are also addressed. Cyclic lives determined under full thermo-mechanical conditions were shown to be significantly reduced from those obtained under comparable isothermal and in-phase bi-thermal conditions. Fractography and metallography from specimens subjected to isothermal, out-of-phase and in-phase conditions reveal distinct differences in damage-failure modes. Isothermal metallography revealed extensive matrix cracking associated with fiber damage throughout the entire cross-section of the specimen. Out-of-phase metallography revealed extensive matrix damage associated with minimal (if any) fiber cracking. However, the damage was located exclusively at surface and near-surface locations. In-phase conditions produced extensive fiber cracking throughout the entire cross-section, associated with minimal (if any) matrix damage.

Design and implementation of online automatic judging system

NASA Astrophysics Data System (ADS)

Liang, Haohui; Chen, Chaojie; Zhong, Xiuyu; Chen, Yuefeng

2017-06-01

For lower efficiency and poorer reliability in programming training and competition by currently artificial judgment, design an Online Automatic Judging (referred to as OAJ) System. The OAJ system including the sandbox judging side and Web side, realizes functions of automatically compiling and running the tested codes, and generating evaluation scores and corresponding reports. To prevent malicious codes from damaging system, the OAJ system utilizes sandbox, ensuring the safety of the system. The OAJ system uses thread pools to achieve parallel test, and adopt database optimization mechanism, such as horizontal split table, to improve the system performance and resources utilization rate. The test results show that the system has high performance, high reliability, high stability and excellent extensibility.

Damage Precursor Identification via Microstructure-Sensitive Nondestructive Evaluation

NASA Astrophysics Data System (ADS)

Wisner, Brian John

Damage in materials is a complex and stochastic process bridging several time and length scales. This dissertation focuses on investigating the damage process in a particular class of precipitate-hardened aluminum alloys which is widely used in automotive and aerospace applications. Most emphasis in the literature has been given either on their ductility for manufacturing purposes or fracture for performance considerations. In this dissertation, emphasis is placed on using nondestructive evaluation (NDE) combined with mechanical testing and characterization methods applied at a scale where damage incubation and initiation is occurring. Specifically, a novel setup built inside a Scanning Electron Microscope (SEM) and retrofitted to be combined with characterization and NDE capabilities was developed with the goal to track the early stages of the damage process in this type of material. The characterization capabilities include Electron Backscatter Diffraction (EBSD) and Energy Dispersive Spectroscopy (EDS) in addition to X-ray micro-computed tomography (μ-CT) and nanoindentation, in addition to microscopy achieved by the Secondary Electron (SE) and Back Scatter Electron (BSE) detectors. The mechanical testing inside the SEM was achieved with the use of an appropriate stage that fitted within its chamber and is capable of applying both axial and bending monotonic and cyclic loads. The NDE capabilities, beyond the microscopy and μ-CT, include the methods of Acoustic Emission and Digital Image Correlation (DIC). This setup was used to identify damage precursors in this material system and their evolution over time and space. The experimental results were analyzed by a custom signal processing scheme that involves both feature-based analyses as well as a machine learning method to relate recorded microstructural data to damage in this material. Extensions of the presented approach to include information from computational methods as well as its applicability to other material systems are discussed.

Development of testing and training simulator for CEDMCS in KSNP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nam, C. H.; Park, C. Y.; Nam, J. I.

2006-07-01

This paper presents a newly developed testing and training simulator (TTS) for automatically diagnosing and tuning the Control Element Drive Mechanism Control System (CEDMCS). TTS includes a new automatic, diagnostic, method for logic control cards and a new tuning method for phase synchronous pulse cards. In Korea Standard Nuclear Power Plants (KSNP). reactor trips occasionally occur due to a damaged logic control card in CEDMCS. However, there is no pre-diagnostic tester available to detect a damaged card in CEDMCS before it causes a reactor trip. Even after the reactor trip occurs, it is difficult to find the damaged card. Tomore » find the damaged card. ICT is usually used. ICT is an automated, computer-controlled testing system with measurement capabilities for testing active and passive components, or clusters of components, on printed circuit boards (PCB) and/or assemblies. However, ICT cannot detect a time dependent fault correctly and requires removal of the waterproof mating to perform the test. Therefore, the additional procedure of re-coating the PCB card is required after the test. TTS for CEDMCS is designed based on real plant conditions, both electrically and mechanically. Therefore, the operator can operate the Control Element Drive Mechanism (CEDM), which is mounted on the closure head of the reactor vessel (RV) using the soft control panel in ITS, which duplicates the Main Control Board (MCB) in the Main Control Room (MCR). However, during the generation of electric power in a nuclear power plant, it is difficult to operate the CEDM so a CEDM and Control Element Assembly (CEA) mock-up facility was developed to simulate a real plant CEDM. ITS was used for diagnosing and tuning control logic cards in CEDMCS in the Ulchin Nuclear Power Plant No. 4 during the plant overhaul period. It exhibited good performance in detecting the damaged cards and tuning the phase synchronous pulse cards. In addition, TTS was useful in training the CEDMCS operator by supplying detail signal information from the logic cards. (authors)« less

Structural damage detection for in-service highway bridge under operational and environmental variability

NASA Astrophysics Data System (ADS)

Jin, Chenhao; Li, Jingcheng; Jang, Shinae; Sun, Xiaorong; Christenson, Richard

2015-03-01

Structural health monitoring has drawn significant attention in the past decades with numerous methodologies and applications for civil structural systems. Although many researchers have developed analytical and experimental damage detection algorithms through vibration-based methods, these methods are not widely accepted for practical structural systems because of their sensitivity to uncertain environmental and operational conditions. The primary environmental factor that influences the structural modal properties is temperature. The goal of this article is to analyze the natural frequency-temperature relationships and detect structural damage in the presence of operational and environmental variations using modal-based method. For this purpose, correlations between natural frequency and temperature are analyzed to select proper independent variables and inputs for the multiple linear regression model and neural network model. In order to capture the changes of natural frequency, confidence intervals to detect the damages for both models are generated. A long-term structural health monitoring system was installed on an in-service highway bridge located in Meriden, Connecticut to obtain vibration and environmental data. Experimental testing results show that the variability of measured natural frequencies due to temperature is captured, and the temperature-induced changes in natural frequencies have been considered prior to the establishment of the threshold in the damage warning system. This novel approach is applicable for structural health monitoring system and helpful to assess the performance of the structure for bridge management and maintenance.

Impact Damage and Strain Rate Effects for Toughened Epoxy Composite Structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Minnetyan, Levon

2006-01-01

Structural integrity of composite systems under dynamic impact loading is investigated herein. The GENOA virtual testing software environment is used to implement the effects of dynamic loading on fracture progression and damage tolerance. Combinations of graphite and glass fibers with a toughened epoxy matrix are investigated. The effect of a ceramic coating for the absorption of impact energy is also included. Impact and post impact simulations include verification and prediction of (1) Load and Impact Energy, (2) Impact Damage Size, (3) Maximum Impact Peak Load, (4) Residual Strength, (5) Maximum Displacement, (6) Contribution of Failure Modes to Failure Mechanisms, (7) Prediction of Impact Load Versus Time, and (8) Damage, and Fracture Pattern. A computer model is utilized for the assessment of structural response, progressive fracture, and defect/damage tolerance characteristics. Results show the damage progression sequence and the changes in the structural response characteristics due to dynamic impact. The fundamental premise of computational simulation is that the complete evaluation of composite fracture requires an assessment of ply and subply level damage/fracture processes as the structure is subjected to loads. Simulation results for the graphite/epoxy composite were compared with the impact and tension failure test data, correlation and verification was obtained that included: (1) impact energy, (2) damage size, (3) maximum impact peak load, (4) residual strength, (5) maximum displacement, and (6) failure mechanisms of the composite structure.

The Bender Gestalt Test with the Human Figure Drawing Test for Young School Children. A Manual for Use with the Koppitz Scoring System.

ERIC Educational Resources Information Center

Koppitz, Elizabeth Munsterberg

Presented is a manual for scoring the Bender Gestalt Test and the Human Figure Drawing Test for screening and diagnostic uses with emotionally disturbed, brain damaged, or perceptually handicapped 5- to 11-year-old children. Given are suggestions for administering and scoring the Bender test which examines distortion of shape, rotation,…

Ingham County Geriatric Medical Care Facility solar water-heating system refurbishments. Final technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The tasks of the refurbishment of a damaged solar water heating system are outlined. The system is a closed loop, 50% glycol antifreeze system consisting of 14 rows of 6 series manifolds each containing 6 solar collectors connected in parallel for a total of 504 modules. The Wyle Laboratories' test report for the Revere Model 132 flat plate collector is appended. A collector test plan and photographs are also appended. Reference CAPE-2834. (LS)

Development and Evaluation of Sensor Concepts for Ageless Aerospace Vehicles: Report 5 - Phase 2 Implementation of the Concept Demonstrator

NASA Technical Reports Server (NTRS)

Batten, Adam; Dunlop, John; Edwards, Graeme; Farmer, Tony; Gaffney, Bruce; Hedley, Mark; Hoschke, Nigel; Isaacs, Peter; Johnson, Mark; Lewis, Chris;

Damage tolerance modeling and validation of a wireless sensory composite panel for a structural health monitoring system

NASA Astrophysics Data System (ADS)

Talagani, Mohamad R.; Abdi, Frank; Saravanos, Dimitris; Chrysohoidis, Nikos; Nikbin, Kamran; Ragalini, Rose; Rodov, Irena

2013-05-01

The paper proposes the diagnostic and prognostic modeling and test validation of a Wireless Integrated Strain Monitoring and Simulation System (WISMOS). The effort verifies a hardware and web based software tool that is able to evaluate and optimize sensorized aerospace composite structures for the purpose of Structural Health Monitoring (SHM). The tool is an extension of an existing suite of an SHM system, based on a diagnostic-prognostic system (DPS) methodology. The goal of the extended SHM-DPS is to apply multi-scale nonlinear physics-based Progressive Failure analyses to the "as-is" structural configuration to determine residual strength, remaining service life, and future inspection intervals and maintenance procedures. The DPS solution meets the JTI Green Regional Aircraft (GRA) goals towards low weight, durable and reliable commercial aircraft. It will take advantage of the currently developed methodologies within the European Clean sky JTI project WISMOS, with the capability to transmit, store and process strain data from a network of wireless sensors (e.g. strain gages, FBGA) and utilize a DPS-based methodology, based on multi scale progressive failure analysis (MS-PFA), to determine structural health and to advice with respect to condition based inspection and maintenance. As part of the validation of the Diagnostic and prognostic system, Carbon/Epoxy ASTM coupons were fabricated and tested to extract the mechanical properties. Subsequently two composite stiffened panels were manufactured, instrumented and tested under compressive loading: 1) an undamaged stiffened buckling panel; and 2) a damaged stiffened buckling panel including an initial diamond cut. Next numerical Finite element models of the two panels were developed and analyzed under test conditions using Multi-Scale Progressive Failure Analysis (an extension of FEM) to evaluate the damage/fracture evolution process, as well as the identification of contributing failure modes. The comparisons between predictions and test results were within 10% accuracy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negres, Raluca A.; Stolz, Christopher J.; Thomas, Michael D.

Here, this competition aimed to survey state-of-the-art UV high reflectors. The requirements of the coatings are a minimum reflection of 99.5% at 45 degrees incidence angle for P-polarized light at 355-nm. The choice of coating materials, design, and deposition method were left to the participants. Laser damage testing was performed at a single testing facility using the raster scan method with a 5-ns pulse length laser system operating at 10 Hz in a single longitudinal mode. A double blind test assured sample and submitter anonymity. Finally, in addition to the laser damage resistance results, details of the deposition processes, cleaningmore » method, coating materials and layer count are also shared.« less

Development of a rocking R/C shear wall system implementing repairable structural fuses

NASA Astrophysics Data System (ADS)

Parsafar, Saeed; Moghadam, Abdolreza S.

2017-09-01

In the last decades, the concept of earthquake resilient structural systems is becoming popular in which the rocking structure is considered as a viable option for buildings in regions of high seismicity. To this end, a novel wall-base connection based on the " repairable structure" approach is proposed and evaluated. The proposed system is made of several steel plates and high strength bolts act as a friction connection. To achieve the desired rocking motion in the proposed system, short-slotted holes are used in vertical directions for connecting the steel plates to the shear wall (SW). The experimental and numerical studies were performed using a series of displacement control quasi-static cyclic tests on a reference model and four different configurations of the proposed connection installed at the wall corners. The seismic response of the proposed system is compared to the conventional SW in terms of energy dissipation and damage accumulation. In terms of energy dissipation, the proposed system depicted better performance with 95% more energy dissipation capability compared to conventional SW. In terms of damage accumulation, the proposed SW system is nearly undamaged compared to the conventional wall system, which was severely damaged at the wall-base region. Overall, the introduced concept presents a feasible solution for R/C structures when a low-damage design is targeted, which can improve the seismic performance of the structural system significantly.

Mean Flow Augmented Acoustics in Rocket Systems

NASA Technical Reports Server (NTRS)

Fischbach, Sean R.

2015-01-01

Combustion instability in solid rocket motors and liquid engines is a complication that continues to plague designers and engineers. Many rocket systems experience violent fluctuations in pressure, velocity, and temperature originating from the complex interactions between the combustion process and gas dynamics. During sever cases of combustion instability fluctuation amplitudes can reach values equal to or greater than the average chamber pressure. Large amplitude oscillations lead to damaged injectors, loss of rocket performance, damaged payloads, and in some cases breach of case/loss of mission. Historic difficulties in modeling and predicting combustion instability has reduced most rocket systems experiencing instability into a costly fix through testing paradigm or to scrap the system entirely.

Alternative approach for cavitation damage study utilizing repetitive laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Fei; Wang, Jy-An John; Wang, Hong

2010-01-01

Cavitation is a common phenomenon in fluid systems that can lead to dramatic degradation of solid materials surface in contact with the cavitating media. Study of cavitation damage has great significance in many engineering fields. Current techniques for cavitation damage study either require large scale equipments or tend to introduce damages from other mechanisms. In this project, we utilized the cavitation phenomenon induced by laser optical breakdown and developed a prototype apparatus for cavitation damage study. In our approach, cavitation was generated by the repetitive pressure waves induced by high-power laser pulses. As proof of principal study, stainless steel andmore » aluminum samples were tested using the novel apparatus. Surface characterization via scanning electron microscopy revealed damages such as indentation and surface pitting, which were similar to those reported in literature using other state-of-the-art techniques. These preliminary results demonstrated the new device was capable of generating cavitation damages and could be used as an alternative method for cavitation damage study.« less

Effect law of Damage Characteristics of Rock Similar Material with Pre-Existing Cracks

NASA Astrophysics Data System (ADS)

Li, S. G.; Cheng, X. Y.; Liu, C.

2017-11-01

In order to further study the failure mechanism for rock similar materials, this study established the damage model based on accumulative AE events, investigated the damage characteristics for rock similar material samples with pre-existing cracks of varying width under uniaxial compression load. The equipment used in this study is the self-developed YYW-II strain controlled unconfined compression apparatus and the PCIE-8 acoustic emission (AE) monitoring system. The influences of the width of the pre-existing cracks to the damage characteristics of rock similar materials are analyzed. Results show that, (1) the damage model can better describe the damage characteristics of rock similar materials; (2) the tested samples have three stages during failure: initial damage stage, stable development of damage stage, and accelerated development of damage stage; (3) with the width of pre-existing cracks vary from 3mm to 5mm, the damage of rock similar materials increases gradually. The outcomes of this study provided additional values to the research of the failure mechanism for geotechnical similar material models.

Study of thermal sensitivity and thermal explosion violence of energetic materials in the LLNL ODTX system

NASA Astrophysics Data System (ADS)

Hsu, P. C.; Hust, G.; Zhang, M. X.; Lorenz, T. K.; Reynolds, J. G.; Fried, L.; Springer, H. K.; Maienschein, J. L.

2014-05-01

Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 °C) and the violence from thermal explosion may cause significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to explosion, threshold thermal explosion temperature, and determine kinetic parameters of energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. Recent ODTX experimental data are reported in the paper.

[Automobile tyre colloidal particle induced allergic damage of respiratory system in traffic policemen and its allergenicity].

PubMed

Zhang, Yong-xing; Wei, Qing-yu; Wang, Juan; Qiao, Ting-hui; Bai, Hong-bing; Cai, Li-na

2007-06-01

To explore the damage of respiratory system in the traffic policemen induced by automobile tyre colloidal particle and its allergenicity. The respiratory system symptoms in 445 traffic policemen working outside their offices and 243 controls were investigated and their pulmonary ventilation function index such as FVC, FEV(1.0), MMF and V(50) were determined. The specific IgE antibody of automobile tyre colloidal particle of their serum was determined and the skin-prick test of automobile tyre colloidal particle antigen was performed. Sixty-six traffic policemen working outside their offices and 5 controls with the positive of IgE antibody among them were detected by nasal mucosa provocation test. Sixty-six traffic policemen working outside their offices with the positive of IgE antibody were determined by Terbutaline inhalation test. The positive rate of respiratory system symptoms of traffic policemen such as cough, stethocatharsis, short breath, nasal obstruction, sneeze and nose running was 38.02%, 27.03%, 20.00%, 23.08%, 27.47%, 32.09% and 34.95% respectively and significantly higher than those of the control with significant difference (P < 0.01) or (P < 0.05). The positive rate of specific IgE antibody of automobile tyre colloidal particle, skin- prick test and nasal mucosa provocation test was 14.51%, 23.73% and 54.55% respectively with significant difference (P < 0.01) and (P < 0.05). The percentage, the actual figure compared with the prediction figure, of the index of pulmonary ventilation function (FVC, FEV(1.0) MMF and V(50)) of traffic policemen were significantly lower than those of the control. Terbutaline inhalation test in 66 positive subjects of specific IgE antibody of automobile tyre colloidal particle was positive in 44 subjects, accounting for 9.67% in all policemen investigated. The automobile tyre colloidal particle is one of etiological factors that induce pulmonary ventilation function damage and could result in allergic asthma of traffic police.

ONE-DIMENSIONAL TIME TO EXPLOSION (THERMAL SENSITIVITY) TESTS ON PETN, PBX-9407, LX-10, AND LX-17

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Peter C.; Strout, Steve; McClelland, Matthew

Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to thermal explosion, threshold thermal explosion temperature, and determine the kinetic parameters of thermal decomposition of energeticmore » materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. This report summarizes the results of our recent ODTX experiments on PETN powder, PBX-9407 pressed part, LX-10 pressed part, LX-17 pressed part and compares the test data that were obtained decades ago with the older version of ODTX system. Test results show the thermal sensitivity of various materials tested in the following order: PETN> PBX-9407 > LX-10 > LX-17.« less

Study on Determination Method of Fatigue Testing Load for Wind Turbine Blade

NASA Astrophysics Data System (ADS)

Liao, Gaohua; Wu, Jianzhong

2017-07-01

In this paper, the load calculation method of the fatigue test was studied for the wind turbine blade under uniaxial loading. The characteristics of wind load and blade equivalent load were analyzed. The fatigue property and damage theory of blade material were studied. The fatigue load for 2MW blade was calculated by Bladed, and the stress calculated by ANSYS. Goodman modified exponential function S-N curve and linear cumulative damage rule were used to calculate the fatigue load of wind turbine blades. It lays the foundation for the design and experiment of wind turbine blade fatigue loading system.

Mitigation of Crack Damage in Metallic Materials

NASA Technical Reports Server (NTRS)

Leser, Patrick E.; Newman, John A.; Smith, Stephen W.; Leser, William P.; Wincheski, Russell A.; Wallace, Terryl A.; Glaessgen, Edward H.; Piascik, Robert S.

2014-01-01

A system designed to mitigate or heal crack damage in metallic materials has been developed where the protected material or component is coated with a low-melting temperature film. After a crack is formed, the material is heated, melting the film which then infiltrates the crack opening through capillary action. Upon solidification, the healing material inhibits further crack damage in two ways. While the crack healing material is intact, it acts like an adhesive that bonds or bridges the crack faces together. After fatigue loading damages, the healing material in the crack mouth inhibits further crack growth by creating artificially-high crack closure levels. Mechanical test data show that this method sucessfully arrests or retards crack growth in laboratory specimens.

Real Time Fatigue Damage Growth Assessment of a Composite Three-Stringer Panel Using Passive Thermography

NASA Technical Reports Server (NTRS)

Zalameda, Joseph N.; Burke, Eric R.; Horne, Michael R.; Bly, James B.

2015-01-01

Fatigue testing of advanced composite structures is critical to validate both structural designs and damage prediction models. In-situ inspection methods are necessary to track damage onset and growth as a function of load cycles. Passive thermography is a large area, noncontact inspection technique that is used to detect composite damage onset and growth in real time as a function of fatigue cycles. The thermal images are acquired in synchronicity to the applied compressive load using a dual infrared camera acquisition system for full (front and back) coverage. Image processing algorithms are investigated to increase defect contrast areas. The thermal results are compared to non-immersion ultrasound inspections and acoustic emission data.

Use of nondestructive inspection and fiber optic sensing for damage characterization in carbon fiber fuselage structure

NASA Astrophysics Data System (ADS)

Neidigk, Stephen; Le, Jacqui; Roach, Dennis; Duvall, Randy; Rice, Tom

2014-04-01

To investigate a variety of nondestructive inspection technologies and assess impact damage characteristics in carbon fiber aircraft structure, the FAA Airworthiness Assurance Center, operated by Sandia National Labs, fabricated and impact tested two full-scale composite fuselage sections. The panels are representative of structure seen on advanced composite transport category aircraft and measured approximately 56"x76". The structural components consisted of a 16 ply skin, co-cured hat-section stringers, fastened shear ties and frames. The material used to fabricate the panels was T800 unidirectional pre-preg (BMS 8-276) and was processed in an autoclave. Simulated hail impact testing was conducted on the panels using a high velocity gas gun with 2.4" diameter ice balls in collaboration with the University of California San Diego (UCSD). Damage was mapped onto the surface of the panels using conventional, hand deployed ultrasonic inspection techniques, as well as more advanced ultrasonic and resonance scanning techniques. In addition to the simulated hail impact testing performed on the panels, 2" diameter steel tip impacts were used to produce representative impact damage which can occur during ground maintenance operations. The extent of impact damage ranges from less than 1 in2 to 55 in2 of interply delamination in the 16 ply skin. Substructure damage on the panels includes shear tie cracking and stringer flange disbonding. It was demonstrated that the fiber optic distributed strain sensing system is capable of detecting impact damage when bonded to the backside of the fuselage.

Design and realization of test system for testing parallelism and jumpiness of optical axis of photoelectric equipment

NASA Astrophysics Data System (ADS)

Shi, Sheng-bing; Chen, Zhen-xing; Qin, Shao-gang; Song, Chun-yan; Jiang, Yun-hong

2014-09-01

With the development of science and technology, photoelectric equipment comprises visible system, infrared system, laser system and so on, integration, information and complication are higher than past. Parallelism and jumpiness of optical axis are important performance of photoelectric equipment,directly affect aim, ranging, orientation and so on. Jumpiness of optical axis directly affect hit precision of accurate point damage weapon, but we lack the facility which is used for testing this performance. In this paper, test system which is used fo testing parallelism and jumpiness of optical axis is devised, accurate aim isn't necessary and data processing are digital in the course of testing parallelism, it can finish directly testing parallelism of multi-axes, aim axis and laser emission axis, parallelism of laser emission axis and laser receiving axis and first acuualizes jumpiness of optical axis of optical sighting device, it's a universal test system.

Laboratory simulation of high-frequency GPR responses of damaged tunnel liners

NASA Astrophysics Data System (ADS)

Siggins, A. F.; Whiteley, Robert J.

2000-04-01

Concrete lined tunnels and pipelines commonly suffer from damage due to subsidence or poor drainage in the surrounding soils, corrosion of reinforcement if present, and acid vapor leaching of the lining. There is a need to conduct tunnel condition monitoring using non-destructive testing methods (NDT) on a regular basis in many buried installations, for example sewers and storm water drains. A wide variety of NDT methods have been employed in the past to monitor these linings including closed circuit TV (CCTV) inspection, magnetic and various electromagnetic and seismic methods. Ground penetrating radar, GPR, is a promising technique for this application, however there are few systems currently available that can provide the high resolution imaging needed to test the lining. A recently developed Australian GPR system operating at 1400 MHz offers the potential to overcome many of these limitations while maintaining adequate resolution to the rear of the linings which are typically less than 0.5 meters thick. The new high frequency GPR has a nominal resolution of 0.03 m at the center of the pulse band-width. This is a significant improvement over existing radars with the possible exception of some horn based systems. This paper describes the results of a laboratory study on a model tunnel lining using the new 1.4 GHz radar. The model simulated a concrete lining with various degrees of damage including, heavily leached sections, voids and corroded reinforcing. The test results established that the new GPR was capable of imaging subtle variations in the concrete structure and that simulated damage could be detected throughout the liner depth. Furthermore, resolution was found to exceed 0.02 m which was significantly better than expected.

Evaluation of Cable Harness Post-Installation Testing. Part B

NASA Technical Reports Server (NTRS)

King, M. S.; Iannello, C. J.

2011-01-01

The Cable Harness Post-Installation Testing Report was written in response to an action issued by the Ares Project Control Board (PCB). The action for the Ares I Avionics & Software Chief Engineer and the Avionics Integration and Vehicle Systems Test Work Breakdown Structure (WBS) Manager in the Vehicle Integration Office was to develop a set of guidelines for electrical cable harnesses. Research showed that post-installation tests have been done since the Apollo era. For Ares I-X, the requirement for post-installation testing was removed to make it consistent with the avionics processes used on the Atlas V expendable launch vehicle. Further research for the report involved surveying government and private sector launch vehicle developers, military and commercial aircraft, spacecraft developers, and harness vendors. Responses indicated crewed launch vehicles and military aircraft perform post-installation tests. Key findings in the report were as follows: Test requirements identify damage, human-rated vehicles should be tested despite the identification of statistically few failures, data does not support the claim that post-installation testing damages the harness insulation system, and proper planning can reduce overhead associated with testing. The primary recommendation of the report is for the Ares projects to retain the practice of post-fabrication and post-installation cable harness testing.

Flight Set 360L006 STS-34 field joint protection system, thermal protection system, and systems tunnel components, volume 4

NASA Technical Reports Server (NTRS)

Wilkinson, J. P.

1990-01-01

The performance of the thermal protection system, field joint protection system, and systems tunnel components of Flight Set 360L006, are documented, as evaluated by postflight hardware inspection. The condition of both motors was similar to previous flights. Sixteen aft edge hits were noted on the ground environment instrumentation thermal protection system. Each hit left a clean substrate, indicating that the damage was caused by nozzle severance debris and/or water impact. No National Space and Transporation System debris criteria for missing thermal protection system were violated. One 5.0 by 1.0 in. unbond was observed on the left hand center field joint K5NA closeout and was elevated to an in-flight anomaly (STS-34-M-4) by the NASA Ice/Debris team. Aft edge damage to the K5NA and an associated black streak indicate that burning debris from the nozzle severance system was the likely cause of the damage. Minor divots caused by debris were seen on previous flights, but this is the first occurrence of a K5NA unbond. Since the unbond occurred after booster separation there is no impact on flight safety and no corrective actions was taken. The right hand center field joint primary heater failed the dielectric withstanding voltage test after joint closeout. The heater was then disabled by opening the circuit breaker, and the redundant heater was used. The redundant heater performed nominally during the launch countdown. A similar condition occurred on Flight 4 when a secondary joint heater failed the dielectric withstanding voltage test.

Stiffness monitoring and damage assessment of bridges under moving vehicular loads using spatially-distributed optical fiber sensors

NASA Astrophysics Data System (ADS)

Wu, Bitao; Wu, Gang; Lu, Huaxi; Feng, De-chen

2017-03-01

Fiber optic sensing technology has been widely used in civil infrastructure health monitoring due to its various advantages, e.g., anti-electromagnetic interference, corrosion resistance, etc. This paper investigates a new method for stiffness monitoring and damage identification of bridges under moving vehicle loads using spatially-distributed optical fiber sensors. The relationship between the element stiffness of the bridge and the long-gauge strain history is firstly studied, and a formula which is expressed by the long-gauge strain history is derived for the calculation of the bridge stiffness. Meanwhile, the stiffness coefficient from the formula can be used to identify the damage extent of the bridge. In order to verify the proposed method, a model test of a 1:10 scale bridge-vehicle system is conducted and the long-gauge strain history is obtained through fiber Bragg grating sensors. The test results indicate that the proposed method is suitable for stiffness monitoring and damage assessment of bridges under moving vehicular loads.

Full-Scale Test and Analysis of a PRSEUS Fuselage Panel to Assess Damage-Containment Features

NASA Technical Reports Server (NTRS)

Bergan, Andrew; Bakuckas, John G.; Lovejoy, Andrew E.; Jegley, Dawn C.; Linton, Kim A.; Korkosz, Gregory; Awerbuch, Jonathan; Tan, Tein-Min

2011-01-01

Stitched composite technology has the potential to substantially decrease structural weight through enhanced damage containment capabilities. The most recent generation of stitched composite technology, the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, has been shown to successfully arrest damage at the sub-component level through tension testing of a three stringer panel with damage in the form of a two-bay notch. In a joint effort undertaken by the National Aeronautics and Space Administration (NASA), the Federal Aviation Administration (FAA), and the Boeing Company, further studies are being conducted to characterize the damage containment features of the PRSEUS concept. A full-scale residual strength test will be performed on a fuselage panel to determine if the load capacity will meet strength, deformation, and damage tolerance requirements. A curved panel was designed, fabricated, and prepared for residual strength testing. A pre-test Finite Element Model (FEM) was developed using design allowables from previous test programs to predict test panel deformation characteristics and margins of safety. Three phases of testing with increasing damage severity include: (1) as manufactured; (2) barely visible impact damage (BVID) and visible impact damage (VID); and (3) discrete source damage (DSD) where the panel will be loaded to catastrophic failure. This paper presents the background information, test plan, and experimental procedure. This paper is the first of several future articles reporting the test preparations, results, and analysis conducted in the test program.

Overcoming complexities: Damage detection using dictionary learning framework

NASA Astrophysics Data System (ADS)

Alguri, K. Supreet; Melville, Joseph; Deemer, Chris; Harley, Joel B.

2018-04-01

For in situ damage detection, guided wave structural health monitoring systems have been widely researched due to their ability to evaluate large areas and their ability detect many types of damage. These systems often evaluate structural health by recording initial baseline measurements from a pristine (i.e., undamaged) test structure and then comparing later measurements with that baseline. Yet, it is not always feasible to have a pristine baseline. As an alternative, substituting the baseline with data from a surrogate (nearly identical and pristine) structure is a logical option. While effective in some circumstance, surrogate data is often still a poor substitute for pristine baseline measurements due to minor differences between the structures. To overcome this challenge, we present a dictionary learning framework to adapt surrogate baseline data to better represent an undamaged test structure. We compare the performance of our framework with two other surrogate-based damage detection strategies: (1) using raw surrogate data for comparison and (2) using sparse wavenumber analysis, a precursor to our framework for improving the surrogate data. We apply our framework to guided wave data from two 108 mm by 108 mm aluminum plates. With 20 measurements, we show that our dictionary learning framework achieves a 98% accuracy, raw surrogate data achieves a 92% accuracy, and sparse wavenumber analysis achieves a 57% accuracy.

Detailed Post-Soft Impact Progressive Damage Assessment for Hybrid Structure Jet Engines

NASA Technical Reports Server (NTRS)

Siddens, Aaron; Bayandor, Javid; Celestina, Mark L.

2014-01-01

Currently, certification of engine designs for resistance to bird strike is reliant on physical tests. Predictive modeling of engine structural damage has mostly been limited to evaluation of individual forward section components, such as fan blades within a fixed frame of reference, to direct impact with a bird. Such models must be extended to include interactions among engine components under operating conditions to evaluate the full extent of engine damage. This paper presents the results of a study aim to develop a methodology for evaluating bird strike damage in advanced propulsion systems incorporating hybrid composite/metal structures. The initial degradation and failure of individual fan blades struck by a bird were investigated. Subsequent damage to other fan blades and engine components due to resultant violent fan assembly vibrations and fragmentation was further evaluated. Various modeling parameters for the bird and engine components were investigated to determine guidelines for accurately capturing initial damage and progressive failure of engine components. Then, a novel hybrid structure modeling approach was investigated and incorporated into the crashworthiness methodology. Such a tool is invaluable to the process of design, development, and certification of future advanced propulsion systems.

Rapid building damage assessment system using mobile phone technology

NASA Astrophysics Data System (ADS)

Cimellaro, Gian Paolo; Scura, G.; Renschler, C. S.; Reinhorn, A. M.; Kim, H. U.

2014-09-01

One common scenario during disasters such as earthquakes is that the activity of damage field reconnaissance on site is not well-coordinated. For example in Italy the damage assessment of structures after an earthquake is managed from the Italian Emergency Authority, using printed forms (AeDES) which are filled by experts on site generating a lot of confusion in filling and transferring the forms to the Disaster Management Operative Center. Because of this, the paper explores the viability of using mobile communication technologies (smart phones) and the Web to develop response systems that would aid communities after a major disaster, providing channels for allowing residents and responders of uploading and distributing information, related to structural damages coordinating the damage field reconnaissance. A mobile application that can be run by residents on smart phones has been developed, to give an initial damage evaluation of the area, which is going to be very useful when resources (e.g. the number of experts is limited). The mobile application has been tested for the first time during 2012 Emilia earthquake to enhance the emergency response, showing the efficiency of the proposed method in statistical terms comparing the proposed procedure with the standard procedure.

Advanced Durability and Damage Tolerance Design and Analysis Methods for Composite Structures: Lessons Learned from NASA Technology Development Programs

NASA Technical Reports Server (NTRS)

Harris, Charles E.; Starnes, James H., Jr.; Shuart, Mark J.

2003-01-01

Aerospace vehicles are designed to be durable and damage tolerant. Durability is largely an economic life-cycle design consideration whereas damage tolerance directly addresses the structural airworthiness (safety) of the vehicle. However, both durability and damage tolerance design methodologies must address the deleterious effects of changes in material properties and the initiation and growth of microstructural damage that may occur during the service lifetime of the vehicle. Durability and damage tolerance design and certification requirements are addressed for commercial transport aircraft and NASA manned spacecraft systems. The state-of-the-art in advanced design and analysis methods is illustrated by discussing the results of several recently completed NASA technology development programs. These programs include the NASA Advanced Subsonic Technology Program demonstrating technologies for large transport aircraft and the X-33 hypersonic test vehicle demonstrating technologies for a single-stage-to-orbit space launch vehicle.

Neurocognitive Dysfunction in Systemic Lupus Erythematosus: Association with Antiphospholipid Antibodies, Disease Activity and Chronic Damage

PubMed Central

Conti, Fabrizio; Alessandri, Cristiano; Perricone, Carlo; Scrivo, Rossana; Rezai, Soheila; Ceccarelli, Fulvia; Spinelli, Francesca Romana; Ortona, Elena; Marianetti, Massimo; Mina, Concetta; Valesini, Guido

2012-01-01

Introduction Systemic lupus erythematosus (SLE) is characterized by frequent neuropsychiatric involvement, which includes cognitive impairment (CI). We aimed at assessing CI in a cohort of Italian SLE patients by using a wide range of neurocognitive tests specifically designed to evaluate the fronto-subcortical dysfunction. Furthermore, we aimed at testing whether CI in SLE is associated with serum autoantibodies, disease activity and chronic damage. Methods Fifty-eight consecutive patients were enrolled. Study protocol included data collection, evaluation of serum levels of ANA, anti-dsDNA, anti-cardiolipin, anti-β2-glycoprotein I, anti-P ribosomal, anti-endothelial cell, and anti-Nedd5 antibodies. SLEDAI-2000 and SLICC were used to assess disease activity and chronic damage. Patients were administered a test battery specifically designed to detect fronto-subcortical dysfunction across five domains: memory, attention, abstract reasoning, executive function and visuospatial function. For each patient, the raw scores from each test were compared with published norms, then transformed into Z scores (deviation from normal mean), and finally summed in the Global Cognitive Dysfunction score (GCDs). Results Nineteen percent of patients had mild GCDs impairment (GCDs 2–3), 7% moderate (GCDs 4–5) and 5% severe (GCDs≥6). The visuospatial domain was the most compromised (MDZs = −0.89±1.23). Anti-cardiolipin IgM levels were associated with visuospatial domain impairment (r = 0.331, P = 0.005). SLEDAI correlated with GCDs, and attentional and executive domains; SLICC correlated with GCDs, and with visuospatial and attentional domains impairment. Conclusions Anti-phospholipids, disease activity, and chronic damage are associated with cognitive dysfunction in SLE. The use of a wide spectrum of tests allowed for a better selection of the relevant factors involved in SLE cognitive dysfunction, and standardized neuropsychological testing methods should be used for routine assessment of SLE patients. PMID:22461897

Damage detection in bridges through fiber optic structural health monitoring

NASA Astrophysics Data System (ADS)

Doornink, J. D.; Phares, B. M.; Wipf, T. J.; Wood, D. L.

2006-10-01

A fiber optic structural health monitoring (SHM) system was developed and deployed by the Iowa State University (ISU) Bridge Engineering Center (BEC) to detect gradual or sudden damage in fracture-critical bridges (FCBs). The SHM system is trained with measured performance data, which are collected by fiber optic strain sensors to identify typical bridge behavior when subjected to ambient traffic loads. Structural responses deviating from the trained behavior are considered to be signs of structural damage or degradation and are identified through analytical procedures similar to control chart analyses used in statistical process control (SPC). The demonstration FCB SHM system was installed on the US Highway 30 bridge near Ames, IA, and utilizes 40 fiber bragg grating (FBG) sensors to continuously monitor the bridge response when subjected to ambient traffic loads. After the data is collected and processed, weekly evaluation reports are developed that summarize the continuous monitoring results. Through use of the evaluation reports, the bridge owner is able to identify and estimate the location and severity of the damage. The information presented herein includes an overview of the SHM components, results from laboratory and field validation testing on the system components, and samples of the reduced and analyzed data.

Pulmonary exposure to cellulose nanocrystals caused deleterious effects to reproductive system in male mice

PubMed Central

Farcas, Mariana T.; Kisin, Elena R.; Menas, Autumn L.; Gutkin, Dmitriy W.; Star, Alexander; Reiner, Richard S.; Yanamala, Naveena; Savolainen, Kai; Shvedova, Anna A.

2016-01-01

Over the past several years there has been an increased number of applications of cellulosic materials in many sectors, including the food industry, cosmetics, and pharmaceuticals. However, to date, there are few studies investigating the potential adverse effects of cellulose nanocrystals (CNC). The objective of this study was to determine long-term outcomes on the male reproductive system of mice upon repeated pharyngeal aspiration exposure to CNC. To achieve this, cauda epididymal sperm samples were analyzed for sperm concentration, motility, morphological abnormalities, and DNA damage. Testicular and epididymal oxidative damage was evaluated, as well as histopathology examination of testes. In addition, changes in levels of testosterone in testes and serum and of luteinizing hormone (LH) in serum were determined. Three months after the last administration, CNC exposure significantly altered sperm concentration, motility, cell morphology, and sperm DNA integrity. These parameters correlated with elevated proinflammatory cytokines levels and myeloperoxidase (MPO) activity in testes, as well as oxidative stress in both testes and epididymis. Exposure to CNC also produced damage to testicular structure, as evidenced by presence of interstitial edema, frequent dystrophic seminiferous tubules with arrested spermatogenesis and degenerating spermatocytes, and imbalance in levels of testosterone and LH. Taken together, these results demonstrate that pulmonary exposure to CNC induces sustained adverse effects in spermatocytes/spermatozoa, suggesting male reproductive toxicity. PMID:27558875

Development and Testing of PRD-66 Hot Gas Filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chambers, J.A.; Garnier, J.E.; McMahon, T. J.

1996-12-31

The overall objective of this program is to develop and commercialize PRD-66 hot gas filters for application in pressurized fluidized bed combustors (PFBC) and Integrated Gas Combined Cycle (IGCC) power generation systems. The work is being carried out in phases with the following specific objectives: 1. Demonstrate acceptable mechanical, chemical, and filtration properties in exposure tests. 2. Produce and qualify selected prototype design filter elements in high temperature high pressure (HTHP) simulated PFBC exposure tests. 3. (Option) Generate a manufacturing plan to support commercial scale-up. 4. (Option) Recommend process equipment upgrades and produce 50 candle filters. Since the beginning ofmore » this program, a parallel evaluation of DuPont Lanxide Composites Inc. (DLC) PRD-66 hot gas candle filters took place using AEP`s TIDD PFBC facility. Several PRD-66 filters experienced damage during the final testing phase at TIDD, after highly successful testing in earlier runs. During the past year, DLC has undertaken a study under this contract to understand the mechanism of damage sustained in TIDD Test Segment 5. DLC has formulated a hypothesis for the damage mechanism based on the available evidence, and verified that the damage mechanism is possible given the conditions known to exist in TIDD. Improvements to the filter design to eliminate the root cause of the failure have been undertaken. This report details DLC`s conclusions regarding the failure mechanism, the evidence supporting the conclusions, and steps being taken to eliminate the root cause.« less

Mobile Uninterruptible Power Supply

NASA Technical Reports Server (NTRS)

Mears, Robert L.

1990-01-01

Proposed mobile unit provides 20 kVA of uninterruptible power. Used with mobile secondary power-distribution centers to provide power to test equipment with minimal cabling, hazards, and obstacles. Wheeled close to test equipment and system being tested so only short cable connections needed. Quickly moved and set up in new location. Uninterruptible power supply intended for tests which data lost or equipment damaged during even transient power failure.

Wellbore Seal Repair Using Nanocomposite Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stormont, John

2016-08-31

Nanocomposite wellbore repair materials have been developed, tested, and modeled through an integrated program of laboratory testing and numerical modeling. Numerous polymer-cement nanocomposites were synthesized as candidate wellbore repair materials using various combinations of base polymers and nanoparticles. Based on tests of bond strength to steel and cement, ductility, stability, flowability, and penetrability in opening of 50 microns and less, we identified Novolac epoxy reinforced with multi-walled carbon nanotubes and/or alumina nanoparticles to be a superior wellbore seal material compared to conventional microfine cements. A system was developed for testing damaged and repaired wellbore specimens comprised of a cement sheathmore » cast on a steel casing. The system allows independent application of confining pressures and casing pressures while gas flow is measured through the specimens along the wellbore axis. Repair with the nanocomposite epoxy base material was successful in dramatically reducing the flow through flaws of various sizes and types, and restoring the specimen comparable to an intact condition. In contrast, repair of damaged specimens with microfine cement was less effective, and the repair degraded with application of stress. Post-test observations confirm the complete penetration and sealing of flaws using the nanocomposite epoxy base material. A number of modeling efforts have supported the material development and testing efforts. We have modeled the steel-repair material interface behavior in detail during slant shear tests, which we used to characterize bond strength of candidate repair materials. A numerical model of the laboratory testing of damaged wellbore specimens was developed. This investigation found that microannulus permeability can satisfactorily be described by a joint model. Finally, a wellbore model has been developed that can be used to evaluate the response of the wellbore system (casing, cement, and microannulus), including the use of either cement or a nanocomposite in the microannulus to represent a repaired system. This wellbore model was successfully coupled with a field-scale model of CO 2 injection, to enable predictions of stress and strains in the wellbore subjected to subsurface changes (i.e. domal uplift) associated with fluid injection.« less

Evaluating the Thermal Damage Resistance of Reduced Graphene Oxide/Carbon Nanotube Hybrid Coatings

NASA Astrophysics Data System (ADS)

David, Lamuel; Feldman, Ari; Mansfield, Elisabeth; Lehman, John; Singh, Gurpreet; National Institute of Standards and Technology Collaboration

2014-03-01

Carbon nanotubes and graphene are known to exhibit some exceptional thermal (K ~ 2000 to 4400 W.m-1K-1 at 300K) and optical properties. Here, we demonstrate preparation and testing of multiwalled carbon nanotubes and chemically modified graphene-composite spray coatings for use on thermal detectors for high-power lasers. The synthesized nanocomposite material was tested by preparing spray coatings on aluminum test coupons used as a representation of the thermal detector's surface. These coatings were then exposed to increasing laser powers and extended exposure times to quantify their damage threshold and optical absorbance. The graphene/carbon nanotube (prepared at varying mass% of graphene in CNTs) coatings demonstrated significantly higher damage threshold values at 2.5 kW laser power (10.6 μm wavelength) than carbon paint or MWCNTs alone. Electron microscopy and Raman spectroscopy of irradiated specimens showed that the composite coating endured high laser-power densities (up to 2 kW.cm-2) without significant visual damage. This research is based on work supported by the National Science Foundation (Chemical, Bioengineering, Environmental, and Transport Systems Division), under grant no. 1335862 to G. Singh.

Development of damage suppression system using embedded SMA foil sensor and actuator

NASA Astrophysics Data System (ADS)

Ogisu, Toshimichi; Nomura, Masato; Ando, Norio; Takaki, Junji; Song, Dong Y.; Takeda, Nobuo

2000-06-01

The recent studies suggest possible applications of shape memory alloy (SMA) for a smart health monitoring and suppression of damage growth. The authors have been conducting research and development studies on applications of embedded SMA foil sensors and actuators in CFRP laminates. The goal of this research is suppression of damage growth in CFRP laminates. At first, the authors proposed a concept of damage suppression in CFRP laminates. Then, the development studies are conducted in three phases. The first phase is the improvement of interlaminar shear strength between SMA and CFRP laminates. Some surface treatments were investigated for the improvement of bonding property by peel resistance test and single lap shear strength test. The second phase is the investigation of fabrication technique for producing a CFRP panel with embedded SMA foils. Fixture jigs were devised to introduce tensile loads during the fabrication process. The third phase is the strength demonstration of CFRP laminates with embedded SMA foils. Some strength test were conducted to obtain the design data for aircraft structures. It is confirmed that the shrinking force of pre-strained SMA influences to the strength and the crack density of CFRP panel.

Segmenting data sets for RIP.

PubMed

de Sanctis, Daniele; Nanao, Max H

2012-09-01

Specific radiation damage can be used for the phasing of macromolecular crystal structures. In practice, however, the optimization of the X-ray dose used to `burn' the crystal to induce specific damage can be difficult. Here, a method is presented in which a single large data set that has not been optimized in any way for radiation-damage-induced phasing (RIP) is segmented into multiple sub-data sets, which can then be used for RIP. The efficacy of this method is demonstrated using two model systems and two test systems. A method to improve the success of this type of phasing experiment by varying the composition of the two sub-data sets with respect to their separation by image number, and hence by absorbed dose, as well as their individual completeness is illustrated.

Locking Nut with Stress-Distributing Insert

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.

2010-01-01

Reusable holders have been devised for evaluating high-temperature, plasma-resistant re-entry materials, especially fabrics. Typical material samples tested support thermal-protection-system damage repair requiring evaluation prior to re-entry into terrestrial atmosphere. These tests allow evaluation of each material to withstand the most severe predicted re-entry conditions.

Evaluation of SHM system produced by additive manufacturing via acoustic emission and other NDT methods.

PubMed

Strantza, Maria; Aggelis, Dimitrios G; de Baere, Dieter; Guillaume, Patrick; van Hemelrijck, Danny

2015-10-21

During the last decades, structural health monitoring (SHM) systems are used in order to detect damage in structures. We have developed a novel structural health monitoring approach, the so-called "effective structural health monitoring" (eSHM) system. The current SHM system is incorporated into a metallic structure by means of additive manufacturing (AM) and has the possibility to advance life safety and reduce direct operative costs. It operates based on a network of capillaries that are integrated into an AM structure. The internal pressure of the capillaries is continuously monitored by a pressure sensor. When a crack nucleates and reaches the capillary, the internal pressure changes signifying the existence of the flaw. The main objective of this paper is to evaluate the crack detection capacity of the eSHM system and crack location accuracy by means of various non-destructive testing (NDT) techniques. During this study, detailed acoustic emission (AE) analysis was applied in AM materials for the first time in order to investigate if phenomena like the Kaiser effect and waveform parameters used in conventional metals can offer valuable insight into the damage accumulation of the AM structure as well. Liquid penetrant inspection, eddy current and radiography were also used in order to confirm the fatigue damage and indicate the damage location on un-notched four-point bending AM metallic specimens with an integrated eSHM system. It is shown that the eSHM system in combination with NDT can provide correct information on the damage condition of additive manufactured metals.

Evaluation of SHM System Produced by Additive Manufacturing via Acoustic Emission and Other NDT Methods

PubMed Central

Strantza, Maria; Aggelis, Dimitrios G.; de Baere, Dieter; Guillaume, Patrick; van Hemelrijck, Danny

2015-01-01

During the last decades, structural health monitoring (SHM) systems are used in order to detect damage in structures. We have developed a novel structural health monitoring approach, the so-called “effective structural health monitoring” (eSHM) system. The current SHM system is incorporated into a metallic structure by means of additive manufacturing (AM) and has the possibility to advance life safety and reduce direct operative costs. It operates based on a network of capillaries that are integrated into an AM structure. The internal pressure of the capillaries is continuously monitored by a pressure sensor. When a crack nucleates and reaches the capillary, the internal pressure changes signifying the existence of the flaw. The main objective of this paper is to evaluate the crack detection capacity of the eSHM system and crack location accuracy by means of various non-destructive testing (NDT) techniques. During this study, detailed acoustic emission (AE) analysis was applied in AM materials for the first time in order to investigate if phenomena like the Kaiser effect and waveform parameters used in conventional metals can offer valuable insight into the damage accumulation of the AM structure as well. Liquid penetrant inspection, eddy current and radiography were also used in order to confirm the fatigue damage and indicate the damage location on un-notched four-point bending AM metallic specimens with an integrated eSHM system. It is shown that the eSHM system in combination with NDT can provide correct information on the damage condition of additive manufactured metals. PMID:26506349

An automatic damage detection algorithm based on the Short Time Impulse Response Function

NASA Astrophysics Data System (ADS)

Auletta, Gianluca; Carlo Ponzo, Felice; Ditommaso, Rocco; Iacovino, Chiara

2016-04-01

Structural Health Monitoring together with all the dynamic identification techniques and damage detection techniques are increasing in popularity in both scientific and civil community in last years. The basic idea arises from the observation that spectral properties, described in terms of the so-called modal parameters (eigenfrequencies, mode shapes, and modal damping), are functions of the physical properties of the structure (mass, energy dissipation mechanisms and stiffness). Damage detection techniques traditionally consist in visual inspection and/or non-destructive testing. A different approach consists in vibration based methods detecting changes of feature related to damage. Structural damage exhibits its main effects in terms of stiffness and damping variation. Damage detection approach based on dynamic monitoring of structural properties over time has received a considerable attention in recent scientific literature. We focused the attention on the structural damage localization and detection after an earthquake, from the evaluation of the mode curvature difference. The methodology is based on the acquisition of the structural dynamic response through a three-directional accelerometer installed on the top floor of the structure. It is able to assess the presence of any damage on the structure providing also information about the related position and severity of the damage. The procedure is based on a Band-Variable Filter, (Ditommaso et al., 2012), used to extract the dynamic characteristics of systems that evolve over time by acting simultaneously in both time and frequency domain. In this paper using a combined approach based on the Fourier Transform and on the seismic interferometric analysis, an useful tool for the automatic fundamental frequency evaluation of nonlinear structures has been proposed. Moreover, using this kind of approach it is possible to improve some of the existing methods for the automatic damage detection providing stable results also during the strong motion phase. This approach helps to overcome the limitation derived from the use of techniques based on simple Fourier Transform that provide good results when the response of the monitored system is stationary, but fails when the system exhibits a non-stationary behaviour. The main advantage derived from the use of the proposed approach for Structural Health Monitoring is based on the simplicity of the interpretation of the nonlinear variations of the fundamental frequency. The proposed methodology has been tested on numerical models of reinforced concrete structures designed for only gravity loads without and with the presence of infill panels. In order to verify the effectiveness of the proposed approach for the automatic evaluation of the fundamental frequency over time, the results of an experimental campaign of shaking table tests conducted at the seismic laboratory of University of Basilicata (SISLAB) have been used. Acknowledgements This study was partially funded by the Italian Civil Protection Department within the project DPC-RELUIS 2015 - RS4 ''Seismic observatory of structures and health monitoring''. References Ditommaso, R., Mucciarelli, M., Ponzo, F.C. (2012) Analysis of non-stationary structural systems by using a band-variable filter. Bulletin of Earthquake Engineering. DOI: 10.1007/s10518-012-9338-y.

Impact damage monitoring in CFRP using fiber Bragg grating ultrasound sensors

NASA Astrophysics Data System (ADS)

Tsuda, Hiroshi; Lee, Jung-Ryul; Eguchi, Shunji

2006-03-01

Impact damage in CFRP was monitored by ultrasonic inspection method using small-diameter fiber Bragg grating (FBG) sensors. The FBG ultrasound detection system consisted of broadband light source, FBG sensor and tunable optical filter. Broadband light was launched into the FBG sensor. Light reflected from the FBG sensor was transmitted through the tunable optical filter whose transmissive wavelength range is comparable to the reflected wavelength range of the FBG sensor. The operating wavelength of tunable filter was set to optimize the sensitivity of ultrasound detection. Ultrasound vibration was converted into change in intensity of light transmitted through the filter. A cross-ply carbon fiber-reinforced plastic (CFRP) plate was used as a test specimen for impact damage monitoring. A 6.3 X 9mm2 impact damage was introduced by ball dropping. Both FBG ultrasound sensor and piezoelectric ultrasound transmitter were attached on the CFRP surface. The change in responses to ultrasound excited by either spike signal or toneburst signal before and after impact damage was investigated. In response to ultrasound excited by spike signal, the response after impact damage showed a scattered behavior where the period of response signal got longer. In response to ultrasound excited by toneburst signal, damage signal features scattered and distorted waveform. Experimental results proved that the FBG inspection system could monitor a 6.3 X 9mm2 impact damage in CFRP.

Acoustic-sensor-based detection of damage in composite aircraft structures

NASA Astrophysics Data System (ADS)

Foote, Peter; Martin, Tony; Read, Ian

2004-03-01

Acoustic emission detection is a well-established method of locating and monitoring crack development in metal structures. The technique has been adapted to test facilities for non-destructive testing applications. Deployment as an operational or on-line automated damage detection technology in vehicles is posing greater challenges. A clear requirement of potential end-users of such systems is a level of automation capable of delivering low-level diagnosis information. The output from the system is in the form of "go", "no-go" indications of structural integrity or immediate maintenance actions. This level of automation requires significant data reduction and processing. This paper describes recent trials of acoustic emission detection technology for the diagnosis of damage in composite aerospace structures. The technology comprises low profile detection sensors using piezo electric wafers encapsulated in polymer film ad optical sensors. Sensors are bonded to the structure"s surface and enable acoustic events from the loaded structure to be located by triangulation. Instrumentation has been enveloped to capture and parameterise the sensor data in a form suitable for low-bandwidth storage and transmission.

Diagnostic methods for CW laser damage testing

NASA Astrophysics Data System (ADS)

Stewart, Alan F.; Shah, Rashmi S.

2004-06-01

High performance optical coatings are an enabling technology for many applications - navigation systems, telecom, fusion, advanced measurement systems of many types as well as directed energy weapons. The results of recent testing of superior optical coatings conducted at high flux levels will be presented. The diagnostics used in this type of nondestructive testing and the analysis of the data demonstrates the evolution of test methodology. Comparison of performance data under load to the predictions of thermal and optical models shows excellent agreement. These tests serve to anchor the models and validate the performance of the materials and coatings.

A bio-inspired structural health monitoring system based on ambient vibration

NASA Astrophysics Data System (ADS)

Lin, Tzu-Kang; Kiremidjian, Anne; Lei, Chi-Yang

2010-11-01

A structural health monitoring (SHM) system based on naïve Bayesian (NB) damage classification and DNA-like expression data was developed in this research. Adapted from the deoxyribonucleic acid (DNA) array concept in molecular biology, the proposed structural health monitoring system is constructed utilizing a double-tier regression process to extract the expression array from the structural time history recorded during external excitations. The extracted array is symbolized as the various genes of the structure from the viewpoint of molecular biology and reflects the possible damage conditions prevalent in the structure. A scaled down, six-story steel building mounted on the shaking table of the National Center for Research on Earthquake Engineering (NCREE) was used as the benchmark. The structural response at different damage levels and locations under ambient vibration was collected to support the database for the proposed SHM system. To improve the precision of detection in practical applications, the system was enhanced by an optimization process using the likelihood selection method. The obtained array representing the DNA array of the health condition of the structure was first evaluated and ranked. A total of 12 groups of expression arrays were regenerated from a combination of four damage conditions. To keep the length of the array unchanged, the best 16 coefficients from every expression array were selected to form the optimized SHM system. Test results from the ambient vibrations showed that the detection accuracy of the structural damage could be greatly enhanced by the optimized expression array, when compared to the original system. Practical verification also demonstrated that a rapid and reliable result could be given by the final system within 1 min. The proposed system implements the idea of transplanting the DNA array concept from molecular biology into the field of SHM.

Force Limit System

NASA Technical Reports Server (NTRS)

Pawlik, Ralph; Krause, David; Bremenour, Frank

2011-01-01

The Force Limit System (FLS) was developed to protect test specimens from inadvertent overload. The load limit value is fully adjustable by the operator and works independently of the test system control as a mechanical (non-electrical) device. When a test specimen is loaded via an electromechanical or hydraulic test system, a chance of an overload condition exists. An overload applied to a specimen could result in irreparable damage to the specimen and/or fixturing. The FLS restricts the maximum load that an actuator can apply to a test specimen. When testing limited-run test articles or using very expensive fixtures, the use of such a device is highly recommended. Test setups typically use electronic peak protection, which can be the source of overload due to malfunctioning components or the inability to react quickly enough to load spikes. The FLS works independently of the electronic overload protection.

Debonding damage analysis in composite-masonry strengthening systems with polymer- and mortar-based matrix by means of the acoustic emission technique

NASA Astrophysics Data System (ADS)

Verstrynge, E.; Wevers, M.; Ghiassi, B.; Lourenço, P. B.

2016-01-01

Different types of strengthening systems, based on fiber reinforced materials, are under investigation for external strengthening of historic masonry structures. A full characterization of the bond behavior and of the short- and long-term failure mechanisms is crucial to ensure effective design, compatibility with the historic substrate and durability of the strengthening solution. Therein, non-destructive techniques are essential for bond characterization, durability assessment and on-site condition monitoring. In this paper, the acoustic emission (AE) technique is evaluated for debonding characterization and localization on fiber reinforced polymer (FRP) and steel reinforced grout-strengthened clay bricks. Both types of strengthening systems are subjected to accelerated ageing tests under thermal cycles and to single-lap shear bond tests. During the reported experimental campaign, AE data from the accelerated ageing tests demonstrated the thermal incompatibility between brick and epoxy-bonded FRP composites, and debonding damage was successfully detected, characterized and located. In addition, a qualitative comparison is made with digital image correlation and infrared thermography, in view of efficient on-site debonding detection.

Protective Effects of Hydrogen against Low-Dose Long-Term Radiation-Induced Damage to the Behavioral Performances, Hematopoietic System, Genital System, and Splenic Lymphocytes in Mice

PubMed Central

Lei, Xiao; Zhao, Hainan; Liu, Pengfei; Xu, Yang; Chen, Yuanyuan; Chuai, Yunhai

2016-01-01

Molecular hydrogen (H2) has been previously reported playing an important role in ameliorating damage caused by acute radiation. In this study, we investigated the effects of H2 on the alterations induced by low-dose long-term radiation (LDLTR). All the mice in hydrogen-treated or radiation-only groups received 0.1 Gy, 0.5 Gy, 1.0 Gy, and 2.0 Gy whole-body gamma radiation, respectively. After the last time of radiation exposure, all the mice were employed for the determination of the body mass (BM) observation, forced swim test (FST), the open field test (OFT), the chromosome aberration (CA), the peripheral blood cells parameters analysis, the sperm abnormality (SA), the lymphocyte transformation test (LTT), and the histopathological studies. And significant differences between the treatment group and the radiation-only groups were observed, showing that H2 could diminish the detriment induced by LDLTR and suggesting the protective efficacy of H2 in multiple systems in mice against LDLTR. PMID:27774116

An overheight vehicle bridge collision monitoring system using piezoelectric transducers

NASA Astrophysics Data System (ADS)

Song, G.; Olmi, C.; Gu, H.

2007-04-01

With increasing traffic volume follows an increase in the number of overheight truck collisions with highway bridges. The detection of collision impact and evaluation of the impact level is a critical issue in the maintenance of a concrete bridge. In this paper, an overheight collision detection and evaluation system is developed for concrete bridge girders using piezoelectric transducers. An electric circuit is designed to detect the impact and to activate a digital camera to take photos of the offending truck. Impact tests and a health monitoring test were conducted on a model concrete bridge girder by using three piezoelectric transducers embedded before casting. From the experimental data of the impact test, it can be seen that there is a linear relation between the output of sensor energy and the impact energy. The health monitoring results show that the proposed damage index indicates the level of damage inside the model concrete bridge girder. The proposed overheight truck-bridge collision detection and evaluation system has the potential to be applied to the safety monitoring of highway bridges.

Burst annealing of high temperature GaAs solar cells

NASA Technical Reports Server (NTRS)

Brothers, P. R.; Horne, W. E.

1991-01-01

One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles.

Mechanical and histological characterization of trachea tissue subjected to blast-type pressures

NASA Astrophysics Data System (ADS)

Butler, B. J.; Bo, C.; Tucker, A. W.; Jardine, A. P.; Proud, W. G.; Williams, A.; Brown, K. A.

2014-05-01

Injuries to the respiratory system can be a component of polytrauma in blast-loading injuries. Tissues located at air-liquid interfaces, including such tissues in the respiratory system, are particularly vulnerable to damage by blast overpressures. There is a lack of information about the mechanical and cellular responses that contribute to the damage of this class of tissues subjected to the high strain rates associated with blast loading. Here, we describe the results of dynamic blast-like pressure loading tests at high strain rates on freshly harvested ex vivo trachea tissue specimens.

Infrared Thermography as a Non-destructive Testing Solution for Thermal Spray Metal Coatings

NASA Astrophysics Data System (ADS)

Santangelo, Paolo E.; Allesina, Giulio; Bolelli, Giovanni; Lusvarghi, Luca; Matikainen, Ville; Vuoristo, Petri

2017-12-01

In this work, an infrared (IR) thermographic procedure was evaluated as a non-destructive testing tool to detect damage in thermal spray metallic coatings. As model systems, polished HVOF- and HVAF-sprayed Fe-based layers deposited onto steel plates were employed. Damage by external-object impingement was simulated through a cyclic impact-test apparatus, which induced circumferential and radial cracks across all model systems, and interface cracks of different sizes in distinct samples. Damaged and undamaged plates were bulk-heated to above 100 °C using an IR lamp; their free-convection cooling was then recorded by an IR thermocamera. The intentionally induced defects were hardly detectable in IR thermograms, due to IR reflection and artificial "hot" spots induced by residuals of transfer material from the impacting counterbody. As a micrometer-thin layer of black paint was applied, surface emissivity got homogenized and any artifacts were effectively suppressed, so that failed coating areas clearly showed up as "cold spots." This effect was more apparent when large interface cracks occurred. Finite-element modeling proved the physical significance of the IR-thermography approach, showing that failed coating areas are cooled by surrounding air faster than they are heated by conduction from the hot substrate, which is due to the insulating effect of cracks.

A novel overall approach for sediment-related disaster prevention in urban areas, South Korea

NASA Astrophysics Data System (ADS)

Kim, Dongyeob; Lee, Changwoo; Woo, Choongshik; Jeong, Seonhwan

2015-04-01

In South Korea, we had 140 landslides around Mt. Umyeon of Seoul city on July 27, 2011, which caused 16 deaths and more than 150 house damages. These landslides were triggered by a severe rainfall event with the total amount of 365 mm, equivalent to a 100-year-recurrence interval event. The landslide disaster in Mt. Umyeon is the first sediment-related disaster posing the significant serious damages to urban areas in South Korea which requires overall reconsideration about prevention, warning, countermeasure and rehabilitation to sediment-related disasters in urban areas. To meet such demands of society, the Korea Forest Research Institute (KFRI), competent to the sediment-related disasters research, is committed to conducting on a research project of development of a prevention system for sediment-related disasters in urban areas including non-structural countermeasures such as construction of landslide early warning system and structural ones such as development of urban-typed debris flow barriers. Of these countermeasures, a proto-type of landslide early warning system consisting of a variety of sensors such as soil moisture content sensor and tensiometer has been tested in-situ in a point view of system performance maintenance. We have also tried to find the threshold of the sensors by slope failure experiments. Meanwhile, two types of debris flow barriers for urban areas were developed and their functioning abilities have been tested by both of flume test and computational structure analysis. We hope these research results would mitigate potential damages efficiently by sediment-related disasters in urban areas.

Acoustic Emission Detection of Impact Damage on Space Shuttle Structures

NASA Technical Reports Server (NTRS)

Prosser, William H.; Gorman, Michael R.; Madaras, Eric I.

2004-01-01

The loss of the Space Shuttle Columbia as a result of impact damage from foam debris during ascent has led NASA to investigate the feasibility of on-board impact detection technologies. AE sensing has been utilized to monitor a wide variety of impact conditions on Space Shuttle components ranging from insulating foam and ablator materials, and ice at ascent velocities to simulated hypervelocity micrometeoroid and orbital debris impacts. Impact testing has been performed on both reinforced carbon composite leading edge materials as well as Shuttle tile materials on representative aluminum wing structures. Results of these impact tests will be presented with a focus on the acoustic emission sensor responses to these impact conditions. These tests have demonstrated the potential of employing an on-board Shuttle impact detection system. We will describe the present plans for implementation of an initial, very low frequency acoustic impact sensing system using pre-existing flight qualified hardware. The details of an accompanying flight measurement system to assess the Shuttle s acoustic background noise environment as a function of frequency will be described. The background noise assessment is being performed to optimize the frequency range of sensing for a planned future upgrade to the initial impact sensing system.

Results on the Slosson Drawing Coordination Test with Appalachian Sheltered Workshop Clients.

ERIC Educational Resources Information Center

Rogers, George W., Jr.; Richmond, Bert O.

Fifty-four clients (13- to 52-years-old) in an Appalachian sheltered workshop were administered the Slosson Drawing Coordination Test (SDCT) and the Bender Visual Motor Gestalt Test. Twenty-nine Ss were labeled possibly brain damaged by the SDCT, and 17 Ss by the M. Hutt scoring system for the Bender-Gestalt. Two psychologists using all available…

Assessment of genotoxic effects of flumorph by the comet assay in mice organs.

PubMed

Zhang, T; Zhao, Q; Zhang, Y; Ning, J

2014-03-01

The present study investigated the genotoxic effects of flumorph in various organs (brain, liver, spleen, kidney and sperm) of mice. The DNA damage, measured as comet tail length (µm), was determined using the alkaline comet assay. The comet assay is a sensitive assay for the detection of genotoxicity caused by flumorph using mice as a model. Statistically significant increases in comet assay for both dose-dependent and duration-dependent DNA damage were observed in all the organs assessed. The organs exhibited the maximum DNA damage in 96 h at 54 mg/kg body weight. Brain showed maximum DNA damage followed by spleen > kidney > liver > sperm. Our data demonstrated that flumorph had induced systemic genotoxicity in mammals as it caused DNA damage in all tested vital organs, especially in brain and spleen.

Quantification and identification of lightning damage in tropical forests.

PubMed

Yanoviak, Stephen P; Gora, Evan M; Burchfield, Jeffrey M; Bitzer, Phillip M; Detto, Matteo

2017-07-01

Accurate estimates of tree mortality are essential for the development of mechanistic forest dynamics models, and for estimating carbon storage and cycling. However, identifying agents of tree mortality is difficult and imprecise. Although lightning kills thousands of trees each year and is an important agent of mortality in some forests, the frequency and distribution of lightning-caused tree death remain unknown for most forests. Moreover, because all evidence regarding the effects of lightning on trees is necessarily anecdotal and post hoc, rigorous tests of hypotheses regarding the ecological effects of lightning are impossible. We developed a combined electronic sensor/camera-based system for the location and characterization of lightning strikes to the forest canopy in near real time and tested the system in the forest of Barro Colorado Island, Panama. Cameras mounted on towers provided continuous video recordings of the forest canopy that were analyzed to determine the locations of lightning strikes. We used a preliminary version of this system to record and locate 18 lightning strikes to the forest over a 3-year period. Data from field surveys of known lightning strike locations (obtained from the camera system) enabled us to develop a protocol for reliable, ground-based identification of suspected lightning damage to tropical trees. In all cases, lightning damage was relatively inconspicuous; it would have been overlooked by ground-based observers having no knowledge of the event. We identified three types of evidence that can be used to consistently identify lightning strike damage in tropical forests: (1) localized and directionally biased branch mortality associated with flashover among tree and sapling crowns, (2) mortality of lianas or saplings near lianas, and (3) scorched or wilting epiphytic and hemiepiphytic plants. The longitudinal trunk scars that are typical of lightning-damaged temperate trees were never observed in this study. Given the prevalence of communications towers worldwide, the lightning detection system described here could be implemented in diverse forest types. Data from multiple systems would provide an outstanding opportunity for comparative research on the ecological effects of lightning. Such comparative data are increasingly important given expected increases in lightning frequency with climatic change.

ATR suppresses endogenous DNA damage and allows completion of homologous recombination repair.

PubMed

Brown, Adam D; Sager, Brian W; Gorthi, Aparna; Tonapi, Sonal S; Brown, Eric J; Bishop, Alexander J R

2014-01-01

DNA replication fork stalling or collapse that arises from endogenous damage poses a serious threat to genome stability, but cells invoke an intricate signaling cascade referred to as the DNA damage response (DDR) to prevent such damage. The gene product ataxia telangiectasia and Rad3-related (ATR) responds primarily to replication stress by regulating cell cycle checkpoint control, yet it's role in DNA repair, particularly homologous recombination (HR), remains unclear. This is of particular interest since HR is one way in which replication restart can occur in the presence of a stalled or collapsed fork. Hypomorphic mutations in human ATR cause the rare autosomal-recessive disease Seckel syndrome, and complete loss of Atr in mice leads to embryonic lethality. We recently adapted the in vivo murine pink-eyed unstable (pun) assay for measuring HR frequency to be able to investigate the role of essential genes on HR using a conditional Cre/loxP system. Our system allows for the unique opportunity to test the effect of ATR loss on HR in somatic cells under physiological conditions. Using this system, we provide evidence that retinal pigment epithelium (RPE) cells lacking ATR have decreased density with abnormal morphology, a decreased frequency of HR and an increased level of chromosomal damage.

Characterization of C/Enhanced SiC Composite During Creep-Rupture Tests Using an Ultrasonic Guided Wave Scan System

NASA Technical Reports Server (NTRS)

Roth, Don J.; Verrilli, Michael J.; Martin, Richard E.; Cosgriff, Laura M.

2004-01-01

An ultrasonic guided wave scan system was used to nondestructively monitor damage over time and position in a C/enhanced SiC sample that was creep tested to failure at 1200 C in air at a stress of 69 MPa (10 ksi). The use of the guided wave scan system for mapping evolving oxidation profiles (via porosity gradients resulting from oxidation) along the sample length and predicting failure location was explored. The creep-rupture tests were interrupted for ultrasonic evaluation every two hours until failure at approx. 17.5 cumulative hours.

Synergistic Effects of Physical Aging and Damage on Long-Term Behavior of Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Brinson, L. Cate

1999-01-01

The research consisted of two major parts, first modeling and simulation of the combined effects of aging and damage on polymer composites and secondly an experimental phase examining composite response at elevated temperatures, again activating both aging and damage. For the simulation, a damage model for polymeric composite laminates operating at elevated temperatures was developed. Viscoelastic behavior of the material is accounted for via the correspondence principle and a variational approach is adopted to compute the temporal stresses within the laminate. Also, the effect of physical aging on ply level stress and on overall laminate behavior is included. An important feature of the model is that damage evolution predictions for viscoelastic laminates can be made. This allows us to track the mechanical response of the laminate up to large load levels though within the confines of linear viscoelastic constitutive behavior. An experimental investigation of microcracking and physical aging effects in polymer matrix composites was also pursued. The goal of the study was to assess the impact of aging on damage accumulation, in ten-ns of microcracking, and the impact of damage on aging and viscoelastic behavior. The testing was performed both at room and elevated temperatures on [+/- 45/903](sub s) and [02/903](sub s) laminates, both containing a set of 90 deg plies centrally located to facilitate investigation of microcracking. Edge replication and X-ray-radiography were utilized to quantify damage. Sequenced creep tests were performed to characterize viscoelastic and aging parameters. Results indicate that while the aging times studied have limited ]Influence on damage evolution, elevated temperature and viscoelastic effects have a profound effect on the damage mode seen. Some results are counterintuitive, including the lower strain to failure for elevated temperature tests and the catastrophic failure mode observed for the [+/- 45/9O3](sub s), specimens. The fracture toughness for transverse cracks increases with increasing temperature for both systems: transverse cracking was completely absent prior to failure in [+/- 45/903](sub s), and was suppressed for [02/903](sub s). No significant effect of damage on aging or viscoelastic parameters was observed.

Development of a Remote External Repair Tool for Damaged or Defective Polyethylene Pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenneth H. Green; Willie E. Rochefort; Nick Wannenmacher

2006-06-30

Current procedures for repairing polyethylene (PE) gas pipe require excavation, isolation, and removal of the damaged section of pipe followed by fusing a new section of pipe into place. These techniques are costly and very disruptive. An alternative repair method was developed at Timberline Tool with support from Oregon State University (OSU) and funding by the U. S. Department of Energy National Energy Technology Laboratory (DOE/NETL). This project was undertaken to design, develop and test a tool and method for repairing damaged PE pipe remotely and externally in situ without squeezing off the flow of gas, eliminating the need formore » large-scale excavations. Through an iterative design and development approach, a final engineered prototype was developed that utilizes a unique thermo-chemical and mechanical process to apply a permanent external patch to repair small nicks, gouges and punctures under line pressure. The project identified several technical challenges during the design and development process. The repair tool must be capable of being installed under live conditions and operate in an 18-inch keyhole. This would eliminate the need for extensive excavations thus reducing the cost of the repair. Initially, the tool must be able to control the leak by encapsulating the pipe and apply slight pressure at the site of damage. Finally, the repair method must be permanent at typical operating pressures. The overall results of the project have established a permanent external repair method for use on damaged PE gas pipe in a safe and cost-effective manner. The engineered prototype was subjected to comprehensive testing and evaluation to validate the performance. Using the new repair tool, samples of 4-inch PE pipe with simulated damage were successfully repaired under line pressure to the satisfaction of DOE/NETL and the following natural gas companies: Northwest Natural; Sempra Energy, Southwest Gas Corporation, Questar, and Nicor. However, initial results of accelerated age testing on repaired pipe samples showed that the high density polyethylene (HDPE) pipe patch material developed a small crack at the high stress areas surrounding the patched hole within the first 48 hours of hot water testing, indicating that the patch material has a 25-year lifespan. Based on these results, further research is continuing to develop a stronger repair patch for a satisfactory 50-year patch system. Additional tests were also conducted to evaluate whether any of the critical performance properties of the PE pipe were reduced or compromised by the repair technique. This testing validated a satisfactory 50-year patch system for the pipe.« less

The principal phenolic and alcoholic components of wine protect human lymphocytes against hydrogen peroxide- and ionizing radiation-induced DNA damage in vitro.

PubMed

Greenrod, William; Fenech, Michael

2003-03-01

We have tested the hypothesis that the alcoholic and phenolic components of wine are protective against the DNA-damaging and cytotoxic effects of hydrogen peroxide and gamma-radiation in vitro. The components of wine tested were ethanol, glycerol, a mixture of the phenolic compounds catechin and caffeic acid and tartaric acid, all at concentrations that were 2.5 or 10.0% of the concentration in a typical Australian white wine (Riesling). These components were tested individually or combined as a mixture and compared to a white wine stripped of polyphenols, as well as a Hanks balanced salt solution control, which was the diluent for the wine components. The effect of the components was tested in lymphocytes, using the cytokinesis-block micronucleus assay, after 30 min incubation in plasma or whole blood for the hydrogen peroxide or gamma-radiation challenge, respectively. The results obtained showed that ethanol, glycerol, the catechin-caffeic acid mixture, the mixture of all components and the stripped white wine significantly reduced the DNA-damaging effects of hydrogen peroxide and gamma-radiation (P = 0.043-0.001, ANOVA). The strongest protective effect against DNA damage by gamma-irradiation was observed for the catechin-caffeic acid mixture and the mixture of all components (30 and 32% reduction, respectively). These two treatments as well as ethanol produced the strongest protective effects against DNA damage by hydrogen peroxide (24, 25 and 18%, respectively). The protection provided by the mixture did not account for the expected additive protective effects of the individual components. Ethanol was the only component that significantly increased baseline DNA damage rate, however, this effect was negated in the mixture. In conclusion, our results suggest that the main phenolic and alcoholic components of wine can reduce the DNA-damaging effects of two important oxidants, i.e. hydrogen peroxide and ionizing radiation, in this physiologically relevant in vitro system.

Thermomechanical Fatigue Damage/Failure Mechanisms in SCS-6/Timetal 21S [0/90](Sub S) Composite

NASA Technical Reports Server (NTRS)

Castelli, Michael G.

1994-01-01

The thermomechanical fatigue (TMF) deformation, damage, and life behaviors of SCS6/Timetal 21S (0/90)s were investigated under zero-tension conditions. In-phase (IP) and out-of-phase (OP) loadings were investigated with a temperature cycle from 150 to 650 deg C. An advanced TMF test technique was used to quantify mechanically damage progression. The technique incorporated explicit measurements of the macroscopic (1) isothermal static moduli at the temperature extremes of the TMF cycle and (2) coefficient of thermal expansion (CTE) as functions of the TMF cycles. The importance of thermal property degradation and its relevance to accurate post-test data analysis and interpretation is briefly addressed. Extensive fractography and metallography were conducted on specimens from failed and interrupted tests to characterize the extent of damage at the microstructure level. Fatigue life results indicated trends analogous to those established for similar unidirectional(0) reinforced titanium matrix composite systems. High stress IP and mid to low stress OP loading conditions were life-limiting in comparison to maximum temperature isothermal conditions. Dominant damage mechanisms changed with cycle type. Damage resulting from IP TMF conditions produced measurable decreases in static moduli but only minimal changes in the CTE. Metallography on interrupted and failed specimens revealed extensive (0) fiber cracking with sparse matrix damage. No surface initiated matrix cracks were present. Comparable OP TMF conditions initiated environment enhanced surface cracking and matrix cracking initiated at (90) fiber/matrix (F/M) interfaces. Notable static moduli and CTE degradations were measured. Fractography and metallography revealed that the transverse cracks originating from the surface and (90) F/M interfaces tended to converge and coalesce at the (0) fibers.

Dynamic Capability of an Operating Stirling Convertor

NASA Technical Reports Server (NTRS)

Goodnight, Thomas W.; Hughes, William O.; McNelis, Mark E.

2000-01-01

The NASA John H. Glenn Research Center and the US Department of Energy are currently developing a Stirling convertor for use as an advanced spacecraft power system for future NASA deep-space missions. NASA Headquarters has recently identified the Stirling technology generator for potential use as the spacecraft power system for two of NASA's new missions, the Europa Orbiter and the Solar Probe missions (planned for launch in 2006 and 2007 respectively). As part of the development of this power system, a Stirling Technology Demonstration Convertor was vibration tested at NASA John H. Glenn Research Center to verify its survivability and capability of withstanding the harsh dynamic environment typically seen by the spacecraft when it is launched by an expendable launch vehicle. The Technology Demonstration Convertor was fully operational (producing power) during the random vibration testing. The output power of the convertor and other convertor performance indicators were measured during the testing, and these results are discussed in this paper. Numerous accelerometers and force gauges also were used to provide information on the dynamic characteristics of the Technology Demonstration Convertor and as an indication of any possible damage due to the vibration. These measurements will also be discussed in this paper. The vibration testing of the Stirling Technology Demonstration Convertor was extremely successful. The Technology Demonstration Convertor survived all its vibration testing with no structural damage or functional performance degradation. As a result of this testing, the Stirling convertor's capability to withstand vibration has been demonstrated, enabling its usage in future spacecraft power systems.

Reduction of thermal damage in photodynamic therapy by laser irradiation techniques.

PubMed

Lim, Hyun Soo

2012-12-01

General application of continuous-wave (CW) laser irradiation modes in photodynamic therapy can cause thermal damage to normal tissues in addition to tumors. A new photodynamic laser therapy system using a pulse irradiation mode was optimized to reduce nonspecific thermal damage. In in vitro tissue specimens, tissue energy deposition rates were measured in three irradiation modes, CW, pulse, and burst-pulse. In addition, methods were tested for reducing variations in laser output and specific wavelength shifts using a thermoelectric cooler and thermistor. The average temperature elevation per 10 J/cm2 was 0.27°C, 0.09°C, and 0.08°C using the three methods, respectively, in pig muscle tissue. Variations in laser output were controlled within ± 0.2%, and specific wavelength shift was limited to ± 3 nm. Thus, optimization of a photodynamic laser system was achieved using a new pulse irradiation mode and controlled laser output to reduce potential thermal damage during conventional CW-based photodynamic therapy.

Study on mechanical properties and damage behaviors of Kevlar fiber reinforced epoxy composites by digital image correlation technique under optical microscope

NASA Astrophysics Data System (ADS)

Gao, Xiang; Shao, Wenquan; Ji, Hongwei

2010-10-01

Kevlar fiber-reinforced epoxy (KFRE) composites are widely used in the fields of aerospace, weapon, shipping, and civil industry, due to their outstanding capabilities. In this paper, mechanical properties and damage behaviors of KFRE laminate (02/902) were tested and studied under tension condition. To precisely measure the tensile mechanical properties of the material and investigate its micro-scale damage evolution, a micro-image measuring system with in-situ tensile device was designed. The measuring system, by which the in-situ tensile test can be carried out and surface morphology evolution of the tensile specimen can be visually monitored and recorded during the process of loading, includes an ultra-long working distance zoom microscope and a in-situ tensile loading device. In this study, a digital image correlation method (DICM) was used to calculate the deformation of the tensile specimen under different load levels according to the temporal series images captured by an optical microscope and CCD camera. Then, the elastic modulus and Poisson's ratio of the KFRE was obtained accordingly. The damage progresses of the KFRE laminates were analyzed. Experimental results indicated that: (1) the KFRE laminate (02/902) is almost elastic, its failure mode is brittle tensile fracture.(2) Mechanical properties parameters of the material are as follows: elastic modulus is 14- 16GPa, and tensile ultimate stress is 450-480 Mpa respectively. (3) The damage evolution of the material is that cracks appear in epoxy matrix firstly, then, with the increasing of the tensile loading, matrix cracks add up and extend along a 45° angle direction with tensile load. Furthermore, decohesion between matrix and fibers as well as delamination occurs. Eventually, fibers break and the material is damaged.

Seismic Retrofit for Electric Power Systems

DOE PAGES

Romero, Natalia; Nozick, Linda K.; Dobson, Ian; ...

2015-05-01

Our paper develops a two-stage stochastic program and solution procedure to optimize the selection of seismic retrofit strategies to increase the resilience of electric power systems against earthquake hazards. The model explicitly considers the range of earthquake events that are possible and, for each, an approximation of the distribution of damage experienced. Furthermore, this is important because electric power systems are spatially distributed and so their performance is driven by the distribution of component damage. We also test this solution procedure against the nonlinear integer solver in LINGO 13 and apply the formulation and solution strategy to the Eastern Interconnection,more » where seismic hazard stems from the New Madrid seismic zone.« less

An Evaluation of Relative Damage to the Powertrain System in Tracked Vehicles

PubMed Central

Lee, Sang-Ho; Lee, Jeong-Hwan; Goo, Sang-Hwa; Cho, Yong-Cheol; Cho, Ho-Young

2009-01-01

The objective of this study was to improve the reliability of the endurance test for the powertrain system of military tracked vehicles. The measurement system that measures the driving duty applied to the powertrain system caused by mobility on roads consists of eight analog channels and two pulse channels, including the propeller shaft output torques for the left and right sides. The data obtained from this measurement system can be used to introduce a new technology that produces the output torque of a torque converter and that can be applied to analyze the revolution counting for the endurance and road mobility in the front unit and represent the relative fatigue damages analysis technique and its results according to the driven roads through a cumulative fatigue method. PMID:22573990

Instrumentation Cables Test Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muna, Alice Baca; LaFleur, Chris Bensdotter

A fire at a nuclear power plant (NPP) has the potential to damage structures, systems, and components important to safety, if not promptly detected and suppressed. At Browns Ferry Nuclear Power Plant on March 22, 1975, a fire in the reactor building damaged electrical power and control systems. Damage to instrumentation cables impeded the function of both normal and standby reactor coolant systems, and degraded the operators’ plant monitoring capability. This event resulted in additional NRC involvement with utilities to ensure that NPPs are properly protected from fire as intended by the NRC principle design criteria (i.e., general design criteriamore » 3, Fire Protection). Current guidance and methods for both deterministic and performance based approaches typically make conservative (bounding) assumptions regarding the fire-induced failure modes of instrumentation cables and those failure modes effects on component and system response. Numerous fire testing programs have been conducted in the past to evaluate the failure modes and effects of electrical cables exposed to severe thermal conditions. However, that testing has primarily focused on control circuits with only a limited number of tests performed on instrumentation circuits. In 2001, the Nuclear Energy Institute (NEI) and the Electric Power Research Institute (EPRI) conducted a series of cable fire tests designed to address specific aspects of the cable failure and circuit fault issues of concern1. The NRC was invited to observe and participate in that program. The NRC sponsored Sandia National Laboratories to support this participation, whom among other things, added a 4-20 mA instrumentation circuit and instrumentation cabling to six of the tests. Although limited, one insight drawn from those instrumentation circuits tests was that the failure characteristics appeared to depend on the cable insulation material. The results showed that for thermoset insulated cables, the instrument reading tended to drift and fluctuate, while the thermoplastic insulated cables, the instrument reading fell off-scale rapidly. From an operational point of view, the latter failure characteristics would likely be identified as a failure from the effects of fire, while the former may result in inaccurate readings.« less

An experimental study of the self-healing behavior of ionomeric systems under ballistic impact tests

NASA Astrophysics Data System (ADS)

Grande, A. M.; Coppi, S.; Di Landro, L.; Sala, G.; Giacomuzzo, C.; Francesconi, A.; Rahman, M. A.

2012-04-01

This research deals with the investigation of the self-healing behavior after ballistic damage of ethylene-methacrylic acid ionomers and theirs blends with epoxidized natural rubber (ENR). The self-healing capability was studied by ballistic puncture tests under different experimental conditions as sample thickness, bullet speed, diameter and shape. Bullet speed ranging from few hundreds meters per second to few km/s were employed. The healing efficiency was evaluated by applying a pressure gradient trough the plates and by checking for possible flow at the damage zone. A morphology analysis of the impact area was made observing all samples by scanning electron microscope.

Phentolamine tests and catecholamine levels in normotensive CVA patients.

PubMed

Favazza, A R

1974-11-01

Ten normotensive patients diagnosed as having a CVA had Regitine tests and urinary VMA and catecholamine determinations during the first day of hospitalization. The VMA and catecholamine levels were all within normal limits (except for one elevated VMA level) but did not correlate well with each other. The average response to phentolamine was an average drop in blood pressure of 30mm. Hg systolic and 19 mm. Hg diastolic. Mechanisms by which hypertensive states or cerebral damage might effect blood pressure are discussed. It is suggested that CNS damage might induce a vasolabile or hypersensitive state via connections and consequent alterations in the autonomic vasomotor system.

The Thirty Meter Telescope Site Testing Robotic Computer System

NASA Astrophysics Data System (ADS)

Riddle, Reed L.; Schöck, M.; Skidmore, W.; Els, S.; Travouillon, T.

2008-03-01

The Thirty Meter Telescope (TMT) project is currently testing five remote sites as candidates for the final location of the telescope. Each site has several instruments, including seeing monitors, weather stations, and turbulence profile measuring systems, each of which is computer controlled. As the sites are remote, they require a control system that can automatically manage the operations of all the varied subsystems, keep the systems safe from damage and recover from errors during operation. The robotic system must also be robust enough to operate without human intervention and when internet connections are lost. It is also critical that a data archiving system diligently records all data as gathered. This is a discussion of the TMT site testing robotic computer system as implemented.

Use of FBG sensors for health monitoring of pipelines

NASA Astrophysics Data System (ADS)

Felli, Ferdinando; Paolozzi, Antonio; Vendittozzi, Cristian; Paris, Claudio; Asanuma, Hiroshi

2016-04-01

The infrastructures for oil and gas production and distribution need reliable monitoring systems. The risks for pipelines, in particular, are not only limited to natural disasters (landslides, earthquakes, extreme environmental conditions) and accidents, but involve also the damages related to criminal activities, such as oil theft. The existing monitoring systems are not adequate for detecting damages from oil theft, and in several occasion the illegal activities resulted in leakage of oil and catastrophic environmental pollution. Systems based on fiber optic FBG (Fiber Bragg Grating) sensors present a number of advantages for pipeline monitoring. FBG sensors can withstand harsh environment, are immune to interferences, and can be used to develop a smart system for monitoring at the same time several physical characteristics, such as strain, temperature, acceleration, pressure, and vibrations. The monitoring station can be positioned tens of kilometers away from the measuring points, lowering the costs and the complexity of the system. This paper describes tests on a sensor, based on FBG technology, developed specifically for detecting damages of pipeline due to illegal activities (drilling of the pipes), that can be integrated into a smart monitoring chain.

The quest for better quality-of-life - learning from large-scale shaking table tests

NASA Astrophysics Data System (ADS)

Nakashima, M.; Sato, E.; Nagae, T.; Kunio, F.; Takahito, I.

2010-12-01

Earthquake engineering has its origins in the practice of “learning from actual earthquakes and earthquake damages.” That is, we recognize serious problems by witnessing the actual damage to our structures, and then we develop and apply engineering solutions to solve these problems. This tradition in earthquake engineering, i.e., “learning from actual damage,” was an obvious engineering response to earthquakes and arose naturally as a practice in a civil and building engineering discipline that traditionally places more emphasis on experience than do other engineering disciplines. But with the rapid progress of urbanization, as society becomes denser, and as the many components that form our society interact with increasing complexity, the potential damage with which earthquakes threaten the society also increases. In such an era, the approach of ”learning from actual earthquake damages” becomes unacceptably dangerous and expensive. Among the practical alternatives to the old practice is to “learn from quasi-actual earthquake damages.” One tool for experiencing earthquake damages without attendant catastrophe is the large shaking table. E-Defense, the largest one we have, was developed in Japan after the 1995 Hyogoken-Nanbu (Kobe) earthquake. Since its inauguration in 2005, E-Defense has conducted over forty full-scale or large-scale shaking table tests, applied to a variety of structural systems. The tests supply detailed data on actual behavior and collapse of the tested structures, offering the earthquake engineering community opportunities to experience and assess the actual seismic performance of the structures, and to help society prepare for earthquakes. Notably, the data were obtained without having to wait for the aftermaths of actual earthquakes. Earthquake engineering has always been about life safety, but in recent years maintaining the quality of life has also become a critical issue. Quality-of-life concerns include nonstructural damage, business continuity, public health, quickness of damage assessment, infrastructure, data and communication networks, and other issues, and not enough useful empirical data have emerged about these issues from the experiences of actual earthquakes. To provide quantitative data that can be used to reduce earthquake risk to our quality of life, E-Defense recently has been implementing two comprehensive research projects in which a base-isolated hospital and a steel high-rise building were tested using the E-Defense shaking table and their seismic performance were examined particularly in terms of the nonstructural damage, damage to building contents and furniture, and operability, functionality, and business-continuity capability. The paper presents the overview of the two projects, together with major findings obtained from the projects.

49 CFR 173.35 - Hazardous materials in IBCs.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., cracks, cuts, or other damage which would render it unable to pass the prescribed design type test to... of this subchapter. Additional marking allowed for each design type may be present. Required markings... percent of its water capacity. (e) Where two or more closure systems are fitted in series, the system...

A three-dimensional `Kaiser damage-memory' effect through true-triaxial loading

NASA Astrophysics Data System (ADS)

Meredith, P. G.; Browning, J.; Harland, S. R.; Healy, D.; Stuart, C.; Mitchell, T. M.

2017-12-01

Microcrack damage leading to failure in rocks evolves in response to differential loading. The vast majority of experimental studies investigate damage evolution, the `Kaiser damage-memory' effect, and rock failure using conventional triaxial stress states (σ1 > σ2 = σ3). Such stress states develop a crack population that displays cylindrical transverse isotropy. However, in nature the stress state is in general truly triaxial (σ1 > σ2 > σ3) and experiments that utilise such loading conditions can generate crack populations that display planar transverse isotropy which in turn influences properties such as permeability and strength. We investigate the evolution of crack damage under both conventional and true triaxial stress conditions using results from measurements made on cubic samples of sandstone deformed in three orthogonal directions with independently controlled stress paths. We have measured, simultaneously with stress and strain, the changes in ultrasonic compressional and shear wave velocities in the three principal directions, together with the bulk acoustic emission (AE) output. Changes in acoustic wave velocities are associated with both elastic closure and opening of pre-existing cracks, and the inelastic formation of new cracks. By contrast, AE is only associated with the inelastic growth of new crack damage and as such, we use the onset of AE to determine the initiation of new crack damage. By mapping these damage onsets under both conventional triaxial and true triaxial sequential cyclic loading, we have shown that `damage envelopes' evolve dynamically and can be pushed closer to the failure envelope. Whether a stress state has been `visited' before is key to determining and understanding damage states. Crack damage populations can be generated with multiple orientations depending on the arrangement of loading directions and hence principal stress directions. The sequential cyclic loading tests show that further damage in any one population commences only when the previous maximum differential stress `seen' by that population is exceeded. Understanding anisotropic damage is important for applying the results of true-triaxial tests and hence better replicating natural fractured systems.

Monitoring and evaluating civil structures using measured vibration

NASA Astrophysics Data System (ADS)

Straser, Erik G.; Kiremidjian, Anne S.

1996-04-01

The need for a rapid assessment of the state of critical and conventional civil structures, such as bridges, control centers, airports, and hospitals, among many, has been amply demonstrated during recent natural disasters. Research is underway at Stanford University to develop a state-of-the-art automated damage monitoring system for long term and extreme event monitoring based on both ambient and forced response measurements. Such research requires a multi-disciplinary approach harnessing the talents and expertise of civil, electrical, and mechanical engineering to arrive at a novel hardware and software solution. Recent advances in silicon micro-machining and microprocessor design allow for the economical integration of sensing, processing, and communication components. Coupling these technological advances with parameter identification algorithms allows for the realization of extreme event damage monitoring systems for civil structures. This paper addresses the first steps toward the development of a near real-time damage diagnostic and monitoring system based on structural response to extreme events. Specifically, micro-electro-mechanical- structures (MEMS) and microcontroller embedded systems (MES) are demonstrated to be an effective platform for the measurement and analysis of civil structures. Experimental laboratory tests with small scale model specimens and a preliminary sensor module are used to evaluate hardware and obtain structural response data from input accelerograms. A multi-step analysis procedure employing ordinary least squares (OLS), extended Kalman filtering (EKF), and a substructuring approach is conducted to extract system characteristics of the model. Results from experimental tests and system identification (SI) procedures as well as fundamental system design issues are presented.

Investigation of Current Methods to Identify Helicopter Gear Health

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Lewicki, David G.; Le, Dy D.

2007-01-01

This paper provides an overview of current vibration methods used to identify the health of helicopter transmission gears. The gears are critical to the transmission system that provides propulsion, lift and maneuvering of the helicopter. This paper reviews techniques used to process vibration data to calculate conditions indicators (CI's), guidelines used by the government aviation authorities in developing and certifying the Health and Usage Monitoring System (HUMS), condition and health indicators used in commercial HUMS, and different methods used to set thresholds to detect damage. Initial assessment of a method to set thresholds for vibration based condition indicators applied to flight and test rig data by evaluating differences in distributions between comparable transmissions are also discussed. Gear condition indicator FM4 values are compared on an OH58 helicopter during 14 maneuvers and an OH58 transmission test stand during crack propagation tests. Preliminary results show the distributions between healthy helicopter and rig data are comparable and distributions between healthy and damaged gears show significant differences.

Investigation of Current Methods to Identify Helicopter Gear Health

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Lewicki, David G.; Le, Dy D.

2007-01-01

This paper provides an overview of current vibration methods used to identify the health of helicopter transmission gears. The gears are critical to the transmission system that provides propulsion, lift and maneuvering of the helicopter. This paper reviews techniques used to process vibration data to calculate conditions indicators (CI s), guidelines used by the government aviation authorities in developing and certifying the Health and Usage Monitoring System (HUMS), condition and health indicators used in commercial HUMS, and different methods used to set thresholds to detect damage. Initial assessment of a method to set thresholds for vibration based condition indicators applied to flight and test rig data by evaluating differences in distributions between comparable transmissions are also discussed. Gear condition indicator FM4 values are compared on an OH58 helicopter during 14 maneuvers and an OH58 transmission test stand during crack propagation tests. Preliminary results show the distributions between healthy helicopter and rig data are comparable and distributions between healthy and damaged gears show significant differences.

Experimental evaluation of a new system for laser tissue welding applied on damaged lungs.

PubMed

Schiavon, Marco; Marulli, Giuseppe; Zuin, Andrea; Lunardi, Francesca; Villoresi, Paolo; Bonora, Stefano; Calabrese, Fiorella; Rea, Federico

2013-05-01

Alveolar air leaks represent a challenging problem in thoracic surgery, leading to increased patient morbidity and prolonged hospitalization. Several methods have been used, but no ideal technique exists yet. We investigated the lung-sealing capacity of an experimental kit for laser tissue welding. The kit is composed of a semiconductor laser system applied on a protein substrate associated with a chromophore that increases absorption. In vitro tests on porcine lung tissue were done to define ideal laser parameters (power 100 Å, frequency 50 Hz, pulse duration 400 µs) and protein substrate dilution (50%). For in vivo tests, through a left thoracotomy, 14 pigs received two different lung damages: a linear incision and a circular incision. Protein substrate applied on damaged areas was treated with laser to obtain a layer that reconstituted the integrity of the visceral pleura. Air leaks were intraoperatively evaluated by water submersion test with an airway pressure of 20 cmH2O. Animals were sacrificed at postoperative days 0 and 7 to study early and late pathological features. After applying laser treatment, no air leaks were seen in all proofs except in 2 cases in which a second application was required. At time 0, pathological damage mostly consisted of superficial alveolar necrotic tissue covered by protein membrane. At time 7, a complete recovery of lung lesions by fibrous scar with slight inflammatory reaction of adjacent lung tissue was seen. This experimental study demonstrated the effectiveness of laser tissue welding applied to seal air leaks after lung surgery. Further studies are needed to verify acceptability for human application.

Heat shock proteins and proteasomal degradation in normal and tumor cells.

PubMed

Karademir, Betul; Bozaykut, Perinur; Kartal Ozer, Nesrin

2014-10-01

Proteasomal degradation of oxidized proteins is a crucial mechanism to prevent the accumulation of cellular damage. The removal of the damage is generally a required process for healthy organisms to keep the integrity while in cancer cells the situation may be different. In normal conditions, cancer cells have higher proteasome activity compared to normal cells. During cancer treatment, cellular damage by chemotherapy is an expected process to be able to kill the tumor cells. And the accumulation of this damage accompanied by the decrease in protein repair and removal systems may increase the efficacy of the cancer therapy. Heat shock proteins (Hsp) as molecular chaperones are involved in the folding, activation and assembly of a variety of proteins. Among these Hsp40, Hsp70 and Hsp90 are believed to act as a chaperone system to regulate the proteasomal degradation. In this study, we tested the role of heat stress response on the proteasomal degradation of oxidized proteins. We used two different cell lines to observe the difference in normal and tumor cells. First the effect of heat stress (42°C, 1h) were tested in terms of protein oxidation tested by protein carbonyl formation and proteasomal degradation. The results were extremely different in normal fibroblast cells and hippocampal tumor cells. In the same direction, the expressions of Hsp40, Hsp70 and Hsp90 were affected in a different manner in two cell lines, will be discussed in detail. Supported by TUBITAK COST-CM1001-110S281. Copyright © 2014. Published by Elsevier Inc.

Dynamic fiber Bragg gratings based health monitoring system of composite aerospace structures

NASA Astrophysics Data System (ADS)

Panopoulou, A.; Loutas, T.; Roulias, D.; Fransen, S.; Kostopoulos, V.

2011-09-01

The main purpose of the current work is to develop a new system for structural health monitoring of composite aerospace structures based on real-time dynamic measurements, in order to identify the structural state condition. Long-gauge Fibre Bragg Grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The algorithm that was developed for structural damage detection utilizes the collected dynamic response data, analyzes them in various ways and through an artificial neural network identifies the damage state and its location. Damage was simulated by slightly varying locally the mass of the structure (by adding a known mass) at different zones of the structure. Lumped masses in different locations upon the structure alter the eigen-frequencies in a way similar to actual damage. The structural dynamic behaviour has been numerically simulated and experimentally verified by means of modal testing on two different composite aerospace structures. Advanced digital signal processing techniques, e.g. the wavelet transform (WT), were used for the analysis of the dynamic response for feature extraction. WT's capability of separating the different frequency components in the time domain without loosing frequency information makes it a versatile tool for demanding signal processing applications. The use of WT is also suggested by the no-stationary nature of dynamic response signals and the opportunity of evaluating the temporal evolution of their frequency contents. Feature extraction is the first step of the procedure. The extracted features are effective indices of damage size and location. The classification step comprises of a feed-forward back propagation network, whose output determines the simulated damage location. Finally, dedicated training and validation activities were carried out by means of numerical simulations and experimental procedures. Experimental validation was performed initially on a flat stiffened panel, representing a section of a typical aeronautical structure, manufactured and tested in the lab and, as a second step, on a scaled up space oriented structure, which is a composite honeycomb plate, used as a deployment base for antenna arrays. An integrated FBG sensor network, based on the advantage of multiplexing, was mounted on both structures and different excitation positions and boundary conditions were used. The analysis of operational dynamic responses was employed to identify both the damage and its position. The system that was designed and tested initially on the thin composite panel, was successfully validated on the larger honeycomb structure. Numerical simulation of both structures was used as a support tool at all the steps of the work providing among others the location of the optical sensors used. The proposed work will be the base for the whole system qualification and validation on an antenna reflector in future work.

Acoustic Emission Beamforming for Detection and Localization of Damage

NASA Astrophysics Data System (ADS)

Rivey, Joshua Callen

The aerospace industry is a constantly evolving field with corporate manufacturers continually utilizing innovative processes and materials. These materials include advanced metallics and composite systems. The exploration and implementation of new materials and structures has prompted the development of numerous structural health monitoring and nondestructive evaluation techniques for quality assurance purposes and pre- and in-service damage detection. Exploitation of acoustic emission sensors coupled with a beamforming technique provides the potential for creating an effective non-contact and non-invasive monitoring capability for assessing structural integrity. This investigation used an acoustic emission detection device that employs helical arrays of MEMS-based microphones around a high-definition optical camera to provide real-time non-contact monitoring of inspection specimens during testing. The study assessed the feasibility of the sound camera for use in structural health monitoring of composite specimens during tensile testing for detecting onset of damage in addition to nondestructive evaluation of aluminum inspection plates for visualizing stress wave propagation in structures. During composite material monitoring, the sound camera was able to accurately identify the onset and location of damage resulting from large amplitude acoustic feedback mechanisms such as fiber breakage. Damage resulting from smaller acoustic feedback events such as matrix failure was detected but not localized to the degree of accuracy of larger feedback events. Findings suggest that beamforming technology can provide effective non-contact and non-invasive inspection of composite materials, characterizing the onset and the location of damage in an efficient manner. With regards to the nondestructive evaluation of metallic plates, this remote sensing system allows us to record wave propagation events in situ via a single-shot measurement. This is a significant improvement over the conventional wave propagation tracking technique based on laser doppler vibrometry that requires synchronization of data acquired from numerous excitations and measurements. The proposed technique can be used to characterize and localize damage by detecting the scattering, attenuation, and reflections of stress waves resulting from damage and defects. These studies lend credence to the potential development of new SHM/NDE techniques based on acoustic emission beamforming for characterizing a wide spectrum of damage modes in next-generation materials and structures without the need for mounted contact sensors.

Next generation testing strategy for assessment of genomic damage: A conceptual framework and considerations.

PubMed

Dearfield, Kerry L; Gollapudi, B Bhaskar; Bemis, Jeffrey C; Benz, R Daniel; Douglas, George R; Elespuru, Rosalie K; Johnson, George E; Kirkland, David J; LeBaron, Matthew J; Li, Albert P; Marchetti, Francesco; Pottenger, Lynn H; Rorije, Emiel; Tanir, Jennifer Y; Thybaud, Veronique; van Benthem, Jan; Yauk, Carole L; Zeiger, Errol; Luijten, Mirjam

2017-06-01

For several decades, regulatory testing schemes for genetic damage have been standardized where the tests being utilized examined mutations and structural and numerical chromosomal damage. This has served the genetic toxicity community well when most of the substances being tested were amenable to such assays. The outcome from this testing is usually a dichotomous (yes/no) evaluation of test results, and in many instances, the information is only used to determine whether a substance has carcinogenic potential or not. Over the same time period, mechanisms and modes of action (MOAs) that elucidate a wider range of genomic damage involved in many adverse health outcomes have been recognized. In addition, a paradigm shift in applied genetic toxicology is moving the field toward a more quantitative dose-response analysis and point-of-departure (PoD) determination with a focus on risks to exposed humans. This is directing emphasis on genomic damage that is likely to induce changes associated with a variety of adverse health outcomes. This paradigm shift is moving the testing emphasis for genetic damage from a hazard identification only evaluation to a more comprehensive risk assessment approach that provides more insightful information for decision makers regarding the potential risk of genetic damage to exposed humans. To enable this broader context for examining genetic damage, a next generation testing strategy needs to take into account a broader, more flexible approach to testing, and ultimately modeling, of genomic damage as it relates to human exposure. This is consistent with the larger risk assessment context being used in regulatory decision making. As presented here, this flexible approach for examining genomic damage focuses on testing for relevant genomic effects that can be, as best as possible, associated with an adverse health effect. The most desired linkage for risk to humans would be changes in loci associated with human diseases, whether in somatic or germ cells. The outline of a flexible approach and associated considerations are presented in a series of nine steps, some of which can occur in parallel, which was developed through a collaborative effort by leading genetic toxicologists from academia, government, and industry through the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) Genetic Toxicology Technical Committee (GTTC). The ultimate goal is to provide quantitative data to model the potential risk levels of substances, which induce genomic damage contributing to human adverse health outcomes. Any good risk assessment begins with asking the appropriate risk management questions in a planning and scoping effort. This step sets up the problem to be addressed (e.g., broadly, does genomic damage need to be addressed, and if so, how to proceed). The next two steps assemble what is known about the problem by building a knowledge base about the substance of concern and developing a rational biological argument for why testing for genomic damage is needed or not. By focusing on the risk management problem and potential genomic damage of concern, the next step of assay(s) selection takes place. The work-up of the problem during the earlier steps provides the insight to which assays would most likely produce the most meaningful data. This discussion does not detail the wide range of genomic damage tests available, but points to types of testing systems that can be very useful. Once the assays are performed and analyzed, the relevant data sets are selected for modeling potential risk. From this point on, the data are evaluated and modeled as they are for any other toxicology endpoint. Any observed genomic damage/effects (or genetic event(s)) can be modeled via a dose-response analysis and determination of an estimated PoD. When a quantitative risk analysis is needed for decision making, a parallel exposure assessment effort is performed (exposure assessment is not detailed here as this is not the focus of this discussion; guidelines for this assessment exist elsewhere). Then the PoD for genomic damage is used with the exposure information to develop risk estimations (e.g., using reference dose (RfD), margin of exposure (MOE) approaches) in a risk characterization and presented to risk managers for informing decision making. This approach is applicable now for incorporating genomic damage results into the decision-making process for assessing potential adverse outcomes in chemically exposed humans and is consistent with the ILSI HESI Risk Assessment in the 21st Century (RISK21) roadmap. This applies to any substance to which humans are exposed, including pharmaceuticals, agricultural products, food additives, and other chemicals. It is time for regulatory bodies to incorporate the broader knowledge and insights provided by genomic damage results into the assessments of risk to more fully understand the potential of adverse outcomes in chemically exposed humans, thus improving the assessment of risk due to genomic damage. The historical use of genomic damage data as a yes/no gateway for possible cancer risk has been too narrowly focused in risk assessment. The recent advances in assaying for and understanding genomic damage, including eventually epigenetic alterations, obviously add a greater wealth of information for determining potential risk to humans. Regulatory bodies need to embrace this paradigm shift from hazard identification to quantitative analysis and to incorporate the wider range of genomic damage in their assessments of risk to humans. The quantitative analyses and methodologies discussed here can be readily applied to genomic damage testing results now. Indeed, with the passage of the recent update to the Toxic Substances Control Act (TSCA) in the US, the new generation testing strategy for genomic damage described here provides a regulatory agency (here the US Environmental Protection Agency (EPA), but suitable for others) a golden opportunity to reexamine the way it addresses risk-based genomic damage testing (including hazard identification and exposure). Environ. Mol. Mutagen. 58:264-283, 2017. © 2016 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc. © 2016 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc.

A Generalized Orthotropic Elasto-Plastic Material Model for Impact Analysis

NASA Astrophysics Data System (ADS)

Hoffarth, Canio

Composite materials are now beginning to provide uses hitherto reserved for metals in structural systems such as airframes and engine containment systems, wraps for repair and rehabilitation, and ballistic/blast mitigation systems. These structural systems are often subjected to impact loads and there is a pressing need for accurate prediction of deformation, damage and failure. There are numerous material models that have been developed to analyze the dynamic impact response of polymer matrix composites. However, there are key features that are missing in those models that prevent them from providing accurate predictive capabilities. In this dissertation, a general purpose orthotropic elasto-plastic computational constitutive material model has been developed to predict the response of composites subjected to high velocity impacts. The constitutive model is divided into three components - deformation model, damage model and failure model, with failure to be added at a later date. The deformation model generalizes the Tsai-Wu failure criteria and extends it using a strain-hardening-based orthotropic yield function with a non-associative flow rule. A strain equivalent formulation is utilized in the damage model that permits plastic and damage calculations to be uncoupled and capture the nonlinear unloading and local softening of the stress-strain response. A diagonal damage tensor is defined to account for the directionally dependent variation of damage. However, in composites it has been found that loading in one direction can lead to damage in multiple coordinate directions. To account for this phenomena, the terms in the damage matrix are semi-coupled such that the damage in a particular coordinate direction is a function of the stresses and plastic strains in all of the coordinate directions. The overall framework is driven by experimental tabulated temperature and rate-dependent stress-strain data as well as data that characterizes the damage matrix and failure. The developed theory has been implemented in a commercial explicit finite element analysis code, LS-DYNARTM, as MAT213. Several verification and validation tests using a commonly available carbon-fiber composite, Toyobo's T800/F3900, have been carried and the results show that the theory and implementation are efficient, robust and accurate.

Effects of ozone (O3) therapy on cisplatin-induced ototoxicity in rats.

PubMed

Koçak, Hasan Emre; Taşkın, Ümit; Aydın, Salih; Oktay, Mehmet Faruk; Altınay, Serdar; Çelik, Duygu Sultan; Yücebaş, Kadir; Altaş, Bengül

2016-12-01

The aim of this study is to investigate the effect of rectal ozone and intratympanic ozone therapy on cisplatin-induced ototoxicity in rats. Eighteen female Wistar albino rats were included in our study. External auditory canal and tympanic membrane examinations were normal in all rats. The rats were randomly divided into three groups. Initially, all the rats were tested with distortion product otoacoustic emissions (DPOAE), and emissions were measured normally. All rats were injected with 5-mg/kg/day cisplatin for 3 days intraperitoneally. Ototoxicy had developed in all rats, as confirmed with DPOAE after 1 week. Rectal and intratympanic ozone therapy group was Group 1. No treatment was administered for the rats in Group 2 as the control group. The rats in Group 3 were treated with rectal ozone. All the rats were tested with DPOAE under general anesthesia, and all were sacrificed for pathological examination 1 week after ozone administration. Their cochleas were removed. The outer hair cell damage and stria vascularis damage were examined. In the statistical analysis conducted, a statistically significant difference between Group 1 and Group 2 was observed in all frequencies according to the DPOAE test. In addition, between Group 2 and Group 3, a statistically significant difference was observed in the DPOAE test. However, a statistically significant difference was not observed between Group 1 and Group 3 according to the DPOAE test. According to histopathological scoring, the outer hair cell damage score was statistically significantly high in Group 2 compared with Group 1. In addition, the outer hair cell damage score was also statistically significantly high in Group 2 compared with Group 3. Outer hair cell damage scores were low in Group 1 and Group 3, but there was no statistically significant difference between these groups. There was no statistically significant difference between the groups in terms of stria vascularis damage score examinations. Systemic ozone gas therapy is effective in the treatment of cell damage in cisplatin-induced ototoxicity. The intratympanic administration of ozone gas does not have any additional advantage over the rectal administration.

Ballistic Puncture Self-Healing Polymeric Materials

NASA Technical Reports Server (NTRS)

Gordon, Keith L.; Siochi, Emilie J.; Yost, William T.; Bogert, Phil B.; Howell, Patricia A.; Cramer, K. Elliott; Burke, Eric R.

2017-01-01

Space exploration launch costs on the order of $10,000 per pound provide an incentive to seek ways to reduce structural mass while maintaining structural function to assure safety and reliability. Damage-tolerant structural systems provide a route to avoiding weight penalty while enhancing vehicle safety and reliability. Self-healing polymers capable of spontaneous puncture repair show promise to mitigate potentially catastrophic damage from events such as micrometeoroid penetration. Effective self-repair requires these materials to quickly heal following projectile penetration while retaining some structural function during the healing processes. Although there are materials known to possess this capability, they are typically not considered for structural applications. Current efforts use inexpensive experimental methods to inflict damage, after which analytical procedures are identified to verify that function is restored. Two candidate self-healing polymer materials for structural engineering systems are used to test these experimental methods.

Limits of performance: CW laser damage

NASA Astrophysics Data System (ADS)

Shah, Rashmi S.; Rey, Justin J.; Stewart, Alan F.

2007-01-01

High performance optical coatings are an enabling technology for many applications - navigation systems, telecom, fusion, advanced measurement systems of many types as well as directed energy weapons. The results of recent testing of superior optical coatings conducted at high flux levels have been presented. Failure of these coatings was rare. However, induced damage was not expected from simple thermal models relating flux loading to induced temperatures. Clearly, other mechanisms must play a role in the occurrence of laser damage. Contamination is an obvious mechanism-both particulate and molecular. Less obvious are structural defects and the role of induced stresses. These mechanisms are examined through simplified models and finite element analysis. The results of the models are compared to experiment, for induced temperatures and observed stress levels. The role of each mechanism is described and limiting performance is determined.

Nondestructive assessment of waveguides using an integrated electromechanical impedance and ultrasonic waves approach

NASA Astrophysics Data System (ADS)

Nasrollahi, Amir; Ma, Zhaoyun; Rizzo, Piervincenzo

2017-04-01

In this paper we present a structural health monitoring (SHM) paradigm based on the simultaneous use of ultrasounds and electromechanical impedance (EMI) to monitor waveguides. The paradigm uses guided ultrasonic waves (GUWs) in pitch-catch mode and EMI simultaneously. The two methodologies are driven by the same sensing/hardware/software unit. To assess the feasibility of this unified system an aluminum plate was monitored for varying damage location. Damage was simulated by adding small masses to the plate. The results associated with pitch-catch GUW testing mode were used in ultrasonic tomography, and statistical analysis was used to detect the damages using the EMI measurements. The results of GUW and EMI monitoring show that the proposed system is robust and can be developed further to address the challenges associated with the SHM of complex structures.

Test Facilities in Support of High Power Electric Propulsion Systems

NASA Technical Reports Server (NTRS)

VanDyke, Melissa; Houts, Mike; Godfroy, Thomas; Dickens, Ricky; Martin, James J.; Salvail, Patrick; Carter, Robert

2002-01-01

Successful development of space fission systems requires an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through non-nuclear testing. Through demonstration of systems concepts (designed by DOE National Laboratories) in relevant environments, this philosophy has been demonstrated through hardware testing in the High Power Propulsion Thermal Simulator (HPPTS). The HPPTS is designed to enable very realistic non-nuclear testing of space fission systems. Ongoing research at the HPPTS is geared towards facilitating research, development, system integration, and system utilization via cooperative efforts with DOE labs, industry, universities, and other NASA centers. Through hardware based design and testing, the HPPTS investigates High Power Electric Propulsion (HPEP) component, subsystem, and integrated system design and performance.

Testing in Support of Space Fission System Development and Qualification

NASA Technical Reports Server (NTRS)

Houts, Mike; Bragg-Sitton, Shannon; Garber, Anne; Godfrey, Tom; Martin, Jim; Pearson, Boise; Webster, Kenny

2007-01-01

Extensive data would be required for the qualification of a fission surface power (FSP) system. The strategy for qualifying a FSP system could have a significant programmatic impact. This paper explores potential options that could be used for qualifying FSP systems, including cost-effective means for obtaining required data. three methods for obtaining qualification data are analysis, non-nuclear testing, and nuclear testing. It has been over 40 years since the US qualified a space reactor for launch. During that time, advances have been made related to all three methods. Perhaps the greatest advancement has occurred in the area of computational tools for design and analysis. Tools that have been developed, coupled with modem computers, would have a significant impact on a FSP qualification. This would be especially true for systems with materials and fuels operating well within temperature, irradiation damage, and burnup limits. The ability to perform highly realistic non-nuclear testing has also advanced throughout the past four decades. Instrumented thermal simulators were developed during the 1970s and 1980s to assist in the development, operation, and assessment of terrestrial fission systems. Instrumented thermal simulators optimized for assisting in the development, operation, and assessment of modem FSP systems have been under development (and utilized) since 1998. These thermal simulators enable heat from fission to be closely mimicked (axial power profile, radial power profile, temperature, heat flux, etc.} and extensive data to be taken from the core region. Both steady-state and transient operation can be tested. For transient testing, reactivity feedback is calculated (or measured in cold/warm criticals) based on reactor temperature and/or dimensional changes. Pin power during a transient is then calculated based on the reactivity feedback that would occur given measured values of temperature and/or dimensional change. In this way nonnuclear testing can be used to provide very realistic information related to nuclear operation. Non-nuclear testing can be used at all levels, including component, subsystem, and integrated system testing. Realistic non-nuclear testing is most useful for systems operating within known temperature, irradiation damage, and burnup capabilities.

Damage tolerance certification of a fighter horizontal stabilizer

NASA Astrophysics Data System (ADS)

Huang, Jia-Yen; Tsai, Ming-Yang; Chen, Jong-Sheng; Ong, Ching-Long

1995-05-01

A review of the program for the damage tolerance certification test of a composite horizontal stabilizer (HS) of a fighter is presented. The object of this program is to certify that the fatigue life and damage tolerance strength of a damaged composite horizontal stabilizer meets the design requirements. According to the specification for damage tolerance certification, a test article should be subjected to two design lifetimes of flight-by-flight load spectra simulating the in-service fatigue loading condition for the aircraft. However, considering the effect of environmental change on the composite structure, one additional lifetime test was performed. In addition, to evaluate the possibilities for extending the service life of the structure, one more lifetime test was carried out with the spectrum increased by a factor of 1.4. To assess the feasibility and reliability of repair technology on a composite structure, two damaged areas were repaired after two lifetimes of damage tolerance test. On completion of four lifetimes of the damage tolerance test, the static residual strength was measured to check whether structural strength after repair met the requirements. Stiffness and static strength of the composite HS with and without damage were evaluated and compared.

Structural Response and Failure of a Full-Scale Stitched Graphite-Epoxy Wing

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Lovejoy, Andrew E.; Bush, Harold G.

2001-01-01

Analytical and experimental results of the test for an all-composite full-scale wing box are presented. The wing box is representative of a section of a 220-passenger commercial transport aircraft wing box and was designed and constructed by The Boeing Company as part of the NASA Advanced Subsonics Technology (AST) program. The semi-span wing was fabricated from a graphite-epoxy material system with cover panels and spars held together using Kevlar stitches through the thickness. No mechanical fasteners were used to hold the stiffeners to the skin of the cover panels. Tests were conducted with and without low-speed impact damage, discrete source damage and repairs. Up-bending down-bending and brake roll loading conditions were applied. The structure with nonvisible impact damage carried 97% of Design Ultimate Load prior to failure through a lower cover panel access hole. Finite element and experimental results agree for the global response of the structure.

Cleanliness for the NIF 1ω Laser Amplifiers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spaeth, M. L.; Manes, K. R.; Honig, J.

During the years before the National Ignition Facility (NIF) laser system, a set of generally accepted cleaning procedures had been developed for the large 1ω amplifiers of an inertial confinement fusion laser, and up until 1999 similar procedures were planned for NIF. Several parallel sets of test results were obtained from 1992 to 1999 for large amplifiers using these accepted cleaning procedures in the Beamlet physics test bed and in the Amplifier Module Prototype Laboratory (AMPLAB), a four-slab-high prototype large amplifier structure. Both of these showed damage to their slab surfaces that, if projected to operating conditions for NIF, wouldmore » lead to higher than acceptable slab-refurbishment rates. Finally, this study tracks the search for the smoking gun origin of this damage and describes the solution employed in NIF for avoiding flashlamp-induced aerosol damage to its 1ω amplifier slabs.« less

Cleanliness for the NIF 1ω Laser Amplifiers

DOE PAGES

Spaeth, M. L.; Manes, K. R.; Honig, J.

2017-03-23

During the years before the National Ignition Facility (NIF) laser system, a set of generally accepted cleaning procedures had been developed for the large 1ω amplifiers of an inertial confinement fusion laser, and up until 1999 similar procedures were planned for NIF. Several parallel sets of test results were obtained from 1992 to 1999 for large amplifiers using these accepted cleaning procedures in the Beamlet physics test bed and in the Amplifier Module Prototype Laboratory (AMPLAB), a four-slab-high prototype large amplifier structure. Both of these showed damage to their slab surfaces that, if projected to operating conditions for NIF, wouldmore » lead to higher than acceptable slab-refurbishment rates. Finally, this study tracks the search for the smoking gun origin of this damage and describes the solution employed in NIF for avoiding flashlamp-induced aerosol damage to its 1ω amplifier slabs.« less

Comparison of mechanical characteristics of focused ion beam fabricated silicon nanowires

NASA Astrophysics Data System (ADS)

Ina, Ginnosuke; Fujii, Tatsuya; Kozeki, Takahiro; Miura, Eri; Inoue, Shozo; Namazu, Takahiro

2017-06-01

In this study, we investigate the effects of focused ion beam (FIB)-induced damage and specimen size on the mechanical properties of Si nanowires (NWs) by a microelectromechanical system (MEMS)-based tensile testing technique. By an FIB fabrication technique, three types of Si NWs, which are as-FIB-fabricated, annealed, and FIB-implanted NWs, are prepared. A sacrificial-oxidized NW is also prepared to compare the mechanical properties of these FIB-based NWs. The quasi-static uniaxial tensile tests of all the NWs are conducted by scanning electron microscopy (SEM). The fabrication process and specimen size dependences on Young’s modulus and fracture strength are observed. Annealing is effective for improving the Young’s modulus of the FIB-damaged Si. Transmission electron microscopy (TEM) suggests that the mechanism behind the process dependence on the mechanical characteristics is related to the crystallinity of the FIB-damaged portion.

Cell-Based Genotoxicity Testing

NASA Astrophysics Data System (ADS)

Reifferscheid, Georg; Buchinger, Sebastian

Genotoxicity test systems that are based on bacteria display an important role in the detection and assessment of DNA damaging chemicals. They belong to the basic line of test systems due to their easy realization, rapidness, broad applicability, high sensitivity and good reproducibility. Since the development of the Salmonella microsomal mutagenicity assay by Ames and coworkers in the early 1970s, significant development in bacterial genotoxicity assays was achieved and is still a subject matter of research. The basic principle of the mutagenicity assay is a reversion of a growth inhibited bacterial strain, e.g., due to auxotrophy, back to a fast growing phenotype (regain of prototrophy). Deeper knowledge of the ­mutation events allows a mechanistic understanding of the induced DNA-damage by the utilization of base specific tester strains. Collections of such specific tester strains were extended by genetic engineering. Beside the reversion assays, test systems utilizing the bacterial SOS-response were invented. These methods are based on the fusion of various SOS-responsive promoters with a broad variety of reporter genes facilitating numerous methods of signal detection. A very important aspect of genotoxicity testing is the bioactivation of ­xenobiotics to DNA-damaging compounds. Most widely used is the extracellular metabolic activation by making use of rodent liver homogenates. Again, genetic engineering allows the construction of highly sophisticated bacterial tester strains with significantly enhanced sensitivity due to overexpression of enzymes that are involved in the metabolism of xenobiotics. This provides mechanistic insights into the toxification and detoxification pathways of xenobiotics and helps explaining the chemical nature of hazardous substances in unknown mixtures. In summary, beginning with "natural" tester strains the rational design of bacteria led to highly specific and sensitive tools for a rapid, reliable and cost effective ­genotoxicity testing that is of outstanding importance in the risk assessment of compounds (REACH) and in ecotoxicology.

Necrotizing vasculitis

MedlinePlus

The health care provider will do a complete physical exam. A nervous system (neurological) exam may show signs of nerve damage. Tests that may be done include: Complete blood count, comprehensive chemistry panel, and urinalysis Chest x-ray C-reactive ...

SSC_NASA Tests Upgraded Water System for the B-2 Test Stand - Highlights with Music

NASA Image and Video Library

2017-12-04

On December 4, Stennis Space Center conducted a water flow test on the B-2 test stand to check the water system’s upgraded modifications in preparation for Space Launch System’s Core Stage testing. During a test, rocket engine fire and exhaust is redirected out of the stand by a large flame trench. For this test, the water deluge system, with the capability of flowing 335,000 gallons of water per minute, directed more than 240,000 gallons of water per minute through more than 32,000 5/32-inch holes in the B2 stand flame deflector, cooling the exhaust and protecting the trench from damage.

NASA Tests Upgraded Water System for Stennis Space Center's B-2 Test Stand

NASA Image and Video Library

2017-12-04

On December 4, Stennis Space Center conducted a water flow test on the B-2 test stand to check the water system’s upgraded modifications in preparation for Space Launch System’s Core Stage testing. During a test, rocket engine fire and exhaust is redirected out of the stand by a large flame trench. For this test, the water deluge system, with the capability of flowing 335,000 gallons of water per minute, directed more than 240,000 gallons of water per minute through more than 32,000 5/32-inch holes in the B2 stand flame deflector, cooling the exhaust and protecting the trench from damage.

A Comparison of Vibration and Oil Debris Gear Damage Detection Methods Applied to Pitting Damage

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.

2000-01-01

Helicopter Health Usage Monitoring Systems (HUMS) must provide reliable, real-time performance monitoring of helicopter operating parameters to prevent damage of flight critical components. Helicopter transmission diagnostics are an important part of a helicopter HUMS. In order to improve the reliability of transmission diagnostics, many researchers propose combining two technologies, vibration and oil monitoring, using data fusion and intelligent systems. Some benefits of combining multiple sensors to make decisions include improved detection capabilities and increased probability the event is detected. However, if the sensors are inaccurate, or the features extracted from the sensors are poor predictors of transmission health, integration of these sensors will decrease the accuracy of damage prediction. For this reason, one must verify the individual integrity of vibration and oil analysis methods prior to integrating the two technologies. This research focuses on comparing the capability of two vibration algorithms, FM4 and NA4, and a commercially available on-line oil debris monitor to detect pitting damage on spur gears in the NASA Glenn Research Center Spur Gear Fatigue Test Rig. Results from this research indicate that the rate of change of debris mass measured by the oil debris monitor is comparable to the vibration algorithms in detecting gear pitting damage.

Experimental and Analytical Seismic Studies of a Four-Span Bridge System with Innovative Materials

NASA Astrophysics Data System (ADS)

Cruz Noguez, Carlos Alonso

As part of a multi-university project utilizing the NSF Network for Earthquake Engineering Simulation (NEES), a quarter-scale model of a four-span bridge incorporating plastic hinges with different advanced materials was tested to failure on the three shake table system at the University of Nevada, Reno (UNR). The bridge was the second test model in a series of three 4-span bridges, with the first model being a conventional reinforced-concrete (RC) structure. The purpose of incorporating advanced materials was to improve the seismic performance of the bridge with respect to two damage indicators: (1) column damage and (2) permanent deformations. The goals of the study presented in this document were to (1) evaluate the seismic performance of a 4-span bridge system incorporating SMA/ECC and built-in rubber pad plastic hinges as well as post-tensioned piers, (2) quantify the relative merit of these advanced materials and details compared to each other and to conventional reinforced concrete plastic hinges, (3) determine the influence of abutment-superstructure interaction on the response, (4) examine the ability of available elaborate analytical modeling techniques to model the performance of advanced materials and details, and (5) conduct an extensive parametric study of different variations of the bridge model to study several important issues in bridge earthquake engineering. The bridge model included six columns, each pair of which utilized a different advanced detail at bottom plastic hinges: shape memory alloys (SMA), special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning tendons. The design of the columns, location of the bents, and selection of the loading protocol were based on pre-test analyses conducted using computer program OpenSees. The bridge model was subjected to two-horizontal components of simulated earthquake records of the 1994 Northridge earthquake. Over 340 channels of data were collected. The test results showed the effectiveness of the advanced materials in reducing damage and permanent displacements. The damage was minimal in plastic hinges with SMA/ECC and those with built-in elastomeric pads. Conventional RC plastic hinges were severely damaged due to spalling of concrete and rupture of the longitudinal and transverse reinforcement. Extensive post-test analytical studies were conducted and it was determined that a computational model of the bridge that included bridge-abutment interaction using OpenSees was able to provide satisfactory estimations of key structural parameters such as superstructure displacements and base shears. The analytical model was also used to conduct parametric studies on single-column and bridge-system response under near-fault ground motions. The effects of vertical excitations and transverse shear-keys at the bridge abutments on the superstructure displacement and column drifts were also explored.

Simulating the Impact Response of Full-Scale Composite Airframe Structures

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Jackson, Karen E.; Littell, Justin D.; Seal, Michael D.

2012-01-01

NASA Langley Research Center obtained a composite helicopter cabin structure in 2010 from the US Army's Survivable Affordable Repairable Airframe Program (SARAP) that was fabricated by Sikorsky Aircraft Corporation. The cabin had been subjected to a vertical drop test in 2008 to evaluate a tilting roof concept to limit the intrusion of overhead masses into the fuselage cabin. Damage to the cabin test article was limited primarily to the roof. Consequently, the roof area was removed and the remaining structure was cut into test specimens including a large subfloor section and a forward framed fuselage section. In 2011, NASA and Sikorsky entered into a cooperative research agreement to study the impact responses of composite airframe structures and to evaluate the capabilities of the explicit transient dynamic finite element code, LS-DYNA®, to simulate these responses including damage initiation and progressive failure. Most of the test articles were manufactured of graphite unidirectional tape composite with a thermoplastic resin system. However, the framed fuselage section was constructed primarily of a plain weave graphite fabric material with a thermoset resin system. Test data were collected from accelerometers and full-field photogrammetry. The focus of this paper will be to document impact testing and simulation results for the longitudinal impact of the subfloor section and the vertical drop test of the forward framed fuselage section.

CON4EI: Development of serious eye damage and eye irritation testing strategies with respect to the requirements of the UN GHS/EU CLP hazard categories.

PubMed

Verstraelen, Sandra; Van Rompay, An R

2018-06-01

The main objective of the CON4EI (CONsortium for in vitro Eye Irritation testing strategy) project (2015-2016) was to develop tiered, non-animal testing strategies for serious eye damage and eye irritation assessment in relation to the most important drivers of classification. The serious eye damage and eye irritation potential of a set of 80 chemicals was identified based on existing in vivo Draize eye test data and testing was conducted using the following eight alternative test methods: BCOP (Bovine Corneal Opacity and Permeability)+histopathology, BCOP-LLBO (BCOP Laser Light-Based Opacitometer), ICE (Isolated Chicken Eye)+histopathology, STE (Short Term Exposure), EpiOcular™ EIT (EpiOcular Eye Irritation Test), EpiOcular™ ET-50 (EpiOcular™ Time-to-toxicity), SkinEthic™ HCE EIT (SkinEthic™ Human Corneal Epithelial Eye Irritation Test), and SMI (Slug Mucosal Irritation). Project management decided to not include the ICE data in this project since the execution showed relevant, and not predictable, deviations from Organisation for Economic Co-operation and Development (OECD) Test Guideline (TG) 438 and Guidance Document 160. At this stage, the outcome of these deviations has not been fully assessed. In addition to these alternative test methods, the computational models Toxtree and Case Ultra were taken into account. This project assessed the relevance of these test methods, their applicability domains and limitations in terms of 'drivers of classification', and their strengths and weaknesses. In this way, methods were identified that fit into a tiered-testing strategy for serious eye damage/eye irritation assessment to distinguish United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS) Category 1 (Cat 1) chemicals from non-Cat 1 chemicals and address the gap namely distinguish between Category 2 (Cat 2) and Cat 1 chemicals. Copyright © 2017 Elsevier Ltd. All rights reserved.

A nonlinear CDM based damage growth law for ductile materials

NASA Astrophysics Data System (ADS)

Gautam, Abhinav; Priya Ajit, K.; Sarkar, Prabir Kumar

2018-02-01

A nonlinear ductile damage growth criterion is proposed based on continuum damage mechanics (CDM) approach. The model is derived in the framework of thermodynamically consistent CDM assuming damage to be isotropic. In this study, the damage dissipation potential is also derived to be a function of varying strain hardening exponent in addition to damage strain energy release rate density. Uniaxial tensile tests and load-unload-cyclic tensile tests for AISI 1020 steel, AISI 1030 steel and Al 2024 aluminum alloy are considered for the determination of their respective damage variable D and other parameters required for the model(s). The experimental results are very closely predicted, with a deviation of 0%-3%, by the proposed model for each of the materials. The model is also tested with predictabilities of damage growth by other models in the literature. Present model detects the state of damage quantitatively at any level of plastic strain and uses simpler material tests to find the parameters of the model. So, it should be useful in metal forming industries to assess the damage growth for the desired deformation level a priori. The superiority of the new model is clarified by the deviations in the predictability of test results by other models.

Impact Testing on Reinforced Carbon-Carbon Flat Panels with Ice Projectiles for the Space Shuttle Return to Flight Program

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

2009-01-01

Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1--fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2--subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3--full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with ice projectile impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated three types of debris projectiles: Single-crystal, polycrystal, and "soft" ice. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the ice and RCC models for use in LS-DYNA.

Impact Testing on Reinforced Carbon-Carbon Flat Panels With BX-265 and PDL-1034 External Tank Foam for the Space Shuttle Return to Flight Program

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

2009-01-01

Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1-fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2-subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3-full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with external tank foam impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated two types of debris projectiles: BX-265 and PDL-1034 external tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the foam and RCC models for use in LS-DYNA.

Structural Health Monitoring of Large Structures

NASA Technical Reports Server (NTRS)

Kim, Hyoung M.; Bartkowicz, Theodore J.; Smith, Suzanne Weaver; Zimmerman, David C.

1994-01-01

This paper describes a damage detection and health monitoring method that was developed for large space structures using on-orbit modal identification. After evaluating several existing model refinement and model reduction/expansion techniques, a new approach was developed to identify the location and extent of structural damage with a limited number of measurements. A general area of structural damage is first identified and, subsequently, a specific damaged structural component is located. This approach takes advantage of two different model refinement methods (optimal-update and design sensitivity) and two different model size matching methods (model reduction and eigenvector expansion). Performance of the proposed damage detection approach was demonstrated with test data from two different laboratory truss structures. This space technology can also be applied to structural inspection of aircraft, offshore platforms, oil tankers, ridges, and buildings. In addition, its applications to model refinement will improve the design of structural systems such as automobiles and electronic packaging.

Hippocampal damage causes retrograde but not anterograde memory loss for context fear discrimination in rats.

PubMed

Lee, Justin Q; Sutherland, Robert J; McDonald, Robert J

2017-09-01

There is a substantial body of evidence that the hippocampus (HPC) plays and essential role in context discrimination in rodents. Studies reporting anterograde amnesia (AA) used repeated, alternating, distributed conditioning and extinction sessions to measure context fear discrimination. In addition, there is uncertainty about the extent of damage to the HPC. Here, we induced conditioned fear prior to discrimination tests and rats sustained extensive, quantified pre- or post-training HPC damage. Unlike previous work, we found that extensive HPC damage spares context discrimination, we observed no AA. There must be a non-HPC system that can acquire long-term memories that support context fear discrimination. Post-training HPC damage caused retrograde amnesia (RA) for context discrimination, even when rats are fear conditioned for multiple sessions. We discuss the implications of these findings for understanding the role of HPC in long-term memory. © 2017 Wiley Periodicals, Inc.

Function and Dysfunction of Prefrontal Brain Circuitry in Alcoholic Korsakoff’s Syndrome

PubMed Central

Oscar-Berman, Marlene

2013-01-01

The signature symptom of alcohol-induced persisting amnestic disorder, more commonly referred to as alcoholic Korsakoff’s syndrome (KS), is anterograde amnesia, or memory loss for recent events, and until the mid 20th Century, the putative brain damage was considered to be in diencephalic and medial temporal lobe structures. Overall intelligence, as measured by standardized IQ tests, usually remains intact. Preservation of IQ occurs because memories formed before the onset of prolonged heavy drinking — the types of information and abilities tapped by intelligence tests — remain relatively well preserved compared with memories recently acquired. However, clinical and experimental evidence has shown that neurobehavioral dysfunction in alcoholic patients with KS does include nonmnemonic abilities, and further brain damage involves extensive frontal and limbic circuitries. Among the abnormalities are confabulation, disruption of elements of executive functioning and cognitive control, and emotional impairments. Here, we discuss the relationship between neurobehavioral impairments in KS and alcoholism-related brain damage. More specifically, we examine the role of damage to prefrontal brain systems in the neuropsychological profile of alcoholic KS. PMID:22538385

A Damage Resistance Comparison Between Candidate Polymer Matrix Composite Feedline Materials

NASA Technical Reports Server (NTRS)

Nettles, A. T

2000-01-01

As part of NASAs focused technology programs for future reusable launch vehicles, a task is underway to study the feasibility of using the polymer matrix composite feedlines instead of metal ones on propulsion systems. This is desirable to reduce weight and manufacturing costs. The task consists of comparing several prototype composite feedlines made by various methods. These methods are electron-beam curing, standard hand lay-up and autoclave cure, solvent assisted resin transfer molding, and thermoplastic tape laying. One of the critical technology drivers for composite components is resistance to foreign objects damage. This paper presents results of an experimental study of the damage resistance of the candidate materials that the prototype feedlines are manufactured from. The materials examined all have a 5-harness weave of IM7 as the fiber constituent (except for the thermoplastic, which is unidirectional tape laid up in a bidirectional configuration). The resin tested were 977-6, PR 520, SE-SA-1, RS-E3 (e-beam curable), Cycom 823 and PEEK. The results showed that the 977-6 and PEEK were the most damage resistant in all tested cases.

Ultrasonic characterization of damage in a simulated CF-18 composite structure

NASA Astrophysics Data System (ADS)

McRae, K. I.; Finlayson, R. D.; Sturrock, W. R.; Liesch, D. S.

1993-02-01

A simulated CF-18 aircraft door component was constructed and subjected to treatment during manufacturing with the object of inducing damage in the composite material in a known and well-defined manner. The simulated component was then sent to participants in a nondestructive evaluation study. Results are reported for tests conducted with a scanning apparatus and data acquisition system which consisted of three components: ultrasonic transducer and scanner comprising a two-axis scanning frame to which a modified commercial transducer was attached; an acquisition system for ultrasonic data known as Signal Processing Ultrasonic Device (SPUD); and a data analysis and display system (DETECT/NDE) specifically designed to manipulate large three dimensional ultrasonic data sets. A series of five large-area scans was performed, each scan about 52 cm square. A total of eight regions of interest were identified for a more detailed analysis of the delamination damage, seven detailed scans covering a 13-cm square and one covering a 20.8-cm square. It was often possible to identify the probable source of the damage as that resulting from impact or caused by overloading of fasteners. Flaws of all significant dimensions were located and fully characterized using the ultrasonic procedure.

Accurate Damage Location in Complex Composite Structures and Industrial Environments using Acoustic Emission

NASA Astrophysics Data System (ADS)

Eaton, M.; Pearson, M.; Lee, W.; Pullin, R.

2015-07-01

The ability to accurately locate damage in any given structure is a highly desirable attribute for an effective structural health monitoring system and could help to reduce operating costs and improve safety. This becomes a far greater challenge in complex geometries and materials, such as modern composite airframes. The poor translation of promising laboratory based SHM demonstrators to industrial environments forms a barrier to commercial up take of technology. The acoustic emission (AE) technique is a passive NDT method that detects elastic stress waves released by the growth of damage. It offers very sensitive damage detection, using a sparse array of sensors to detect and globally locate damage within a structure. However its application to complex structures commonly yields poor accuracy due to anisotropic wave propagation and the interruption of wave propagation by structural features such as holes and thickness changes. This work adopts an empirical mapping technique for AE location, known as Delta T Mapping, which uses experimental training data to account for such structural complexities. The technique is applied to a complex geometry composite aerospace structure undergoing certification testing. The component consists of a carbon fibre composite tube with varying wall thickness and multiple holes, that was loaded under bending. The damage location was validated using X-ray CT scanning and the Delta T Mapping technique was shown to improve location accuracy when compared with commercial algorithms. The onset and progression of damage were monitored throughout the test and used to inform future design iterations.

Seismic Rehabilitation of RC Frames by Using Steel Panels

NASA Astrophysics Data System (ADS)

Mowrtage, Waiel

2008-07-01

Every major earthquake in Turkey causes a large number of building suffer moderate damage due to poor construction. If a proper and fast retrofit is not applied, the aftershocks, which may sometimes come days or weeks after the main shock, can push a moderately damaged building into a major damage or even total collapse. This paper presents a practical retrofit method for moderately damaged buildings, which increases the seismic performance of the structural system by reducing the displacement demand. Fabricated steel panels are used for the retrofit. They are light-weight, easy to handle, and can be constructed very quickly. Moreover, they are cheap, and do not need formwork or skilled workers. They can be designed to compensate for the stiffness and strength degradation, and to fit easily inside a moderately damaged reinforced concrete frame. To test the concept, a half-scale, single-story 3D reinforced concrete frame specimen was constructed at the shake-table laboratories of the Kandilli Observatory and Earthquake Research Institute of Bogazici University, and subjected to recorded real earthquake base accelerations. The amplitudes of base accelerations were increased until a moderate damage level is reached. Then, the damaged RC frames was retrofitted by means of steel panels and tested under the same earthquake. The seismic performance of the specimen before and after the retrofit was evaluated using FEMA356 standards, and the results were compared in terms of stiffness, strength, and deformability. The results have confirmed effectiveness of the proposed retrofit scheme.

Development of damage suppression system using embedded SMA foil in CFRP laminates

NASA Astrophysics Data System (ADS)

Ogisu, Toshimichi; Nomura, Masato; Ando, Norio; Takaki, Junji; Kobayashi, Masakazu; Okabe, Tomonaga; Takeda, Nobuo

2001-07-01

Some recent studies have suggested possible applications of Shape Memory Alloy (SMA) for a smart health monitoring and suppression of damage growth. The authors have been conducting research and development studies on applications of embedded SMA foil actuators in CFRP laminates as the basic research for next generation aircrafts. First the effective surface treatment for improvement of bonding properties between SMA and CFRP was studied. It was certified that the anodic oxide treatment by 10% NaOH solution was the most effective treatment from the results of peel resistance test and shear strength test. Then, CFRP laminates with embedded SMA foils were successfully fabricated using this effective surface treatment. The damage behavior of quasi-isotropic CFRP laminates with embedded SMA foils was characterized in both quasi-static load-unload and fatigue tests. The relationship between crack density and applied strain was obtained. The recovery stress generated by embedded SMA foils could increase the onset strain of transverse cracking by 0.2%. The onset strain of delmination in CFRP laminates was also increased accordingly. The shear-lag analysis was also conducted to predict the damage evolution in CFRP laminates with embedded SMA foils. The adhesive layers on both sides of SMA foils were treated as shear elements. The theoretical analysis successfully predicted the experimental results.

Wireless sensing system for bridge condition assessment and health monitoring

NASA Astrophysics Data System (ADS)

Gangone, Michael V.; Whelan, Matthew J.; Janoyan, Kerop D.

2009-03-01

Discussed in this paper is the deployment of a universal and low-cost dense wireless sensor system for structural monitoring, load rating and condition assessment of bridges. The wireless sensor system developed is designed specifically for diagnostic bridge monitoring, providing independent conditioning for both accelerometers and strain transducers in addition to high-rate wireless data transmission. The system was field deployed on a three span simply supported bridge superstructure, where strain and acceleration measurements were obtained simultaneously and in realtime at critical locations under several loading conditions, providing reliable quantitative information as to the actual performance level of the bridge. Monitoring was also conducted as the bridge was subjected to various controlled damage scenarios on the final day of testing. Select cases of detected damage using strain and modal based analysis are presented.

Fatigue crack detection and identification by the elastic wave propagation method

NASA Astrophysics Data System (ADS)

Stawiarski, Adam; Barski, Marek; Pająk, Piotr

2017-05-01

In this paper the elastic wave propagation phenomenon was used to detect the initiation of the fatigue damage in isotropic plate with a circular hole. The safety and reliability of structures mostly depend on the effectiveness of the monitoring methods. The Structural Health Monitoring (SHM) system based on the active pitch-catch measurement technique was proposed. The piezoelectric (PZT) elements was used as an actuators and sensors in the multipoint measuring system. The comparison of the intact and defected structures has been used by damage detection algorithm. One part of the SHM system has been responsible for detection of the fatigue crack initiation. The second part observed the evolution of the damage growth and assess the size of the defect. The numerical results of the wave propagation phenomenon has been used to present the effectiveness and accuracy of the proposed method. The preliminary experimental analysis has been carried out during the tension test of the aluminum plate with a circular hole to determine the efficiency of the measurement technique.

Lifetime laser damage performance of β -Ga2O3 for high power applications

NASA Astrophysics Data System (ADS)

Yoo, Jae-Hyuck; Rafique, Subrina; Lange, Andrew; Zhao, Hongping; Elhadj, Selim

2018-03-01

Gallium oxide (Ga2O3) is an emerging wide bandgap semiconductor with potential applications in power electronics and high power optical systems where gallium nitride and silicon carbide have already demonstrated unique advantages compared to gallium arsenide and silicon-based devices. Establishing the stability and breakdown conditions of these next-generation materials is critical to assessing their potential performance in devices subjected to large electric fields. Here, using systematic laser damage performance tests, we establish that β-Ga2O3 has the highest lifetime optical damage performance of any conductive material measured to date, above 10 J/cm2 (1.4 GW/cm2). This has direct implications for its use as an active component in high power laser systems and may give insight into its utility for high-power switching applications. Both heteroepitaxial and bulk β-Ga2O3 samples were benchmarked against a heteroepitaxial gallium nitride sample, revealing an order of magnitude higher optical lifetime damage threshold for β-Ga2O3. Photoluminescence and Raman spectroscopy results suggest that the exceptional damage performance of β-Ga2O3 is due to lower absorptive defect concentrations and reduced epitaxial stress.

Developmental approach towards high resolution optical coherence tomography for glaucoma diagnostics

NASA Astrophysics Data System (ADS)

Kemper, Björn; Ketelhut, Steffi; Heiduschka, Peter; Thorn, Marie; Larsen, Michael; Schnekenburger, Jürgen

2018-02-01

Glaucoma is caused by a pathological rise in the intraocular pressure, which results in a progressive loss of vision by a damage to retinal cells and the optical nerve head. Early detection of pressure-induced damage is thus essential for the reduction of eye pressure and to prevent severe incapacity or blindness. Within the new European Project GALAHAD (Glaucoma Advanced, Label free High Resolution Automated OCT Diagnostics), we will develop a new low-cost and high-resolution OCT system for the early detection of glaucoma. The device is designed to improve diagnosis based on a new system of optical coherence tomography. Although OCT systems are at present available in ophthalmology centres, high-resolution devices are extremely expensive. The novelty of the new Galahad system is its super wideband light source to achieve high image resolution at a reasonable cost. Proof of concept experiments with cell and tissue Glaucoma test standards and animal models are planned for the test of the new optical components and new algorithms performance for the identification of Glaucoma associated cell and tissue structures. The intense training of the software systems with various samples should result in a increased sensitivity and specificity of the OCT software system.

MECHANICAL PROPERTY CHARACTERIZATIONS AND PERFORMANCE MODELING OF SOFC SEALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koeppel, Brian J.; Vetrano, John S.; Nguyen, Ba Nghiep

2008-03-26

This study provides modeling tools for the design of reliable seals for SOFC stacks. The work consists of 1) experimental testing to determine fundamental properties of SOFC sealing materials, and 2) numerical modeling of stacks and sealing systems. The material tests capture relevant temperature-dependent physical and mechanical data needed by the analytical models such as thermal expansion, strength, fracture toughness, and relaxation behavior for glass-ceramic seals and other materials. Testing has been performed on both homogenous specimens and multiple material assemblies to investigate the effect of interfacial reactions. A viscoelastic continuum damage model for a glass-ceramic seal was developed tomore » capture the nonlinear behavior of this material at high temperatures. This model was implemented in the MSC MARC finite element code and was used for a detailed analysis of a planar SOFC stack under thermal cycling conditions. Realistic thermal loads for the stack were obtained using PNNL’s in-house multiphysics solver. The accumulated seal damage and component stresses were evaluated for multiple thermal loading cycles, and regions of high seal damage susceptible to cracking were identified. Selected test results, numerical model development, and analysis results will be presented.« less

Quantitative impact characterization of aeronautical CFRP materials with non-destructive testing methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiefel, Denis, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com; Stoessel, Rainer, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com; Grosse, Christian, E-mail: Grosse@tum.de

2015-03-31

In recent years, an increasing number of safety-relevant structures are designed and manufactured from carbon fiber reinforced polymers (CFRP) in order to reduce weight of airplanes by taking the advantage of their specific strength into account. Non-destructive testing (NDT) methods for quantitative defect analysis of damages are liquid- or air-coupled ultrasonic testing (UT), phased array ultrasonic techniques, and active thermography (IR). The advantage of these testing methods is the applicability on large areas. However, their quantitative information is often limited on impact localization and size. In addition to these techniques, Airbus Group Innovations operates a micro x-ray computed tomography (μ-XCT)more » system, which was developed for CFRP characterization. It is an open system which allows different kinds of acquisition, reconstruction, and data evaluation. One main advantage of this μ-XCT system is its high resolution with 3-dimensional analysis and visualization opportunities, which enables to gain important quantitative information for composite part design and stress analysis. Within this study, different NDT methods will be compared at CFRP samples with specified artificial impact damages. The results can be used to select the most suitable NDT-method for specific application cases. Furthermore, novel evaluation and visualization methods for impact analyzes are developed and will be presented.« less

Prediction of load threshold of fibre-reinforced laminated composite panels subjected to low velocity drop-weight impact using efficient data filtering techniques

NASA Astrophysics Data System (ADS)

Farooq, Umar; Myler, Peter

This work is concerned with physical testing of carbon fibrous laminated composite panels with low velocity drop-weight impacts from flat and round nose impactors. Eight, sixteen, and twenty-four ply panels were considered. Non-destructive damage inspections of tested specimens were conducted to approximate impact-induced damage. Recorded data were correlated to load-time, load-deflection, and energy-time history plots to interpret impact induced damage. Data filtering techniques were also applied to the noisy data that unavoidably generate due to limitations of testing and logging systems. Built-in, statistical, and numerical filters effectively predicted load thresholds for eight and sixteen ply laminates. However, flat nose impact of twenty-four ply laminates produced clipped data that can only be de-noised involving oscillatory algorithms. Data filtering and extrapolation of such data have received rare attention in the literature that needs to be investigated. The present work demonstrated filtering and extrapolation of the clipped data using Fast Fourier Convolution algorithm to predict load thresholds. Selected results were compared to the damage zones identified with C-scan and acceptable agreements have been observed. Based on the results it is proposed that use of advanced data filtering and analysis methods to data collected by the available resources has effectively enhanced data interpretations without resorting to additional resources. The methodology could be useful for efficient and reliable data analysis and impact-induced damage prediction of similar cases' data.

Damage detection in sandwich composite materials using laser vibrometry in conjunction with nonlinear system identification

NASA Astrophysics Data System (ADS)

Underwood, Sara; Koester, David; Adams, Douglas E.

2009-03-01

Fiberglass sandwich panels are tested to study a vibration-based method for locating damage in composite materials. This method does not rely on a direct comparison of the natural frequencies, mode shapes, or residues in the forced vibration response data. Specifically, a nonlinear system identification based method for damage detection is sought that reduces the sensitivity of damage detection results to changes in vibration measurements due to variations in boundary conditions, environmental conditions, and material properties of the panel. Damage mechanisms considered include a disbond between the core and face sheet and a crack within the core. A panel is excited by a skewed piezoelectric actuator over a broad frequency range while a three-dimensional scanning laser vibrometer measures the surface velocity of the panel along three orthogonal axes. The forced frequency response data measured using the scanning laser vibrometer at multiple excitation amplitudes is processed to identify areas of the panel that exhibit significant nonlinear response characteristics. It is demonstrated that these localized nonlinearities in the panel coincide with the damaged areas of the composite material. Because changes in the measured frequency response functions due to nonlinear distortions associated with the damage can be identified without comparing the vibration data to a reference (baseline) signature of the undamaged material, this vibration technique for damage detection in composite materials exhibits less sensitivity to variations in the underlying linear characteristics than traditional methods. It is also demonstrated that the damage at a given location can be classified as either due to a disbond or core crack because these two types of damage produce difference signatures when comparing the multi-amplitude frequency response functions.

The Thirty Meter Telescope site testing robotic computer system

NASA Astrophysics Data System (ADS)

Riddle, Reed L.; Schöck, Matthias; Skidmore, Warren

2006-06-01

The Thirty Meter Telescope (TMT) project is currently testing six remote sites as candidates for the final location of the telescope. Each site has several instruments, including seeing monitors, weather stations, and turbulence profile measuring systems, each of which is computer controlled. As the sites are remote (usually hours from the nearest town), they requires a system that can control the operations of all the varied subsystems, keep the systems safe from damage and recover from errors during operation. The robotic system must also be robust enough to operate without human intervention and when internet connections are lost. It is also critical that a data archiving system diligently records all data as gathered. This paper is a discussion of the TMT site testing robotic computer system as implemented.

One-Dimensional Time to Explosion (Thermal Sensitivity) of ANPZ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, P.; Hust, G.; McClelland, M.

Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to explosion, threshold thermal explosion temperature, and determine kinetic parameters of energetic materials. Samples of different configurationsmore » (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. This report summarizes the recent ODTX experimental data and modeling results for 2,6-diamino-3,5-dintropyrazine (ANPZ).« less

Debonding characteristics of adhesively bonded woven Kevlar composites

NASA Technical Reports Server (NTRS)

Mall, S.; Johnson, W. S.

1988-01-01

The fatigue damage mechanism of an adhesively bonded joint between fabric reinforced composite adherends was investigated with cracked-lap-shear specimens. Two bonded systems were studied: fabric Kevlar 49/5208 epoxy adherends bonded together with either EC 3445 or FM-300 adhesive. For each bonded system, two specimen geometries were tested. In all specimens tested, fatigue damage occurred in the form of cyclic debonding; however, the woven Kevlar specimens gave significantly slower debond growth rates and higher fracture toughness than previously found in the nonwoven adherend specimens. The surfaces for the woven adherends were not smooth; rather, they had regular crests (high spots) and troughs (low spots) due to the weave pattern. Radiographs of the specimens and examination of their failure surfaces revealed that fiber bridging occurred between the crests of the two adherends in the debonded region. The observed improvements in debond growth resistance and static fracture toughness are attributed to this bridging.

A Progressive Damage Model for Predicting Permanent Indentation and Impact Damage in Composite Laminates

NASA Astrophysics Data System (ADS)

Ji, Zhaojie; Guan, Zhidong; Li, Zengshan

2017-10-01

In this paper, a progressive damage model was established on the basis of ABAQUS software for predicting permanent indentation and impact damage in composite laminates. Intralaminar and interlaminar damage was modelled based on the continuum damage mechanics (CDM) in the finite element model. For the verification of the model, low-velocity impact tests of quasi-isotropic laminates with material system of T300/5228A were conducted. Permanent indentation and impact damage of the laminates were simulated and the numerical results agree well with the experiments. It can be concluded that an obvious knee point can be identified on the curve of the indentation depth versus impact energy. Matrix cracking and delamination develops rapidly with the increasing impact energy, while considerable amount of fiber breakage only occurs when the impact energy exceeds the energy corresponding to the knee point. Predicted indentation depth after the knee point is very sensitive to the parameter μ which is proposed in this paper, and the acceptable value of this parameter is in range from 0.9 to 1.0.

Monitoring and Failure Analysis of Corroded Bridge Cables under Fatigue Loading Using Acoustic Emission Sensors

PubMed Central

Li, Dongsheng; Ou, Jinping; Lan, Chengming; Li, Hui

2012-01-01

Cables play an important role in cable-stayed systems, but are vulnerable to corrosion and fatigue damage. There is a dearth of studies on the fatigue damage evolution of corroded cable. In the present study, the acoustic emission (AE) technology is adopted to monitor the fatigue damage evolution process. First, the relationship between stress and strain is determined through a tensile test for corroded and non-corroded steel wires. Results show that the mechanical performance of corroded cables is changed considerably. The AE characteristic parameters for fatigue damage are then established. AE energy cumulative parameters can accurately describe the fatigue damage evolution of corroded cables. The failure modes in each phase as well as the type of acoustic emission source are determined based on the results of scanning electron microscopy. The waveform characteristics, damage types, and frequency distribution of the corroded cable at different damage phases are collected. Finally, the number of broken wires and breakage time of the cables are determined according to the variation in the margin index. PMID:22666009

Irreversible entropy model for damage diagnosis in resistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuadras, Angel, E-mail: angel.cuadras@upc.edu; Crisóstomo, Javier; Ovejas, Victoria J.

2015-10-28

We propose a method to characterize electrical resistor damage based on entropy measurements. Irreversible entropy and the rate at which it is generated are more convenient parameters than resistance for describing damage because they are essentially positive in virtue of the second law of thermodynamics, whereas resistance may increase or decrease depending on the degradation mechanism. Commercial resistors were tested in order to characterize the damage induced by power surges. Resistors were biased with constant and pulsed voltage signals, leading to power dissipation in the range of 4–8 W, which is well above the 0.25 W nominal power to initiate failure. Entropymore » was inferred from the added power and temperature evolution. A model is proposed to understand the relationship among resistance, entropy, and damage. The power surge dissipates into heat (Joule effect) and damages the resistor. The results show a correlation between entropy generation rate and resistor failure. We conclude that damage can be conveniently assessed from irreversible entropy generation. Our results for resistors can be easily extrapolated to other systems or machines that can be modeled based on their resistance.« less

[Digital ischemia revealing multiple myeloma].

PubMed

Khammar, Z; Ouazzani, M; Bennani, B; Oubelkacem, N; Berrady, R

2018-02-01

Digital ulcers generally arise in a context of microangiopathy-related focal ischemia. In women, connective tissue diseases are the main etiology, while in men the cause is often diffuse arterial disease, e.g. Leo-Buerger disease, or emboligenic heart disease. A paraneoplastic origin of digital necrosis due to ischemia is rarely reported. A 75-year-old man presented with cyanosis of the fingertips and toes that had begun one month earlier. The physical examination found pulp ulcers on the fingers and toes of both hands and feet. Two weeks later, necrotic damage developed distally, with no other associated symptoms. Blood tests were suggestive of Kahler disease; immunodeficiency disorders tests were negative; the cyroglobulin test was positive. Multiple-drug chemotherapy was followed by clinical improvement. Distal necrotic damage is a frequent inaugural symptom in vascular disease. If the common causal mechanisms (iatrogenic, occupational, toxic, atheromatous, emboligenic heart disease, or systemic disease) have been ruled out, it is important to search for a blood disorder or cancer as the cause of distal necrotic damage. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

In situ micro-compression testing of He2+ ion irradiated titanium aluminide

NASA Astrophysics Data System (ADS)

Wei, Tao; Xu, Alan; Zhu, Hanliang; Ionescu, Mihail; Bhattacharyya, Dhriti

2017-10-01

A titanium aluminide (TiAl) alloy 45XD has been irradiated by a He ion beam with an energy of 5 MeV on a tandem accelerator at the Australian Nuclear Science and Technology Organization (ANSTO). The total fluence of He ions was 5 × 1017 ion cm-2. A 17 μm uniform damage region from the material surface with a helium concentration of about 5000 appm was achieved by using an energy degrading wheel in front of the TiAl target. The micro-size test specimens from the damage layer were fabricated using a focused ion beam & scanning electron microscope (FIB-SEM) system. The in situ SEM micromechanical compressive testing was carried out inside an SEM and the results indicated irradiation embrittlement in the helium affected region. Electron back scatter diffraction (EBSD) analysis has been applied to reveal the orientation of the lamellae in the TiAl specimens, and used to understand the deformation processes in the sample. The irradiation damage of gallium ion beam from FIB on the surface of TiAl sample was also investigated.

Damage Tolerance of Pre-Stressed Composite Panels Under Impact Loads

NASA Astrophysics Data System (ADS)

Johnson, Alastair F.; Toso-Pentecôte, Nathalie; Schueler, Dominik

2014-02-01

An experimental test campaign studied the structural integrity of carbon fibre/epoxy panels preloaded in tension or compression then subjected to gas gun impact tests causing significant damage. The test programme used representative composite aircraft fuselage panels composed of aerospace carbon fibre toughened epoxy prepreg laminates. Preload levels in tension were representative of design limit loads for fuselage panels of this size, and maximum compression preloads were in the post-buckle region. Two main impact scenarios were considered: notch damage from a 12 mm steel cube projectile, at velocities in the range 93-136 m/s; blunt impact damage from 25 mm diameter glass balls, at velocities 64-86 m/s. The combined influence of preload and impact damage on panel residual strengths was measured and results analysed in the context of damage tolerance requirements for composite aircraft panels. The tests showed structural integrity well above design limit loads for composite panels preloaded in tension and compression with visible notch impact damage from hard body impact tests. However, blunt impact tests on buckled compression loaded panels caused large delamination damage regions which lowered plate bending stiffness and reduced significantly compression strengths in buckling.

Chronic inflammatory demyelinating polyneuropathy: evaluation of the vestibular system with cervical and ocular vestibular evoked myogenic potentials.

PubMed

Magliulo, Giuseppe; Iannella, Giannicola; Manno, Alessandra; Libonati, Laura; Onesti, Emanuela; Vestri, Annarita; Fegatelli, Danilo Alunni; Angeletti, Diletta; Pace, Annalisa; Gulotta, Giampiero; Gagliardi, Silvia; Inghilleri, Maurizio

2018-06-01

To investigate the possibility of vestibular damage in a group of patients suffering from chronic inflammatory demyelinating polyneuropathy (CIDP) using a diagnostic protocol including the caloric test, C-VEMPs and O-VEMPs. Twenty patients suffering from CIDP (mean age 58.5 years, range 33-80 years; 4 women and 16 men) were investigated. To assess any eventual audio-vestibular involvement, all patients of the study underwent pure tone audiometry, Fitzgerald-Hallpike caloric vestibular test, C-VEMPs and O-VEMPs. In 11 patients with CIDP values of both O-VEMPs and C-VEMPs were either absent or abnormal. An absent trace at O-VEMPs testing occurred in 36% of these pathological patients, whereas an increase of n10 latency and amplitude was present in the other 64% . A specific diagnostic protocol including the caloric test, C-VEMPS, O-VEMPS, could be useful when employed for identifying vestibular damage in CIDP patients.

Repeatability and uncertainty analyses of light gas gun test data

NASA Technical Reports Server (NTRS)

Schonberg, William P.; Cooper, David

1994-01-01

All large spacecraft are susceptible to high-speed impacts by meteoroids and pieces of orbiting space debris which can damage flight-critical systems and in turn lead to catastrophic failure. One way to obtain information on the response of a structure to a meteoroid impact or an orbital debris impact is to simulate the impact conditions of interest in the laboratory and analyze the resulting damage to a target structure. As part of the Phase B and C/D development activities for the Space Station Freedom, 950 impact tests were performed using the NASA/Marshall Space Flight Center (MSFC) light gas gun from 1985-1991. This paper presents the results of impact phenomena repeatability and data uncertainty studies performed using the information obtained from those tests. The results of these studies can be used to assess the utility of individual current and future NASA/MSFC impact test results in the design of long-duration spacecraft.

A comparison of LIDT behavior of metal-dielectric mirrors in ns and ps pulse regime at 1030 nm with regard to the coating technology

NASA Astrophysics Data System (ADS)

Škoda, Václav; Vanda, Jan; Uxa, Štěpán

2017-11-01

Several sets of mirror samples with multilayer system Ta2O5/SiO2 on silver metal layer were manufactured using either PVD or IAD coating technology. Both BK7 and fused silica substrates were used for preparation of samples. Laserinduced- damage-threshold (LIDT) of metal-dielectric mirrors was tested using a laser apparatus working at 1030 nm wavelength, in ns and ps pulse length domains in S-on-1 test mode. The measured damage threshold values at 45 deg angle of incidence and P-polarization were compared for different pulse length, substrate materials and coating technology.

Acetylcholine test in patients with angina pectoris and normal coronary angiography

NASA Astrophysics Data System (ADS)

Barbieri, Enrico; Destro, Gianni; Oliva, Massimo; Zardini, Piero

1994-02-01

Angina pectoris with normal coronary artery on the coronary angiography is an intriguing issue. Intracoronary infusion of acetylcholine has recently been used to test the integrity of endothelial cells. We studied 16 patients with this syndrome. A relationship has been found between the acetylcholine test and the exercise stress test in normotensive patients. The presence of hypertension makes the evaluation of the test more unpredictable, probably because of the damage on the endothelial cells related to systemic hypertension.

Multiaxis Rainflow Fatigue Methods for Nonstationary Vibration

NASA Technical Reports Server (NTRS)

Irvine, T.

2016-01-01

Mechanical structures and components may be subjected to cyclical loading conditions, including sine and random vibration. Such systems must be designed and tested accordingly. Rainflow cycle counting is the standard method for reducing a stress time history to a table of amplitude-cycle pairings prior to the Palmgren-Miner cumulative damage calculation. The damage calculation is straightforward for sinusoidal stress but very complicated for random stress, particularly for nonstationary vibration. This paper evaluates candidate methods and makes a recommendation for further study of a hybrid technique.

Laser Damage in Thin Film Optical Coatings

DTIC Science & Technology

1992-07-01

10) using E- beam evaporation and laser tests performed to determine the effect of conditioning laser spot size and coating design on improvement in...1.06 pm) consisting of a 15 layer 3 quarter-wave design (HFO2/SiO 2 and ZrO2/SiO 2) were fabricated by E- beam evaporation. Sol-gel processing was used to... designers select laser damage resistant coatings for optical elements to be employed in military systems using lasers or encountering lasers used as

Shake Table Testing of an Elevator System in a Full-Scale Five-Story Building

PubMed Central

Wang, Xiang; Hutchinson, Tara C.; Astroza, Rodrigo; Conte, Joel P.; Restrepo, José I.; Hoehler, Matthew S.; Ribeiro, Waldir

2016-01-01

SUMMARY This paper investigates the seismic performance of a functional traction elevator as part of a full-scale five-story building shake table test program. The test building was subjected to a suite of earthquake input motions of increasing intensity, first while the building was isolated at its base, and subsequently while it was fixed to the shake table platen. In addition, low-amplitude white noise base excitation tests were conducted while the elevator system was placed in three different configurations, namely, by varying the vertical location of its cabin and counterweight, to study the acceleration amplifications of the elevator components due to dynamic excitations. During the earthquake tests, detailed observation of the physical damage and operability of the elevator as well as its measured response are reported. Although the cabin and counterweight sustained large accelerations due to impact during these tests, the use of well-restrained guide shoes demonstrated its effectiveness in preventing the cabin and counterweight from derailment during high-intensity earthquake shaking. However, differential displacements induced by the building imposed undesirable distortion of the elevator components and their surrounding support structure, which caused damage and inoperability of the elevator doors. It is recommended that these aspects be explicitly considered in elevator seismic design. PMID:28242957

Shake Table Testing of an Elevator System in a Full-Scale Five-Story Building.

PubMed

Wang, Xiang; Hutchinson, Tara C; Astroza, Rodrigo; Conte, Joel P; Restrepo, José I; Hoehler, Matthew S; Ribeiro, Waldir

2017-03-01

This paper investigates the seismic performance of a functional traction elevator as part of a full-scale five-story building shake table test program. The test building was subjected to a suite of earthquake input motions of increasing intensity, first while the building was isolated at its base, and subsequently while it was fixed to the shake table platen. In addition, low-amplitude white noise base excitation tests were conducted while the elevator system was placed in three different configurations, namely, by varying the vertical location of its cabin and counterweight, to study the acceleration amplifications of the elevator components due to dynamic excitations. During the earthquake tests, detailed observation of the physical damage and operability of the elevator as well as its measured response are reported. Although the cabin and counterweight sustained large accelerations due to impact during these tests, the use of well-restrained guide shoes demonstrated its effectiveness in preventing the cabin and counterweight from derailment during high-intensity earthquake shaking. However, differential displacements induced by the building imposed undesirable distortion of the elevator components and their surrounding support structure, which caused damage and inoperability of the elevator doors. It is recommended that these aspects be explicitly considered in elevator seismic design.

Comparing the ISO-recommended and the cumulative data-reduction algorithms in S-on-1 laser damage test by a reverse approach method

NASA Astrophysics Data System (ADS)

Zorila, Alexandru; Stratan, Aurel; Nemes, George

2018-01-01

We compare the ISO-recommended (the standard) data-reduction algorithm used to determine the surface laser-induced damage threshold of optical materials by the S-on-1 test with two newly suggested algorithms, both named "cumulative" algorithms/methods, a regular one and a limit-case one, intended to perform in some respects better than the standard one. To avoid additional errors due to real experiments, a simulated test is performed, named the reverse approach. This approach simulates the real damage experiments, by generating artificial test-data of damaged and non-damaged sites, based on an assumed, known damage threshold fluence of the target and on a given probability distribution function to induce the damage. In this work, a database of 12 sets of test-data containing both damaged and non-damaged sites was generated by using four different reverse techniques and by assuming three specific damage probability distribution functions. The same value for the threshold fluence was assumed, and a Gaussian fluence distribution on each irradiated site was considered, as usual for the S-on-1 test. Each of the test-data was independently processed by the standard and by the two cumulative data-reduction algorithms, the resulting fitted probability distributions were compared with the initially assumed probability distribution functions, and the quantities used to compare these algorithms were determined. These quantities characterize the accuracy and the precision in determining the damage threshold and the goodness of fit of the damage probability curves. The results indicate that the accuracy in determining the absolute damage threshold is best for the ISO-recommended method, the precision is best for the limit-case of the cumulative method, and the goodness of fit estimator (adjusted R-squared) is almost the same for all three algorithms.

Damage Detection Response Characteristics of Open Circuit Resonant (SansEC) Sensors

NASA Technical Reports Server (NTRS)

Dudley, Kenneth L.; Szatkowski, George N.; Smith, Laura J.; Koppen, Sandra V.; Ely, Jay J.; Nguyen, Truong X.; Wang, Chuantong; Ticatch, Larry A.; Mielnik, John J.

2013-01-01

The capability to assess the current or future state of the health of an aircraft to improve safety, availability, and reliability while reducing maintenance costs has been a continuous goal for decades. Many companies, commercial entities, and academic institutions have become interested in Integrated Vehicle Health Management (IVHM) and a growing effort of research into "smart" vehicle sensing systems has emerged. Methods to detect damage to aircraft materials and structures have historically relied on visual inspection during pre-flight or post-flight operations by flight and ground crews. More quantitative non-destructive investigations with various instruments and sensors have traditionally been performed when the aircraft is out of operational service during major scheduled maintenance. Through the use of reliable sensors coupled with data monitoring, data mining, and data analysis techniques, the health state of a vehicle can be detected in-situ. NASA Langley Research Center (LaRC) is developing a composite aircraft skin damage detection method and system based on open circuit SansEC (Sans Electric Connection) sensor technology. Composite materials are increasingly used in modern aircraft for reducing weight, improving fuel efficiency, and enhancing the overall design, performance, and manufacturability of airborne vehicles. Materials such as fiberglass reinforced composites (FRC) and carbon-fiber-reinforced polymers (CFRP) are being used to great advantage in airframes, wings, engine nacelles, turbine blades, fairings, fuselage structures, empennage structures, control surfaces and aircraft skins. SansEC sensor technology is a new technical framework for designing, powering, and interrogating sensors to detect various types of damage in composite materials. The source cause of the in-service damage (lightning strike, impact damage, material fatigue, etc.) to the aircraft composite is not relevant. The sensor will detect damage independent of the cause. Damage in composite material is generally associated with a localized change in material permittivity and/or conductivity. These changes are sensed using SansEC. The unique electrical signatures (amplitude, frequency, bandwidth, and phase) are used for damage detection and diagnosis. An operational system and method would incorporate a SansEC sensor array on select areas of the aircraft exterior surfaces to form a "Smart skin" sensing surface. In this paper a new method and system for aircraft in-situ damage detection and diagnosis is presented. Experimental test results on seeded fault damage coupons and computational modeling simulation results are presented. NASA LaRC has demonstrated with individual sensors that SansEC sensors can be effectively used for in-situ composite damage detection of delamination, voids, fractures, and rips. Keywords: Damage Detection, Composites, Integrated Vehicle Health Monitoring (IVHM), Aviation Safety, SansEC Sensors

Glenn Refractory Adhesive for Bonding and Exterior Repair (GRABER) Developed for Repairing Shuttle Damage

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Shpargel, Tarah P.

2005-01-01

Advanced in-space repair technologies for reinforced carbon/carbon composite (RCC) thermal protection system (TPS) structures are critically needed for the space shuttle Return To Flight (RTF) efforts. These technologies are also critical for the repair and refurbishment of thermal protection system structures of future Crew Exploration Vehicles of space exploration programs. The Glenn Refractory Adhesive for Bonding and Exterior Repair (GRABER) material developed at the NASA Glenn Research Center has demonstrated capabilities for repair of small cracks and damage in RCC leading-edge material. The concept consists of preparing an adhesive paste of desired ceramic in a polymer/phenolic resin matrix with appropriate additives, such as surfactants, and then applying the paste into the damaged or cracked area of the RCC composite components with caulking guns. The adhesive paste cures at 100 to 120 C and transforms into a high-temperature ceramic during simulated vehicle reentry testing conditions.

Brain effect of insulin and clonazepam in diabetic rats under depressive-like behavior.

PubMed

Wayhs, Carlos Alberto Yasin; Mescka, Caroline Paula; Vanzin, Camila Simioni; Ribas, Graziela Schmitt; Guerreiro, Gilian; Nin, Maurício Schüler; Manfredini, Vanusa; Barros, Helena Maria Tannhauser; Vargas, Carmen Regla

2013-12-01

Diabetes mellitus is characterized by hyperglycemia resulting from defects on insulin secretion, insulin action, or both. It has recently become clear that the central nervous system is not spared from the deleterious effects of diabetes, since diabetic encephalopathy was recognized as a complication of this heterogeneous metabolic disorder. There is a well recognized association between depression and diabetes, once prevalence of depression in diabetic patients is higher than in general population, and clonazepam is being used to treat this complication. Oxidative stress is widely accepted as playing a key mediatory role in the development and progression of diabetes and its complications. In this work we analyzed DNA damage by comet assay and lipid damage in prefrontal cortex, hippocampus and striatum of streptozotocin-induced diabetic rats submitted to the forced swimming test. It was verified that the diabetic group presented DNA and lipid damage in the brain areas evaluated, when compared to the control groups. Additionally, a significant reduction of the DNA and lipid damage in animals treated with insulin and/or clonazepam was observed. These data suggest that the association of these two drugs could protect against DNA and lipid damage in diabetic rats submitted to the forced swimming test, an animal model of depression.

In-process, non-destructive, dynamic testing of high-speed polymer composite rotors

NASA Astrophysics Data System (ADS)

Kuschmierz, Robert; Filippatos, Angelos; Günther, Philipp; Langkamp, Albert; Hufenbach, Werner; Czarske, Jürgen; Fischer, Andreas

2015-03-01

Polymer composite rotors are lightweight and offer great perspectives in high-speed applications such as turbo machinery. Currently, novel rotor structures and materials are investigated for the purpose of increasing machine efficiency and lifetime, as well as allowing for higher dynamic loads. However, due to the complexity of the composite materials an in-process measurement system is required. This allows for monitoring the evolution of damages under dynamic loads, for testing and predicting the structural integrity of composite rotors in process. In rotor design, it can be used for calibrating and improving models, simulating the dynamic behaviour of polymer composite rotors. The measurement system is to work non-invasive, offer micron uncertainty, as well as a high measurement rate of several tens of kHz. Furthermore, it must be applicable at high surface speeds and under technical vacuum. In order to fulfil these demands a novel laser distance measurement system was developed. It provides the angle resolved measurement of the biaxial deformation of a fibre-reinforced polymer composite rotor with micron uncertainty at surface speeds of more than 300 m/s. Furthermore, a simulation procedure combining a finite element model and a damage mechanics model is applied. A comparison of the measured data and the numerically calculated data is performed to validate the simulation towards rotor expansion. This validating procedure can be used for a model calibration in the future. The simulation procedure could be used to investigate different damage-test cases of the rotor, in order to define its structural behaviour without further experiments.

Reliability of plant root comet assay in comparison with human leukocyte comet assay for assessment environmental genotoxic agents.

PubMed

Reis, Gabriela Barreto Dos; Andrade-Vieira, Larissa Fonseca; Moraes, Isabella de Campos; César, Pedro Henrique Souza; Marcussi, Silvana; Davide, Lisete Chamma

2017-08-01

Comet assay is an efficient test to detect genotoxic compounds based on observation of DNA damage. The aim of this work was to compare the results obtained from the comet assay in two different type of cells extracted from the root tips from Lactuca sativa L. and human blood. For this, Spent Pot Liner (SPL), and its components (aluminum and fluoride) were applied as toxic agents. SPL is a solid waste generated in industry from the aluminum mining and processing with known toxicity. Three concentrations of all tested solutions were applied and the damages observed were compared to negative and positive controls. It was observed an increase in the frequency of DNA damage for human leukocytes and plant cells, in all treatments. On human leukocytes, SPL induced the highest percentage of damage, with an average of 87.68%. For root tips cells of L. sativa the highest percentage of damage was detected for aluminum (93.89%). Considering the arbitrary units (AU), the average of nuclei with high levels of DNA fragmentation was significant for both cells type evaluated. The tested cells demonstrated equal effectiveness for detection of the genotoxicity induced by the SPL and its chemical components, aluminum and fluoride. Further, using a unique method, the comet assay, we proved that cells from root tips of Lactuca sativa represent a reliable model to detect DNA damage induced by genotoxic pollutants is in agreement of those observed in human leukocytes as model. So far, plant cells may be suggested as important system to assess the toxicological risk of environmental agents. Copyright © 2017 Elsevier Inc. All rights reserved.

Time-Dependent Damage Investigation of Rock Mass in an In Situ Experimental Tunnel

PubMed Central

Jiang, Quan; Cui, Jie; Chen, Jing

2012-01-01

In underground tunnels or caverns, time-dependent deformation or failure of rock mass, such as extending cracks, gradual rock falls, etc., are a costly irritant and a major safety concern if the time-dependent damage of surrounding rock is serious. To understand the damage evolution of rock mass in underground engineering, an in situ experimental testing was carried out in a large belowground tunnel with a scale of 28.5 m in width, 21 m in height and 352 m in length. The time-dependent damage of rock mass was detected in succession by an ultrasonic wave test after excavation. The testing results showed that the time-dependent damage of rock mass could last a long time, i.e., nearly 30 days. Regression analysis of damage factors defined by wave velocity, resulted in the time-dependent evolutional damage equation of rock mass, which corresponded with logarithmic format. A damage viscoelastic-plastic model was developed to describe the exposed time-dependent deterioration of rock mass by field test, such as convergence of time-dependent damage, deterioration of elastic modules and logarithmic format of damage factor. Furthermore, the remedial measures for damaged surrounding rock were discussed based on the measured results and the conception of damage compensation, which provides new clues for underground engineering design.

Laser damage threshold of gelatin and a copper phthalocyanine doped gelatin optical limiter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brant, M.C.; McLean, D.G.; Sutherland, R.L.

1996-12-31

The authors demonstrate optical limiting in a unique guest-host system which uses neither the typical liquid or solid host. Instead, they dope a gelatin gel host with a water soluble Copper (II) phthalocyaninetetrasulfonic acid, tetrasodium salt (CuPcTs). They report on the gelatin`s viscoelasticity, laser damage threshold, and self healing of this damage. The viscoelastic gelatin has mechanical properties quite different than a liquid or solid. The authors` laser measurements demonstrate that the single shot damage threshold of the undoped gelatin host increases with decreasing gelatin concentration. The gelatin also has a much higher laser damage threshold than a stiff acrylic.more » Unlike brittle solids, the soft gelatin self heals from laser induced damage. Optical limiting test also show the utility of a gelatin host doped with CuPcTs. The CuPcTs/gelatin matrix is not damaged at incident laser energies 5 times the single shot damage threshold of the gelatin host. However, at this high laser energy the CuPcTs is photo bleached at the beam waist. The authors repair photo bleached sites by annealing the CuPcTs/gelatin matrix.« less

Damage Characterization of Bio and Green Polyethylene-Birch Composites under Creep and Cyclic Testing with Multivariable Acoustic Emissions.

PubMed

Bravo, Alencar; Toubal, Lotfi; Koffi, Demagna; Erchiqui, Fouad

2015-11-02

Despite the knowledge gained in recent years regarding the use of acoustic emissions (AEs) in ecologically friendly, natural fiber-reinforced composites (including certain composites with bio-sourced matrices), there is still a knowledge gap in the understanding of the difference in damage behavior between green and biocomposites. Thus, this article investigates the behavior of two comparable green and biocomposites with tests that better reflect real-life applications, i.e. , load-unloading and creep testing, to determine the evolution of the damage process. Comparing the mechanical results with the AE, it can be concluded that the addition of a coupling agent (CA) markedly reduced the ratio of AE damage to mechanical damage. CA had an extremely beneficial effect on green composites because the Kaiser effect was dominant during cyclic testing. During the creep tests, the use of a CA also avoided the transition to new damaging phases in both composites. The long-term applications of PE green material must be chosen carefully because bio and green composites with similar properties exhibited different damage processes in tests such as cycling and creep that could not be previously understood using only monotonic testing.

Damage Characterization of Bio and Green Polyethylene–Birch Composites under Creep and Cyclic Testing with Multivariable Acoustic Emissions

PubMed Central

Bravo, Alencar; Toubal, Lotfi; Koffi, Demagna; Erchiqui, Fouad

2015-01-01

Despite the knowledge gained in recent years regarding the use of acoustic emissions (AEs) in ecologically friendly, natural fiber-reinforced composites (including certain composites with bio-sourced matrices), there is still a knowledge gap in the understanding of the difference in damage behavior between green and biocomposites. Thus, this article investigates the behavior of two comparable green and biocomposites with tests that better reflect real-life applications, i.e., load-unloading and creep testing, to determine the evolution of the damage process. Comparing the mechanical results with the AE, it can be concluded that the addition of a coupling agent (CA) markedly reduced the ratio of AE damage to mechanical damage. CA had an extremely beneficial effect on green composites because the Kaiser effect was dominant during cyclic testing. During the creep tests, the use of a CA also avoided the transition to new damaging phases in both composites. The long-term applications of PE green material must be chosen carefully because bio and green composites with similar properties exhibited different damage processes in tests such as cycling and creep that could not be previously understood using only monotonic testing. PMID:28793640

Development of Guidelines for In-Situ Repair of SLS-Class Composite Flight Hardware

NASA Technical Reports Server (NTRS)

Weber, Thomas P., Jr.; Cox, Sarah B.

2018-01-01

The purpose of composite repair development at KSC (John F. Kennedy Space Center) is to provide support to the CTE (Composite Technology for Exploration) project. This is a multi-space center effort with the goal of developing bonded joint technology for SLS (Space Launch System) -scale composite hardware. At KSC, effective and efficient repair processes need to be developed to allow for any potential damage to composite components during transport or launch preparation. The focus of the composite repair development internship during the spring of 2018 was on the documentation of repair processes and requirements for process controls based on techniques developed through hands-on work with composite test panels. Three composite test panels were fabricated for the purpose of repair and surface preparation testing. The first panel included a bonded doubler and was fabricated to be damaged and repaired. The second and third panels were both fabricated to be cut into lap-shear samples to test the strength of bond of different surface preparation techniques. Additionally, jointed composite test panels were impacted at MSFC (Marshall Space Flight Center) and analyzed for damage patterns. The observations after the impact tests guided the repair procedure at KSC to focus on three repair methods. With a finalized repair plan in place, future work will include the strength testing of different surface preparation techniques, demonstration of repair methods, and repair of jointed composite test panels being impacted at MSFC.

F-5F Shark Nose radome lightning test

NASA Technical Reports Server (NTRS)

Scott, G. W.

1980-01-01

A unique F-5F radome wtih a geometry similar to a Shark Nose profile was tested with a high voltage Marx generator, 1,200,000 volts in order to demonstrate the effectiveness of the lightning protection system with currents from 5,000 amperes or greater. An edge discontinuity configuration is a characteristic feature in the forward region of the radome and occasionally serves as an attachment point. The results of nineteen attachment tests at various aspect angles with an air gap of one meter indicated that no damage occurred to the dielectric material of the radom. The test proved the effectiveness of the lightning protection system.

Fuel containment and damage tolerance for large composite primary aircraft structures. Phase 1: Testing

NASA Technical Reports Server (NTRS)

Sandifer, J. P.

1983-01-01

Technical problems associated with fuel containment and damage tolerance of composite material wings for transport aircraft were identified. The major tasks are the following: (1) the preliminary design of damage tolerant wing surface using composite materials; (2) the evaluation of fuel sealing and lightning protection methods for a composite material wing; and (3) an experimental investigation of the damage tolerant characteristics of toughened resin graphite/epoxy materials. The test results, the test techniques, and the test data are presented.

A ruggedness evaluation of procedures for damage threshold testing optical materials

NASA Technical Reports Server (NTRS)

Hooker, Matthew W.; Thomas, Milfred E.; Wise, Stephanie A.; Tappan, Nina D.

1995-01-01

A ruggedness evaluation of approaches to damage threshold testing was performed to determine the influence of three procedural variables on damage threshold data. The differences between the number of test sites evaluated at an applied fluence level (1 site versus 10 sites), the number of laser pulses at each test site (1 pulse versus 200 pulses), and the beam diameter (0.35 mm versus 0.70 mm) were all found to significantly influence the damage threshold data over a 99-percent confidence interval.

The Use of Logistic Model in RUL Assessment

NASA Astrophysics Data System (ADS)

Gumiński, R.; Radkowski, S.

2017-12-01

The paper takes on the issue of assessment of remaining useful life (RUL). The goal of the paper was to develop a method, which would enable use of diagnostic information in the task of reducing the uncertainty related to technical risk. Prediction of the remaining useful life (RUL) of the system is a very important task for maintenance strategy. In the literature RUL of an engineering system is defined as the first future time instant in which thresholds of conditions (safety, operational quality, maintenance cost, etc) are violated. Knowledge of RUL offers the possibility of planning the testing and repair activities. Building models of damage development is important in this task. In the presented work, logistic function will be used to model fatigue crack development. It should be remembered that modeling of every phase of damage development is very difficult, yet modeling of every phase of damage separately, especially including on-line diagnostic information is more effective. Particular attention was paid to the possibility of forecasting the occurrence of damage due to fatigue while relying on the analysis of the structure of a vibroacoustic signal.

Improving Metallic Thermal Protection System Hypervelocity Impact Resistance Through Design of Experiments Approach

NASA Technical Reports Server (NTRS)

Poteet, Carl C.; Blosser, Max L.

2001-01-01

A design of experiments approach has been implemented using computational hypervelocity impact simulations to determine the most effective place to add mass to an existing metallic Thermal Protection System (TPS) to improve hypervelocity impact protection. Simulations were performed using axisymmetric models in CTH, a shock-physics code developed by Sandia National Laboratories, and validated by comparison with existing test data. The axisymmetric models were then used in a statistical sensitivity analysis to determine the influence of five design parameters on degree of hypervelocity particle dispersion. Several damage metrics were identified and evaluated. Damage metrics related to the extent of substructure damage were seen to produce misleading results, however damage metrics related to the degree of dispersion of the hypervelocity particle produced results that corresponded to physical intuition. Based on analysis of variance results it was concluded that the most effective way to increase hypervelocity impact resistance is to increase the thickness of the outer foil layer. Increasing the spacing between the outer surface and the substructure is also very effective at increasing dispersion.

Phase 1 Space Fission Propulsion System Testing and Development Progress

NASA Technical Reports Server (NTRS)

VanDyke, Melissa; Houts, Mike; Godfroy, Tom; Dickens, Ricky; Poston, David; Kapernick, Rick; Reid, Bob; Salvail, Pat; Ring, Peter; Schafer, Charles (Technical Monitor)

2001-01-01

Successful development of space fission systems requires an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. The Safe Affordable Fission Engine (SAFE) test series, whose ultimate goal is the demonstration of a 300 kW flight configuration system, has demonstrated that realistic testing can be performed using non-nuclear methods. This test series, carried out in collaboration with other NASA centers, other government agencies, industry, and universities, successfully completed a testing program with a 30 kWt core, Stirling engine, and ion engine configuration. Additionally, a 100 kWt core is in fabrication and appropriate test facilities are being reconfigured. This paper describes the current SAFE non-nuclear tests, which includes test article descriptions, test results and conclusions, and future test plans.

Noise and cardiovascular effects in workers of the sanitary fixtures industry.

PubMed

Assunta, Capozzella; Ilaria, Samperi; Simone, De Sio; Gianfranco, Tomei; Teodorico, Casale; Carmina, Sacco; Anastasia, Suppi; Roberto, Giubilati; Francesco, Tomei; Valeria, Rosati Maria

2015-01-01

The aim of the present study is to evaluate whether workers in the sanitary fixtures industry are a category at risk of developing cardiovascular diseases, and in particular, whether chronic noise exposure may play a role in cardiovascular effects in exposed workers. Seventy-five employees engaged in sanitation fixtures production and a control group of sixty-four office workers, who were not exposed to agents that could damage the cardiovascular system, participated in our study. The selected workers completed a clinical-anamnestic questionnaire, and underwent a medical examination, blood pressure test, electrocardiogram (ECG), blood tests, and audiometry. Measurements of environmental noise, dust, and lead were also carried out. The exposed workers, in comparison to the control group, showed a higher frequency of hypertension, systolic and diastolic blood pressure (p<0.05, p<0.05), as well as electrocardiographic abnormalities (p<0.05). There was also a higher frequency of hypertension and electrocardiographic abnormalities among subjects with audiometric deficit compared to normoacoustic subjects (p<0.05 and p<0.05). from our study suggest that work activity in the sanitary fixtures industry can have an influence on the cardiovascular system, and noise can be the main cause of damage for the cardiovascular system in exposed workers, as cardiovascular damage seems to be linked to hearing loss. Copyright © 2014 Elsevier GmbH. All rights reserved.

The Two Modes of Visual Processing: Implications for Spatial Orientation

NASA Technical Reports Server (NTRS)

Leibowitz, H. W.; Shupert, C. L.; Post, R. B.

1984-01-01

The roles of the focal and ambient visual systems in spatial orientation are discussed. The two modes are defined and compared. The contribution of each system is illustrated through examples such as spatial disorientation/motion sickness, vehicle guidance/night driving, visual narrowing under stress/cortical brain damage, and aircraft instrumentation. Emphasis is placed on the need for testing procedures for the ambient system.

Self-diagnosis of damage in fibrous composites using electrical resistance measurements

NASA Astrophysics Data System (ADS)

Kang, Ji Ho; Paty, Spandana; Kim, Ran Y.; Tandon, G. P.

2006-03-01

The objective of this research was to develop a practical integrated approach using extracted features from electrical resistance measurements and coupled electromechanical models of damage, for in situ damage detection and sensing in carbon fiber reinforced plastic (CFRP) composite structures. To achieve this objective, we introduced specific known damage (in terms of type, size, and location) into CFRP laminates and established quantitative relationships with the electrical resistance measurements. For processing of numerous measurement data, an autonomous data acquisition system was devised. We also established a specimen preparation procedure and a method for electrode setup. Coupon and panel CFRP laminate specimens with several known damage were tested and post-processed with the measurement data. Coupon specimens with various sizes of artificial delaminations obtained by inserting Teflon film were manufactured and the resistance was measured. The measurement results showed that increase of delamination size led to increase of resistance implying that it is possible to sense the existence and size of delamination. Encouraged by the results of coupon specimens, we implemented the measurement system on panel specimens. Three different quasi-isotropic panels were designed and manufactured: a panel with artificial delamination by inserting Teflon film at the midplane, a panel with artificial delamination by inserting Teflon film between the second and third plies from the surface, and an undamaged panel. The first two panels were designed to determine the feasibility of detecting delamination using the developed measurement system. The third panel had no damage at first, and then three different sizes of holes were drilled at a chosen location. Panels were prepared using the established procedures with six electrode connections on each side making a total of twenty-four electrode connections for a panel. All possible pairs of electrodes were scanned and the resistance was measured for each pair. The measurement results showed the possibility of the established measurement system for an in-situ damage detection method for CFRP composite structures.

Threshold Assessment of Gear Diagnostic Tools on Flight and Test Rig Data

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Mosher, Marianne; Huff, Edward M.

2003-01-01

A method for defining thresholds for vibration-based algorithms that provides the minimum number of false alarms while maintaining sensitivity to gear damage was developed. This analysis focused on two vibration based gear damage detection algorithms, FM4 and MSA. This method was developed using vibration data collected during surface fatigue tests performed in a spur gearbox rig. The thresholds were defined based on damage progression during tests with damage. The thresholds false alarm rates were then evaluated on spur gear tests without damage. Next, the same thresholds were applied to flight data from an OH-58 helicopter transmission. Results showed that thresholds defined in test rigs can be used to define thresholds in flight to correctly classify the transmission operation as normal.

Modulation of the Early Inflammatory Microenvironment in the Alkali-Burned Eye by Systemically Administered Interferon-γ-Treated Mesenchymal Stromal Cells

PubMed Central

Javorkova, Eliska; Trosan, Peter; Zajicova, Alena; Krulova, Magdalena; Hajkova, Michaela

2014-01-01

The aim of this study was to investigate the effects of systemically administered bone-marrow-derived mesenchymal stromal cells (MSCs) on the early acute phase of inflammation in the alkali-burned eye. Mice with damaged eyes were either untreated or treated 24 h after the injury with an intravenous administration of fluorescent-dye-labeled MSCs that were unstimulated or pretreated with interleukin-1α (IL-1α), transforming growth factor-β (TGF-β), or interferon-γ (IFN-γ). Analysis of cell suspensions prepared from the eyes of treated mice on day 3 after the alkali burn revealed that MSCs specifically migrated to the damaged eye and that the number of labeled MSCs was more than 30-times higher in damaged eyes compared with control eyes. The study of the composition of the leukocyte populations within the damaged eyes showed that all types of tested MSCs slightly decreased the number of infiltrating lymphoid and myeloid cells, but only MSCs pretreated with IFN-γ significantly decreased the percentage of eye-infiltrating cells with a more profound effect on myeloid cells. Determining cytokine and NO production in the damaged eyes confirmed that the most effective immunomodulation was achieved with MSCs pretreated with IFN-γ, which significantly decreased the levels of the proinflammatory molecules IL-1α, IL-6, and NO. Taken together, the results show that systemically administered MSCs specifically migrate to the damaged eye and that IFN-γ-pretreated MSCs are superior in inhibiting the acute phase of inflammation, decreasing leukocyte infiltration, and attenuating the early inflammatory environment. PMID:24849741

Operational Forecasting and Warning systems for Coastal hazards in Korea

NASA Astrophysics Data System (ADS)

Park, Kwang-Soon; Kwon, Jae-Il; Kim, Jin-Ah; Heo, Ki-Young; Jun, Kicheon

2017-04-01

Coastal hazards caused by both Mother Nature and humans cost tremendous social, economic and environmental damages. To mitigate these damages many countries have been running the operational forecasting or warning systems. Since 2009 Korea Operational Oceanographic System (KOOS) has been developed by the leading of Korea Institute of Ocean Science and Technology (KIOST) in Korea and KOOS has been operated in 2012. KOOS is consists of several operational modules of numerical models and real-time observations and produces the basic forecasting variables such as winds, tides, waves, currents, temperature and salinity and so on. In practical application systems include storm surges, oil spills, and search and rescue prediction models. In particular, abnormal high waves (swell-like high-height waves) have occurred in the East coast of Korea peninsula during winter season owing to the local meteorological condition over the East Sea, causing property damages and the loss of human lives. In order to improve wave forecast accuracy even very local wave characteristics, numerical wave modeling system using SWAN is established with data assimilation module using 4D-EnKF and sensitivity test has been conducted. During the typhoon period for the prediction of sever waves and the decision making support system for evacuation of the ships, a high-resolution wave forecasting system has been established and calibrated.

An examination of impact damage in glass-phenolic and aluminum honeycomb core composite panels

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Lance, D. G.; Hodge, A. J.

1990-01-01

An examination of low velocity impact damage to glass-phenolic and aluminum core honeycomb sandwich panels with carbon-epoxy facesheets is presented. An instrumented drop weight impact test apparatus was utilized to inflict damage at energy ranges between 0.7 and 4.2 joules. Specimens were checked for extent of damage by cross sectional examination. The effect of core damage was assessed by subjecting impact-damaged beams to four-point bend tests. Skin-only specimens (facings not bonded to honeycomb) were also tested for comparison purposes. Results show that core buckling is the first damage mode, followed by delaminations in the facings, matrix cracking, and finally fiber breakage. The aluminum honeycomb panels exhibited a larger core damage zone and more facing delaminations than the glass-phenolic core, but could withstand more shear stress when damaged than the glass-phenolic core specimens.

Nondestructive Structural Damage Detection in Flexible Space Structures Using Vibration Characterization

NASA Technical Reports Server (NTRS)

Ricles, James M.

1991-01-01

Spacecraft are susceptible to structural damage over their operating life from impact, environmental loads, and fatigue. Structural damage that is not detected and not corrected may potentially cause more damage and eventually catastrophic structural failure. NASA's current fleet of reusable spacecraft, namely the Space Shuttle, has been flown on several missions. In addition, configurations of future NASA space structures, e.g. Space Station Freedom, are larger and more complex than current structures, making them more susceptible to damage as well as being more difficult to inspect. Consequently, a reliable structural damage detection capability is essential to maintain the flight safety of these structures. Visual inspections alone can not locate impending material failure (fatigue cracks, yielding); it can only observe post-failure situations. An alternative approach is to develop an inspection and monitoring system based on vibration characterization that assesses the integrity of structural and mechanical components. A methodology for detecting structural damage is presented. This methodology is based on utilizing modal test data in conjunction with a correlated analytical model of the structure to: (1) identify the structural dynamic characteristics (resonant frequencies and mode shapes) from measurements of ambient motions and/or force excitation; (2) calculate modal residual force vectors to identify the location of structural damage; and (3) conduct a weighted sensitivity analysis in order to assess the extent of mass and stiffness variations, where structural damage is characterized by stiffness reductions. The approach is unique from other existing approaches in that varying system mass and stiffness, mass center locations, the perturbation of both the natural frequencies and mode shapes, and statistical confidence factors for structural parameters and experimental instrumentation are all accounted for directly.

On the Constitutive Response Characterization for Composite Materials Via Data-Driven Design Optimization

Treesearch

John G. Michopoulos; John G. Hermanson; Athanasios lliopoulos; Samuel Lambrakos; Tomonari Furukawa

2011-01-01

In the present paper we focus on demonstrating the use of design optimization for the constitutive characterization of anisotropic material systems such as polymer matrix composites, with or without damage. All approaches are based on the availability of experimental data originating from mechatronic material testing systems that can expose specimens to...

Preliminary tests of vulnerability of typical aircraft electronics to lightning-induced voltages

NASA Technical Reports Server (NTRS)

Plumer, J. A.; Walko, L. C.

1974-01-01

Tests made on two pieces of typical aircraft electronics equipment to ascertain their vulnerability to simulated lightning-induced transient voltages representative of those which might occur in flight when the aircraft is struck by lightning were conducted. The test results demonstrated that such equipment can be interfered with or damaged by transient voltages as low as 21 volts peak. Greater voltages can cause failure of semiconductor components within the equipment. The results emphasize a need for establishment of coordinated system susceptibility and component vulnerability criteria to achieve lightning protection of aerospace electrical and electronic systems.

Using electrolyte leakage tests to determine lifting windows and detect tissue damage

Treesearch

Richard W. Tinus

2002-01-01

Physiological testing is rapidly coming into use as a means to determine the condition of nursery stock and predict how it will respond to treatment or use. One such test, the electrolyte leakage test, can be used to measure cold hardiness and detect tissue damage. The principle of this test is that when cell membranes are damaged, electrolytes leak out into the water...

First Generation Least Expensive Approach to Fission (FiGLEAF) Testing Results

NASA Technical Reports Server (NTRS)

VanDyke, Melissa; Houts, Mike; Pedersen, Kevin; Godfroy, Tom; Dickens, Ricky; Poston, David; Reid, Bob; Salvail. Pat; Ring, Peter; Schmidt, George R. (Technical Monitor)

2000-01-01

Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. Testing can be divided into two categories, non-nuclear tests and nuclear tests. Full power nuclear tests of space fission systems are expensive, time consuming, and of limited use, even in the best of programmatic environments. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. Non-nuclear tests are affordable and timely, and the cause of component and system failures can be quickly and accurately identified. MSFC is leading a Safe Affordable Fission Engine (SAFE) test series whose ultimate goal is the demonstration of a 300 kW flight configuration system using non-nuclear testing. This test series is carried out in collaboration with other NASA centers, other government agencies, industry, and universities. The paper describes the SAFE test series, which includes test article descriptions, test results and conclusions, and future test plans.

Shock and vibration tests of a SNAP-8 NaK pump

NASA Technical Reports Server (NTRS)

Stromquist, A. J.; Nelson, R. B.; Hibben, L.

1971-01-01

The pump used for reactor cooling in the SNAP 8 space power system was subjected to the expected vehicle launch vibration, and shock loading in accordance with the SNAP 8 environmental specification. Subsequent disassembly revealed damage to the thrust bearing pins, which should be redesigned and strengthened. The unit was operational, however, when run in a test loop after reassembly.

Resistance to Spodoptera frugiperda (Lepidoptera: Noctuidae) and Euxesta stigmatias (Diptera: Ulidiidae) in sweet corn derived from exogenous and endogenous genetic systems.

PubMed

Nuessly, G S; Scully, B T; Hentz, M G; Beiriger, R; Snook, M E; Widstrom, N W

2007-12-01

Field trials using Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) and Euxesta stigmatias Loew (Diptera: Ulidiidae) were conducted to evaluate resistance and potential damage interactions between these two primary corn, Zea mays L., pests against Lepidoptera-resistant corn varieties derived from both endogenous and exogenous sources. The endogenous source of resistance was maysin, a C-glycosyl flavone produced in high concentrations in varieties 'Zapalote Chico 2451' and 'Zapalote Chico sh2'. The exogenous resistance source was the Bacillus thuringiensis (Bt)11 gene that expresses Cry1A(b) insecticidal protein found in 'Attribute GSS-0966'. Damage by the two pests was compared among these resistant varieties and the susceptible 'Primetime'. Single-species tests determined that the Zapalote Chico varieties and GSS-0966 effectively reduced S. frugiperda larval damage compared with Primetime. E. stigmatias larval damage was less in the Zapalote Chico varieties than the other varieties in single-species tests. E. stigmatias damage was greater on S. frugiperda-infested versus S. frugiperda-excluded ears. Ears with S. frugiperda damage to husk, silk and kernels had greater E. stigmatias damage than ears with less S. frugiperda damage. Reversed phase high-performance liquid chromatography analysis of nonpollinated corn silk collected from field plots determined that isoorientin, maysin, and apimaysin plus 3'-methoxymaysin concentrations followed the order Zapalote Chico sh2 > Zapalote Chico 2451 > Attribute GSS-0966 = Primetime. Chlorogenic acid concentrations were greatest in Zapalote Chico 2451. The two high maysin Zapalote Chico varieties did as well against fall armyworm as the Bt-enhanced GSS-0966, and they outperformed GSS-0966 against E. stigmatias.

Rain droplet erosion mechanisms in transparent plastic materials

NASA Technical Reports Server (NTRS)

Schmitt, G. F., Jr.

1974-01-01

Tests were conducted to determine the damaging effects of rain erosion on optically transparent materials. The rotating arm test equipment used for the tests is described. Typical transparent materials such as those found in windshields, infrared windows, lasers, and television systems were tested. Nominal velocities of 400, 500, and 600 miles per hour and rainfall conditions of one inch per hour simulated rainfall were used in the tests. It was determined that an 80 percent reduction in laser transmittance can occur in plastics submitted to rain erosion. Significant results of the environmental tests are explained.

Compression of thick laminated composite beams with initial impact-like damage

NASA Technical Reports Server (NTRS)

Breivik, N. L.; Guerdal, Z.; Griffin, O. H., Jr.

1992-01-01

While the study of compression after impact of laminated composites has been under consideration for many years, the complexity of the damage initiated by low velocity impact has not lent itself to simple predictive models for compression strength. The damage modes due to non-penetrating, low velocity impact by large diameter objects can be simulated using quasi-static three-point bending. The resulting damage modes are less coupled and more easily characterized than actual impact damage modes. This study includes the compression testing of specimens with well documented initial damage states obtained from three-point bend testing. Compression strengths and failure modes were obtained for quasi-isotropic stacking sequences from 0.24 to 1.1 inches thick with both grouped and interspersed ply stacking. Initial damage prior to compression testing was divided into four classifications based on the type, extent, and location of the damage. These classifications are multiple through-thickness delaminations, isolated delamination, damage near the surface, and matrix cracks. Specimens from each classification were compared to specimens tested without initial damage in order to determine the effects of the initial damage on the final compression strength and failure modes. A finite element analysis was used to aid in the understanding and explanation of the experimental results.

An Overview of My 2004 Summer Internship

NASA Technical Reports Server (NTRS)

Hertert, Lucien

2004-01-01

This summer I have been working with the Non-destructive evaluation (NDE) group and NASA Glenn Research Center. As this is my second summer with the group, I was able to begin working as soon as I arrived. My first task was to develop a system to acquire an impedance analyzer. The basic setup of the system is as follows: a piezo- electric patch is attached to a sample, and a lead is attached to that patch. Another lead is attached directly to the sample, and the leads are connected to the impedance analyzer. The system then puts a voltage through the material over a range of frequencies, and the corresponding impedances are measured for each frequency. After data is collected, it can be compared to another data set, and through a series of calculations a damage parameter is produced. For the time being, we are using a correlation calculation to find the damage parameter. The hope for this project is that a baseline measurement can be taken, and then sometime later another measurement could be taken, and the damage parameter would determine how much damage had been done to the sample. To test this hypothesis, we took baseline data from a sample, and then sent it out to have a notch cut into it. When it was returned, we again took measurements on the sample, and the damage parameter was significantly lower. Another project that I have been working on pertains to the group's newly acquired acoustography system. This system creates a full field ultrasonic signal on one side of a sample, and an acousto-optic sensor is placed on the other side of the sample.

Current Simulation Methods in Military Systems Vulnerability Assessment

DTIC Science & Technology

1990-11-01

Weapons * 1990: JASON Review of the Army Approach to Vulnerability Testing Many of the suggestions and recommendations made by these committees concern...damage vectors. Ongoing work by the JASONs 29 is also targeted to developing statistical methods for LF-test/SQuASH-model comparisons in Space 2]. We...Technical Report BRL-TR-3113, June 1990. 28. L. Tonnessen, A. Fries , L. Starkey and A. Stein, Live Fire Testing in the Evaluation of the Vulnerability of

Smart acoustic emission system for wireless monitoring of concrete structures

NASA Astrophysics Data System (ADS)

Yoon, Dong-Jin; Kim, Young-Gil; Kim, Chi-Yeop; Seo, Dae-Cheol

2008-03-01

Acoustic emission (AE) has emerged as a powerful nondestructive tool to detect preexisting defects or to characterize failure mechanisms. Recently, this technique or this kind of principle, that is an in-situ monitoring of inside damages of materials or structures, becomes increasingly popular for monitoring the integrity of large structures. Concrete is one of the most widely used materials for constructing civil structures. In the nondestructive evaluation point of view, a lot of AE signals are generated in concrete structures under loading whether the crack development is active or not. Also, it was required to find a symptom of damage propagation before catastrophic failure through a continuous monitoring. Therefore we have done a practical study in this work to fabricate compact wireless AE sensor and to develop diagnosis system. First, this study aims to identify the differences of AE event patterns caused by both real damage sources and the other normal sources. Secondly, it was focused to develop acoustic emission diagnosis system for assessing the deterioration of concrete structures such as a bridge, dame, building slab, tunnel etc. Thirdly, the wireless acoustic emission system was developed for the application of monitoring concrete structures. From the previous laboratory study such as AE event patterns analysis under various loading conditions, we confirmed that AE analysis provided a promising approach for estimating the condition of damage and distress in concrete structures. In this work, the algorithm for determining the damage status of concrete structures was developed and typical criteria for decision making was also suggested. For the future application of wireless monitoring, a low energy consumable, compact, and robust wireless acoustic emission sensor module was developed and applied to the concrete beam for performance test. Finally, based on the self-developed diagnosis algorithm and compact wireless AE sensor, new AE system for practical AE diagnosis was demonstrated for assessing the conditions of damage and distress in concrete structures.

Method of recognizing the high-speed railway noise barriers based on the distance image

NASA Astrophysics Data System (ADS)

Ma, Le; Shao, Shuangyun; Feng, Qibo; Liu, Bingqian; Kim, Chol Ryong

2016-10-01

The damage or lack of the noise barriers is one of the important hidden troubles endangering the safety of high-speed railway. In order to obtain the vibration information of the noise barriers, the online detection systems based on laser vision were proposed. The systems capture images of the laser stripe on the noise barriers and export data files containing distance information between the detection systems on the train and the noise barriers. The vibration status or damage of the noise barriers can be estimated depending on the distance information. In this paper, we focused on the method of separating the area of noise barrier from the background automatically. The test results showed that the proposed method is in good efficiency and accuracy.

Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

NASA Astrophysics Data System (ADS)

Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

2017-01-01

Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s-1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling.

PubMed

Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

2017-01-28

Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 10 3 to 10 4  s -1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. © 2016 The Author(s).

Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

PubMed Central

Erzar, Benjamin

2017-01-01

Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s−1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual–Forquin–Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’. PMID:27956504

Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP) Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

PubMed Central

Gao, Hang; Wang, Xu; Guo, Dongming; Liu, Ziyuan

2018-01-01

Laser induced damage threshold (LIDT) is an important optical indicator for nonlinear Potassium Dihydrogen Phosphate (KDP) crystal used in high power laser systems. In this study, KDP optical crystals are initially machined with single point diamond turning (SPDT), followed by water dissolution ultra-precision polishing (WDUP) and then tested with 355 nm nanosecond pulsed-lasers. Power spectral density (PSD) analysis shows that WDUP process eliminates the laser-detrimental spatial frequencies band of micro-waviness on SPDT machined surface and consequently decreases its modulation effect on the laser beams. The laser test results show that LIDT of WDUP machined crystal improves and its stability has a significant increase by 72.1% compared with that of SPDT. Moreover, a subsequent ultrasonic assisted solvent cleaning process is suggested to have a positive effect on the laser performance of machined KDP crystal. Damage crater investigation indicates that the damage morphologies exhibit highly thermal explosion features of melted cores and brittle fractures of periphery material, which can be described with the classic thermal explosion model. The comparison result demonstrates that damage mechanisms for SPDT and WDUP machined crystal are the same and WDUP process reveals the real bulk laser resistance of KDP optical crystal by removing the micro-waviness and subsurface damage on SPDT machined surface. This improvement of WDUP method makes the LIDT more accurate and will be beneficial to the laser performance of KDP crystal. PMID:29534032

Dysfunction of the Human Mirror Neuron System in Ideomotor Apraxia: Evidence from Mu Suppression.

PubMed

Frenkel-Toledo, Silvi; Liebermann, Dario G; Bentin, Shlomo; Soroker, Nachum

2016-06-01

Stroke patients with ideomotor apraxia (IMA) have difficulties controlling voluntary motor actions, as clearly seen when asked to imitate simple gestures performed by the examiner. Despite extensive research, the neurophysiological mechanisms underlying failure to imitate gestures in IMA remain controversial. The aim of the current study was to explore the relationship between imitation failure in IMA and mirror neuron system (MNS) functioning. Mirror neurons were found to play a crucial role in movement imitation and in imitation-based motor learning. Their recruitment during movement observation and execution is signaled in EEG recordings by suppression of the lower (8-10 Hz) mu range. We examined the modulation of EEG in this range in stroke patients with left (n = 21) and right (n = 15) hemisphere damage during observation of video clips showing different manual movements. IMA severity was assessed by the DeRenzi standardized diagnostic test. Results showed that failure to imitate observed manual movements correlated with diminished mu suppression in patients with damage to the right inferior parietal lobule and in patients with damage to the right inferior frontal gyrus pars opercularis-areas where major components of the human MNS are assumed to reside. Voxel-based lesion symptom mapping revealed a significant impact on imitation capacity for the left inferior and superior parietal lobules and the left post central gyrus. Both left and right hemisphere damages were associated with imitation failure typical of IMA, yet a clear demonstration of relationship to the MNS was obtained only in the right hemisphere damage group. Suppression of the 8-10 Hz range was stronger in central compared with occipital sites, pointing to a dominant implication of mu rather than alpha rhythms. However, the suppression correlated with De Renzi's apraxia test scores not only in central but also in occipital sites, suggesting a multifactorial mechanism for IMA, with a possible impact for deranged visual attention (alpha suppression) beyond the effect of MNS damage (mu suppression).

Comet Assay: A Method to Evaluate Genotoxicity of Nano-Drug Delivery System

PubMed Central

Vandghanooni, Somayeh; Eskandani, Morteza

2011-01-01

Introduction Drug delivery systems could induce cellular toxicity as side effect of nanomaterials. The mechanism of toxicity usually involves DNA damage. The comet assay or single cell gel electrophoresis (SCGE) is a sensitive method for detecting strand damages in the DNA of a cell with applications in genotoxicity testing and molecular epidemiology as well as fundamental research in DNA damage and repair. Methods In the current study, we reviewed recent drug delivery researches related to SCGE. Results We found that one preference for choosing the assay is that comet images may result from apoptosis-mediated nuclear fragmentation. This method has been widely used over the last decade in several different areas. Overall cells, such as cultured cells are embedded in agarose on a microscope slide, lysed with detergent, and treated with high salt. Nucleoids are supercoiled DNA form. When the slide is faced to alkaline electrophoresis any breakages present in the DNA cause the supercoiling to relax locally and loops of DNA extend toward the anode as a ‘‘comet tail’’. Conclusion This article provides a relatively comprehensive review upon potentiality of the comet assay for assessment of DNA damage and accordingly it can be used as an informative platform in genotoxicity studies of drug delivery systems. PMID:23678412

In-process, non-destructive multimodal dynamic testing of high-speed composite rotors

NASA Astrophysics Data System (ADS)

Kuschmierz, Robert; Filippatos, Angelos; Langkamp, Albert; Hufenbach, Werner; Czarske, Jürgern W.; Fischer, Andreas

2014-03-01

Fibre reinforced plastic (FRP) rotors are lightweight and offer great perspectives in high-speed applications such as turbo machinery. Currently, novel rotor structures and materials are investigated for the purpose of increasing machine efficiency, lifetime and loading limits. Due to complex rotor structures, high anisotropy and non-linear behavior of FRP under dynamic loads, an in-process measurement system is necessary to monitor and to investigate the evolution of damages under real operation conditions. A non-invasive, optical laser Doppler distance sensor measurement system is applied to determine the biaxial deformation of a bladed FRP rotor with micron uncertainty as well as the tangential blade vibrations at surface speeds above 300 m/s. The laser Doppler distance sensor is applicable under vacuum conditions. Measurements at varying loading conditions are used to determine elastic and plastic deformations. Furthermore they allow to determine hysteresis, fatigue, Eigenfrequency shifts and loading limits. The deformation measurements show a highly anisotropic and nonlinear behavior and offer a deeper understanding of the damage evolution in FRP rotors. The experimental results are used to validate and to calibrate a simulation model of the deformation. The simulation combines finite element analysis and a damage mechanics model. The combination of simulation and measurement system enables the monitoring and prediction of damage evolutions of FRP rotors in process.

Shake Test Results and Dynamic Calibration Efforts for the Large Rotor Test Apparatus

NASA Technical Reports Server (NTRS)

Russell, Carl R.

2014-01-01

A shake test of the Large Rotor Test Apparatus (LRTA) was performed in an effort to enhance NASAscapability to measure dynamic hub loads for full-scale rotor tests. This paper documents the results of theshake test as well as efforts to calibrate the LRTA balance system to measure dynamic loads.Dynamic rotor loads are the primary source of vibration in helicopters and other rotorcraft, leading topassenger discomfort and damage due to fatigue of aircraft components. There are novel methods beingdeveloped to reduce rotor vibrations, but measuring the actual vibration reductions on full-scale rotorsremains a challenge. In order to measure rotor forces on the LRTA, a balance system in the non-rotatingframe is used. The forces at the balance can then be translated to the hub reference frame to measure therotor loads. Because the LRTA has its own dynamic response, the balance system must be calibrated toinclude the natural frequencies of the test rig.

Effector T-cells are expanded in systemic lupus erythematosus patients with high disease activity and damage indexes.

PubMed

Piantoni, S; Regola, F; Zanola, A; Andreoli, L; Dall'Ara, F; Tincani, A; Airo', P

2018-01-01

Background and objectives T-cell activation may be one of the pathogenic mechanisms of systemic lupus erythematosus (SLE). After repeated antigenic stimulation, T-cells undergo different modifications, leading to the differentiation into effector memory T-cells (CCR7-CD45RA-) and terminally differentiated effector memory (TDEM) T-cells (CCR7-CD45RA+). Similarly, down-modulation of CD28 may lead to the expansion of the CD28- T-cells, a subpopulation with peculiar effector activities. The aim of this study was the characterization of T-cell phenotype in a cohort of patients with SLE according to disease activity and damage index. Materials and methods Phenotypic analysis of peripheral blood T lymphocytes of 51 SLE patients and 21 healthy controls was done by flow-cytometry. SLE disease activity was evaluated by SLE Disease Activity Index-2000 (SLEDAI-2K) and damage by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology damage index (SDI). The variations between different groups were evaluated by Mann-Whitney test. Bonferroni correction was applied to adjust for multiple comparisons ( p adj ). Spearman rank test was used to evaluate the correlations between quantitative variables. Results CD4+ lymphopenia was found among SLE patients. Patients showed a trend for a higher percentage of TDEM among the CD4+ T-cell subpopulation in comparison with healthy controls ( p = .04). SLE patients were divided into two groups according to disease activity: patients with SLEDAI-2K ≥ 6 ( n = 13) had a higher percentage of circulating CD4+ T-cells with CD28- phenotype ( p adj  = .005) as well as those with an effector memory ( p adj  = .004) and TDEM ( p adj  = .002) phenotype and a trend of decrease of regulatory T-cells (TREGs) ( p = .02), in comparison with patients with low disease activity ( n = 38). Patients with damage (SDI ≥ 1) tended to show an expansion of TDEM among CD4+ T-cells as compared with patients with no damage ( p = .01). In SLE patients an inverse correlation was found between the percentages of TREGs and those of TDEM ( p < .01) or CD4 + CD28- ( p < .01) T-cells. Conclusions CD4+ T-cell subpopulations displaying phenotype characteristics of effector lymphocytes are proportionally expanded in patients with active SLE and a higher damage index. These findings may suggest a role of effector T-cells in the pathogenesis of the disease and in the mechanisms of damage in SLE.

Aging, Loss-of-Coolant Accident (LOCA), and high potential testing of damaged cables

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vigil, R.A.; Jacobus, M.J.

1994-04-01

Experiments were conducted to assess the effects of high potential testing of cables and to assess the survivability of aged and damaged cables under Loss-of-Coolant Accident (LOCA) conditions. High potential testing at 240 Vdc/mil on undamaged cables suggested that no damage was incurred on the selected virgin cables. During aging and LOCA testing, Okonite ethylene propylene rubber (EPR) cables with a bonded jacket experienced unexpected failures. The failures appear to be primarily related to the level of thermal aging and the presence of a bonded jacket that ages more rapidly than the insulation. For Brand Rex crosslinked polyolefin (XLPO) cables,more » the results suggest that 7 mils of insulation remaining should give the cables a high probability of surviving accident exposure following aging. The voltage necessary to detect when 7 mils of insulation remain on unaged Brand Rex cables is approximately 35 kVdc. This voltage level would almost certainly be unacceptable to a utility for use as a damage assessment tool. However, additional tests indicated that a 35 kvdc voltage application would not damage virgin Brand Rex cables when tested in water. Although two damaged Rockbestos silicone rubber cables also failed during the accident test, no correlation between failures and level of damage was apparent.« less

Dimethyl Sulfoxide (DMSO) Produces Widespread Apoptosis in the Developing Central Nervous System

PubMed Central

Hanslick, Jennifer L.; Lau, Karen; Noguchi, Kevin K.; Olney, John W.; Zorumski, Charles F.; Mennerick, Steven; Farber, Nuri B.

2009-01-01

Dimethyl sulfoxide (DMSO) is a solvent that is routinely used as a cryopreservative in allogous bone marrow and organ transplantion. We exposed C57Bl/6 mice of varying postnatal ages (P0–P30) to DMSO in order to study whether DMSO could produce apoptotic degeneration in the developing CNS. DMSO produced widespread apoptosis in the developing mouse brain at all ages tested. Damage was greatest at P7. Significant elevations above the background rate of apoptosis occurred at the lowest dose tested, 0.3 ml/kg. In an in vitro rat hippocampal culture preparation, DMSO produced neuronal loss at concentrations of 0.5% and 1.0%. The ability of DMSO to damage neurons in dissociated cultures indicates that the toxicity likely results from a direct cellular effect. Because children, who undergo bone marrow transplantation, are routinely exposed to DMSO at doses higher than 0.3 ml/kg, there is concern that DMSO might be producing similar damage in human children. PMID:19100327

The Experiment and Numerical Simulation of Composite Countersunk-head Fasteners Pull-through Mechanical Behavior

NASA Astrophysics Data System (ADS)

Mu, Junwu; Guan, Zhidong; Bian, Tianya; Li, Zengshan; Wang, Kailun; Liu, Sui

2014-10-01

Fasteners made of the anisotropic carbon/carbon (C/C) composite material have been developed for joining C/C composite material components in the high-temperature environment. The fastener specimens are fabricated from the C/C composites which are made from laminated carbon cloths with Z-direction carbon fibers being punctured as perform. Densification process cycles such as the thermal gradient chemical vapor infiltration (CVI) technology were repeated to obtain high density C/C composites fastener. The fasteners were machined parallel to the carbon cloths (X-Y direction). A method was proposed to test pull-through mechanical behavior of the countersunk-head C/C composite material fasteners. The damage morphologies of the fasteners were observed through the charge coupled device (CCD) and the scanning electron microscope (SEM). The internal micro-structure were observed through the high-resolution Mirco-CT systems. Finally, an excellent simulation of the C/C composite countersunk-head fasteners were performed with the finite element method (FEM), in which the damage evolution model of the fastener was established based on continuum damage mechanics. The simulation is correspond well with the test result . The damage evolution process and the relation between the countersunk depth and the ultimate load was investigated.

Health and immunology study following exposure to toxigenic fungi (Stachybotrys chartarum) in a water-damaged office environment.

PubMed

Johanning, E; Biagini, R; Hull, D; Morey, P; Jarvis, B; Landsbergis, P

1996-01-01

There is growing concern about adverse health effects of fungal bio-aerosols on occupants of water-damaged buildings. Accidental, occupational exposure in a nonagricultural setting has not been investigated using modern immunological laboratory tests. The objective of this study was to evaluate the health status of office workers after exposure to fungal bio-aerosols, especially Stachybotrys chartarum (atra) (S. chartarum) and its toxigenic metabolites (satratoxins), and to study laboratory parameters or biomarkers related to allergic or toxic human health effects. Exposure characterization and quantification were performed using microscopic, culture, and chemical techniques. The study population (n = 53) consisted of 39 female and 14 male employees (mean age 34.8 years) who had worked for a mean of 3.1 years at a problem office site; a control group comprised 21 persons (mean age 37.5 years) without contact with the problem office site. Health complaints were surveyed with a 187-item standardized questionnaire. A comprehensive test battery was used to study the red and white blood cell system, serum chemistry, immunology/antibodies, lymphocyte enumeration and function. Widespread fungal contamination of water-damaged, primarily cellulose material with S. chartarum was found. S. chartarum produced a macrocyclic trichothecene, satratoxin H, and spirocyclic lactones. Strong associations with exposure indicators and significant differences between employees (n = 53) and controls (n = 21) were found for lower respiratory system symptoms, dermatological symptoms, eye symptoms, constitutional symptoms, chronic fatigue symptoms and several enumeration and function laboratory tests, mainly of the white blood cell system. The proportion of mature T-lymphocyte cells (CD3%) was lower in employees than in controls, and regression analyses showed significantly lower CD3% among those reporting a history of upper respiratory infections. Specific S. chartarum antibody tests (IgE and IgG) showed small differences (NS). It is concluded that prolonged and intense exposure to toxigenic S. chartarum and other atypical fungi was associated with reported disorders of the respiratory and central nervous systems, reported disorders of the mucous membranes and a few parameters pertaining to the cellular and humoral immune system, suggesting a possible immune competency dysfunction.

Damage identification in highway bridges using distribution factors

NASA Astrophysics Data System (ADS)

Gangone, Michael V.; Whelan, Matthew J.

2017-04-01

The U.S. infrastructure system is well behind the needs of the 21st century and in dire need of improvements. The American Society of Civil Engineers (ASCE) graded America's Infrastructure as a "D+" in its recent 2013 Report Card. Bridges are a major component of the infrastructure system and were awarded a "C+". Nearly 25 percent of the nation's bridges are categorized as deficient by the Federal Highway Administration (FWHA). Most bridges were designed with an expected service life of roughly 50 years and today the average age of a bridge is 42 years. Finding alternative methods of condition assessment which captures the true performance of the bridge is of high importance. This paper discusses the monitoring of two multi-girder/stringer bridges at different ages of service life. Normal strain measurements were used to calculate the load distribution factor at the midspan of the bridge under controlled loading conditions. Controlled progressive damage was implemented to one of the superstructures to determine if the damage could be detected using the distribution factor. An uncertainty analysis, based on the accuracy and precision of the normal strain measurement, was undertaken to determine how effective it is to use the distribution factor measurement as a damage indicator. The analysis indicates that this load testing parameter may be an effective measure for detecting damage.

Application of fault detection techniques to spiral bevel gear fatigue data

NASA Technical Reports Server (NTRS)

Zakrajsek, James J.; Handschuh, Robert F.; Decker, Harry J.

1994-01-01

Results of applying a variety of gear fault detection techniques to experimental data is presented. A spiral bevel gear fatigue rig was used to initiate a naturally occurring fault and propagate the fault to a near catastrophic condition of the test gear pair. The spiral bevel gear fatigue test lasted a total of eighteen hours. At approximately five and a half hours into the test, the rig was stopped to inspect the gears for damage, at which time a small pit was identified on a tooth of the pinion. The test was then stopped an additional seven times throughout the rest of the test in order to observe and document the growth and propagation of the fault. The test was ended when a major portion of a pinion tooth broke off. A personal computer based diagnostic system was developed to obtain vibration data from the test rig, and to perform the on-line gear condition monitoring. A number of gear fault detection techniques, which use the signal average in both the time and frequency domain, were applied to the experimental data. Among the techniques investigated, two of the recently developed methods appeared to be the first to react to the start of tooth damage. These methods continued to react to the damage as the pitted area grew in size to cover approximately 75% of the face width of the pinion tooth. In addition, information gathered from one of the newer methods was found to be a good accumulative damage indicator. An unexpected result of the test showed that although the speed of the rig was held to within a band of six percent of the nominal speed, and the load within eighteen percent of nominal, the resulting speed and load variations substantially affected the performance of all of the gear fault detection techniques investigated.

Acute And Subchronic Toxicity Studies Of SNEDDS (Self Nanoemulsifying Drug Delivery Systems) From Ethyl Acetate Extract Of Bay Leaf (Eugenia polyantha W.) with Virgin Coconut Oil As Oil Phase

NASA Astrophysics Data System (ADS)

Prihapsara, F.; Alamsyah, R. I.; Widiyani, T.; Artanti, A. N.

2018-03-01

Bay leaf (Eugenia polyantha) is widely used as an alternative therapy for diabetic and hypercholesterol. However, the administration of the extract has a low oral bioavailability, therefore it is prepared by Self Nanoemulsifying Drug Delivery Systems (SNEDDS) ethyl acetate extract of bay leaf. Therefore, acute and subchronic toxicity test is required. The toxicity test performed was an experimental study, including acute and subchronic toxicity tests. Animal experiments were used using Wistar strain rats. Acute toxicity test using 5 groups (n=5) consisted of 1 control group and 4 groups of SNEDDS dose with 48 mg/kgBW 240 mg/kg, 1200 mg/kg, and 6000 mg/kg, while for subchronic toxicity test with 1 group control and 3 groups of doses of SNEDDS with dose group variation 91.75 mg/kgBW, 183.5 mg/kg, and 367 mg/kg. Duration of observation at acute toxicity test for 14 days while for subcronic toxicity test for 28 days with continuous SNEDDS dosage. The results of the acute toxicity test showed toxic symptoms and obtained median lethal dose (LD50) values from SNEDDS from ethyl acetate extract of bay leaf 1409.30 mg/kgBW belonging to slightly toxic category. Subchronic toxicity studies show that the test drug has minor damage in liver and kidneys and moderate damage in pancreas.

Application of laser scanning technique in earthquake protection of Istanbul's historical heritage buildings

NASA Astrophysics Data System (ADS)

Çaktı, Eser; Ercan, Tülay; Dar, Emrullah

2017-04-01

Istanbul's vast historical and cultural heritage is under constant threat of earthquakes. Historical records report repeated damages to the city's landmark buildings. Our efforts towards earthquake protection of several buildings in Istanbul involve earthquake monitoring via structural health monitoring systems, linear and non-linear structural modelling and analysis in search of past and future earthquake performance, shake-table testing of scaled models and non-destructive testing. More recently we have been using laser technology in monitoring structural deformations and damage in five monumental buildings which are Hagia Sophia Museum and Fatih, Sultanahmet, Süleymaniye and Mihrimah Sultan Mosques. This presentation is about these efforts with special emphasis on the use of laser scanning in monitoring of edifices.

Qualification and Testing of Quantum Cascade Lasers for Harsh Environments

NASA Astrophysics Data System (ADS)

Brauer, C. S.; Myers, T. L.; Cannon, B. D.; Anderson, C. G.; Crowther, B. G.; Hansen, S.

2014-12-01

Quantum cascade lasers (QCLs) offer the potential for the development of novel, laser-based instruments for both terrestrial and space applications. In order to withstand harsh conditions encountered in these environments, lasers must be robust, and rigorous testing is required before new systems can be utilized. A particular concern for space applications is the potential damage to laser performance caused by radiation exposure. While the effects of radiation exposure in diode lasers have been studied extensively, the effect on QCLs, which are fundamentally different from diode lasers, is not well known. We thus present work to quantify the performance of QCLs after exposure to moderate and high levels of radiation from different sources, including protons and gamma rays, to determine the effects of radiation damage.

Phase 1 space fission propulsion system testing and development progress

NASA Astrophysics Data System (ADS)

van Dyke, Melissa; Houts, Mike; Pedersen, Kevin; Godfroy, Tom; Dickens, Ricky; Poston, David; Reid, Bob; Salvail, Pat; Ring, Peter

2001-02-01

Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. Testing can be divided into two categories, non-nuclear tests and nuclear tests. Full power nuclear tests of space fission systems are expensive, time consuming, and of limited use, even in the best of programmatic environments. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. Non-nuclear tests are affordable and timely, and the cause of component and system failures can be quickly and accurately identified, MSFC is leading a Safe Affordable Fission Engine (SAFE) test series whose ultimate goal is the demonstration of a 300 kW flight configuration system using non-nuclear testing. This test series is carried out in collaboration with other NASA centers, other government agencies, industry, and universities. If SAFE-related nuclear tests are desired, they will have a high probability of success and can be performed at existing nuclear facilities. The paper describes the SAFE non-nuclear test series, which includes test article descriptions, test results and conclusions, and future test plans. .

Rotordynamic Analysis and Feasibility Study of a Disk Spin Test Facility for Rotor Health Monitoring

NASA Technical Reports Server (NTRS)

Sawicki, Jerzy T.

2005-01-01

Recently, National Aeronautics and Space Administration (NASA) initiated a program to achieve the significant improvement in aviation safety. One of the technical challenges is the design and development of accelerated experiments that mimic critical damage cases encountered in engine components. The Nondestructive Evaluation (NDE) Group at the NASA Glenn Research Center (GRC) is currently addressing the goal concerning propulsion health management and the development of propulsion system specific technologies intended to detect potential failures prior to catastrophe. For this goal the unique disk spin simulation system was assembled at NASA GRC, which allows testing of rotors with the spinning speeds up to 10K RPM, and at the elevated temperature environment reaching 540 C (1000 F). It is anticipated that the facility can be employed for detection of Low Cycle Fatigue disk cracking and further High Cycle Fatigue blade vibration. The controlled crack growth studies at room and elevated temperatures can be conducted on the turbine wheels, and various NDE techniques can be integrated and assessed as in-situ damage monitoring tools. Critical rotating parts in advanced gas turbine engines such as turbine disks frequently operate at high temperature and stress for long periods of time. The integrity of these parts must be proven by non-destructive evaluation (NDE) during various machining steps ranging from forging blank to finished shape, and also during the systematic overhaul inspections. Conventional NDE methods, however, have unacceptable limits. Some of these techniques are time-consuming and inconvenient for service aircraft testing. Almost all of these techniques require that the vicinity of the damage is known in advance. These experimental techniques can provide only local information and no indication of the structural strength at a component and/or system level. The shortcomings of currently available NDE methods lead to the requirement of new damage detection techniques that can provide global information on the rotating components/system, and, in addition, they do not require direct human access to the operating system. During this period of research considerable effort was directed towards the further development of experimental facility and development of the vibration-based crack detection methodology for rotating disks and shafts. A collection of papers and reports were written to describe the results of this work. The attached captures that effort and represents the research output during the grant period.

Launch Pad 39 Hail Monitor Array System

NASA Technical Reports Server (NTRS)

2008-01-01

Weather conditions at Kennedy Space Center are extremely dynamic, and they greatly affect the safety of the Space Shuttles sitting on the launch pads. For example, on May 13, 1999, the foam on the External Tank (ET) of STS-96 was significantly damaged by hail at the launch pad, requiring rollback to the Vehicle Assembly Building. The loss of ET foam on STS-114 in 2005 intensified interest in monitoring and measuring damage to ET foam, especially from hail. But hail can be difficult to detect and monitor because it is often localized and obscured by heavy rain. Furthermore, the hot Florida climate usually melts the hail even before the rainfall subsides. In response, the hail monitor array (HMA) system, a joint effort of the Applied Physics Laboratory operated by NASA and ASRC Aerospace at KSC, was deployed for operational testing in the fall of 2006. Volunteers from the Community Collaborative Rain, Hail, and Snow (CoCoRaHS) network, in conjunction with Colorado State University, continue to test duplicate hail monitor systems deployed in the high plains of Colorado.

The ODTX System for the Study of Thermal Sensitivity and Thermal Explosion Violence of Energetic Materials

NASA Astrophysics Data System (ADS)

Hsu, Peter; Hust, Gary; Reynolds, John; Springer, Keo; Fried, Larry; Maienschein, Jon

2013-06-01

Incidents caused by fire and combat operations in battlefields can expose energetic materials to unexpected heat that may cause thermal explosion, structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (<100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory can measure times to explosion, threshold thermal explosion temperature, and determine kinetic parameters of energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. In this paper, we will present some recent ODTX experimental data and compare thermal explosion violence of different energetic materials. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Value engineering and cost effectiveness of various fiber reinforced polymer (FRP) repair systems.

DOT National Transportation Integrated Search

2006-06-01

Seventeen 40 year old C-Channel type prestressed concrete bridge girders and one impact damaged AASHTO : Type II prestressed concrete girder were tested under static and fatigue loading to determine the cost-effectiveness : and value engineering aspe...

Real-Time Condition Monitoring and Fault Diagnosis of Gear Train Systems Using Instantaneous Angular Speed (IAS) Analysis

NASA Astrophysics Data System (ADS)

Sait, Abdulrahman S.

This dissertation presents a reliable technique for monitoring the condition of rotating machinery by applying instantaneous angular speed (IAS) analysis. A new analysis of the effects of changes in the orientation of the line of action and the pressure angle of the resultant force acting on gear tooth profile of spur gear under different levels of tooth damage is utilized. The analysis and experimental work discussed in this dissertation provide a clear understating of the effects of damage on the IAS by analyzing the digital signals output of rotary incremental optical encoder. A comprehensive literature review of state of the knowledge in condition monitoring and fault diagnostics of rotating machinery, including gearbox system is presented. Progress and new developments over the past 30 years in failure detection techniques of rotating machinery including engines, bearings and gearboxes are thoroughly reviewed. This work is limited to the analysis of a gear train system with gear tooth surface faults utilizing angular motion analysis technique. Angular motion data were acquired using an incremental optical encoder. Results are compared to a vibration-based technique. The vibration data were acquired using an accelerometer. The signals were obtained and analyzed in the phase domains using signal averaging to determine the existence and position of faults on the gear train system. Forces between the mating teeth surfaces are analyzed and simulated to validate the influence of the presence of damage on the pressure angle and the IAS. National Instruments hardware is used and NI LabVIEW software code is developed for real-time, online condition monitoring systems and fault detection techniques. The sensitivity of optical encoders to gear fault detection techniques is experimentally investigated by applying IAS analysis under different gear damage levels and different operating conditions. A reliable methodology is developed for selecting appropriate testing/operating conditions of a rotating system to generate an alarm system for damage detection.

Emotional memory and perception in temporal lobectomy patients with amygdala damage.

PubMed

Brierley, B; Medford, N; Shaw, P; David, A S

2004-04-01

The human amygdala is implicated in the formation of emotional memories and the perception of emotional stimuli--particularly fear--across various modalities. To discern the extent to which these functions are related. 28 patients who had anterior temporal lobectomy (13 left and 15 right) for intractable epilepsy were recruited. Structural magnetic resonance imaging showed that three of them had atrophy of their remaining amygdala. All participants were given tests of affect perception from facial and vocal expressions and of emotional memory, using a standard narrative test and a novel test of word recognition. The results were standardised against matched healthy controls. Performance on all emotion tasks in patients with unilateral lobectomy ranged from unimpaired to moderately impaired. Perception of emotions in faces and voices was (with exceptions) significantly positively correlated, indicating multimodal emotional processing. However, there was no correlation between the subjects' performance on tests of emotional memory and perception. Several subjects showed strong emotional memory enhancement but poor fear perception. Patients with bilateral amygdala damage had greater impairment, particularly on the narrative test of emotional memory, one showing superior fear recognition but absent memory enhancement. Bilateral amygdala damage is particularly disruptive of emotional memory processes in comparison with unilateral temporal lobectomy. On a cognitive level, the pattern of results implies that perception of emotional expressions and emotional memory are supported by separate processing systems or streams.

Impact testing of textile composite materials

NASA Technical Reports Server (NTRS)

Portanova, Marc

1995-01-01

The objectives of this report were to evaluate the impact damage resistance and damage tolerance of a variety of textile composite materials. Static indentation and impact tests were performed on the stitched and unstitched uniweave composites constructed from AS4/3501-6 Carbon/Epoxy with a fiberglass yarn woven in to hold the fibers together while being stitched. Compression and tension were measured after the tests to determine the damage resistance, residual strength and the damage tolerance of the specimens.

Research on the time-temperature-damage superposition principle of NEPE propellant

NASA Astrophysics Data System (ADS)

Han, Long; Chen, Xiong; Xu, Jin-sheng; Zhou, Chang-sheng; Yu, Jia-quan

2015-11-01

To describe the relaxation behavior of NEPE (Nitrate Ester Plasticized Polyether) propellant, we analyzed the equivalent relationships between time, temperature, and damage. We conducted a series of uniaxial tensile tests and employed a cumulative damage model to calculate the damage values for relaxation tests at different strain levels. The damage evolution curve of the tensile test at 100 mm/min was obtained through numerical analysis. Relaxation tests were conducted over a range of temperature and strain levels, and the equivalent relationship between time, temperature, and damage was deduced based on free volume theory. The equivalent relationship was then used to generate predictions of the long-term relaxation behavior of the NEPE propellant. Subsequently, the equivalent relationship between time and damage was introduced into the linear viscoelastic model to establish a nonlinear model which is capable of describing the mechanical behavior of composite propellants under a uniaxial tensile load. The comparison between model prediction and experimental data shows that the presented model provides a reliable forecast of the mechanical behavior of propellants.

Integrated health management and control of complex dynamical systems

NASA Astrophysics Data System (ADS)

Tolani, Devendra K.

2005-11-01

A comprehensive control and health management strategy for human-engineered complex dynamical systems is formulated for achieving high performance and reliability over a wide range of operation. Results from diverse research areas such as Probabilistic Robust Control (PRC), Damage Mitigating/Life Extending Control (DMC), Discrete Event Supervisory (DES) Control, Symbolic Time Series Analysis (STSA) and Health and Usage Monitoring System (HUMS) have been employed to achieve this goal. Continuous-domain control modules at the lower level are synthesized by PRC and DMC theories, whereas the upper-level supervision is based on DES control theory. In the PRC approach, by allowing different levels of risk under different flight conditions, the control system can achieve the desired trade off between stability robustness and nominal performance. In the DMC approach, component damage is incorporated in the control law to reduce the damage rate for enhanced structural durability. The DES controller monitors the system performance and, based on the mission requirements (e.g., performance metrics and level of damage mitigation), switches among various lower-level controllers. The core idea is to design a framework where the DES controller at the upper-level, mimics human intelligence and makes appropriate decisions to satisfy mission requirements, enhance system performance and structural durability. Recently developed tools in STSA have been used for anomaly detection and failure prognosis. The DMC deals with the usage monitoring or operational control part of health management, where as the issue of health monitoring is addressed by the anomaly detection tools. The proposed decision and control architecture has been validated on two test-beds, simulating the operations of rotorcraft dynamics and aircraft propulsion.

Characterization of explosive devices in luggage: Initial results of the ART-IIC test series

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akerman, M.A.; Kass, M.D.; Clough, B.T.

1993-12-31

Characteristics and damage associated with exploded luggage aboard aircraft are presented in this paper. Plastic-sided suitcases filled with typical travel possessions were exploded inside the fuselage of decomissioned B-52 aircraft. Multilayered shield panels, mounted to one side of the fuselage, served to protect the aircraft body and flight system components from both the blast wave and exploded fragments. The resulting damage produced by the explosions was characterized and the absorbing characteristics of the shielding were evaluated. In addition, the energy of the luggage fragments was estimated.

Using chaotic forcing to detect damage in a structure

USGS Publications Warehouse

Moniz, L.; Nichols, J.; Trickey, S.; Seaver, M.; Pecora, D.; Pecora, L.

2005-01-01

In this work we develop a numerical test for Holder continuity and apply it and another test for continuity to the difficult problem of detecting damage in structures. We subject a thin metal plate with incremental damage to the plate changes, its filtering properties, and therefore the phase space trajectories of the response chaotic excitation of various bandwidths. Damage to the plate changes its filtering properties and therefore the phase space of the response. Because the data are multivariate (the plate is instrumented with multiple sensors) we use a singular value decomposition of the set of the output time series to reduce the embedding dimension of the response time series. We use two geometric tests to compare an attractor reconstructed from data from an undamaged structure to that reconstructed from data from a damaged structure. These two tests translate to testing for both generalized and differentiable synchronization between responses. We show loss of synchronization of responses with damage to the structure. ?? 2005 American Institute of Physics.

Using chaotic forcing to detect damage in a structure.

USGS Publications Warehouse

Moniz, L.; Nichols, J.; Trickey, S.; Seaver, M.; Pecora, D.; Pecora, L.

2005-01-01

In this work we develop a numerical test for Holder continuity and apply it and another test for continuity to the difficult problem of detecting damage in structures. We subject a thin metal plate with incremental damage to the plate changes, its filtering properties, and therefore the phase space trajectories of the response chaotic excitation of various bandwidths. Damage to the plate changes its filtering properties and therefore the phase space of the response. Because the data are multivariate (the plate is instrumented with multiple sensors) we use a singular value decomposition of the set of the output time series to reduce the embedding dimension of the response time series. We use two geometric tests to compare an attractor reconstructed from data from an undamaged structure to that reconstructed from data from a damaged structure. These two tests translate to testing for both generalized and differentiable synchronization between responses. We show loss of synchronization of responses with damage to the structure.

Application of damage tolerance methodology in certification of the Piaggio P-180 Avanti

NASA Technical Reports Server (NTRS)

Johnson, Jerry

1992-01-01

The Piaggio P-180 Avanti, a twin pusher-prop engine nine-passenger business aircraft was certified in 1990, to the requirements of FAR Part 23 and Associated Special Conditions for Composite Structure. Certification included the application of a damage tolerant methodology to the design of the composite forward wing and empennage (vertical fin, horizontal stabilizer, tailcone, and rudder) structure. This methodology included an extensive analytical evaluation coupled with sub-component and full-scale testing of the structure. The work from the Damage Tolerance Analysis Assessment was incorporated into the full-scale testing. Damage representing hazards such as dropped tools, ground equipment, handling, and runway debris, was applied to the test articles. Additional substantiation included allowing manufacturing discrepancies to exist unrepaired on the full-scale articles and simulated bondline failures in critical elements. The importance of full-scale testing in the critical environmental conditions and the application of critical damage are addressed. The implication of damage tolerance on static and fatigue testing is discussed. Good correlation between finite element solutions and experimental test data was observed.

Foam on Tile Impact Modeling for the STS-107 Investigation

NASA Technical Reports Server (NTRS)

Stellingwerf, R. F.; Robinson, J. H.; Richardson, S.; Evans, S. W.; Stallworth, R.; Hovater, M.

2004-01-01

Following the breakup of the Space Shuttle Columbia during reentry a NASA/Contractor investigation team was formed to examine the probable damage inflicted on Orbiter Thermal Protection System elements by impact of External Tank insulating foam projectiles. The authors formed a working subgroup within the larger team to apply the Smooth Particle Hydrodynamics code SPHC to the damage estimation problem. Numerical models of the Orbiter's tiles and of the Tank's foam were constructed and used as inputs into the code. Material properties needed to properly model the tiles and foam were obtained from other working subgroups who performed tests on these items for this purpose. Two- and three-dimensional models of the tiles were constructed, including the glass outer layer, the main body of LI-900 insulation, the densified lower layer of LI-900, the Nomex felt mounting layer, and the Aluminum 2024 vehicle skin. A model for the BX-250 foam including porous compression, elastic rebound, and surface erosion was developed. Code results for the tile damage and foam behavior were extensively validated through comparison with Southwest Research Institute foam-on-tile impact experiments carried out in 1999. These tests involved small projectiles striking individual tiles and small tile arrays. Following code and model validation we simulated impacts of larger foam projectiles on the examples of tile systems used on the Orbiter. Results for impacts on the main landing gear door are presented in this paper, including effects of impacts at several angles, and of rapidly rotating projectiles. General results suggest that foam impacts on tiles at about 500 mph could cause appreciable damage if the impact angle is greater than about 20 degrees. Some variations of the foam properties, such as increased brittleness or increased density could increase damage in some cases. Rotation up to 17 rps failed to increase the damage for the two cases considered. This does not rule out other cases in which the rotational energy might lead to an increase in tile damage, but suggests that in most cases rotation will not be an important factor.

Space station integrated wall damage and penetration damage control. Task 5: Space debris measurement, mapping and characterization system

NASA Technical Reports Server (NTRS)

Lempriere, B. M.

1987-01-01

The procedures and results of a study of a conceptual system for measuring the debris environment on the space station is discussed. The study was conducted in two phases: the first consisted of experiments aimed at evaluating location of impact through panel response data collected from acoustic emission sensors; the second analyzed the available statistical description of the environment to determine the probability of the measurement system producing useful data, and analyzed the results of the previous tests to evaluate the accuracy of location and the feasibility of extracting impactor characteristics from the panel response. The conclusions were that for one panel the system would not be exposed to any event, but that the entire Logistics Module would provide a modest amount of data. The use of sensors with higher sensitivity than those used in the tests could be advantageous. The impact location could be found with sufficient accuracy from panel response data. The waveforms of the response were shown to contain information on the impact characteristics, but the data set did not span a sufficient range of the variables necessary to evaluate the feasibility of extracting the information.

ShakeMapple : tapping laptop motion sensors to map the felt extents of an earthquake

NASA Astrophysics Data System (ADS)

Bossu, Remy; McGilvary, Gary; Kamb, Linus

2010-05-01

There is a significant pool of untapped sensor resources available in portable computer embedded motion sensors. Included primarily to detect sudden strong motion in order to park the disk heads to prevent damage to the disks in the event of a fall or other severe motion, these sensors may also be tapped for other uses as well. We have developed a system that takes advantage of the Apple Macintosh laptops' embedded Sudden Motion Sensors to record earthquake strong motion data to rapidly build maps of where and to what extent an earthquake has been felt. After an earthquake, it is vital to understand the damage caused especially in urban environments as this is often the scene for large amounts of damage caused by earthquakes. Gathering as much information from these impacts to determine where the areas that are likely to be most effected, can aid in distributing emergency services effectively. The ShakeMapple system operates in the background, continuously saving the most recent data from the motion sensors. After an earthquake has occurred, the ShakeMapple system calculates the peak acceleration within a time window around the expected arrival and sends that to servers at the EMSC. A map plotting the felt responses is then generated and presented on the web. Because large-scale testing of such an application is inherently difficult, we propose to organize a broadly distributed "simulated event" test. The software will be available for download in April, after which we plan to organize a large-scale test by the summer. At a specified time, participating testers will be asked to create their own strong motion to be registered and submitted by the ShakeMapple client. From these responses, a felt map will be produced representing the broadly-felt effects of the simulated event.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, Andrew D.; Henry, Christopher S.; Fiehn, Oliver

It is increasingly clear that (a) many metabolites undergo spontaneous or enzyme-catalyzed side reactions in vivo, (b) the damaged metabolites formed by these reactions can be harmful, and (c) organisms have biochemical systems that limit the buildup of damaged metabolites. These damage-control systems either return a damaged molecule to its pristine state (metabolite repair) or convert harmful molecules to harmless ones (damage preemption). Because all organisms share a core set of metabolites that suffer the same chemical and enzymatic damage reactions, certain damage-control systems are widely conserved across the kingdoms of life. Relatively few damage reactions and damage-control systems aremore » well known. Uncovering new damage reactions and identifying the corresponding damaged metabolites, damage-control genes, and enzymes demands a coordinated mix of chemistry, metabolomics, cheminformatics, biochemistry, and comparative genomics. This review illustrates the above points using examples from plants, which are at least as prone to metabolite damage as other organisms.« less

Thermal-mechanical fatigue behavior of nickel-base superalloys

NASA Technical Reports Server (NTRS)

Pelloux, R. M.; Marchand, N.

1986-01-01

The main achievements of a 36-month research program are presented. The main objective was to gain more insight into the problem of crack growth under thermal mechanical fatigue (TMF) conditions. This program was conducted at M.I.T. for the period of September 1982 to September 1985. The program was arranged into five technical tasks. Under Task I, the literature of TMF data was reviewed. The goal was to identify the crack propagation conditions in aircraft engines (hot section) and to assess the validity of conventional fracture mechanics parameters to address TMF crack growth. The second task defined the test facilities, test specimen and the testing conditions needed to establish the effectiveness of data correlation parameters identified in Task I. Three materials (Inconel X-750, Hastelloy-X, and B-1900) were chosen for the program. Task II was accomplished in collaboration with Pratt & Whitney Aircraft engineers. Under Task III, a computerized testing system to measure the TMF behavior (LCF and CG behaviors) of various alloys systems was built. The software used to run isothermal and TMF tests was also developed. Built around a conventional servohydraulic machine, the system is capable of push-pull tests under stress or strain and temperature controlled conditions in the temperature range of 25C to 1050C. A crack propagation test program was defined and conducted under Task IV. The test variables included strain range, strain rate (frequency) and temperature. Task V correlated and generalized the Task IV data for isothermal and variable temperature conditions so that several crack propagation parameters could be compared and evaluated. The structural damage (mode of cracking and dislocation substructure) under TMF cycling was identified and contrasted with the isothermal damage to achieve a sound fundamental mechanistic understanding of TMF.

Vibration-based structural health monitoring of the aircraft large component

NASA Astrophysics Data System (ADS)

Pavelko, V.; Kuznetsov, S.; Nevsky, A.; Marinbah, M.

2017-10-01

In the presented paper there are investigated the basic problems of the local system of SHM of large scale aircraft component. Vibration-based damage detection is accepted as a basic condition, and main attention focused to a low-cost solution that would be attractive for practice. The conditions of small damage detection in the full scale structural component at low-frequency excitation were defined in analytical study and modal FEA. In experimental study the dynamic test of the helicopter Mi-8 tail beam was performed at harmonic excitation with frequency close to first natural frequency of the beam. The index of correlation coefficient deviation (CCD) was used for extraction of the features due to embedded pseudo-damage. It is shown that the problem of vibration-based detection of a small damage in the large scale structure at low-frequency excitation can be solved successfully.

Characterization of damage modes in dental ceramic bilayer structures.

PubMed

Deng, Yan; Lawn, Brian R; Lloyd, Isabel K

2002-01-01

Results of contact tests using spherical indenters on flat ceramic coating layers bonded to compliant substrates are reported for selected dental ceramics. Critical loads to produce various damage modes, cone cracking, and quasiplasticity at the top surfaces and radial cracking at the lower (inner) surfaces are measured as a function of ceramic-layer thickness. It is proposed that these damage modes, especially radial cracking, are directly relevant to the failure of all-ceramic dental crowns. The critical load data are analyzed with the use of explicit fracture-mechanics relations, expressible in terms of routinely measurable material parameters (elastic modulus, strength, toughness, hardness) and essential geometrical variables (layer thickness, contact radius). The utility of such analyses in the design of ceramic/substrate bilayer systems for optimal resistance to lifetime-threatening damage is discussed. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 137--145, 2002; DOI 10.1002/jbm.10091

Ocular tolerance of preservatives on the murine cornea.

PubMed

Furrer, P; Mayer, J M; Plazonnet, B; Gurny, R

1999-03-01

We investigated the effects of instilling 13 commonly used preservatives on the murine cornea in vivo. Due to the instillation of preservatives, micro-lesions are formed on the cornea and can be selectively marked by fluorescein. The sum of the resulting fluorescent areas was measured using an episcopic microscope coupled to an image processing system. All the tested preservatives proved to be well-tolerated by the eye at commonly used concentrations. However, in some cases, increased concentrations of preservatives or combinations resulted in significant increase of the amount of corneal damage. With increasing the concentration, corneal lesion increased the most in the case of cetylpyridinium. While a combination of chlorobutanol 0.5% and phenylethylalcohol 0.5% did not result in an increase in corneal damage (when compared to the use of each separately), the associations of thiomersal 0.02% and phenylethylalcohol 0.4% on one hand and of edetate disodium (EDTA) 0.1% and benzalkonium 0.01% on the other, resulted in significant increases in the amount of corneal damage. However, in none of the tested combinations, the increase in the observed damage exceed the limit of ocular intolerance we had defined beforehand: thus, they were all deemed relatively well-tolerated. In the last part of the study, we investigated the effects of combining several preservatives, at usual concentrations, with an anesthetic solution of oxybuprocaine and found no notable increase in ocular damage.

Damage progression in Composite Structures

NASA Technical Reports Server (NTRS)

Minnetyan, Levon

1996-01-01

A computational simulation tool is used to evaluate the various stages of damage progression in composite materials during Iosipescu sheat testing. Unidirectional composite specimens with either the major or minor material axis in the load direction are considered. Damage progression characteristics are described for each specimen using two types of boundary conditions. A procedure is outlined regarding the use of computational simulation in composites testing. Iosipescu shear testing using the V-notched beam specimen is a convenient method to measure both shear strength and shear stiffness simultaneously. The evaluation of composite test response can be made more productive and informative via computational simulation of progressive damage and fracture. Computational simulation performs a complete evaluation of laminated composite fracture via assessment of ply and subply level damage/fracture processes.

Out-of-plane properties

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Portanova, Marc A.

1995-01-01

This paper summarizes three areas of research which were performed to characterize out-of-plane properties of composite materials. In the first investigation, a series of tests was run to characterize the through-the-thickness tensile strength for a variety of composites that included 2D braids, 2D and 3D weaves, and prepreg tapes. A new test method based on a curved beam was evaluated. Failures were significantly different between the 2D materials and the 3D weaves. The 2D materials delaminated between layers due to out-of-plane tensile stresses while the 3D weaves failed due to the formation of radial cracks between the surface plies caused by high circumferential stresses along the inner radius. The strength of the 2D textile composites did not increase relative to the tapes. Final failure in the 3D weaves was caused by a circumferential crack similar to the 2D materials and occurred at a lower bending moment than in other materials. The early failures in the 3D weaves were caused by radial crack formation rather than a low through-the-thickness strength. The second investigation focused on the development of a standard impact test method to measure impact damage resistance. The only impact tests that currently exist are compression after impact (CAI) tests which incorporate elements of both damage resistance and damage tolerance. A new impact test method is under development which uses a quasi-static indentation (QSI) test to directly measure damage resistance. Damage resistance is quantified in terms of the contact force to produce a unit of damage where a metric for damage may be area in C-scan, depth of residual dent , penetration, damage growth, etc. A final draft of an impact standard that uses a QSI test method will be presented to the ASTM Impact Task Group on impact. In the third investigation, the impact damage resistance behavior of a variety of textile materials was studied using the QSI test method. In this study, the force where large damage initiates was measured and the delamination size as a function of force was determined. The force to initiate large damage was significantly lower in braids and weaves. The delamination diameter - impact forace relationship was quanitfied using a damage resistance parameter, Q(*), which related delamination diameter to imapct force over a range of delamination sizes. Using this Q(*) parameter to rate the materials, the stitched uniweaves, toughened epoxy tapes, and through-the-thickness orthogonal interlock weave were the most damage resistant.

Measuring sunscreen protection against solar-simulated radiation-induced structural radical damage to skin using ESR/spin trapping: development of an ex vivo test method.

PubMed

Haywood, Rachel; Volkov, Arsen; Andrady, Carima; Sayer, Robert

2012-03-01

The in vitro star system used for sunscreen UVA-testing is not an absolute measure of skin protection being a ratio of the total integrated UVA/UVB absorption. The in vivo persistent-pigment-darkening method requires human volunteers. We investigated the use of the ESR-detectable DMPO protein radical-adduct in solar-simulator-irradiated skin substitutes for sunscreen testing. Sunscreens SPF rated 20+ with UVA protection, reduced this adduct by 40-65% when applied at 2 mg/cm(2). SPF 15 Organic UVA-UVB (BMDBM-OMC) and TiO(2)-UVB filters and a novel UVA-TiO(2) filter reduced it by 21, 31 and 70% respectively. Conventional broad-spectrum sunscreens do not fully protect against protein radical-damage in skin due to possible visible-light contributions to damage or UVA-filter degradation. Anisotropic spectra of DMPO-trapped oxygen-centred radicals, proposed intermediates of lipid-oxidation, were detected in irradiated sunscreen and DMPO. Sunscreen protection might be improved by the consideration of visible-light protection and the design of filters to minimise radical leakage and lipid-oxidation.

Complex Consequences of Herbivory and Interplant Cues in Three Annual Plants

PubMed Central

Pearse, Ian S.; Porensky, Lauren M.; Yang, Louie H.; Stanton, Maureen L.; Karban, Richard; Bhattacharyya, Lisa; Cox, Rosa; Dove, Karin; Higgins, August; Kamoroff, Corrina; Kirk, Travis; Knight, Christopher; Koch, Rebecca; Parker, Corwin; Rollins, Hilary; Tanner, Kelsey

2012-01-01

Information exchange (or signaling) between plants following herbivore damage has recently been shown to affect plant responses to herbivory in relatively simple natural systems. In a large, manipulative field study using three annual plant species (Achyrachaena mollis, Lupinus nanus, and Sinapis arvensis), we tested whether experimental damage to a neighboring conspecific affected a plant's lifetime fitness and interactions with herbivores. By manipulating relatedness between plants, we assessed whether genetic relatedness of neighboring individuals influenced the outcome of having a damaged neighbor. Additionally, in laboratory feeding assays, we assessed whether damage to a neighboring plant specifically affected palatability to a generalist herbivore and, for S. arvensis, a specialist herbivore. Our study suggested a high level of contingency in the outcomes of plant signaling. For example, in the field, damaging a neighbor resulted in greater herbivory to A. mollis, but only when the damaged neighbor was a close relative. Similarly, in laboratory trials, the palatability of S. arvensis to a generalist herbivore increased after the plant was exposed to a damaged neighbor, while palatability to a specialist herbivore decreased. Across all species, damage to a neighbor resulted in decreased lifetime fitness, but only if neighbors were closely related. These results suggest that the outcomes of plant signaling within multi-species neighborhoods may be far more context-specific than has been previously shown. In particular, our study shows that herbivore interactions and signaling between plants are contingent on the genetic relationship between neighboring plants. Many factors affect the outcomes of plant signaling, and studies that clarify these factors will be necessary in order to assess the role of plant information exchange about herbivory in natural systems. PMID:22675439

Size Effects in Impact Damage of Composite Sandwich Panels

NASA Technical Reports Server (NTRS)

Dobyns, Alan; Jackson, Wade

2003-01-01

Panel size has a large effect on the impact response and resultant damage level of honeycomb sandwich panels. It has been observed during impact testing that panels of the same design but different panel sizes will show large differences in damage when impacted with the same impact energy. To study this effect, a test program was conducted with instrumented impact testing of three different sizes of sandwich panels to obtain data on panel response and residual damage. In concert with the test program. a closed form analysis method was developed that incorporates the effects of damage on the impact response. This analysis method will predict both the impact response and the residual damage of a simply-supported sandwich panel impacted at any position on the panel. The damage is incorporated by the use of an experimental load-indentation curve obtained for the face-sheet/honeycomb and indentor combination under study. This curve inherently includes the damage response and can be obtained quasi-statically from a rigidly-backed specimen or a specimen with any support conditions. Good correlation has been obtained between the test data and the analysis results for the maximum force and residual indentation. The predictions can be improved by using a dynamic indentation curve. Analyses have also been done using the MSC/DYTRAN finite element code.

Structural control and health monitoring of building structures with unknown ground excitations: Experimental investigation

NASA Astrophysics Data System (ADS)

He, Jia; Xu, You-Lin; Zhan, Sheng; Huang, Qin

2017-03-01

When health monitoring system and vibration control system both are required for a building structure, it will be beneficial and cost-effective to integrate these two systems together for creating a smart building structure. Recently, on the basis of extended Kalman filter (EKF), a time-domain integrated approach was proposed for the identification of structural parameters of the controlled buildings with unknown ground excitations. The identified physical parameters and structural state vectors were then utilized to determine the control force for vibration suppression. In this paper, the possibility of establishing such a smart building structure with the function of simultaneous damage detection and vibration suppression was explored experimentally. A five-story shear building structure equipped with three magneto-rheological (MR) dampers was built. Four additional columns were added to the building model, and several damage scenarios were then simulated by symmetrically cutting off these columns in certain stories. Two sets of earthquakes, i.e. Kobe earthquake and Northridge earthquake, were considered as seismic input and assumed to be unknown during the tests. The structural parameters and the unknown ground excitations were identified during the tests by using the proposed identification method with the measured control forces. Based on the identified structural parameters and system states, a switching control law was employed to adjust the current applied to the MR dampers for the purpose of vibration attenuation. The experimental results show that the presented approach is capable of satisfactorily identifying structural damages and unknown excitations on one hand and significantly mitigating the structural vibration on the other hand.

High-intensity power-resolved radiation imaging of an operational nuclear reactor.

PubMed

Beaumont, Jonathan S; Mellor, Matthew P; Villa, Mario; Joyce, Malcolm J

2015-10-09

Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors.

High-intensity power-resolved radiation imaging of an operational nuclear reactor

PubMed Central

Beaumont, Jonathan S.; Mellor, Matthew P.; Villa, Mario; Joyce, Malcolm J.

2015-01-01

Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors. PMID:26450669

R-on-1 automatic mapping: A new tool for laser damage testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hue, J.; Garrec, P.; Dijon, J.

1996-12-31

Laser damage threshold measurement is statistical in nature. For a commercial qualification or for a user, the threshold determined by the weakest point is a satisfactory characterization. When a new coating is designed, threshold mapping is very useful. It enables the technology to be improved and followed more accurately. Different statistical parameters such as the minimum, maximum, average, and standard deviation of the damage threshold as well as spatial parameters such as the threshold uniformity of the coating can be determined. Therefore, in order to achieve a mapping, all the tested sites should give data. This is the major interestmore » of the R-on-1 test in spite of the fact that the laser damage threshold obtained by this method may be different from the 1-on-1 test (smaller or greater). Moreover, on the damage laser test facility, the beam size is smaller (diameters of a few hundred micrometers) than the characteristic sizes of the components in use (diameters of several centimeters up to one meter). Hence, a laser damage threshold mapping appears very interesting, especially for applications linked to large optical components like the Megajoule project or the National Ignition Facility (N.I.F). On the test bench used, damage detection with a Nomarski microscope and scattered light measurement are almost equivalent. Therefore, it becomes possible to automatically detect on line the first defects induced by YAG irradiation. Scattered light mappings and laser damage threshold mappings can therefore be achieved using a X-Y automatic stage (where the test sample is located). The major difficulties due to the automatic capabilities are shown. These characterizations are illustrated at 355 nm. The numerous experiments performed show different kinds of scattering curves, which are discussed in relation with the damage mechanisms.« less

Numerical and experimental investigations on cavitation erosion

NASA Astrophysics Data System (ADS)

Fortes Patella, R.; Archer, A.; Flageul, C.

2012-11-01

A method is proposed to predict cavitation damage from cavitating flow simulations. For this purpose, a numerical process coupling cavitating flow simulations and erosion models was developed and applied to a two-dimensional (2D) hydrofoil tested at TUD (Darmstadt University of Technology, Germany) [1] and to a NACA 65012 tested at LMH-EPFL (Lausanne Polytechnic School) [2]. Cavitation erosion tests (pitting tests) were carried out and a 3D laser profilometry was used to analyze surfaces damaged by cavitation [3]. The method allows evaluating the pit characteristics, and mainly the volume damage rates. The paper describes the developed erosion model, the technique of cavitation damage measurement and presents some comparisons between experimental results and numerical damage predictions. The extent of cavitation erosion was correctly estimated in both hydrofoil geometries. The simulated qualitative influence of flow velocity, sigma value and gas content on cavitation damage agreed well with experimental observations.

Bulk Electrical Cable Non-Destructive Examination Methods for Nuclear Power Plant Cable Aging Management Programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glass, Samuel W.; Jones, Anthony M.; Fifield, Leonard S.

This Pacific Northwest National Laboratory milestone report describes progress to date on the investigation of nondestructive test methods focusing particularly on bulk electrical test methods that provide key indicators of cable aging and damage. The work includes a review of relevant literature as well as hands-on experimental verification of inspection capabilities. As nuclear power plants consider applying for second, or subsequent, license renewal to extend their operating period from 60 years to 80 years, it is important to understand how the materials installed in plant systems and components will age during that time and develop aging management programs to assuremore » continued safe operation under normal and design basis events (DBE). Normal component and system tests typically confirm the cables can perform their normal operational function. The focus of the cable test program, however, is directed toward the more demanding challenge of assuring the cable function under accident or DBE. The industry has adopted 50% elongation at break (EAB) relative to the un-aged cable condition as the acceptability standard. All tests are benchmarked against the cable EAB test. EAB, however, is a destructive test so the test programs must apply an array of other nondestructive examination (NDE) tests to assure or infer the overall set of cable’s system integrity. Assessment of cable integrity is further complicated in many cases by vendor’s use of dissimilar material for jacket and insulation. Frequently the jacket will degrade more rapidly than the underlying insulation. Although this can serve as an early alert to cable damage, direct test of the cable insulation without violating the protective jacket becomes problematic. This report addresses the range of bulk electrical NDE cable tests that are or could be practically implemented in a field-test situation with a particular focus on frequency domain reflectometry (FDR). The FDR test method offers numerous advantages over many other bulk electrical tests. Two commercial FDR systems plus a laboratory vector network analyzer are used to test an array of aged and un-aged cables under identical conditions. Several conclusions are set forth, and a number of knowledge gaps are identified.« less

Investigation of Gear and Bearing Fatigue Damage Using Debris Particle Distributions

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Lewicki, David G.; Decker, Harry J.

2004-01-01

A diagnostic tool was developed for detecting fatigue damage to spur gears, spiral bevel gears, and rolling element bearings. This diagnostic tool was developed and evaluated experimentally by collecting oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig, Spiral Bevel Gear Test Facility, and the 500hp Helicopter Transmission Test Stand. During each test, data from an online, in-line, inductance type oil debris sensor was monitored and recorded for the occurrence of pitting damage. Results indicate oil debris alone cannot discriminate between bearing and gear fatigue damage.

Advances in self-healing materials based on vascular networks with mechanical self-repair characteristics.

PubMed

Lee, Min Wook; An, Seongpil; Yoon, Sam S; Yarin, Alexander L

2018-02-01

Here, we review the state-of-the-art in the field of engineered self-healing materials. These materials mimic the functionalities of various natural materials found in the human body (e.g., the healing of skin and bones by the vascular system). The fabrication methods used to produce these "vascular-system-like" engineered self-healing materials, such as electrospinning (including co-electrospinning and emulsion spinning) and solution blowing (including coaxial solution blowing and emulsion blowing) are discussed in detail. Further, a few other approaches involving the use of hollow fibers are also described. In addition, various currently used healing materials/agents, such as dicyclopentadiene and Grubbs' catalyst, poly(dimethyl siloxane), and bisphenol-A-based epoxy, are described. We also review the characterization methods employed to verify the physical and chemical aspects of self-healing, that is, the methods used to confirm that the healing agent has been released and that it has resulted in healing, as well as the morphological changes induced in the damaged material by the healing agent. These characterization methods include different visualization and spectroscopy techniques and thermal analysis methods. Special attention is paid to the characterization of the mechanical consequences of self-healing. The effects of self-healing on the mechanical properties such as stiffness and adhesion of the damaged material are evaluated using the tensile test, double cantilever beam test, plane strip test, bending test, and adhesion test (e.g., blister test). Finally, the future direction of the development of these systems is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Space Fission Propulsion Testing and Development Progress. Phase 1

NASA Technical Reports Server (NTRS)

VanDyke, Melissa; Houts, Mike; Pedersen, Kevin; Godfroy, Tom; Dickens, Ricky; Poston, David; Reid, Bob; Salvail, Pat; Ring, Peter; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. Testing can be divided into two categories, non-nuclear tests and nuclear tests. Full power nuclear tests of space fission systems we expensive, time consuming, and of limited use, even in the best of programmatic environments. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. Non-nuclear tests are affordable and timely, and the cause of component and system failures can be quickly and accurately identified. MSFC is leading a Safe Affordable Fission Engine (SAFE) test series whose ultimate goal is the demonstration of a 300 kW flight configuration system using non-nuclear testing. This test series is carried out in collaboration with other NASA centers, other government agencies, industry, and universities. If SAFE-related nuclear tests are desired they will have a high probability of success and can be performed at existing nuclear facilities. The paper describes the SAFE non-nuclear test series, which includes test article descriptions, test results and conclusions, and future test plans.

Predicting knee replacement damage in a simulator machine using a computational model with a consistent wear factor.

PubMed

Zhao, Dong; Sakoda, Hideyuki; Sawyer, W Gregory; Banks, Scott A; Fregly, Benjamin J

2008-02-01

Wear of ultrahigh molecular weight polyethylene remains a primary factor limiting the longevity of total knee replacements (TKRs). However, wear testing on a simulator machine is time consuming and expensive, making it impractical for iterative design purposes. The objectives of this paper were first, to evaluate whether a computational model using a wear factor consistent with the TKR material pair can predict accurate TKR damage measured in a simulator machine, and second, to investigate how choice of surface evolution method (fixed or variable step) and material model (linear or nonlinear) affect the prediction. An iterative computational damage model was constructed for a commercial knee implant in an AMTI simulator machine. The damage model combined a dynamic contact model with a surface evolution model to predict how wear plus creep progressively alter tibial insert geometry over multiple simulations. The computational framework was validated by predicting wear in a cylinder-on-plate system for which an analytical solution was derived. The implant damage model was evaluated for 5 million cycles of simulated gait using damage measurements made on the same implant in an AMTI machine. Using a pin-on-plate wear factor for the same material pair as the implant, the model predicted tibial insert wear volume to within 2% error and damage depths and areas to within 18% and 10% error, respectively. Choice of material model had little influence, while inclusion of surface evolution affected damage depth and area but not wear volume predictions. Surface evolution method was important only during the initial cycles, where variable step was needed to capture rapid geometry changes due to the creep. Overall, our results indicate that accurate TKR damage predictions can be made with a computational model using a constant wear factor obtained from pin-on-plate tests for the same material pair, and furthermore, that surface evolution method matters only during the initial "break in" period of the simulation.

A 5000-hour test of a grid-translation beam-deflection system for a 5-cm diameter Kaufman thruster

NASA Technical Reports Server (NTRS)

Lathem, W. C.

1973-01-01

A grid-translation type beam deflection system was tested on a 5-cm diameter mercury ion thruster for 5000 hours at a thrust level of about 0.36 mlb. During the first 2000 hours the beam was vectored 10 degrees in one direction. No erosion damage attributable to beam deflection was detected. Results indicate a possible lifetime of 15,000 to 20,000 hours. An optimized neutralizer position was used which eliminated the sputter erosion groove observed on the SERT 2 thrusters.

Coefficient of Friction Patterns Can Identify Damage in Native and Engineered Cartilage Subjected to Frictional-Shear Stress

PubMed Central

Whitney, G. A.; Mansour, J. M.; Dennis, J. E.

2015-01-01

The mechanical loading environment encountered by articular cartilage in situ makes frictional-shear testing an invaluable technique for assessing engineered cartilage. Despite the important information that is gained from this testing, it remains under-utilized, especially for determining damage behavior. Currently, extensive visual inspection is required to assess damage; this is cumbersome and subjective. Tools to simplify, automate, and remove subjectivity from the analysis may increase the accessibility and usefulness of frictional-shear testing as an evaluation method. The objective of this study was to determine if the friction signal could be used to detect damage that occurred during the testing. This study proceeded in two phases: first, a simplified model of biphasic lubrication that does not require knowledge of interstitial fluid pressure was developed. In the second phase, frictional-shear tests were performed on 74 cartilage samples, and the simplified model was used to extract characteristic features from the friction signals. Using support vector machine classifiers, the extracted features were able to detect damage with a median accuracy of approximately 90%. The accuracy remained high even in samples with minimal damage. In conclusion, the friction signal acquired during frictional-shear testing can be used to detect resultant damage to a high level of accuracy. PMID:25691395

Integration of bridge damage detection concepts and components : tech transfer summary.

DOT National Transportation Integrated Search

2013-10-01

Although bridge testing has been an important tool for evaluating structures for several decades, it has only been within the last decade that specific effort has been given to develop systems that are capable of operating in an autonomous fashion. T...

Development of COPVS for High pressure, In-Space, Cryogenic Fuel Storage

NASA Technical Reports Server (NTRS)

DeLay, Tom; Schneider, Judy; Dyess, Mark; Hastings, Chad; Noorda, Ryan; Noorda, Jared; Patterson, James

2008-01-01

Polymeric composite overwrapped pressure vessels (COPVs) provide an attractive material system to support developing commercial launch business and alternate fuel ventures. However to be able to design with these materials, the mechanical behavior of the materials must be understood with regards to processing, performance, damage tolerance, and environment. For the storage of cryogenic propellants, it is important to evaluate the materials performance and impact damage resistance at cryogenic temperatures in order to minimize weight and to ensure safety and reliability. To evaluate the ultimate performance, various polymeric COPV's have been statically burst tested at cryogenic conditions before and after exposure to irradiation. Materials selected for these COPVs were based on the measured mechanical properties of candidate resin systems and fibers that were also tested at cryogenic conditions before and after exposure to irradiation. The correlation of COPV burst pressures with the constituent material properties has proven to be a valuable screening method for selection of suitable candidate materials with resistance to material degradation due to exposure to temperature and radiation.

Large Capacity SMES for Voltage Dip Compensation

NASA Astrophysics Data System (ADS)

Iwatani, Yu; Saito, Fusao; Ito, Toshinobu; Shimada, Mamoru; Ishida, Satoshi; Shimanuki, Yoshio

Voltage dips of power grids due to thunderbolts, snow damage, and so on, cause serious damage to production lines of precision instruments, for example, semiconductors. In recent years, in order to solve this problem, uninterruptible power supply systems (UPS) are used. UPS, however, has small capacity, so a great number of UPS are needed in large factories. Therefore, we have manufactured the superconducting magnetic energy storage (SMES) system for voltage dip compensation able to protect loads with large capacity collectively. SMES has advantages such as space conservation, long lifetime and others. In field tests, cooperating with CHUBU Electric Power Co., Inc. we proved that SMES is valuable for compensating voltage dips. Since 2007, 10MVA SMES improved from field test machines has been running in a domestic liquid crystal display plant, and in 2008, it protected plant loads from a number of voltage dips. In this paper, we report the action principle and components of the improved SMES for voltage dip compensation, and examples of waveforms when 10MVA SMES compensated voltage dips.

Integrated approach for investigating the durability of self-consolidating concrete to sulfate attack

NASA Astrophysics Data System (ADS)

Bassuoni, Mohamed Tamer F.

The growing use of self-consolidating concrete (SCC) in various infrastructure applications exposed to sulfate-rich environments necessitates conducting comprehensive research to evaluate its durability to external sulfate attack. Since the reliability and adequacy of standard sulfate immersion tests have been questioned, the current thesis introduced an integrated testing approach for assessing the durability of a wide scope of SCC mixtures to external sulfate attack. This testing approach involved progressive levels of complexity from single to multiple damage processes. A new series of sulfate attack tests involving multiple field-like parameters and combined damage mechanisms (various cations, controlled pH, wetting-drying, partial immersion, freezing-thawing, and cyclic cold-hot conditions with or without sustained flexural loading) were designed to evaluate the performance (suitability) of the SCC mixtures under various sulfate attack exposure scenarios. The main mixture design variables of SCC included the type of binder (single, binary, ternary and quaternary), air-entrainment, sand-to-aggregate mass ratio and hybrid fibre reinforcement. The comprehensive database and knowledge obtained from this research were used to develop smart models (fuzzy and neuro-fuzzy inference systems) based on artificial-intelligence to evaluate and predict the performance of the SCC mixtures under various sulfate attack exposure regimes implemented in this study. In full immersion tests involving high concentration sodium and magnesium sulfate solutions with controlled pH, the low penetrability of SCC was responsible for the high durability of specimens. Ternary and quaternary cementitious systems with or without limestone materials provided a passivating layer, with or without acid neutralization capacity, which protected SCC from severe damage in the aggressive sulfuric acid and ammonium sulfate solutions. In contrast to conclusions drawn from the sodium sulfate immersion tests, the combined sulfate attack tests captured performance risks and complex damage mechanisms associated with the SCC pore structure and constituent materials. Sodium sulfate attack with wetting-drying cycles and/or partial immersion under temperate-hot conditions synergistically caused significant damage to specimens, especially to quaternary cementitious systems having very fine pore structure, due to the build-up of salt crystals and sulfate reaction products. The deleterious effects of sulfate reaction products and salt crystallization on all cementitious systems were more severe under the combined sodium sulfate and freezing-thawing exposure, with a potential of sudden brittle failure. Laboratory experiments in the current work documented evidence for the occurrence of thaumasite sulfate attack (TSA) in cementitious systems containing limestone filler, not only under cold but also under temperate-hot conditions, which made specimens more vulnerable to damage in the combined sulfate attack tests. The field-like combined exposure of sodium sulfate, cyclic environments and flexural loading had synergistic effects on SCC specimens and caused the coexistence of multiple-complex degradation mechanisms (sulfate attack, TSA, stress-corrosion, salt crystallization, surface scaling and corrosion of surface steel fibres) depending on the mixture design variables. The current thesis demonstrates that relying only on sulfate immersion tests to evaluate the performance of cement-based materials can be risky. It also shows that linear and deterministic modeling of the performance of concrete structures under external sulfate attack is unrealistic. Fuzzy and adaptive-neuro fuzzy inference systems developed in the current thesis accurately and rationally predicted the serviceability, deterioration in engineering properties and time to failure of the SCC mixtures under the various sulfate attack exposure regimes adopted in the integrated testing approach. A durability evaluation factor from multiple performance criteria was created for the ammonium sulfate exposure. Environmental charts were developed to determine the level of aggression associated with sodium sulfate attack from temperature, RH and degree of wetting-drying expected in service. This novel modeling approach showed promising success in handling complex durability topics such as the sulfate attack of concrete, which involves non-linearity, ambiguity and interface with operator approximation. The current thesis provides needed fundamental knowledge on the durability of a wide scope of SCC mixtures to various sulfate attack exposure scenarios. It elucidates complex deterioration mechanisms and failure modes of cement-based materials under multi-mechanistic aging processes. It also proposes carefully engineered integrated sulfate attack tests that replicate various sulfate attack exposure regimes, which could be refined and standardized in the future. In addition, the current work introduced original knowledge-based smart models capable of handling uncertainty and providing reliable predictions for the behaviour of concrete under external sulfate attack. The models do not require conducting exhaustive laboratory experiments and/or making assumptions, thus facilitating the selection of optimum concrete mixtures for a specified exposure. Overall, this research should effectively contribute to the development of performance-based standards and specifications for, and improvement of durability-based design and life-cycle analysis of concrete structures subjected to external sulfate attack. Keywords. Sulfate attack, self-consolidating concrete, integrated testing, composite cements, air-entrainment, hybrid fibres, full immersion, cations, pH, wetting-drying, partial immersion, freezing-thawing, cyclic cold-hot conditions, flexural loading, thaumasite, salt crystallization, fuzzy, neuro-fuzzy, systems.

Endovascular Catheter for Magnetic Navigation under MR Imaging Guidance: Evaluation of Safety in Vivo at 1.5T

PubMed Central

Hetts, S.W.; Saeed, M.; Martin, A.J.; Evans, L.; Bernhardt, A.F.; Malba, V.; Settecase, F.; Do, L.; Yee, E.J.; Losey, A.; Sincic, R.; Roy, S.; Arenson, R.L.; Wilson, M.W.

2013-01-01

BACKGROUND AND PURPOSE: Endovascular navigation under MR imaging guidance can be facilitated by a catheter with steerable microcoils on the tip. Not only do microcoils create visible artifacts allowing catheter tracking, but also they create a small magnetic moment permitting remote-controlled catheter tip deflection. A side product of catheter tip electrical currents, however, is the heat that might damage blood vessels. We sought to determine the upper boundary of electrical currents safely usable at 1.5T in a coil-tipped microcatheter system. MATERIALS AND METHODS: Alumina tubes with solenoid copper coils were attached to neurovascular microcatheters with heat shrink-wrap. Catheters were tested in carotid arteries of 8 pigs. The catheters were advanced under x-ray fluoroscopy and MR imaging. Currents from 0 mA to 700 mA were applied to test heating and potential vascular damage. Postmortem histologic analysis was the primary endpoint. RESULTS: Several heat-mitigation strategies demonstrated negligible vascular damage compared with control arteries. Coil currents ≤300 mA resulted in no damage (0/58 samples) compared with 9 (25%) of 36 samples for > 300-mA activations (P = .0001). Tip coil activation ≤1 minute and a proximal carotid guide catheter saline drip > 2 mL/minute also had a nonsignificantly lower likelihood of vascular damage. For catheter tip coil activations ≤300 mA for ≤1 minute in normal carotid flow, 0 of 43 samples had tissue damage. CONCLUSIONS: Activations of copper coils at the tip of microcatheters at low currents in 1.5T MR scanners can be achieved without significant damage to blood vessel walls in a controlled experimental setting. Further optimization of catheter design and procedure protocols is necessary for safe remote control magnetic catheter guidance. PMID:23846795

Damage assessment of long-range rocket system by electromagnetic pulse weapon

NASA Astrophysics Data System (ADS)

Cao, Lingyu; Liu, Guoqing; Li, Jinming

2017-08-01

This paper analyzes the damage mechanism and characteristics of electromagnetic pulse weapon, establishes the index system of survivability of long-range rocket launcher system, and uses AHP method to establish the combat effectiveness model of long-range rocket missile system. According to the damage mechanism and characteristics of electromagnetic pulse weapon, the damage effect of the remote rocket system is established by using the exponential method to realize the damage efficiency of the remote rocket system.

Damage assessment in PRC and RC beams by dynamic tests

NASA Astrophysics Data System (ADS)

Capozucca, R.

2011-07-01

The present paper reports on damaged prestressed reinforced concrete (PRC) beams and reinforced concrete (RC) beams experimentally investigated through dynamic testing in order to verify damage degree due to reinforcement corrosion or cracking correlated to loading. The experimental program foresaw that PRC beams were subjected to artificial reinforcement corrosion and static loading while RC beams were damaged by increasing applied loads to produce bending cracking. Dynamic investigation was developed both on undamaged and damaged PRC and RC beams measuring natural frequencies and evaluating vibration mode shapes. Dynamic testing allowed the recording of frequency response variations at different vibration modes. The experimental results are compared with theoretical results and discussed.

Phenotypic responses to microbial volatiles render a mold fungus more susceptible to insect damage.

PubMed

Caballero Ortiz, Silvia; Trienens, Monika; Pfohl, Katharina; Karlovsky, Petr; Holighaus, Gerrit; Rohlfs, Marko

2018-04-01

In decomposer systems, fungi show diverse phenotypic responses to volatile organic compounds of microbial origin (volatiles). The mechanisms underlying such responses and their consequences for the performance and ecological success of fungi in a multitrophic community context have rarely been tested explicitly. We used a laboratory-based approach in which we investigated a tripartite yeast-mold-insect model decomposer system to understand the possible influence of yeast-borne volatiles on the ability of a chemically defended mold fungus to resist insect damage. The volatile-exposed mold phenotype (1) did not exhibit protein kinase A-dependent morphological differentiation, (2) was more susceptible to insect foraging activity, and (3) had reduced insecticidal properties. Additionally, the volatile-exposed phenotype was strongly impaired in secondary metabolite formation and unable to activate "chemical defense" genes upon insect damage. These results suggest that volatiles can be ecologically important factors that affect the chemical-based combative abilities of fungi against insect antagonists and, consequently, the structure and dynamics of decomposer communities.

Effects of intra- and inter-laminar resin content on the mechanical properties of toughened composite materials

NASA Technical Reports Server (NTRS)

Grande, Dodd H.; Ilcewicz, Larry B.; Avery, William B.; Bascom, Willard D.

1991-01-01

Composite materials having multiphase toughened matrix systems and laminate architectures characterized by resin-rich interlaminar layers (RIL) have been the subject of much recent attention. Such materials are likely to find applications in thick compressively loaded structures such as the keel area of commercial aircraft fuselages. The effects of resin content and its interlaminar and intralaminar distribution on mechanical properties were investigated with test and analysis of two carbon-epoxy systems. The RIL was found to reduce the in situ strengthening effect for matrix cracking in laminates. Mode 2 fracture toughness was found to increase with increasing RIL thickness over the range investigated, and Mode 1 interlaminar toughness was negligibly affected. Compressive failure strains were found to increase with increasing resin content for specimens having no damage, holes, and impact damage. Analytical tools for predicting matrix cracking of off-axis plies and damage tolerance in compression after impact (CAI) were successfully applied to materials with RIL.

Multi-sensor system for in situ shape monitoring and damage identification of high-speed composite rotors

NASA Astrophysics Data System (ADS)

Philipp, K.; Filippatos, A.; Kuschmierz, R.; Langkamp, A.; Gude, M.; Fischer, A.; Czarske, J.

2016-08-01

Glass fibre-reinforced polymer (GFRP) composites offer a higher stiffness-to-weight ratio than conventional rotor materials used in turbomachinery. However, the material behaviour of GFRP high-speed rotors is difficult to predict due to the complexity of the composite material and the dynamic loading conditions. Consequently dynamic expansion measurements of GRFP rotors are required in situ and with micron precision. However, the whirling motion amplitude is about two orders of magnitude higher than the desired precision. To overcome this problem, a multi-sensor system capable of separating rotor expansion and whirling motion is proposed. High measurement rates well above the rotational frequency and micron uncertainty are achieved at whirling amplitudes up to 120μm and surface velocities up to 300 m/s. The dynamic elliptical expansion of a GFRP rotor is investigated in a rotor loading test rig under vacuum conditions. In situ measurements identified not only the introduced damage but also damage initiation and propagation.

The Space Shuttle Program Pre-Flight Meteoroid and Orbital Debris Risk/Damage Predictions and Post-Flight Damage Assessments

NASA Technical Reports Server (NTRS)

Levin, George M.; Christiansen, Eric L.

1997-01-01

The pre-flight predictions and postflight assessments carried out in relation to a series of Space Shuttle missions are reviewed, and data are presented for the meteoroid and orbital debris damage observed on the Hubble Space Telescope during the 1994 Hubble repair mission. Pre-flight collision risk analyses are carried out prior to each mission, and in the case of an unacceptable risk, the mission profile is altered until the risk is considered to be acceptable. The NASA's BUMPER code is used to compute the probability of damage from debris and meteoroid particle impacts based on the Poisson statistical model for random events. The penetration probability calculation requires information concerning the geometry of the critical systems, the penetration resistance and mission profile parameters. Following each flight, the orbiter is inspected for meteoroid and space debris damage. The emphasis is on areas such as the radiator panels, the windows and the reinforced carbon-carbon structures on the leading wing edges and on the nose cap. The contents of damage craters are analyzed using a scanning electron microscope to determine the nature and origin of the impactor. Hypervelocity impact tests are often performed to simulate the observed damage and to estimate the nature of the damaging particles. The number and type of damage observed provides information concerning the orbital debris environment.

A recursive Bayesian approach for fatigue damage prognosis: An experimental validation at the reliability component level

NASA Astrophysics Data System (ADS)

Gobbato, Maurizio; Kosmatka, John B.; Conte, Joel P.

2014-04-01

Fatigue-induced damage is one of the most uncertain and highly unpredictable failure mechanisms for a large variety of mechanical and structural systems subjected to cyclic and random loads during their service life. A health monitoring system capable of (i) monitoring the critical components of these systems through non-destructive evaluation (NDE) techniques, (ii) assessing their structural integrity, (iii) recursively predicting their remaining fatigue life (RFL), and (iv) providing a cost-efficient reliability-based inspection and maintenance plan (RBIM) is therefore ultimately needed. In contribution to these objectives, the first part of the paper provides an overview and extension of a comprehensive reliability-based fatigue damage prognosis methodology — previously developed by the authors — for recursively predicting and updating the RFL of critical structural components and/or sub-components in aerospace structures. In the second part of the paper, a set of experimental fatigue test data, available in the literature, is used to provide a numerical verification and an experimental validation of the proposed framework at the reliability component level (i.e., single damage mechanism evolving at a single damage location). The results obtained from this study demonstrate (i) the importance and the benefits of a nearly continuous NDE monitoring system, (ii) the efficiency of the recursive Bayesian updating scheme, and (iii) the robustness of the proposed framework in recursively updating and improving the RFL estimations. This study also demonstrates that the proposed methodology can lead to either an extent of the RFL (with a consequent economical gain without compromising the minimum safety requirements) or an increase of safety by detecting a premature fault and therefore avoiding a very costly catastrophic failure.

Prolonged fasting does not increase oxidative damage or inflammation in postweaned northern elephant seal pups

PubMed Central

Vázquez-Medina, José Pablo; Crocker, Daniel E.; Forman, Henry Jay; Ortiz, Rudy M.

2010-01-01

Elephant seals are naturally adapted to survive up to three months of absolute food and water deprivation (fasting). Prolonged food deprivation in terrestrial mammals increases reactive oxygen species (ROS) production, oxidative damage and inflammation that can be induced by an increase in the renin–angiotensin system (RAS). To test the hypothesis that prolonged fasting in elephant seals is not associated with increased oxidative stress or inflammation, blood samples and muscle biopsies were collected from early (2–3 weeks post-weaning) and late (7–8 weeks post-weaning) fasted seals. Plasma levels of oxidative damage, inflammatory markers and plasma renin activity (PRA), along with muscle levels of lipid and protein oxidation, were compared between early and late fasting periods. Protein expression of angiotensin receptor 1 (AT1), pro-oxidant (Nox4) and antioxidant enzymes (CuZn- and Mn-superoxide dismutases, glutathione peroxidase and catalase) was analyzed in muscle. Fasting induced a 2.5-fold increase in PRA, a 50% increase in AT1, a twofold increase in Nox4 and a 70% increase in NADPH oxidase activity. By contrast, neither tissue nor systemic indices of oxidative damage or inflammation increased with fasting. Furthermore, muscle antioxidant enzymes increased 40–60% with fasting in parallel with an increase in muscle and red blood cell antioxidant enzyme activities. These data suggest that, despite the observed increases in RAS and Nox4, an increase in antioxidant enzymes appears to be sufficient to suppress systemic and tissue indices of oxidative damage and inflammation in seals that have fasted for a prolonged period. The present study highlights the importance of antioxidant capacity in mammals during chronic periods of stress to help avoid deleterious systemic consequences. PMID:20581282

Prolonged fasting does not increase oxidative damage or inflammation in postweaned northern elephant seal pups.

PubMed

Vázquez-Medina, José Pablo; Crocker, Daniel E; Forman, Henry Jay; Ortiz, Rudy M

2010-07-15

Elephant seals are naturally adapted to survive up to three months of absolute food and water deprivation (fasting). Prolonged food deprivation in terrestrial mammals increases reactive oxygen species (ROS) production, oxidative damage and inflammation that can be induced by an increase in the renin-angiotensin system (RAS). To test the hypothesis that prolonged fasting in elephant seals is not associated with increased oxidative stress or inflammation, blood samples and muscle biopsies were collected from early (2-3 weeks post-weaning) and late (7-8 weeks post-weaning) fasted seals. Plasma levels of oxidative damage, inflammatory markers and plasma renin activity (PRA), along with muscle levels of lipid and protein oxidation, were compared between early and late fasting periods. Protein expression of angiotensin receptor 1 (AT(1)), pro-oxidant (Nox4) and antioxidant enzymes (CuZn- and Mn-superoxide dismutases, glutathione peroxidase and catalase) was analyzed in muscle. Fasting induced a 2.5-fold increase in PRA, a 50% increase in AT(1), a twofold increase in Nox4 and a 70% increase in NADPH oxidase activity. By contrast, neither tissue nor systemic indices of oxidative damage or inflammation increased with fasting. Furthermore, muscle antioxidant enzymes increased 40-60% with fasting in parallel with an increase in muscle and red blood cell antioxidant enzyme activities. These data suggest that, despite the observed increases in RAS and Nox4, an increase in antioxidant enzymes appears to be sufficient to suppress systemic and tissue indices of oxidative damage and inflammation in seals that have fasted for a prolonged period. The present study highlights the importance of antioxidant capacity in mammals during chronic periods of stress to help avoid deleterious systemic consequences.

Experimental study of thin film sensor networks for wind turbine blade damage detection

NASA Astrophysics Data System (ADS)

Downey, A.; Laflamme, S.; Ubertini, F.; Sauder, H.; Sarkar, P.

2017-02-01

Damage detection of wind turbine blades is difficult due to their complex geometry and large size, for which large deployment of sensing systems is typically not economical. A solution is to develop and deploy dedicated sensor networks fabricated from inexpensive materials and electronics. The authors have recently developed a novel skin-type strain gauge for measuring strain over very large surfaces. The skin, a type of large-area electronics, is constituted from a network of soft elastomeric capacitors. The sensing system is analogous to a biological skin, where local strain can be monitored over a global area. In this paper, we propose the utilization of a dense network of soft elastomeric capacitors to detect, localize, and quantify damage on wind turbine blades. We also leverage mature off-the-shelf technologies, in particular resistive strain gauges, to augment such dense sensor network with high accuracy data at key locations, therefore constituting a hybrid dense sensor network. The proposed hybrid dense sensor network is installed inside a wind turbine blade model, and tested in a wind tunnel to simulate an operational environment. Results demonstrate the ability of the hybrid dense sensor network to detect, localize, and quantify damage.

Vibration-based damage detection in wind turbine blades using Phase-based Motion Estimation and motion magnification

NASA Astrophysics Data System (ADS)

Sarrafi, Aral; Mao, Zhu; Niezrecki, Christopher; Poozesh, Peyman

2018-05-01

Vibration-based Structural Health Monitoring (SHM) techniques are among the most common approaches for structural damage identification. The presence of damage in structures may be identified by monitoring the changes in dynamic behavior subject to external loading, and is typically performed by using experimental modal analysis (EMA) or operational modal analysis (OMA). These tools for SHM normally require a limited number of physically attached transducers (e.g. accelerometers) in order to record the response of the structure for further analysis. Signal conditioners, wires, wireless receivers and a data acquisition system (DAQ) are also typical components of traditional sensing systems used in vibration-based SHM. However, instrumentation of lightweight structures with contact sensors such as accelerometers may induce mass-loading effects, and for large-scale structures, the instrumentation is labor intensive and time consuming. Achieving high spatial measurement resolution for a large-scale structure is not always feasible while working with traditional contact sensors, and there is also the potential for a lack of reliability associated with fixed contact sensors in outliving the life-span of the host structure. Among the state-of-the-art non-contact measurements, digital video cameras are able to rapidly collect high-density spatial information from structures remotely. In this paper, the subtle motions from recorded video (i.e. a sequence of images) are extracted by means of Phase-based Motion Estimation (PME) and the extracted information is used to conduct damage identification on a 2.3-m long Skystream® wind turbine blade (WTB). The PME and phased-based motion magnification approach estimates the structural motion from the captured sequence of images for both a baseline and damaged test cases on a wind turbine blade. Operational deflection shapes of the test articles are also quantified and compared for the baseline and damaged states. In addition, having proper lighting while working with high-speed cameras can be an issue, therefore image enhancement and contrast manipulation has also been performed to enhance the raw images. Ultimately, the extracted resonant frequencies and operational deflection shapes are used to detect the presence of damage, demonstrating the feasibility of implementing non-contact video measurements to perform realistic structural damage detection.

Damage Tolerance of Composites

NASA Technical Reports Server (NTRS)

Hodge, Andy

2007-01-01

Fracture control requirements have been developed to address damage tolerance of composites for manned space flight hardware. The requirements provide the framework for critical and noncritical hardware assessment and testing. The need for damage threat assessments, impact damage protection plans, and nondestructive evaluation are also addressed. Hardware intended to be damage tolerant have extensive coupon, sub-element, and full-scale testing requirements in-line with the Building Block Approach concept from the MIL-HDBK-17, Department of Defense Composite Materials Handbook.

Online damage inspection of optics for ATP system

NASA Astrophysics Data System (ADS)

Chen, Jing; Jiang, Yu; Mao, Yao; Gan, Xun; Liu, Qiong

2016-09-01

In the Electro-Optical acquisition-tracking-pointing system (ATP), the optical components will be damaged with the several influencing factors. In this situation, the rate will increase sharply when the arrival of damage to some extent. As the complex processing techniques and long processing cycle of optical components, the damage will cause the great increase of the system development cost and cycle. Therefore, it is significant to detect the laser-induced damage in the ATP system. At present, the major research on the on-line damage detection technology of optical components is for the large optical system in the international. The relevant detection systems have complicated structures and many of components, and require enough installation space reserved, which do not apply for ATP system. To solve the problem mentioned before, This paper use a method based on machine vision to detect the damage on-line for the present ATP system. To start with, CCD and PC are used for image acquisition. Secondly, smoothing filters are used to restrain false damage points produced by noise. Then, with the shape feature included in the damage image, the OTSU Method which can define the best segmentation threshold automatically is used to achieve the goal to locate the damage regions. At last, we can supply some opinions for the lifetime of the optical components by analyzing the damage data, such as damage area, damage position. The method has the characteristics of few-detectors and simple-structures which can be installed without any changes of the original light path. With the method, experimental results show that it is stable and effective to achieve the goal of detecting the damage of optical components on-line in the ATP system.

Image dissector photocathode solar damage test program. [solar radiation shielding using a fast optical lens

NASA Technical Reports Server (NTRS)

Smith, R. A.

1977-01-01

Image dissector sensors of the same type which will be used in the NASA shuttle star tracker were used in a series of tests directed towards obtaining solar radiation/time damage criteria. Data were evaluated to determine the predicted level of operability of the star tracker if tube damage became a reality. During the test series a technique for reducing the solar damage effect was conceived and verified. The damage concepts are outlined and the test methods and data obtained which were used for verification of the technique's feasibility are presented. The ability to operate an image dissector sensor with the solar image focussed on the photocathode by a fast optical lens under certain conditions is feasible and the elimination of a mechanical protection device is possible.

Compendium of Current Total Ionizing Dose and Displacement Damage Results from NASA Goddard Space Flight Center and NASA Electronic Parts and Packaging Program

NASA Technical Reports Server (NTRS)

Topper, Alyson D.; Campola, Michael J.; Chen, Dakai; Casey, Megan C.; Yau, Ka-Yen; Cochran, Donna J.; Label, Kenneth A.; Ladbury, Raymond L.; Mondy, Timothy K.; O'Bryan, Martha V.;

EMP Preferred Test Procedures. Revision

DTIC Science & Technology

1977-02-01

r _ -P ~PREFERRED TEST PROCEDURES,r- -Hnbo -Tkeltted Elec-ront’c Parts) .... . ITR Projs.E6230,E6261, J.E. Bridges W.C. Emberson V.P. Nanda DNA QQ-72...Connectors Surface Transfer Impedance Shielded Enclosures Surface Transfer Admittance Shielded Rooms E- Field Shielding Conduits Effectiveness Resistor Damage H... Field Shielding Capacitor Damage Effectiveness Inductor Damage Conduit Couplers Transformer Damage Capacitor Characterization Resistor

Outer skin protection of columbium Thermal Protection System (TPS) panels

NASA Technical Reports Server (NTRS)

Culp, J. D.

1973-01-01

A coated columbium alloy material system 0.04 centimeter thick was developed which provides for increased reliability to the load bearing character of the system in the event of physical damage to and loss of the exterior protective coating. The increased reliability to the load bearing columbium alloy (FS-85) was achieved by interposing an oxidation resistant columbium alloy (B-1) between the FS-85 alloy and a fused slurry silicide coating. The B-1 alloy was applied as a cladding to the FS-85 and the composite was fused slurry silicide coated. Results of material evaluation testing included cyclic oxidation testing of specimens with intentional coating defects, tensile testing of several material combinations exposed to reentry profile conditions, and emittance testing after cycling of up to 100 simulated reentries. The clad material, which was shown to provide greater reliability than unclad materials, holds significant promise for use in the thermal protection system of hypersonic reentry vehicles.

Impact Behavior of Composite Fan Blade Leading Edge Subcomponent with Thermoplastic Polyurethane Interleave

NASA Technical Reports Server (NTRS)

Miller, Sandi G.; Roberts, Gary D.; Kohlman, Lee W.; Heimann, Paula J.; Pereira, J. Michael; Ruggeri, Charles R.; Martin, Richard E.; McCorkle, Linda S.

2015-01-01

Impact damage tolerance and damage resistance is a critical metric for application of polymer matrix composites where failure caused by impact damage could compromise structural performance and safety. As a result, several materials and/or design approaches to improve impact damage tolerance have been investigated over the past several decades. Many composite toughening methodologies impart a trade-off between increased fracture toughness and compromised in-plane strength and modulus. In large part, mechanical tests to evaluate composite damage tolerance include static methods such as Mode I, Mode II, and mixed mode failures. However, ballistic impact damage resistance does not always correlate with static properties. The intent of this paper is to evaluate the influence of a thermoplastic polyurethane veil interleave on the static and dynamic performance of composite test articles. Static coupon tests included tension, compression, double cantilever beam, and end notch flexure. Measurement of the resistance to ballistic impact damage were made to evaluate the composites response to high speed impact. The interlayer material showed a decrease of in-plane performance with only a moderate improvement to Mode I and Mode II fracture toughness. However, significant benefit to impact damage tolerance was observed through ballistic tests.

Damage Detection Sensitivity of a Vehicle-based Bridge Health Monitoring System

NASA Astrophysics Data System (ADS)

Miyamoto, Ayaho; Yabe, Akito; Lúcio, Válter J. G.

2017-05-01

As one solution to the problem for condition assessment of existing short and medium span (10-30m) reinforced/prestressed concrete bridges, a new monitoring method using a public bus as part of a public transit system (called “Bus monitoring system”) was proposed, along with safety indices, namely, “characteristic deflection”, which is relatively free from the influence of dynamic disturbances due to such factors as the roughness of the road surface, and a structural anomaly parameter. In this study, to evaluate the practicality of the newly developed bus monitoring system, it has been field-tested over a period of about four years by using an in-service fixed-route bus operating on a bus route in the city of Ube, Yamaguchi Prefecture, Japan. In here, although there are some useful monitoring methods for short and medium span bridges based on the qualitative or quantitative information, the sensitivity of damage detection was newly discussed for safety assessment based on long term health monitoring data. The verification results thus obtained are also described in this paper, and also evaluates the sensitivity of the “characteristic deflection”, which is a bridge (health) condition indicator used by the bus monitoring system, in damage detection. Sensitivity of “characteristic deflection” is verified by introducing artificial damage into a bridge that has ended its service life and is awaiting removal. Furthermore, the sensitivity of “characteristic deflection” is verified by 3D FEM analysis.

Engine materials characterization and damage monitoring by using x ray technologies

NASA Technical Reports Server (NTRS)

Baaklini, George Y.

1993-01-01

X ray attenuation measurement systems that are capable of characterizing density variations in monolithic ceramics and damage due to processing and/or mechanical testing in ceramic and intermetallic matrix composites are developed and applied. Noninvasive monitoring of damage accumulation and failure sequences in ceramic matrix composites is used during room-temperature tensile testing. This work resulted in the development of a point-scan digital radiography system and an in situ x ray material testing system. The former is used to characterize silicon carbide and silicon nitride specimens, and the latter is used to image the failure behavior of silicon-carbide-fiber-reinforced, reaction-bonded silicon nitride matrix composites. State-of-the-art x ray computed tomography is investigated to determine its capabilities and limitations in characterizing density variations of subscale engine components (e.g., a silicon carbide rotor, a silicon nitride blade, and a silicon-carbide-fiber-reinforced beta titanium matrix rod, rotor, and ring). Microfocus radiography, conventional radiography, scanning acoustic microscopy, and metallography are used to substantiate the x ray computed tomography findings. Point-scan digital radiography is a viable technique for characterizing density variations in monolithic ceramic specimens. But it is very limited and time consuming in characterizing ceramic matrix composites. Precise x ray attenuation measurements, reflecting minute density variations, are achieved by photon counting and by using microcollimators at the source and the detector. X ray computed tomography is found to be a unique x ray attenuation measurement technique capable of providing cross-sectional spatial density information in monolithic ceramics and metal matrix composites. X ray computed tomography is proven to accelerate generic composite component development. Radiographic evaluation before, during, and after loading shows the effect of preexisting volume flaws on the fracture behavior of composites. Results from one-, three-, five-, and eight-ply ceramic composite specimens show that x ray film radiography can monitor damage accumulation during tensile loading. Matrix cracking, fiber-matrix debonding, fiber bridging, and fiber pullout are imaged throughout the tensile loading of the specimens. In situ film radiography is found to be a practical technique for estimating interfacial shear strength between the silicon carbide fibers and the reaction-bonded silicon nitride matrix. It is concluded that pretest, in situ, and post-test x ray imaging can provide greater understanding of ceramic matrix composite mechanical behavior.

Radial Basis Function Neural Network Application to Power System Restoration Studies

PubMed Central

Sadeghkhani, Iman; Ketabi, Abbas; Feuillet, Rene

2012-01-01

One of the most important issues in power system restoration is overvoltages caused by transformer switching. These overvoltages might damage some equipment and delay power system restoration. This paper presents a radial basis function neural network (RBFNN) to study transformer switching overvoltages. To achieve good generalization capability for developed RBFNN, equivalent parameters of the network are added to RBFNN inputs. The developed RBFNN is trained with the worst-case scenario of switching angle and remanent flux and tested for typical cases. The simulated results for a partial of 39-bus New England test system show that the proposed technique can estimate the peak values and duration of switching overvoltages with good accuracy. PMID:22792093

Vulnerability Methodology and Protective Measures for Aircraft Fire and Explosion Hazards. Volume 2. Aircraft Engine Nacelle Fire Test Programs. Part 1. Fire Detection, Fire Extinguishment and Surface Ignition Studies

DTIC Science & Technology

1986-01-01

by sensors in the test cell and sampled, digitized, averaged, and calibrated by the facility computer system. The data included flowrates calculated ...before the next test could be started. This required about 2 minutes. 6.4 Combat Damage Testing Appendix C contains calculations and analysis...were comparable (Figure 7-5). Agent quantities required per MIL-E-22285 were again calculated using the equations noted in paragraph 7.1.1. The

Social Justice and Evidence-Based Assessment with the Learning Record

ERIC Educational Resources Information Center

Syverson, Margaret A.

2009-01-01

The educational system perpetuates social injustice through structural inequities of assessment and evaluation. High-stakes standardized testing has a destructive effect on teaching and learning that affects all students, teachers, and schools; it is particularly damaging for disadvantaged students--minorities, students with disabilities, students…

Laser Drilling Development Trial Final Report CRADA No. TSB-1538-98

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hermann, M. R.; Hebbar, R. R.

This project performed various laser drilling tests to demonstrate femtosecond laser drilling of fuel injector nozzles with minimal recast, minimal heat affected zone and no collateral damage. LLNL had extensive experience in ultra short-pulse laser systems and developed specialized hardware for these applications.

Pilot simulation tests of propulsion control as backup to loss of primary flight controls for a mid-size jet transport

DOT National Transportation Integrated Search

1995-12-01

Partial failures of aircraft primary flight-control systems and structural : damages to aircraft during flight have led to catastrophic accidents with : subsequent loss of life. These accidents can be prevented if sufficient : alternate control autho...

Materials testing of the IUS techroll seal material

NASA Technical Reports Server (NTRS)

Nichols, R. L.; Hall, W. B.

1984-01-01

As a part of the investigation of the control system failure Inertial Upper Stage on IUS-1 flight to position a Tracking and Data Relay Satellite (TDRS) in geosynchronous orbit, the materials utilized in the techroll seal are evaluated for possible failure models. Studies undertaken included effect of temperature on the strength of the system, effect of fatigue on the strength of the system, thermogravimetric analysis, thermomechanical analysis, differential scanning calorimeter analysis, dynamic mechanical analysis, and peel test. The most likely failure mode is excessive temperature in the seal. In addition, the seal material is susceptible to fatigue damage which could be a contributing factor.

Aircraft Survivability: Aircraft Battle Damage and Repair, Summer 2007

DTIC Science & Technology

2007-01-01

Modeling and Analysis Program ( TMAP ) Missile Modeling System for Advanced Investigation of Countermeasures (MOSAIC) & Joint Surface-to-Air Missle... TMAP Threat System Models (TSM) into engagement simulations (MOSAIC [IR] and JSAMS [RF]). This 3-year project will integrate and fully test six...three per engagement simulation) JASC priority TMAP TSMs in official releases of MOSAIC and JSAMS. Project Engineers— Luke Borntrager (USAF, AFRL) and

Active Reliability Engineering - Technical Concept and Program Plan. A Solid-State Systems Approach to Increased Reliability and Availability in Military Systems.

DTIC Science & Technology

1983-10-05

battle damage. Others are local electrical power and cooling disruptions. Again, a highly critical function is lost if its computer site is destroyed. A...formalized design of the test bed to meet the requirements of the functional description and goals of the program. AMTEC --Z3IT TASKS: 610, 710, 810

Histopomorphic Evaluation of Radiofrequency Mediated Débridement Chondroplasty

PubMed Central

Ganguly, Kumkum; McRury, Ian D; Goodwin, Peter M; Morgan, Roy E; Augé II, Wayne K

2010-01-01

The use of radiofrequency devices has become widespread for surgical ablation procedures. When ablation devices have been deployed in treatment settings requiring tissue preservation like débridement chondroplasty, adoption has been limited due to the collateral damage caused by these devices in healthy tissue surrounding the treatment site. Ex vivo radiofrequency mediated débridement chondroplasty was performed on osteochondral specimens demonstrating surface fibrillation obtained from patients undergoing knee total joint replacement. Three radiofrequency systems designed to perform débridement chondroplasty were tested each demonstrating different energy delivery methods: monopolar ablation, bipolar ablation, and non-ablation energy. Treatment outcomes were compared with control specimens as to clinical endpoint and histopomorphic characteristics. Fibrillated cartilage was removed in all specimens; however, the residual tissue remaining at the treatment site displayed significantly different characteristics attributable to radiofrequency energy delivery method. Systems that delivered ablation-based energies caused tissue necrosis and collateral damage at the treatment site including corruption of cartilage Superficial and Transitional Zones; whereas, the non-ablation system created a smooth articular surface with Superficial Zone maintenance and without chondrocyte death or tissue necrosis. The mechanism of radiofrequency energy deposition upon tissues is particularly important in treatment settings requiring tissue preservation. Ablation-based device systems can cause a worsened state of articular cartilage from that of pre-treatment. Non-ablation energy can be successful in modifying/preconditioning tissue during débridement chondroplasty without causing collateral damage. Utilizing a non-ablation radiofrequency system provides the ability to perform successful débridement chondroplasty without causing additional articular cartilage tissue damage and may allow for other cartilage intervention success. PMID:20721322

Shake table tests of suspended ceilings to simulate the observed damage in the M s7.0 Lushan earthquake, China

NASA Astrophysics Data System (ADS)

Wang, Duozhi; Dai, Junwu; Qu, Zhe; Ning, Xiaoqing

2016-06-01

Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M s7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.

Fast shut-down protection system for radio frequency breakdown and multipactor testing.

PubMed

Graves, T P; Hanson, P; Michaelson, J M; Farkas, A D; Hubble, A A

2014-02-01

Radio frequency (RF) breakdown such as multipactor or ionization breakdown is a device-limiting phenomenon for on-orbit spacecraft used for communication, navigation, or other RF payloads. Ground testing is therefore part of the qualification process for all high power components used in these space systems. This paper illustrates a shut-down protection system to be incorporated into multipactor/ionization breakdown ground testing for susceptible RF devices. This 8 channel system allows simultaneous use of different diagnostic classes and different noise floors. With initiation of a breakdown event, diagnostic signals increase above a user-specified level, which then opens an RF switch to eliminate RF power from the high power amplifier. Examples of this system in use are shown for a typical setup, illustrating the reproducibility of breakdown threshold voltages and the lack of multipactor conditioning. This system can also be utilized to prevent excessive damage to RF components in tests with sensitive or flight hardware.

Flight Test Implementation of a Second Generation Intelligent Flight Control System

NASA Technical Reports Server (NTRS)

Williams-Hayes, Peggy S.

2005-01-01

The NASA F-15 Intelligent Flight Control System project team has developed a series of flight control concepts designed to demonstrate the benefits of a neural network-based adaptive controller. The objective of the team was to develop and flight-test control systems that use neural network technology, to optimize the performance of the aircraft under nominal conditions, and to stabilize the aircraft under failure conditions. Failure conditions include locked or failed control surfaces as well as unforeseen damage that might occur to the aircraft in flight. The Intelligent Flight Control System team is currently in the process of implementing a second generation control scheme, collectively known as Generation 2 or Gen 2, for flight testing on the NASA F-15 aircraft. This report describes the Gen 2 system as implemented by the team for flight test evaluation. Simulation results are shown which describe the experiment to be performed in flight and highlight the ways in which the Gen 2 system meets the defined objectives.

Behavioral pattern identification for structural health monitoring in complex systems

NASA Astrophysics Data System (ADS)

Gupta, Shalabh

Estimation of structural damage and quantification of structural integrity are critical for safe and reliable operation of human-engineered complex systems, such as electromechanical, thermofluid, and petrochemical systems. Damage due to fatigue crack is one of the most commonly encountered sources of structural degradation in mechanical systems. Early detection of fatigue damage is essential because the resulting structural degradation could potentially cause catastrophic failures, leading to loss of expensive equipment and human life. Therefore, for reliable operation and enhanced availability, it is necessary to develop capabilities for prognosis and estimation of impending failures, such as the onset of wide-spread fatigue crack damage in mechanical structures. This dissertation presents information-based online sensing of fatigue damage using the analytical tools of symbolic time series analysis ( STSA). Anomaly detection using STSA is a pattern recognition method that has been recently developed based upon a fixed-structure, fixed-order Markov chain. The analysis procedure is built upon the principles of Symbolic Dynamics, Information Theory and Statistical Pattern Recognition. The dissertation demonstrates real-time fatigue damage monitoring based on time series data of ultrasonic signals. Statistical pattern changes are measured using STSA to monitor the evolution of fatigue damage. Real-time anomaly detection is presented as a solution to the forward (analysis) problem and the inverse (synthesis) problem. (1) the forward problem - The primary objective of the forward problem is identification of the statistical changes in the time series data of ultrasonic signals due to gradual evolution of fatigue damage. (2) the inverse problem - The objective of the inverse problem is to infer the anomalies from the observed time series data in real time based on the statistical information generated during the forward problem. A computer-controlled special-purpose fatigue test apparatus, equipped with multiple sensing devices (e.g., ultrasonics and optical microscope) for damage analysis, has been used to experimentally validate the STSA method for early detection of anomalous behavior. The sensor information is integrated with a software module consisting of the STSA algorithm for real-time monitoring of fatigue damage. Experiments have been conducted under different loading conditions on specimens constructed from the ductile aluminium alloy 7075 - T6. The dissertation has also investigated the application of the STSA method for early detection of anomalies in other engineering disciplines. Two primary applications include combustion instability in a generic thermal pulse combustor model and whirling phenomenon in a typical misaligned shaft.

Potential role of punicalagin against oxidative stress induced testicular damage.

PubMed

Rao, Faiza; Tian, Hui; Li, Wenqing; Hung, Helong; Sun, Fei

2016-01-01

Punicalagin is isolated from pomegranate and widely used for the treatment of different diseases in Chinese traditional medicine. This study aimed to evaluate the effect of Punicalagin (purity ≥98%) on oxidative stress induced testicular damage and its effect on fertility. We detected the antioxidant potential of punicalagin in lipopolysaccharide (LPS) induced oxidative stress damage in testes, also tried to uncover the boosting fertility effect of Punicalagin (PU) against oxidative stress-induced infertility. Results demonstrated that 9 mg kg-1 for 7 days treatment significantly decreases LPS induced oxidative damage in testes and nitric oxide production. The administration of oxidative stress resulted in a significant reduction in testes antioxidants GSH, T-SOD, and CAT raised LPO, but treatment with punicalagin for 7 days increased antioxidant defense GSH, T-SOD, and CAT by the end of the experiment and reduced LPO level as well. PU also significantly activates Nrf2, which is involved in regulation of antioxidant defense systems. Hence, the present research categorically elucidates the protective effect of punicalagin against LPS induced oxidative stress induced perturbation in the process of spermatogenesis and significantly increased sperm health and number. Moreover, fertility success significantly decreased in LPS-injected mice compared to controls. Mice injected with LPS had fertility indices of 12.5%, while others treated with a combination of PU + LPS exhibited 75% indices. By promoting fertility and eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of infertility.

Potential role of punicalagin against oxidative stress induced testicular damage

PubMed Central

Rao, Faiza; Tian, Hui; Li, Wenqing; Hung, Helong; Sun, Fei

2016-01-01

Punicalagin is isolated from pomegranate and widely used for the treatment of different diseases in Chinese traditional medicine. This study aimed to evaluate the effect of Punicalagin (purity ≥98%) on oxidative stress induced testicular damage and its effect on fertility. We detected the antioxidant potential of punicalagin in lipopolysaccharide (LPS) induced oxidative stress damage in testes, also tried to uncover the boosting fertility effect of Punicalagin (PU) against oxidative stress-induced infertility. Results demonstrated that 9 mg kg−1 for 7 days treatment significantly decreases LPS induced oxidative damage in testes and nitric oxide production. The administration of oxidative stress resulted in a significant reduction in testes antioxidants GSH, T-SOD, and CAT raised LPO, but treatment with punicalagin for 7 days increased antioxidant defense GSH, T-SOD, and CAT by the end of the experiment and reduced LPO level as well. PU also significantly activates Nrf2, which is involved in regulation of antioxidant defense systems. Hence, the present research categorically elucidates the protective effect of punicalagin against LPS induced oxidative stress induced perturbation in the process of spermatogenesis and significantly increased sperm health and number. Moreover, fertility success significantly decreased in LPS-injected mice compared to controls. Mice injected with LPS had fertility indices of 12.5%, while others treated with a combination of PU + LPS exhibited 75% indices. By promoting fertility and eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of infertility. PMID:26763544

Sub-Lethal Dose of Shiga Toxin 2 from Enterohemorrhagic Escherichia coli Affects Balance and Cerebellar Cytoarchitecture

PubMed Central

Pinto, Alipio; Cangelosi, Adriana; Geoghegan, Patricia A.; Tironi-Farinati, Carla; Brener, Gabriela J.; Goldstein, Jorge

2016-01-01

Shiga toxin producing Escherichia coli may damage the central nervous system before or concomitantly to manifested hemolytic–uremic syndrome symptoms. The cerebellum is frequently damaged during this syndrome, however, the deleterious effects of Shiga toxin 2 has never been integrally reported by ultrastructural, physiological and behavioral means. The aim of this study was to determine the cerebellar compromise after intravenous administration of a sub-lethal dose of Shiga toxin 2 by measuring the cerebellar blood–brain barrier permeability, behavioral task of cerebellar functionality (inclined plane test), and ultrastructural analysis (transmission electron microscope). Intravenous administration of vehicle (control group), sub-lethal dose of 0.5 and 1 ηg of Stx2 per mouse were tested for behavioral and ultrastructural studies. A set of three independent experiments were performed for each study (n = 6). Blood–brain barrier resulted damaged and consequently its permeability was significantly increased. Lower scores obtained in the inclined plane task denoted poor cerebellar functionality in comparison to their controls. The most significant lower score was obtained after 5 days of 1 ηg of toxin administration. Transmission electron microscope micrographs from the Stx2-treated groups showed neurons with a progressive neurodegenerative condition in a dose dependent manner. As sub-lethal intravenous Shiga toxin 2 altered the blood brain barrier permeability in the cerebellum the toxin penetrated the cerebellar parenchyma and produced cell damaged with significant functional implications in the test balance. PMID:26904009

Comparing Different Fault Identification Algorithms in Distributed Power System

NASA Astrophysics Data System (ADS)

Alkaabi, Salim

A power system is a huge complex system that delivers the electrical power from the generation units to the consumers. As the demand for electrical power increases, distributed power generation was introduced to the power system. Faults may occur in the power system at any time in different locations. These faults cause a huge damage to the system as they might lead to full failure of the power system. Using distributed generation in the power system made it even harder to identify the location of the faults in the system. The main objective of this work is to test the different fault location identification algorithms while tested on a power system with the different amount of power injected using distributed generators. As faults may lead the system to full failure, this is an important area for research. In this thesis different fault location identification algorithms have been tested and compared while the different amount of power is injected from distributed generators. The algorithms were tested on IEEE 34 node test feeder using MATLAB and the results were compared to find when these algorithms might fail and the reliability of these methods.

Damage detection of building structures under ambient excitation through the analysis of the relationship between the modal participation ratio and story stiffness

NASA Astrophysics Data System (ADS)

Park, Hyo Seon; Oh, Byung Kwan

2018-03-01

This paper presents a new approach for the damage detection of building structures under ambient excitation based on the inherent modal characteristics. In this study, without the extraction of modal parameters widely utilized in the previous studies on damage detection, a new index called the modal participation ratio (MPR), which is a representative value of the modal response extracted from dynamic responses measured in ambient vibration tests, is proposed to evaluate the change of the system of a structure according to the reduction of the story stiffness. The relationship between the MPR, representing a modal contribution for a specific mode and degree of freedom in buildings, and the story stiffness damage factor (SSDF), representing the extent of reduction in the story stiffness, is analyzed in various damage scenarios. From the analyses with three examples, several rules for the damage localization of building structures are found based on the characteristics of the MPR variation for the first mode subject to change in the SSDF. In addition, a damage severity function, derived from the relationship between the MPR for the first mode in the lowest story and the SSDF, is constructed to identify the severity of story stiffness reduction. Furthermore, the locations and severities of multiple damages are identified via the superposition of the presented damage severity functions. The presented method was applied to detect damage in a three-dimensional reinforced concrete (RC) structure.

Experimental Hypersonic Aerodynamic Characteristics of the Space Shuttle Orbiter for a Range of Damage Scenarios

NASA Technical Reports Server (NTRS)

Brauckman, Gregory J.; Scallion, William I.

2003-01-01

Aerodynamic tests in support of the Columbia accident investigation were conducted in two hypersonic wind tunnels at the NASA Langley Research Center, the 20-Inch Mach 6 Air Tunnel and the 20-Inch Mach 6 CF4 Tunnel. The primary purpose of these tests was to measure the forces and moments generated by a variety of outer mold line alterations (damage scenarios) using 0.0075-scale models of the Space Shuttle Orbiter (approximately 10 inches in length). Simultaneously acquired global heat transfer mappings were obtained for a majority of the configurations tested. Test parameters include angles of attack from 38 to 42 deg, unit Reynolds numbers from 0.26 to 3.0 x10^6 per foot, and normal shock density ratios of 5 (Mach 6 air) and 12 (Mach 6 CF4). The damage scenarios evaluated included asymmetric boundary layer transition, gouges in the windward surface acreage thermal protection system tiles, wing leading edge damage (partially and fully missing reinforced carbon-carbon (RCC) panels), holes through the wing from the windward surface to the leeside, deformation of the wing windward surface, and main landing gear door and/or gear deployment. The aerodynamic data were compared to the magnitudes and directions observed in flight, and the heating images were evaluated in terms of the location of the generated disturbances and how these disturbance might relate to the response of discrete gages on the Columbia Orbiter vehicle during entry. The measured aerodynamic increments were generally small in magnitude, as were the flight-derived values during most of the entry. Asymmetric boundary layer transition (ABLT) results were consistent with the flight-derived Shuttle ABLT model, but not with the observed flight trends for STS-107. The partially missing leading edge panel results best matched both the early aerodynamic and heating trends observed in flight. A progressive damage scenario is presented that qualitatively matches the flight observations for the full entry.

A continuous damage model based on stepwise-stress creep rupture tests

NASA Technical Reports Server (NTRS)

Robinson, D. N.

1985-01-01

A creep damage accumulation model is presented that makes use of the Kachanov damage rate concept with a provision accounting for damage that results from a variable stress history. This is accomplished through the introduction of an additional term in the Kachanov rate equation that is linear in the stress rate. Specification of the material functions and parameters in the model requires two types of constituting a data base: (1) standard constant-stress creep rupture tests, and (2) a sequence of two-step creep rupture tests.