Correlation Results for a Mass Loaded Vehicle Panel Test Article Finite Element Models and Modal Survey Tests

NASA Technical Reports Server (NTRS)

Maasha, Rumaasha; Towner, Robert L.

2012-01-01

High-fidelity Finite Element Models (FEMs) were developed to support a recent test program at Marshall Space Flight Center (MSFC). The FEMs correspond to test articles used for a series of acoustic tests. Modal survey tests were used to validate the FEMs for five acoustic tests (a bare panel and four different mass-loaded panel configurations). An additional modal survey test was performed on the empty test fixture (orthogrid panel mounting fixture, between the reverb and anechoic chambers). Modal survey tests were used to test-validate the dynamic characteristics of FEMs used for acoustic test excitation. Modal survey testing and subsequent model correlation has validated the natural frequencies and mode shapes of the FEMs. The modal survey test results provide a basis for the analysis models used for acoustic loading response test and analysis comparisons

Buckling Response of a Large-Scale, Seamless, Orthogrid-Stiffened Metallic Cylinder

NASA Technical Reports Server (NTRS)

Rudd, Michelle Tillotson; Hilburger, Mark W.; Lovejoy, Andrew E.; Lindell, Michael C.; Gardner, Nathaniel W.; Schultz, Marc R.

2018-01-01

Results from the buckling test of a compression-loaded 8-ft-diameter seamless (i.e., without manufacturing joints), orthogrid-stiffened metallic cylinder are presented. This test was used to assess the buckling response and imperfection sensitivity characteristics of a seamless cylinder. In addition, the test article and test served as a technology demonstration to show the application of the flow forming manufacturing process to build more efficient buckling-critical structures by eliminating the welded joints that are traditionally used in the manufacturing of large metallic barrels. Pretest predictions of the cylinder buckling response were obtained using a finite-element model that included measured geometric imperfections. The buckling load predicted using this model was 697,000 lb, and the test article buckled at 743,000 lb (6% higher). After the test, the model was revised to account for measured variations in skin and stiffener geometry, nonuniform loading, and material properties. The revised model predicted a buckling load of 754,000 lb, which is within 1.5% of the tested buckling load. In addition, it was determined that the load carrying capability of the seamless cylinder is approximately 28% greater than a corresponding cylinder with welded joints.

Details of Side Load Test Data and Analysis for a Truncated Ideal Contour Nozzle and a Parabolic Contour Nozzle

NASA Technical Reports Server (NTRS)

Ruf, Joseph H.; McDaniels, David M.; Brown, Andrew M.

2010-01-01

Two cold flow subscale nozzles were tested for side load characteristics during simulated nozzle start transients. The two test article contours were a truncated ideal and a parabolic. The current paper is an extension of a 2009 AIAA JPC paper on the test results for the same two nozzle test articles. The side load moments were measured with the strain tube approach in MSFC s Nozzle Test Facility. The processing techniques implemented to convert the strain gage signals into side load moment data are explained. Nozzle wall pressure profiles for separated nozzle flow at many NPRs are presented and discussed in detail. The effect of the test cell diffuser inlet on the parabolic nozzle s wall pressure profiles for separated flow is shown. The maximum measured side load moments for the two contours are compared. The truncated ideal contour s peak side load moment was 45% of that of the parabolic contour. The calculated side load moments, via mean-plus-three-standard-deviations at each nozzle pressure ratio, reproduced the characteristics and absolute values of measured maximums for both contours. The effect of facility vibration on the measured side load moments is quantified and the effect on uncertainty is calculated. The nozzle contour designs are discussed and the impact of a minor fabrication flaw in the nozzle contours is explained.

Nonlinear Analysis and Preliminary Testing Results of a Hybrid Wing Body Center Section Test Article

NASA Technical Reports Server (NTRS)

Przekop, Adam; Jegley, Dawn C.; Rouse, Marshall; Lovejoy, Andrew E.; Wu, Hsi-Yung T.

2015-01-01

A large test article was recently designed, analyzed, fabricated, and successfully tested up to the representative design ultimate loads to demonstrate that stiffened composite panels with through-the-thickness reinforcement are a viable option for the next generation large transport category aircraft, including non-conventional configurations such as the hybrid wing body. This paper focuses on finite element analysis and test data correlation of the hybrid wing body center section test article under mechanical, pressure and combined load conditions. Good agreement between predictive nonlinear finite element analysis and test data is found. Results indicate that a geometrically nonlinear analysis is needed to accurately capture the behavior of the non-circular pressurized and highly-stressed structure when the design approach permits local buckling.

BMI Sandwich Wing Box Analysis and Test

NASA Technical Reports Server (NTRS)

Palm, Tod; Mahler, Mary; Shah, Chandu; Rouse, Marshall; Bush, Harold; Wu, Chauncey; Small, William J.

2000-01-01

A composite sandwich single bay wing box test article was developed by Northrop Grumman and tested recently at NASA Langley Research Center. The objectives for the wing box development effort were to provide a demonstration article for manufacturing scale up of structural concepts related to a high speed transport wing, and to validate the structural performance of the design. The box concept consisted of highly loaded composite sandwich wing skins, with moderately loaded composite sandwich spars. The dimensions of the box were chosen to represent a single bay of the main wing box, with a spar spacing of 30 inches, height of 20 inches constant depth, and length of 64 inches. The bismaleimide facesheet laminates and titanium honeycomb core chosen for this task are high temperature materials able to sustain a 300F service temperature. The completed test article is shown in Figure 1. The tests at NASA Langley demonstrated the structures ability to sustain axial tension and compression loads in excess of 20,000 lb/in, and to maintain integrity in the thermal environment. Test procedures, analysis failure predictions, and test results are presented.

Cardboard Activity Is "Loaded" with Learning

ERIC Educational Resources Information Center

Roman, Harry T.

2010-01-01

In this article, the author presents an activity that uses simple paperboard from the back of a pad of paper to illustrate some basic construction principles as students experiment with conducting load tests. The author describes the steps in conducting a load test as well as adding a strut support system. The important lesson here is that…

Non-Invasive Tension Measurement Devices for Parachute Cordage

NASA Technical Reports Server (NTRS)

Litteken, Douglas A.; Daum, Jared S.

2016-01-01

The need for lightweight and non-intrusive tension measurements has arisen alongside the development of high-fidelity computer models of textile and fluid dynamics. In order to validate these computer models, data must be gathered in the operational environment without altering the design, construction, or performance of the test article. Current measurement device designs rely on severing a cord and breaking the load path to introduce a load cell. These load cells are very reliable, but introduce an area of high stiffness in the load path, directly affecting the structural response, adding excessive weight, and possibly altering the dynamics of the parachute during a test. To capture the required data for analysis validation without affecting the response of the system, non-invasive measurement devices have been developed and tested by NASA. These tension measurement devices offer minimal impact to the mass, form, fit, and function of the test article, while providing reliable, axial tension measurements for parachute cordage.

Change in Soil Porosity under Load

NASA Astrophysics Data System (ADS)

Dyba, V. P.; Skibin, E. G.

2017-11-01

The theoretical basis for the process of soil compaction under various loading paths is considered in the article, the theoretical assumptions are compared with the results of the tests of clay soil on a stabilometer. The variant of the critical state model of the sealing plastic-rigid environment is also considered the strength characteristics of which depend on the porosity coefficient. The loading surface is determined by the results of compression and stabilometrical tests. In order to clarify the results of this task, it is necessary to carry out stabilometric tests under conditions of simple loading, i.e. where the vertical pressure would be proportional to the compression pressure σ3 = kσ1. Within the study the attempts were made to confirm the model given in the beginning of the article by laboratory tests. After the analysis of the results, the provided theoretical assumptions were confirmed.

SLS Intertank Test Article, ITA, is attached to crosshead of loa

NASA Image and Video Library

2018-04-04

SLS Intertank Test Article, ITA, is attached to crosshead of load test Annex, Bldg. 4619, and removed from bed of KMAG transporter. ITA is slowly raised from bed of KMAG transporter and KMAG is removed.

Thermal and Fluid Modeling of the CRYogenic Orbital TEstbed (CRYOTE) Ground Test Article (GTA)

NASA Technical Reports Server (NTRS)

Piryk, David; Schallhorn, Paul; Walls, Laurie; Stopnitzky, Benny; Rhys, Noah; Wollen, Mark

2012-01-01

The purpose of this study was to anchor thermal and fluid system models to data acquired from a ground test article (GTA) for the CRYogenic Orbital TEstbed - CRYOTE. To accomplish this analysis, it was broken into four primary tasks. These included model development, pre-test predictions, testing support at Marshall Space Flight Center (MSFC} and post-test correlations. Information from MSFC facilitated the task of refining and correlating the initial models. The primary goal of the modeling/testing/correlating efforts was to characterize heat loads throughout the ground test article. Significant factors impacting the heat loads included radiative environments, multi-layer insulation (MLI) performance, tank fill levels, tank pressures, and even contact conductance coefficients. This paper demonstrates how analytical thermal/fluid networks were established, and it includes supporting rationale for specific thermal responses seen during testing.

Space Shuttle Projects

NASA Image and Video Library

1987-07-01

A forward segment is being lowered into the Transient Pressure Test Article (TPTA) test stand at the Marshall Space Flight Center (MSFC) east test area. The TPTA test stand, 14-feet wide, 27-feet long, and 33-feet high, was built in 1987 to provide data to verify the sealing capability of the redesign solid rocket motor (SRM) field and nozzle joints. The test facility applies pressure, temperature, and external loads to a short stack of solid rocket motor hardware. The simulated SRM ignition pressure and temperature transients are achieved by firing a small amount of specially configured solid propellant. The pressure transient is synchronized with external programmable dynamic loads that simulate lift off loads at the external tank attach points. Approximately one million pounds of dead weight on top of the test article simulates the weight of the other Shuttle elements.

Space Shuttle Projects

NASA Image and Video Library

1987-07-01

A forward segment is being lowered into the Transient Pressure Test Article (TPTA) test stand at thw Marshall Space Flight Center (MSFC) east test area. The TPTA test stand, 14-feet wide, 27-feet long, and 33-feet high, was built in 1987 to provide data to verify the sealing capability of the redesign solid rocket motor (SRM) field and nozzle joints. The test facility applies pressure, temperature, and external loads to a short stack of solid rocket motor hardware. The simulated SRM ignition pressure and temperature transients are achieved by firing a small amount of specially configured solid propellant. The pressure transient is synchronized with external programmable dynamic loads that simulate lift off loads at the external tank attach points. Approximately one million pounds of dead weight on top of the test article simulates the weight of the other Shuttle elements.

SLS Engine Section Test Article Loaded on Barge Pegasus at NASA's Michoud Assembly Facility

NASA Image and Video Library

2017-04-27

A NASA move team loaded the engine section structural qualification test article for the Space Launch System into the barge Pegasus docked in the harbor at NASA's Michoud Assembly Facility in New Orleans. The rocket's engine section is the bottom of the core stage and houses the four RS-25 engines. The engine section test article was moved from Building 103, Michoud’s 43-acre rocket factory, to the barge where it was loaded for a river trip to NASA’s Marshall Space Flight Center in Huntsville, Alabama. The bottom part of the test article is structurally the same as the engine section that will be flown as part of the SLS core stage. The shiny metal top part simulates the rocket's liquid hydrogen tank, which is the fuel tank that joins to the engine section. The barge Pegasus will travel 1,240 miles by river to Marshall and endure tests that pull, push, and bend it, subjecting it to millions of pounds of force. This ensures the structure can withstand the incredible stresses produced by the 8.8 million pounds of thrust during launch and ascent.

13.1 Foot Diameter Fluted-Core Sandwich Composite Test Article

NASA Image and Video Library

2013-09-26

White light shape and measurement of a 13.1 Foot diameter fluted-core sandwich composite test article designed by LaRC and fabricated by Boeing Under Space Act Agreement SAA1-737, Annex 14. to be tested in LaRC's combined Loads Testing System (COLTS).

13.1 Foot Diameter Fluted-Core Sandwich Composite Test Article

NASA Image and Video Library

2013-09-25

White light shape and measurement of a 13.1 Foot diameter fluted-core sandwich composite test article designed by LaRC and fabricated by Boeing Under Space Act Agreement SAA1-737, Annex 14. to be tested in LaRC's combined Loads Testing System (COLTS).

Fatigue data for polyether ether ketone (PEEK) under fully-reversed cyclic loading

PubMed Central

Shrestha, Rakish; Simsiriwong, Jutima; Shamsaei, Nima

2016-01-01

In this article, the data obtained from the uniaxial fully-reversed fatigue experiments conducted on polyether ether ketone (PEEK), a semi-crystalline thermoplastic, are presented. The tests were performed in either strain-controlled or load-controlled mode under various levels of loading. The data are categorized into four subsets according to the type of tests, including (1) strain-controlled fatigue tests with adjusted frequency to obtain the nominal temperature rise of the specimen surface, (2) strain-controlled fatigue tests with various frequencies, (3) load-controlled fatigue tests without step loadings, and (4) load-controlled fatigue tests with step loadings. Accompanied data for each test include the fatigue life, the maximum (peak) and minimum (valley) stress–strain responses for each cycle, and the hysteresis stress–strain responses for each collected cycle in a logarithmic increment. A brief description of the experimental method is also given. PMID:26937465

Fatigue data for polyether ether ketone (PEEK) under fully-reversed cyclic loading.

PubMed

Shrestha, Rakish; Simsiriwong, Jutima; Shamsaei, Nima

2016-03-01

In this article, the data obtained from the uniaxial fully-reversed fatigue experiments conducted on polyether ether ketone (PEEK), a semi-crystalline thermoplastic, are presented. The tests were performed in either strain-controlled or load-controlled mode under various levels of loading. The data are categorized into four subsets according to the type of tests, including (1) strain-controlled fatigue tests with adjusted frequency to obtain the nominal temperature rise of the specimen surface, (2) strain-controlled fatigue tests with various frequencies, (3) load-controlled fatigue tests without step loadings, and (4) load-controlled fatigue tests with step loadings. Accompanied data for each test include the fatigue life, the maximum (peak) and minimum (valley) stress-strain responses for each cycle, and the hysteresis stress-strain responses for each collected cycle in a logarithmic increment. A brief description of the experimental method is also given.

Experimental Study of the Compression Response of Fluted-Core Composite Panels with Joints

NASA Technical Reports Server (NTRS)

Schultz, Marc R.; Rose, Cheryl A.; Guzman, J. Carlos; McCarville, Douglas; Hilburger, Mark W.

2012-01-01

Fluted-core sandwich composites consist of integral angled web members spaced between laminate face sheets, and may have the potential to provide benefits over traditional sandwich composites for certain aerospace applications. However, fabrication of large autoclave-cured fluted-core cylindrical shells with existing autoclaves will require that the shells be fabricated in segments, and joined longitudinally to form a complete barrel. Two different longitudinal fluted-core joint designs were considered experimentally in this study. In particular, jointed fluted-core-composite panels were tested in longitudinal compression because longitudinal compression is the primary loading condition in dry launch-vehicle barrel sections. One of the joint designs performed well in comparison with unjointed test articles, and the other joint design failed at loads approximately 14% lower than unjointed test articles. The compression-after-impact (CAI) performance of jointed fluted-core composites was also investigated by testing test articles that had been subjected to 6 ft-lb impacts. It was found that such impacts reduced the load-carrying capability by 9% to 40%. This reduction is dependent on the joint concept, component flute size, and facesheet thickness.

Electronic load as part of the test complex of the power processing unit of electric and plasma propulsion

NASA Astrophysics Data System (ADS)

Chubov, S. V.; Soldatov, A. I.

2017-02-01

This article provides the advantages and technical solutions for the use of electronic loads as part of a testing complex of power and management systems of electric and plasma propulsion of three types. The paper shows the parameters that were applied to select the electronic loads and describes their functionality.

Transient Pressure Test Article (TPTA) 1.1 and 1.1A, volume 1

NASA Technical Reports Server (NTRS)

Rebells, Clarence A.

1988-01-01

This final test report presents the results obtained during the static hot firing and cold-gas high Q tests of the first Transient Pressure Test Article (TPTA) 1.1. The TPTA consisted of field test joints A and B, which were the original RSRM J-insulation configuration, with a metal capture feature. It also consisted of a flight configuration nozzle-to-case test joint (Joint D) with shorter vent slots. Fluorocarbon O-rings were used in all the test joints. The purpose of the TPTA tests is to evaluate and characterize the RSMR field and nozzle-to-case joints under the influence of ignition and strut loads during liftoff anf high Q. All objectives of the cold-gas high Q (TPTA 1.1A) test were met and all measurements were close to predicted values. During the static hot-firing test (TPTA 1.1), the motor was inadvertently plugged by the quench injector plug, making it a more severe test, although no strut loads were applied. The motor was depressurized after approximately 11 min using an auxiliary system, and no anomalies were noted. In the static hot-firing test, pressure was incident on the insulation and the test joint gaps were within the predicted range. During the static hot-firing test, no strut loads were applied because the loading system malfunctioned. For this test, all measurements were within range of similar tests performed without strut loads.

Mapping HIV community viral load: space, power and the government of bodies

PubMed Central

Gagnon, Marilou; Guta, Adrian

2012-01-01

HIV plasma viral load testing has become more than just a clinical tool to monitor treatment response at the individual level. Increasingly, individual HIV plasma viral load testing is being reported to public health agencies and is used to inform epidemiological surveillance and monitor the presence of the virus collectively using techniques to measure ‘community viral load’. This article seeks to formulate a critique and propose a novel way of theorizing community viral load. Based on the salient work of Michel Foucault, especially the governmentality literature, this article critically examines the use of community viral load as a new strategy of government. Drawing also on the work of Miller and Rose, this article explores the deployment of ‘community’ through the re-configuration of space, the problematization of viral concentrations in specific microlocales, and the government (in the Foucauldian sense) of specific bodies which are seen as ‘risky’, dangerous and therefore, in need of attention. It also examines community viral load as a necessary precondition — forming the ‘conditions of possibility’ — for the recent shift to high impact prevention tactics that are being scaled up across North America. PMID:23060688

Orion EM-1 Crew Module Structural Test Article loaded onto Guppy

NASA Image and Video Library

2017-04-25

The Orion Exploration Mission-1 (EM-1) structural test article, inside its transport container, is secured in NASA's Super Guppy aircraft at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. The test article will be transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Preparation for Testing a Multi-Bay Box Subjected to Combined Loads

NASA Technical Reports Server (NTRS)

Rouse, Marshall; Jegley, Dawn

2015-01-01

The COmbined Loads Test System (COLTS) facility at NASA Langley Research Center provides a test capability to help develop validated structures technologies. The test machine was design to accommodate a range of fuselage structures and wing sections and subject them to both quasistatic and cyclic loading conditions. The COLTS facility is capable of testing fuselage barrels up to 4.6 m in diameter and 13.7 m long with combined mechanical, internal pressure, and thermal loads. The COLTS facility is currently being prepared to conduct a combined mechanical and pressure loading for a multi-bay pressure box to experimentally verify the structural performance of a composite structure which is 9.1 meters long and representative of a section of a hybrid wing body fuselage section in support of the Environmentally Responsible Aviation Project at NASA. This paper describes development of the multi-bay pressure box test using the COLTS facility. The multi-bay test article will be subjected to mechanical loads and internal pressure loads up to design ultimate load. Mechanical and pressure loads will be applied independently in some tests and simultaneously in others.

Orion EM-1 Crew Module Structural Test Article loaded onto Guppy

NASA Image and Video Library

2017-04-25

On the tarmac at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, the agency's Super Guppy aircraft closes after the Orion Exploration Mission-1 (EM-1) structural test article, in its transport container, is secured inside. The test article will be transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Validation Tests of Fiber Optic Strain-Based Operational Shape and Load Measurements

NASA Technical Reports Server (NTRS)

Bakalyar, John A.; Jutte, Christine

2012-01-01

Aircraft design has been progressing toward reduced structural weight to improve fuel efficiency, increase performance, and reduce cost. Lightweight aircraft structures are more flexible than conventional designs and require new design considerations. Intelligent sensing allows for enhanced control and monitoring of aircraft, which enables increased structurally efficiency. The NASA Dryden Flight Research Center (DFRC) has developed an instrumentation system and analysis techniques that combine to make distributed structural measurements practical for lightweight vehicles. Dryden's Fiber Optic Strain Sensing (FOSS) technology enables a multitude of lightweight, distributed surface strain measurements. The analysis techniques, referred to as the Displacement Transfer Functions (DTF) and Load Transfer Functions (LTF), use surface strain values to calculate structural deflections and operational loads. The combined system is useful for real-time monitoring of aeroelastic structures, along with many other applications. This paper describes how the capabilities of the measurement system were demonstrated using subscale test articles that represent simple aircraft structures. Empirical FOSS strain data were used within the DTF to calculate the displacement of the article and within the LTF to calculate bending moments due to loads acting on the article. The results of the tests, accuracy of the measurements, and a sensitivity analysis are presented.

Open Architecture Data System for NASA Langley Combined Loads Test System

NASA Technical Reports Server (NTRS)

Lightfoot, Michael C.; Ambur, Damodar R.

1998-01-01

The Combined Loads Test System (COLTS) is a new structures test complex that is being developed at NASA Langley Research Center (LaRC) to test large curved panels and cylindrical shell structures. These structural components are representative of aircraft fuselage sections of subsonic and supersonic transport aircraft and cryogenic tank structures of reusable launch vehicles. Test structures are subjected to combined loading conditions that simulate realistic flight load conditions. The facility consists of two pressure-box test machines and one combined loads test machine. Each test machine possesses a unique set of requirements or research data acquisition and real-time data display. Given the complex nature of the mechanical and thermal loads to be applied to the various research test articles, each data system has been designed with connectivity attributes that support both data acquisition and data management functions. This paper addresses the research driven data acquisition requirements for each test machine and demonstrates how an open architecture data system design not only meets those needs but provides robust data sharing between data systems including the various control systems which apply spectra of mechanical and thermal loading profiles.

Orion EM-1 Crew Module Structural Test Article Move for Transport from Kennedy Space Center to Lockheed Martin in Denver Colorado

NASA Image and Video Library

2017-04-24

The Guppy aircraft arrives at the Shuttle Landing Facility (SLF) at Kennedy Space Center, to transport the Orion EM-1 Crew Module (CM) Structural Test Article (STA) to Lockheed Martin in Denver Colorado. The Orion EM-1 CM STA is loaded onto a transport truck at the Operations & Checking Building (O&C) and moved to the SLF. Following this, workers load the spacecraft hardware onto the Guppy aircraft. The Guppy takes off from the SLF, in route to Denver Colorado.

Ability of finger-jointed lumber to maintain load at elevated temperatures

Treesearch

Douglas R. Rammer; Samuel L. Zelinka; Laura E Hasburgh; Steven T. Craft

2018-01-01

This article presents a test method that was developed to screen adhesive formulations for finger-jointed lumber. The goal was to develop a small-scale test that could be used to predict whether an adhesive would pass a full-scale ASTM E119 wall assembly test. The method involved loading a 38-mm square finger-jointed sample in a four-point bending test inside of an...

Nozzle Side Load Testing and Analysis at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Ruf, Joseph H.; McDaniels, David M.; Brown, Andrew M.

2009-01-01

Realistic estimates of nozzle side loads, the off-axis forces that develop during engine start and shutdown, are important in the design cycle of a rocket engine. The estimated magnitude of the nozzle side loads has a large impact on the design of the nozzle shell and the engine s thrust vector control system. In 2004 Marshall Space Flight Center (MSFC) began developing a capability to quantify the relative magnitude of side loads caused by different types of nozzle contours. The MSFC Nozzle Test Facility was modified to measure nozzle side loads during simulated nozzle start. Side load results from cold flow tests on two nozzle test articles, one with a truncated ideal contour and one with a parabolic contour are provided. The experimental approach, nozzle contour designs and wall static pressures are also discussed

Finite Element Analysis and Test Results Comparison for the Hybrid Wing Body Center Section Test Article

NASA Technical Reports Server (NTRS)

Przekop, Adam; Jegley, Dawn C.; Rouse, Marshall; Lovejoy, Andrew E.

2016-01-01

This report documents the comparison of test measurements and predictive finite element analysis results for a hybrid wing body center section test article. The testing and analysis efforts were part of the Airframe Technology subproject within the NASA Environmentally Responsible Aviation project. Test results include full field displacement measurements obtained from digital image correlation systems and discrete strain measurements obtained using both unidirectional and rosette resistive gauges. Most significant results are presented for the critical five load cases exercised during the test. Final test to failure after inflicting severe damage to the test article is also documented. Overall, good comparison between predicted and actual behavior of the test article is found.

Safety envelope for load tolerance of structural element design based on multi-stage testing

DOE PAGES

Park, Chanyoung; Kim, Nam H.

2016-09-06

Structural elements, such as stiffened panels and lap joints, are basic components of aircraft structures. For aircraft structural design, designers select predesigned elements satisfying the design load requirement based on their load-carrying capabilities. Therefore, estimation of safety envelope of structural elements for load tolerances would be a good investment for design purpose. In this article, a method of estimating safety envelope is presented using probabilistic classification, which can estimate a specific level of failure probability under both aleatory and epistemic uncertainties. An important contribution of this article is that the calculation uncertainty is reflected in building a safety envelope usingmore » Gaussian process, and the effect of element test data on reducing the calculation uncertainty is incorporated by updating the Gaussian process model with the element test data. It is shown that even one element test can significantly reduce the calculation uncertainty due to lacking knowledge of actual physics, so that conservativeness in a safety envelope is significantly reduced. The proposed approach was demonstrated with a cantilever beam example, which represents a structural element. The example shows that calculation uncertainty provides about 93% conservativeness against the uncertainty due to a few element tests. As a result, it is shown that even a single element test can increase the load tolerance modeled with the safety envelope by 20%.« less

SLS INTERIM CRYOGENIC PROPULSION STAGE TEST ARTICLE ARRIVAL

NASA Image and Video Library

2016-06-19

SLS INTERIM CRYOGENIC PROPULSION STAGE TEST ARTICLE ARRIVES AT WEST DOCK ON SHIELDS ROAD AND IS OFF LOADED FROM BARGEUAH ENGINEERING STUDENT ROBERT HILLAN TALKS TO SPACE STATION CREW MEMBERS ABOUT HIS WINNING 3-D PRINTED TOOL DESIGNED FOR USE ON ISS, AND IS INTERVIEWED BY LOCAL MEDIA

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.

Erratum: Erratum to: Effects of self-attraction and loading at a regional scale: a test case for the Northwest European Shelf

NASA Astrophysics Data System (ADS)

Irazoqui Apecechea, Maialen; Verlaan, Martin; Zijl, Firmijn; Le Coz, Camille; Kernkamp, Herman

2017-12-01

The article Effects of self-attraction and loading at a regional scale: a test case for the Northwest European Shelf, written by Maialen Irazoqui Apecechea, Martin Verlaan, Firmijn Zijl, Camille Le Coz and Herman Kernkamp, was originally published Online First without open access.

Improving English Learners' Productive Collocation Knowledge: The Effects of Involvement Load, Spacing, and Intentionality

ERIC Educational Resources Information Center

Snoder, Per

2017-01-01

This article reports on a classroom-based experiment that tested the effects of three vocabulary teaching constructs (involvement load, spacing, and intentionality) on the learning of English verb-noun collocations--for example, "shelve a plan." Laufer and Hulstijn's (2001) "involvement load" predicts that the higher the…

Finite Elements Analysis of a Composite Semi-Span Test Article With and Without Discrete Damage

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Jegley, Dawn C. (Technical Monitor)

2000-01-01

AS&M Inc. performed finite element analysis, with and without discrete damage, of a composite semi-span test article that represents the Boeing 220-passenger transport aircraft composite semi-span test article. A NASTRAN bulk data file and drawings of the test mount fixtures and semi-span components were utilized to generate the baseline finite element model. In this model, the stringer blades are represented by shell elements, and the stringer flanges are combined with the skin. Numerous modeling modifications and discrete source damage scenarios were applied to the test article model throughout the course of the study. This report details the analysis method and results obtained from the composite semi-span study. Analyses were carried out for three load cases: Braked Roll, LOG Down-Bending and 2.5G Up-Bending. These analyses included linear and nonlinear static response, as well as linear and nonlinear buckling response. Results are presented in the form of stress and strain plots. factors of safety for failed elements, buckling loads and modes, deflection prediction tables and plots, and strainage prediction tables and plots. The collected results are presented within this report for comparison to test results.

Experimental validation of solid rocket motor damping models

NASA Astrophysics Data System (ADS)

Riso, Cristina; Fransen, Sebastiaan; Mastroddi, Franco; Coppotelli, Giuliano; Trequattrini, Francesco; De Vivo, Alessio

2017-12-01

In design and certification of spacecraft, payload/launcher coupled load analyses are performed to simulate the satellite dynamic environment. To obtain accurate predictions, the system damping properties must be properly taken into account in the finite element model used for coupled load analysis. This is typically done using a structural damping characterization in the frequency domain, which is not applicable in the time domain. Therefore, the structural damping matrix of the system must be converted into an equivalent viscous damping matrix when a transient coupled load analysis is performed. This paper focuses on the validation of equivalent viscous damping methods for dynamically condensed finite element models via correlation with experimental data for a realistic structure representative of a slender launch vehicle with solid rocket motors. A second scope of the paper is to investigate how to conveniently choose a single combination of Young's modulus and structural damping coefficient—complex Young's modulus—to approximate the viscoelastic behavior of a solid propellant material in the frequency band of interest for coupled load analysis. A scaled-down test article inspired to the Z9-ignition Vega launcher configuration is designed, manufactured, and experimentally tested to obtain data for validation of the equivalent viscous damping methods. The Z9-like component of the test article is filled with a viscoelastic material representative of the Z9 solid propellant that is also preliminarily tested to investigate the dependency of the complex Young's modulus on the excitation frequency and provide data for the test article finite element model. Experimental results from seismic and shock tests performed on the test configuration are correlated with numerical results from frequency and time domain analyses carried out on its dynamically condensed finite element model to assess the applicability of different equivalent viscous damping methods to describe damping properties of slender launch vehicles in payload/launcher coupled load analysis.

Experimental validation of solid rocket motor damping models

NASA Astrophysics Data System (ADS)

Riso, Cristina; Fransen, Sebastiaan; Mastroddi, Franco; Coppotelli, Giuliano; Trequattrini, Francesco; De Vivo, Alessio

2018-06-01

In design and certification of spacecraft, payload/launcher coupled load analyses are performed to simulate the satellite dynamic environment. To obtain accurate predictions, the system damping properties must be properly taken into account in the finite element model used for coupled load analysis. This is typically done using a structural damping characterization in the frequency domain, which is not applicable in the time domain. Therefore, the structural damping matrix of the system must be converted into an equivalent viscous damping matrix when a transient coupled load analysis is performed. This paper focuses on the validation of equivalent viscous damping methods for dynamically condensed finite element models via correlation with experimental data for a realistic structure representative of a slender launch vehicle with solid rocket motors. A second scope of the paper is to investigate how to conveniently choose a single combination of Young's modulus and structural damping coefficient—complex Young's modulus—to approximate the viscoelastic behavior of a solid propellant material in the frequency band of interest for coupled load analysis. A scaled-down test article inspired to the Z9-ignition Vega launcher configuration is designed, manufactured, and experimentally tested to obtain data for validation of the equivalent viscous damping methods. The Z9-like component of the test article is filled with a viscoelastic material representative of the Z9 solid propellant that is also preliminarily tested to investigate the dependency of the complex Young's modulus on the excitation frequency and provide data for the test article finite element model. Experimental results from seismic and shock tests performed on the test configuration are correlated with numerical results from frequency and time domain analyses carried out on its dynamically condensed finite element model to assess the applicability of different equivalent viscous damping methods to describe damping properties of slender launch vehicles in payload/launcher coupled load analysis.

Hybrid Wing Body Multi-Bay Test Article Analysis and Assembly Final Report

NASA Technical Reports Server (NTRS)

Velicki, Alexander; Hoffman, Krishna; Linton, Kim A.; Baraja, Jaime; Wu, Hsi-Yung T.; Thrash, Patrick

2017-01-01

This report summarizes work performed by The Boeing Company, through its Boeing Research & Technology organization located in Huntington Beach, California, under the Environmentally Responsible Aviation (ERA) project. The report documents work performed to structurally analyze and assemble a large-scale Multi-bay Box (MBB) Test Article capable of withstanding bending and internal pressure loadings representative of a Hybrid Wing Body (HWB) aircraft. The work included fabrication of tooling elements for use in the fabrication and assembly of the test article.

Orion EM-1 Crew Module Structural Test Article Prepped for Trans

NASA Image and Video Library

2017-04-24

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, technicians secure the transport container with the Orion Exploration Mission-1 (EM-1) structural test article onto a transport vehicle for the move to the Shuttle Landing Facility. The test article will be loaded in NASA's Super Guppy airplane and transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Orion EM-1 Crew Module Structural Test Article Prepped for Trans

NASA Image and Video Library

2017-04-24

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, the Orion Exploration Mission-1 (EM-1) structural test article inside its transport container, is secured onto a transport vehicle for the move to the Shuttle Landing Facility. The test article will be loaded in NASA's Super Guppy airplane and transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Orion EM-1 Crew Module Structural Test Article Prepped for Trans

NASA Image and Video Library

2017-04-24

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, technicians secure the Orion Exploration Mission-1 (EM-1) structural test article in its transport container onto a transport vehicle for the move to the Shuttle Landing Facility. The test article will be loaded in NASA's Super Guppy airplane and transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Orion EM-1 Crew Module Structural Test Article Prepped for Trans

NASA Image and Video Library

2017-04-24

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, the Orion Exploration Mission-1 (EM-1) structural test article, secured inside its transport container, is lowered onto a transport vehicle for the move to the Shuttle Landing Facility. The test article will be loaded in NASA's Super Guppy airplane and transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

CRYogenic Orbital TEstbed Ground Test Article Thermal Analysis

NASA Technical Reports Server (NTRS)

Piryk, David; Schallhorn, Paul; Walls, Laurie; Stopnitzky, Benny; Rhys, Noah; Wollen, Mark

2012-01-01

The purpose of this study was to anchor thermal and fluid system models to CRYOTE ground test data. The CRYOTE ground test artide was jointly developed by Innovative Engineering Solutions, United Launch Alliance and NASA KSC. The test article was constructed out of a titanium alloy tank, Sapphire 77 composite skin (similar to G10), an external secondary payload adapter ring, thermal vent system, multi layer insulation and various data acquisition instrumentation. In efforts to understand heat loads throughout this system, the GTA (filled with liquid nitrogen for safety purposes) was subjected to a series of tests in a vacuum chamber at Marshall Space Flight Center. By anchoring analytical models against test data, higher fidelity thermal environment predictions can be made for future flight articles which would eventually demonstrate critical cryogenic fluid management technologies such as system chilldown, transfer, pressure control and long term storage. Significant factors that influenced heat loads included radiative environments, multi-layer insulation performance, tank fill levels and pressures and even contact conductance coefficients. This report demonstrates how analytical thermal/fluid networks were established and includes supporting rationale for specific thermal responses.

Offgassing Characterization of the Columbus Laboratory Module

NASA Technical Reports Server (NTRS)

Rampini, riccardo; Lobascio, Cesare; Perry, Jay L.; Hinderer, Stephan

2005-01-01

Trace gaseous contamination in the cabin environment is a major concern for manned spacecraft, especially those designed for long duration missions, such as the International Space Station (ISS). During the design phase, predicting the European-built Columbus laboratory module s contribution to the ISS s overall trace contaminant load relied on "trace gas budgeting" based on material level and assembled article tests data. In support of the Qualification Review, a final offgassing test has been performed on the complete Columbus module to gain cumulative system offgassing data. Comparison between the results of the predicted offgassing load based on the budgeted material/assembled article-level offgassing rates and the module-level offgassing test is presented. The Columbus module offgassing test results are also compared to results from similar tests conducted for Node 1, U.S. Laboratory, and Airlock modules.

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

Park, Chanyoung; Kim, Nam H.

Structural elements, such as stiffened panels and lap joints, are basic components of aircraft structures. For aircraft structural design, designers select predesigned elements satisfying the design load requirement based on their load-carrying capabilities. Therefore, estimation of safety envelope of structural elements for load tolerances would be a good investment for design purpose. In this article, a method of estimating safety envelope is presented using probabilistic classification, which can estimate a specific level of failure probability under both aleatory and epistemic uncertainties. An important contribution of this article is that the calculation uncertainty is reflected in building a safety envelope usingmore » Gaussian process, and the effect of element test data on reducing the calculation uncertainty is incorporated by updating the Gaussian process model with the element test data. It is shown that even one element test can significantly reduce the calculation uncertainty due to lacking knowledge of actual physics, so that conservativeness in a safety envelope is significantly reduced. The proposed approach was demonstrated with a cantilever beam example, which represents a structural element. The example shows that calculation uncertainty provides about 93% conservativeness against the uncertainty due to a few element tests. As a result, it is shown that even a single element test can increase the load tolerance modeled with the safety envelope by 20%.« less

Fuel containment and damage tolerance in large composite primary aircraft structures. Phase 2: Testing

NASA Technical Reports Server (NTRS)

Sandifer, J. P.; Denny, A.; Wood, M. A.

1985-01-01

Technical issues associated with fuel containment and damage tolerance of composite wing structures for transport aircraft were investigated. Material evaluation tests were conducted on two toughened resin composites: Celion/HX1504 and Celion/5245. These consisted of impact, tension, compression, edge delamination, and double cantilever beam tests. Another test series was conducted on graphite/epoxy box beams simulating a wing cover to spar cap joint configuration of a pressurized fuel tank. These tests evaluated the effectiveness of sealing methods with various fastener types and spacings under fatigue loading and with pressurized fuel. Another test series evaluated the ability of the selected coatings, film, and materials to prevent fuel leakage through 32-ply AS4/2220-1 laminates at various impact energy levels. To verify the structural integrity of the technology demonstration article structural details, tests were conducted on blade stiffened panels and sections. Compression tests were performed on undamaged and impacted stiffened AS4/2220-1 panels and smaller element tests to evaluate stiffener pull-off, side load and failsafe properties. Compression tests were also performed on panels subjected to Zone 2 lightning strikes. All of these data were integrated into a demonstration article representing a moderately loaded area of a transport wing. This test combined lightning strike, pressurized fuel, impact, impact repair, fatigue and residual strength.

Dual-axis resonance testing of wind turbine blades

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

Hughes, Scott; Musial, Walter; White, Darris

An apparatus (100) for fatigue testing test articles (104) including wind turbine blades. The apparatus (100) includes a test stand (110) that rigidly supports an end (106) of the test article (104). An actuator assembly (120) is attached to the test article (104) and is adapted for substantially concurrently imparting first and second forcing functions in first and second directions on the test article (104), with the first and second directions being perpendicular to a longitudinal axis. A controller (130) transmits first and second sets of displacement signals (160, 164) to the actuator assembly (120) at two resonant frequencies ofmore » the test system (104). The displacement signals (160, 164) initiate the actuator assembly (120) to impart the forcing loads to concurrently oscillate the test article (104) in the first and second directions. With turbine blades, the blades (104) are resonant tested concurrently for fatigue in the flapwise and edgewise directions.« less

Changes in the Strength of the Polymer Concrete Used in the Electroplating Vats Under Operational Load

NASA Astrophysics Data System (ADS)

Radna, Lidia; Sakharov, Volodymyr

2017-12-01

Due to the strong and aggressive electrolyte media and thermal load, design of the electroplating vats in the copper industry often relies on the resin concrete. The article presents the results of the strength tests of the polymer concrete based on the "Derakane" resin, used in the construction of electroplating vats. Samples were taken from the real vats - both new and 17-year old. Strength tests included compression and bending tensile strength test. To assess the effect of operational conditions the tests were performed on the same-age vats, some of which were never used while others were subjected to the operational load. During the operation, the vats sustained load of the anode and cathode weights, cyclic electrolyte loading with a temperatures up to 60°C. As a result, it was noted that the operational conditions led to the increased strength of the polymer concrete material.

Orion EM-1 Crew Module Structural Test Article loaded onto Guppy

NASA Image and Video Library

2017-04-25

NASA's Super Guppy aircraft has been closed and secured at the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida. The Orion Exploration Mission-1 (EM-1) structural test article is secured inside the Super Guppy and will be transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Acoustic-Structure Interaction in Rocket Engines: Validation Testing

NASA Technical Reports Server (NTRS)

Davis, R. Benjamin; Joji, Scott S.; Parks, Russel A.; Brown, Andrew M.

2009-01-01

While analyzing a rocket engine component, it is often necessary to account for any effects that adjacent fluids (e.g., liquid fuels or oxidizers) might have on the structural dynamics of the component. To better characterize the fully coupled fluid-structure system responses, an analytical approach that models the system as a coupled expansion of rigid wall acoustic modes and in vacuo structural modes has been proposed. The present work seeks to experimentally validate this approach. To experimentally observe well-coupled system modes, the test article and fluid cavities are designed such that the uncoupled structural frequencies are comparable to the uncoupled acoustic frequencies. The test measures the natural frequencies, mode shapes, and forced response of cylindrical test articles in contact with fluid-filled cylindrical and/or annular cavities. The test article is excited with a stinger and the fluid-loaded response is acquired using a laser-doppler vibrometer. The experimentally determined fluid-loaded natural frequencies are compared directly to the results of the analytical model. Due to the geometric configuration of the test article, the analytical model is found to be valid for natural modes with circumferential wave numbers greater than four. In the case of these modes, the natural frequencies predicted by the analytical model demonstrate excellent agreement with the experimentally determined natural frequencies.

2009 Continued Testing of the Orion Atmosphere Revitalization Technology

NASA Technical Reports Server (NTRS)

Button, Amy B.; Swerterlitsch, Jeffrey J.

2010-01-01

An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). In three previous years at this conference, reports were presented on extensive Johnson Space Center (JSC) testing of this technology in a sea-level pressure environment, with simulated and real human metabolic loads, in both open and closed-loop configurations. The test article design was iterated a third time before the latest series of such tests, which was performed in the first half of 2009. The new design incorporates a canister configuration modification for overall unit compactness and reduced pressure drop, as well as a new process flow control valve that incorporates both compressed gas purge and dual-end vacuum desorption capabilities. This newest test article is very similar to the flight article designs. Baseline tests of the new unit were performed to compare its performance to that of the previous test articles. Testing of compressed gas purge operations helped refine launchpad operating condition recommendations developed in earlier testing. Operating conditions used in flight program computer models were tested to validate the model projections. Specific operating conditions that were recommended by the JSC test team based on past test results were also tested for validation. The effects of vacuum regeneration line pressure on resulting cabin conditions was studied for high metabolic load periods, and a maximum pressure is recommended

2009 Continued Testing of the Orion Atmosphere Revitalization Technology

NASA Technical Reports Server (NTRS)

Button, Amy Lin; Sweterlitsch, Jeffrey

2009-01-01

An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). In three previous years at this conference, reports were presented on extensive Johnson Space Center (JSC) testing of this technology in a sea-level pressure environment with simulated and real human metabolic loads in both open and closed-loop configurations. The test article design was iterated a third time before the latest series of such tests, which was performed in the first half of 2009. The new design incorporates a canister configuration modification for overall unit compactness and reduced pressure drop, as well as a new process flow control valve that incorporates both compressed gas purge and dual-end vacuum desorption capabilities. This newest test article is very similar to the flight article designs. Baseline tests of the new unit were performed to compare its performance to that of the previous test articles. Testing of compressed gas purge operations helped refine launchpad operating condition recommendations developed in earlier testing. Operating conditions used in flight program computer models were tested to validate the model projections. Specific operating conditions that were recommended by the JSC test team based on past test results were also tested for validation. The effects of vacuum regeneration line pressure on resulting cabin conditions was studied for high metabolic load periods, and a maximum pressure is recommended.

A laboratory comparison of individual Targis/Vectris posts with standard fiberglass posts.

PubMed

Corsalini, Massimo; Genovese, Katia; Lamberti, Luciano; Pappalettere, Carmine; Carella, Mauro; Carossa, Stefano

2007-01-01

This article presents an in vitro analysis of a specific occlusal loading test on endodontically treated teeth restored with 2 different composite post materials. Individual, customized posts (IFPs) were compared to standard fiberglass posts (SFPs). The selected IFPs (standard cylindric Targis/Vectris posts) were compared to SFPs (Conic 6% Post, Ghimas). The posts were first subjected to a 3-point bending test to compare their flexural elastic properties. They were then used to restore 22 endodontically treated artificial maxillary central incisors and subjected to a specific occlusal loading simulation test. The loading test showed that IFP restorations performed better than SFP restorations. A clinical evaluation of this laboratory observation is suggested.

Orion EM-1 Crew Module Structural Test Article Prepped for Trans

NASA Image and Video Library

2017-04-24

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, the Orion Exploration Mission-1 (EM-1) structural test article is secured inside its transport container. Technicians monitor the progress as a crane is used to move the container toward a transport vehicle for the move to the Shuttle Landing Facility. The test article will be loaded in NASA's Super Guppy airplane and transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Orion EM-1 Crew Module Structural Test Article Prepped for Trans

NASA Image and Video Library

2017-04-24

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, the Orion Exploration Mission-1 (EM-1) structural test article is secured inside its transport container. A crane is used to move the container toward a transport vehicle for the move to the Shuttle Landing Facility. The test article will be loaded in NASA's Super Guppy airplane and transported to Lockheed Martin's Denver facility for testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission.

Manipulation of Cognitive Load Variables and Impact on Auscultation Test Performance

ERIC Educational Resources Information Center

Chen, Ruth; Grierson, Lawrence; Norman, Geoffrey

2015-01-01

Health profession educators have identified auscultation skill as a learning need for health professional students. This article explores the application of cognitive load theory (CLT) to designing cardiac and respiratory auscultation skill instruction for senior-level undergraduate nursing students. Three experiments assessed student auscultation…

European Service Module Structural Test Article Load onto Guppy for Transport to Denver Colorado

NASA Image and Video Library

2017-06-23

At Kennedy Space Center's Shuttle Landing Facility in Florida, workers move the Orion service module structural test article for Exploration Mission-1 (EM-1), built by the European Space Agency, inside NASA's Super Guppy aircraft. The module is secured inside the aircraft and shipped to Lockheed Martin's Denver facility to undergo testing. The Orion spacecraft will launch atop the agency's Space Launch System rocket on EM-1 in 2019

Crash-test dummy and pendulum impact tests of ice hockey boards: greater displacement does not reduce impact.

PubMed

Schmitt, Kai-Uwe; Muser, Markus H; Thueler, Hansjuerg; Bruegger, Othmar

2018-01-01

One injury mechanism in ice hockey is impact with the boards. We investigated whether more flexible hockey boards would provide less biomechanical loading on impact than did existing (reference) boards. We conducted impact tests with a dynamic pendulum (mass 60 kg) and with crash test dummies (ES-2 dummy, 4.76 m/s impact speed). Outcomes were biomechanical loading experienced by a player in terms of head acceleration, impact force to the shoulder, spine, abdomen and pelvis as well as compression of the thorax. The more flexible board designs featured substantial displacement at impact. Some so-called flexible boards were displaced four times more than the reference board. The new boards possessed less stiffness and up to 90 kg less effective mass, reducing the portion of the board mass a player experienced on impact, compared with boards with a conventional design. Flexible boards resulted in a similar or reduced loading for all body regions, apart from the shoulder. The displacement of a board system did not correlate directly with the biomechanical loading. Flexible board systems can reduce the loading of a player on impact. However, we found no correlation between the displacement and the biomechanical loading; accordingly, displacement alone was insufficient to characterise the overall loading of a player and thus the risk of injury associated with board impact. Ideally, the performance of boards is assessed on the basis of parameters that show a good correlation to injury risk. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Data on DNA gel sample load, gel electrophoresis, PCR and cost analysis.

PubMed

Kuhn, Ramona; Böllmann, Jörg; Krahl, Kathrin; Bryant, Isaac Mbir; Martienssen, Marion

2018-02-01

The data presented in this article provide supporting information to the related research article "Comparison of ten different DNA extraction procedures with respect to their suitability for environmental samples" (Kuhn et al., 2017) [1]. In that article, we compared the suitability of ten selected DNA extraction methods based on DNA quality, purity, quantity and applicability to universal PCR. Here we provide the data on the specific DNA gel sample load, all unreported gel images of crude DNA and PCR results, and the complete cost analysis for all tested extraction procedures and in addition two commercial DNA extraction kits for soil and water.

Test load verification through strain data analysis

NASA Technical Reports Server (NTRS)

Verderaime, V.; Harrington, F.

1995-01-01

A traditional binding acceptance criterion on polycrystalline structures is the experimental verification of the ultimate factor of safety. At fracture, the induced strain is inelastic and about an order-of-magnitude greater than designed for maximum expected operational limit. At this extreme strained condition, the structure may rotate and displace at the applied verification load such as to unknowingly distort the load transfer into the static test article. Test may result in erroneously accepting a submarginal design or rejecting a reliable one. A technique was developed to identify, monitor, and assess the load transmission error through two back-to-back surface-measured strain data. The technique is programmed for expediency and convenience. Though the method was developed to support affordable aerostructures, the method is also applicable for most high-performance air and surface transportation structural systems.

Overview of the 2nd Gen 3.7m HIAD Static Load Test

NASA Technical Reports Server (NTRS)

Swanson, G. T.; Kazemba, C. D.; Johnson, R. K.; Hughes, S. J.; Calomino, A. M.; Cheatwood, F. M.; Cassell, A. M.; Anderson, P.; Lowery, A.

2015-01-01

To support NASAs long term goal of landing humans on Mars, technologies which enable the landing of heavy payloads are being developed. Current entry, decent, and landing technologies are not practical for human class payloads due to geometric constraints dictated by current launch vehicle fairing limitations. Therefore, past and present technologies are now being explored to provide a mass and volume efficient solution to atmospheric entry, including Hypersonic Inflatable Aerodynamic Decelerators (HIADs). In October of 2014, a 3.7m HIAD inflatable structure with an integrated flexible thermal protection sys-tem (F-TPS) was subjected to a static load test series to verify the designs structural performance. The 3.7m HIAD structure was constructed in a 70 deg sphere-cone stacked-toroid configuration using eight inflatable tori, which were joined together using adhesives and high strength textile webbing to help distribute the loads throughout the inflatable structure. The inflatable structure was fabricated using 2nd generation structural materials that permit an increase in use temperature to 400 C+ as compared to the 250 C limitation of the 1st generation materials. In addition to the temperature benefit, these materials also offer a 40 reduction in structure mass. The 3.7m F-TPS was fabricated using high performance materials to protect the inflatable structure from heat loads that would be seen during atmospheric entry. The F-TPS was constructed of 2nd generation TPS materials increasing its heating capability from 35W sq cm to over 100W sq cm. This test article is the first stacked-torus HIAD to be fabricated and tested with a 70 deg sphere-cone. All previous stacked-torus HIADs have employed a 60o sphere-cone. To perform the static load test series, a custom test fixture was constructed. The fixture consisted of a structural tub rim with enough height to allow for dis-placement of the inflatable structure as loads were applied. The tub rim was attached to the floor to provide an airtight seal. The center body of the inflatable structure was attached to a pedestal mount as seen in Figure 1. Using an impermeable membrane seal draped over the test article, partial vacuum was pulled beneath the HIAD, resulting in a uniform static pressure load applied to the outer surface. During the test series an extensive amount of instrumentation was used to characterize deformed shape, shoulder deflection, strap loads, and cord loads as a function of structural configuration and applied static load. In this overview, the 3.7m HIAD static load test series will be discussed in detail, including the 3.7m HIAD inflatable structure and flexible TPS design, test setup and execution, and finally results and conclusions from the test series.

Wind turbine blade testing system using base excitation

DOEpatents

Cotrell, Jason; Thresher, Robert; Lambert, Scott; Hughes, Scott; Johnson, Jay

2014-03-25

An apparatus (500) for fatigue testing elongate test articles (404) including wind turbine blades through forced or resonant excitation of the base (406) of the test articles (404). The apparatus (500) includes a testing platform or foundation (402). A blade support (410) is provided for retaining or supporting a base (406) of an elongate test article (404), and the blade support (410) is pivotally mounted on the testing platform (402) with at least two degrees of freedom of motion relative to the testing platform (402). An excitation input assembly (540) is interconnected with the blade support (410) and includes first and second actuators (444, 446, 541) that act to concurrently apply forces or loads to the blade support (410). The actuator forces are cyclically applied in first and second transverse directions. The test article (404) responds to shaking of its base (406) by oscillating in two, transverse directions (505, 507).

Finite Element Analysis and Test Correlation of a 10-Meter Inflation-Deployed Solar Sail

NASA Technical Reports Server (NTRS)

Sleight, David W.; Michii, Yuki; Lichodziejewski, David; Derbes, Billy; Mann. Troy O.; Slade, Kara N.; Wang, John T.

2005-01-01

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA's future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive phased test plan is currently being implemented to advance the technology readiness level of the solar sail design. These tests consist of solar sail component, subsystem, and sub-scale system ground tests that simulate the vacuum and thermal conditions of the space environment. Recently, two solar sail test articles, a 7.4-m beam assembly subsystem test article and a 10-m four-quadrant solar sail system test article, were tested in vacuum conditions with a gravity-offload system to mitigate the effects of gravity. This paper presents the structural analyses simulating the ground tests and the correlation of the analyses with the test results. For programmatic risk reduction, a two-prong analysis approach was undertaken in which two separate teams independently developed computational models of the solar sail test articles using the finite element analysis software packages: NEiNastran and ABAQUS. This paper compares the pre-test and post-test analysis predictions from both software packages with the test data including load-deflection curves from static load tests, and vibration frequencies and mode shapes from vibration tests. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were uncertainties in the material properties, test conditions, and modeling assumptions used in the analyses.

Full-Scale Passive Earth Entry Vehicle Landing Tests: Methods and Measurements

NASA Technical Reports Server (NTRS)

Littell, Justin D.; Kellas, Sotiris

2018-01-01

During the summer of 2016, a series of drop tests were conducted on two passive earth entry vehicle (EEV) test articles at the Utah Test and Training Range (UTTR). The tests were conducted to evaluate the structural integrity of a realistic EEV vehicle under anticipated landing loads. The test vehicles were lifted to an altitude of approximately 400m via a helicopter and released via release hook into a predesignated 61 m landing zone. Onboard accelerometers were capable of measuring vehicle free flight and impact loads. High-speed cameras on the ground tracked the free-falling vehicles and data was used to calculate critical impact parameters during the final seconds of flight. Additional sets of high definition and ultra-high definition cameras were able to supplement the high-speed data by capturing the release and free flight of the test articles. Three tests were successfully completed and showed that the passive vehicle design was able to withstand the impact loads from nominal and off-nominal impacts at landing velocities of approximately 29 m/s. Two out of three test resulted in off-nominal impacts due to a combination of high winds at altitude and the method used to suspend the vehicle from the helicopter. Both the video and acceleration data captured is examined and discussed. Finally, recommendations for improved release and instrumentation methods are presented.

Time-Lapse Video of SLS Engine Section Test Article Being Stacked at Michoud

NASA Image and Video Library

2017-04-25

This time-lapse video shows the Space Launch System engine section structural qualification test article being stacked at NASA's Michoud Assembly Facility in New Orleans. The rocket's engine section is the bottom of the core stage and houses the four RS-25 engines. The engine section test article was moved to Michoud's Cell A in Building 110 for vertical stacking with hardware that simulates the rocket's liquid hydrogen tank, which is the fuel tank that joins to the engine section. Once stacked, the entire test article will load onto the barge Pegasus and ship to NASA's Marshall Space Flight Center in Huntsville, Alabama. There, it will be subjected to millions of pounds of force during testing to ensure the hardware can withstand the incredible stresses of launch.

SLS Engine Section Test Article Moved for Stacking at Michoud

NASA Image and Video Library

2017-04-25

Stacking is underway for the Space Launch System core stage engine section structural qualification test article at NASA's Michoud Assembly Facility in New Orleans. The rocket's engine section is the bottom of the core stage and houses the four RS-25 engines. The engine section test article was moved to Michoud's Cell A in Building 110 for vertical stacking with hardware that simulates the rocket's liquid hydrogen tank, which is the fuel tank that joins to the engine section. Once stacked, the entire test article will load onto the barge Pegasus and ship to NASA's Marshall Space Flight Center in Huntsville, Alabama. There, it will be subjected to millions of pounds of force during testing to ensure the hardware can withstand the incredible stresses of launch.

Structural Analysis of an Inflation-Deployed Solar Sail With Experimental Validation

NASA Technical Reports Server (NTRS)

Sleight, David W.; Michii, Yuki; Lichodziejewski, David; Derbes, Billy; Mann, Troy O.

2005-01-01

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive phased test plan is currently being implemented to advance the technology readiness level of the solar sail design. These tests consist of solar sail component, subsystem, and sub-scale system ground tests that simulate the vacuum and thermal conditions of the space environment. Recently, two solar sail test articles, a 7.4-m beam assembly subsystem test article and a 10-m four-quadrant solar sail system test article, were tested in vacuum conditions with a gravity-offload system to mitigate the effects of gravity. This paper presents the structural analyses simulating the ground tests and the correlation of the analyses with the test results. For programmatic risk reduction, a two-prong analysis approach was undertaken in which two separate teams independently developed computational models of the solar sail test articles using the finite element analysis software packages: NEiNastran and ABAQUS. This paper compares the pre-test and post-test analysis predictions from both software packages with the test data including load-deflection curves from static load tests, and vibration frequencies and mode shapes from structural dynamics tests. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were uncertainties in the material properties, test conditions, and modeling assumptions used in the analyses.

Design, Analysis and Testing of a PRSEUS Pressure Cube to Investigate Assembly Joints

NASA Technical Reports Server (NTRS)

Yovanof, Nicolette; Lovejoy, Andrew E.; Baraja, Jaime; Gould, Kevin

2012-01-01

Due to its potential to significantly increase fuel efficiency, the current focus of NASA's Environmentally Responsible Aviation Program is the hybrid wing body (HWB) aircraft. Due to the complex load condition that exists in HWB structure, as compared to traditional aircraft configurations, light-weight, cost-effective and manufacturable structural concepts are required to enable the HWB. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept is one such structural concept. A building block approach for technology development of the PRSEUS concept is being conducted. As part of this approach, a PRSEUS pressure cube was developed as a risk reduction test article to examine a new integral cap joint concept. This paper describes the design, analysis and testing of the PRSEUS pressure cube test article. The pressure cube was required to withstand a 2P, 18.4 psi, overpressure load requirement. The pristine pressure cube was tested to 2.2P with no catastrophic failure. After the addition of barely visible impact damage, the cube was pressure loaded to 48 psi where catastrophic failure occurred, meeting the scale-up requirement. Comparison of pretest and posttest analyses with the cube test response agree well, and indicate that current analysis methods can be used to accurately analyze PRSEUS structure for initial failure response.

Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure . Part II; Severe Damage

NASA Technical Reports Server (NTRS)

Przekop, Adam; Jegley, Dawn C.; Lovejoy, Andrew E.; Rouse, Marshall; Wu, Hsi-Yung T.

2016-01-01

The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a finite element analysis and the testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part II of the paper considers the final test to failure of the test article in the presence of an intentionally inflicted severe discrete source damage under the wing up-bending loading condition. Finite element analysis results are compared with measurements acquired during the test and demonstrate that the hybrid wing body test article was able to redistribute and support the required design loads in a severely damaged condition.

Full-Field Reconstruction of Structural Deformations and Loads from Measured Strain Data on a Wing Using the Inverse Finite Element Method

NASA Technical Reports Server (NTRS)

Miller, Eric J.; Manalo, Russel; Tessler, Alexander

2016-01-01

A study was undertaken to investigate the measurement of wing deformation and internal loads using measured strain data. Future aerospace vehicle research depends on the ability to accurately measure the deformation and internal loads during ground testing and in flight. The approach uses the inverse Finite Element Method (iFEM). The iFEM is a robust, computationally efficient method that is well suited for real-time measurement of real-time structural deformation and loads. The method has been validated in previous work, but has yet to be applied to a large-scale test article. This work is in preparation for an upcoming loads test of a half-span test wing in the Flight Loads Laboratory at the National Aeronautics and Space Administration Armstrong Flight Research Center (Edwards, California). The method has been implemented into an efficient MATLAB® (The MathWorks, Inc., Natick, Massachusetts) code for testing different sensor configurations. This report discusses formulation and implementation along with the preliminary results from a representative aerospace structure. The end goal is to investigate the modeling and sensor placement approach so that the best practices can be applied to future aerospace projects.

Fluid mass and thermal loading effects on the modal characteristics of space shuttle main engine liquid oxygen inlet splitter vanes

NASA Technical Reports Server (NTRS)

Panossian, H. V.; Boehnlein, J. J.

1987-01-01

An analysis and evaluation of experimental modal survey test data on the variations of modal characteristics induced by pressure and thermal loading events are presented. Extensive modal survey tests were carried out on a Space Shuttle Main Engine (SSME) test article using liquid nitrogen under cryogenic temperatures and high pressures. The results suggest that an increase of pressure under constant cryogenic temperature or a decrease of temperature under high pressure induces an upward shift of frequencies of various modes of the structures.

Use of the laboratory tests of soil modulus in modelling pile behaviour

NASA Astrophysics Data System (ADS)

Dyka, Ireneusz

2012-10-01

This article deals with the question of theoretical description of behaviour of a single pile rested in a layered soil medium. Particular attention is paid to soil modulus which is used in calculation method for pile load-settlement curve. A brief analysis of the results obtained by laboratory tests to assess soil modulus and its nonlinear variability has been presented. The results of tests have been used in triaxial apparatus and resonant column/torsional shear device. There have also been presented the results of load-settlement calculation for a single pile under axial load with implementation of different models of soil modulus degradation. On this basis, possibilities of using particular kinds of laboratory tests in calculation procedure of foundation settlement have been presented as well as further developments of them.

Protective Skins for Composite Airliners

NASA Technical Reports Server (NTRS)

Johnson, Vicki S.; Boone, Richard L.; Jones, Shannon; Pendse, Vandana; Hayward, Greg

2014-01-01

Traditional composite aircraft structures are designed for load bearing and then overdesigned for impact damage and hot humid environments. Seeking revolutionary improvement in the performance and weight of composite structures, Cessna Aircraft Company, with sponsorship from the NASA Fundamental Aeronautics Program/Subsonic Fixed Wing Project, has developed and tested a protective skin concept which would allow the primary composite structure to carry only load and would meet the impact, hot and humid, and other requirements through protective skins. A key requirement for the protective skins is to make any impact damage requiring repair visible. Testing from the first generation of skins helped identify the most promising materials which were used in a second generation of test articles. This report summarizes lessons learned from the first generation of protective skins, the design and construction of the second-generation test articles, test results from the second generation for impact, electromagnetic effects, aesthetics and smoothing, thermal, and acoustic (for the first time), and an assessment of the feasibility of the protective skin concept.

Qualifying Spirit and Opportunity to Martian Landing Loads with Centrifuge Testing

NASA Technical Reports Server (NTRS)

Coleman, Michelle R.; Davis, Greg

2004-01-01

This viewgraph presentation reviews the drop test used to test the Mars lander. The objective of the test was to demonstrate the structural and functional integrity of the development test Model (DTM). Rover Basepetal when subjected to the landing event. The test module was instrumented with accelerometers to measure the kinematic response of the test article during impact.

Titanium Honeycomb Panel Testing

NASA Technical Reports Server (NTRS)

Richards, W. Lance; Thompson, Randolph C.

1996-01-01

Thermal-mechanical tests were performed on a titanium honeycomb sandwich panel to experimentally validate the hypersonic wing panel concept and compare test data with analysis. Details of the test article, test fixture development, instrumentation, and test results are presented. After extensive testing to 900 deg. F, non-destructive evaluation of the panel has not detected any significant structural degradation caused by the applied thermal-mechanical loads.

Libbey-Owens-Ford solar collector static load test

NASA Technical Reports Server (NTRS)

1978-01-01

The test article is a flat plate solar collector that uses liquid as the heat transfer medium. The absorber plate is copper and has a double tempered glass cover. Test requirements and procedures are described and results are presented in a table. Results demonstrate that the collector performed satisfactorily.

A Risk-Based Approach to Variable Load Configuration Validation in Steam Sterilization: Application of PDA Technical Report 1 Load Equivalence Topic.

PubMed

Pavell, Anthony; Hughes, Keith A

2010-01-01

This article describes a method for achieving the load equivalence model, described in Parenteral Drug Association Technical Report 1, using a mass-based approach. The item and load bracketing approach allows for mixed equipment load size variation for operational flexibility along with decreased time to introduce new items to the operation. The article discusses the utilization of approximately 67 items/components (Table IV) identified for routine sterilization with varying quantities required weekly. The items were assessed for worst-case identification using four temperature-related criteria. The criteria were used to provide a data-based identification of worst-case items, and/or item equivalence, to carry forward into cycle validation using a variable load pattern. The mass approach to maximum load determination was used to bracket routine production use and allows for variable loading patterns. The result of the item mapping and load bracketing data is "a proven acceptable range" of sterilizing conditions including loading configuration and location. The application of these approaches, while initially more time/test-intensive than alternate approaches, provides a method of cycle validation with long-term benefit of ease of ongoing qualification, minimizing time and requirements for new equipment qualification for similar loads/use, and for rapid and rigorous assessment of new items for sterilization.

The Stress Corrosion Performance Research of Three Kinds of Commonly Used Pipe Materials

NASA Astrophysics Data System (ADS)

Hu, Yayun; Zhang, Yiliang; Jia, Xiaoliang

The corrosion of pipe is most common problem for oil and gas industry. In this article, three kinds of tubes will be analyzed in terms of their resistance against stress corrosion. They are respectively N80 / 1, N80/ Q and P110. The loading method chosen in this test is constant tensile stress loading. In the test, samples will be separated in different groups, gradually loaded under specific levels and then soaked in H2S saturated solution. What can get from this test is threshold value of stress corrosion and stress-life curve, which can be used for evaluating the stress corrosion property of materials, as well as giving guidance for practical engineering.

Response of Buried Vertically Oriented Cylinders to Dynamic Loading,

DTIC Science & Technology

1980-06-01

BALSARA • , . / ,, _,-, -. 1i S ,LESPONSE OF BURIED VERTICALLY 9RIENTED CYLINDERS 𔃺 .-TO DINAMIC LOADING_ 9AYLE E. LRTOrwW&-N JIIMY P./BALSARA Nk...1.7, 2,8, and 4.0 inches). The end caps for the cylinders consisted of a steel shell filled with high- strength concrete; however, the end caps were...not designed to be test articles. The average concrete compressive strength of the cylinders on test day was 44.0 MPa (6,380 psi). The three DEOT

Buckling Test Results and Preliminary Test and Analysis Correlation from the 8-Foot-Diameter Orthogrid-Stiffened Cylinder Test Article TA02

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Waters, W. Allen, Jr.; Haynie, Waddy T.; Thornburgh, Robert P

2017-01-01

Results from the testing of cylinder test article SBKF-P2-CYL-TA02 (referred to herein as TA02) are presented. TA02 is an 8-foot-diameter (96-inches), 78.0-inch-long, aluminum-lithium (Al-Li), orthogrid-stiffened cylindrical shell similar to those used in current state-of-the-art launch-vehicle structures and was designed to exhibit global buckling when subjected to combined compression and bending loads. The testing was conducted at the Marshall Space Flight Center (MSFC), February 3-6, 2009, in support of the Shell Buckling Knockdown Factor Project (SBKF). The test was used to verify the performance of a newly constructed buckling test facility at MSFC and to verify the test article design and analysis approach used by the SBKF researchers.

Nanoceria-loaded injectable hydrogels for potential age-related macular degeneration treatment.

PubMed

Wang, Kai; Mitra, Rajendra Narayan; Zheng, Min; Han, Zongchao

2018-05-12

The major purpose of this article is to evaluate oligochitosan coated cerium oxide nanoparticles (OCCNPs) alginate laden injectable hydrogels and their potential treatment for age-related macular degeneration (AMD). The water soluble OCCNPs were loaded within injectable hydrogels as antioxidative agents. The release of OCCNPs from hydrogel, radical scavenging properties, and biocompatibility were evaluated and calculated in vitro. The effects of OCCNP laden hydrogel downregulating expression of angiogenic proteins and pro-inflammatory cytokines were quantified in human retinal pigment epithlium-19 (ARPE-19) and umbilical endothelium cell lines. The hydrogels behaved with moderate swelling and controllable degradation. The laden OCCNPs were released in a controlled manner in vitro during two months of testing. The OCCNP loaded hydrogels exhibited robust antioxidative properties in oxygen radical absorbance capacity tests and reduced apoptosis in H 2 O 2 -induced ARPE-19 cells. Furthermore, OCCNP loaded injectable hydrogels are biocompatible and suppressed the LPS-induced inflammation response in ARPE-19 cells, and inhibited expression of vascular endothelium growth factor in human ARPE-19 and umbilical endothelium cell lines. The alginate-gelatin injectable hydrogel loaded OCCNPs are biocompatible and have high potential in protecting cells from apoptosis, angiogenesis, and production of pro-inflammatory cytokines in AMD cellular models. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

Crash Testing of Helicopter Airframe Fittings

NASA Technical Reports Server (NTRS)

Clarke, Charles W.; Townsend, William; Boitnott, Richard

2004-01-01

As part of the Rotary Wing Structures Technology Demonstration (RWSTD) program, a surrogate RAH-66 seat attachment fitting was dynamically tested to assess its response to transient, crash impact loads. The dynamic response of this composite material fitting was compared to the performance of an identical fitting subjected to quasi-static loads of similar magnitude. Static and dynamic tests were conducted of both smaller bench level and larger full-scale test articles. At the bench level, the seat fitting was supported in a steel fixture, and in the full-scale tests, the fitting was integrated into a surrogate RAH-66 forward fuselage. Based upon the lessons learned, an improved method to design, analyze, and test similar composite material fittings is proposed.

SLS Test Hardware Taken to Redstone Arsenal Airfield for Guppy Loading

NASA Image and Video Library

2017-07-10

A structural test article of the Orion Stage Adapter for NASA’s Space Launch System, built at NASA's Marshall Space Flight Center, is transported and prepared to be loaded onto NASA's Super Guppy aircraft. With integrated structural testing complete at Marshall, the stage adapter will soon be transported to Lockheed Martin in Denver for further testing with NASA's Orion spacecraft. The Guppy -- a plane large enough to carry cargo weighing more than 26 tons -- arrived at the U.S. Army's Redstone Arsenal Airfield July 10 to transport the stage adapter. On SLS's first integrated flight with Orion, the OSA will connect Orion to the Interim Cryogenic Propulsion Stage.

European Service Module Structural Test Article Load onto Transport Truck

NASA Image and Video Library

2017-06-21

The Orion service module structural test article for Exploration Mission-1 (EM-1), built by the European Space Agency, is prepared for shipment to Lockheed Martin's Denver facility to undergo testing. Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, a crane lifts the module onto a transport truck, where it is secured to be moved to the Shuttle Landing Facility for shipment. The Orion spacecraft will launch atop the agency's Space Launch System rocket on EM-1 in 2019.

European Service Module-Structural Test Article Load onto Transp

NASA Image and Video Library

2017-06-21

The Orion service module structural test article for Exploration Mission-1 (EM-1), built by the European Space Agency, is prepared for shipment to Lockheed Martin's Denver facility to undergo testing. Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, workers secure the protective covering around the module and a crane lifts the module, secured on stand, for the move to the transport truck. The Orion spacecraft will launch atop the agency's Space Launch System rocket on EM-1 in 2019.

HIV Viral Load

MedlinePlus

... Time and International Normalized Ratio (PT/INR) PSEN1 Quantitative Immunoglobulins Red Blood Cell (RBC) Antibody Identification Red ... RNA Test Formal Name Human Immunodeficiency Virus RNA, Quantitative This article was last reviewed on April 4, ...

Titanium reinforced boron-polyimide composite

NASA Technical Reports Server (NTRS)

Clark, G. A.; Clayton, K. I.

1969-01-01

Processing techniques for boron polyimide prepreg were developed whereby composites could be molded under vacuum bag pressure only. A post-cure cycle was developed which resulted in no loss in room temperature mechanical properties of the composite at any time during up to 16 hours at 650 F. A design utilizing laminated titanium foil was developed to achieve a smooth transition of load from the titanium attachment points into the boron-reinforced body of the structure. The box beam test article was subjected to combined bending and torsional loads while exposed to 650 F. Loads were applied incrementally until failure occurred at 83% design limit load.

DACS II - A distributed thermal/mechanical loads data acquisition and control system

NASA Technical Reports Server (NTRS)

Zamanzadeh, Behzad; Trover, William F.; Anderson, Karl F.

1987-01-01

A distributed data acquisition and control system has been developed for the NASA Flight Loads Research Facility. The DACS II system is composed of seven computer systems and four array processors configured as a main computer system, three satellite computer systems, and 13 analog input/output systems interconnected through three independent data networks. Up to three independent heating and loading tests can be run concurrently on different test articles or the entire system can be used on a single large test such as a full scale hypersonic aircraft. Thermal tests can include up to 512 independent adaptive closed loop control channels. The control system can apply up to 20 MW of heating to a test specimen while simultaneously applying independent mechanical loads. Each thermal control loop is capable of heating a structure at rates of up to 150 F per second over a temperature range of -300 to +2500 F. Up to 64 independent mechanical load profiles can be commanded along with thermal control. Up to 1280 analog inputs monitor temperature, load, displacement and strain on the test specimens with real time data displayed on up to 15 terminals as color plots and tabular data displays. System setup and operation is accomplished with interactive menu-driver displays with extensive facilities to assist the users in all phases of system operation.

Effect of added mass on treadmill performance and pulmonary function.

PubMed

Walker, Rachel E; Swain, David P; Ringleb, Stacie I; Colberg, Sheri R

2015-04-01

Military personnel engage in strenuous physical activity and load carriage. This study evaluated the role of body mass and of added mass on aerobic performance (uphill treadmill exercise) and pulmonary function. Performance on a traditional unloaded run test (4.8 km) was compared with performance on loaded tasks. Subjects performed an outdoor 4.8-km run and 4 maximal treadmill tests wearing loads of 0, 10, 20, and 30 kg. Subjects' pulmonary function (forced expired volume in 1 second [FEV1], forced vital capacity [FVC], and maximal voluntary ventilation [MVV]) was tested with each load, and peak values of heart rate, oxygen consumption ((Equation is included in full-text article.)), ventilation (VE), and respiratory exchange ratio (RER) were measured during each treadmill test. Performance on the 4.8-km run was correlated with treadmill performance, measured as time to exhaustion (TTE), with the strength of the correlation decreasing with load (r = 0.87 for 0 kg to 0.76 for 30 kg). Body mass was not correlated with TTE, other than among men with the 30-kg load (r = 0.48). During treadmill exercise, all peak responses other than RER decreased with load. Pulmonary function measures (FEV1, FVC, and MVV) decreased with load. Body mass was poorly correlated with treadmill performance, but added mass decreased performance. The decreased performance may be in part because of decreased pulmonary function. Unloaded 4.8-km run performance was correlated to unloaded uphill treadmill performance, but less so as load increased. Therefore, traditional run tests may not be an effective means of evaluating aerobic performance for military field operations.

Overview of the 6 Meter HIAD Inflatable Structure and Flexible TPS Static Load Test Series

NASA Technical Reports Server (NTRS)

Swanson, Greg; Kazemba, Cole; Johnson, Keith; Calomino, Anthony; Hughes, Steve; Cassell, Alan; Cheatwood, Neil

2014-01-01

To support NASAs long term goal of landing humans on Mars, technologies which enable the landing of heavy payloads are being developed. Current entry, decent, and landing technologies are not practical for this class of payloads due to geometric constraints dictated by current launch vehicle fairing limitations. Therefore, past and present technologies are now being explored to provide a mass and volume efficient solution to atmospheric entry, including Hypersonic Inflatable Aerodynamic Decelerators (HIADs). At the beginning of 2014, a 6m HIAD inflatable structure with an integrated flexible thermal protection system (TPS) was subjected to a static load test series to verify the designs structural performance. The 6m HIAD structure was constructed in a stacked toroid configuration using nine inflatable torus segments composed of fiber reinforced thin films, which were joined together using adhesives and high strength textile woven structural straps to help distribute the loads throughout the inflatable structure. The 6m flexible TPS was constructed using multiple layers of high performance materials to protect the inflatable structure from heat loads that would be seen during atmospheric entry. To perform the static load test series, a custom test fixture was constructed. The fixture consisted of a structural tub rim with enough height to allow for displacement of the inflatable structure as loads were applied. The bottom of the tub rim had an airtight seal with the floor. The centerbody of the inflatable structure was attached to a pedestal mount as seen in Figure 1. Using an impermeable membrane seal draped over the test article, partial vacuum was pulled beneath the HIAD, resulting in a uniform static pressure load applied to the outer surface. During the test series an extensive amount of instrumentation was used to provide many data sets including: deformed shape, shoulder deflection, strap loads, cord loads, inflation pressures, and applied static load.In this overview, the 6m HIAD static load test series will be discussed in detail, including the 6m HIAD inflatable structure and flexible TPS design, test setup and execution, and finally initial results and conclusions from the test series.

Deformation Behavior of Recycled Concrete Aggregate during Cyclic and Dynamic Loading Laboratory Tests

PubMed Central

Sas, Wojciech; Głuchowski, Andrzej; Gabryś, Katarzyna; Soból, Emil; Szymański, Alojzy

2016-01-01

Recycled concrete aggregate (RCA) is a relatively new construction material, whose applications can replace natural aggregates. To do so, extensive studies on its mechanical behavior and deformation characteristics are still necessary. RCA is currently used as a subbase material in the construction of roads, which are subject to high settlements due to traffic loading. The deformation characteristics of RCA must, therefore, be established to find the possible fatigue and damage behavior for this new material. In this article, a series of triaxial cyclic loading and resonant column tests is used to characterize fatigue in RCA as a function of applied deviator stress after long-term cyclic loading. A description of the shakedown phenomenon occurring in the RCA and calculations of its resilient modulus (Mr) as a function of fatigue are also presented. Test result analysis with the stress-life method on the Wohler S-N diagram shows the RCA behavior in accordance with the Basquin law. PMID:28773905

The more total cognitive load is reduced by cues, the better retention and transfer of multimedia learning: A meta-analysis and two meta-regression analyses.

PubMed

Xie, Heping; Wang, Fuxing; Hao, Yanbin; Chen, Jiaxue; An, Jing; Wang, Yuxin; Liu, Huashan

2017-01-01

Cueing facilitates retention and transfer of multimedia learning. From the perspective of cognitive load theory (CLT), cueing has a positive effect on learning outcomes because of the reduction in total cognitive load and avoidance of cognitive overload. However, this has not been systematically evaluated. Moreover, what remains ambiguous is the direct relationship between the cue-related cognitive load and learning outcomes. A meta-analysis and two subsequent meta-regression analyses were conducted to explore these issues. Subjective total cognitive load (SCL) and scores on a retention test and transfer test were selected as dependent variables. Through a systematic literature search, 32 eligible articles encompassing 3,597 participants were included in the SCL-related meta-analysis. Among them, 25 articles containing 2,910 participants were included in the retention-related meta-analysis and the following retention-related meta-regression, while there were 29 articles containing 3,204 participants included in the transfer-related meta-analysis and the transfer-related meta-regression. The meta-analysis revealed a statistically significant cueing effect on subjective ratings of cognitive load (d = -0.11, 95% CI = [-0.19, -0.02], p < 0.05), retention performance (d = 0.27, 95% CI = [0.08, 0.46], p < 0.01), and transfer performance (d = 0.34, 95% CI = [0.12, 0.56], p < 0.01). The subsequent meta-regression analyses showed that dSCL for cueing significantly predicted dretention for cueing (β = -0.70, 95% CI = [-1.02, -0.38], p < 0.001), as well as dtransfer for cueing (β = -0.60, 95% CI = [-0.92, -0.28], p < 0.001). Thus in line with CLT, adding cues in multimedia materials can indeed reduce SCL and promote learning outcomes, and the more SCL is reduced by cues, the better retention and transfer of multimedia learning.

The more total cognitive load is reduced by cues, the better retention and transfer of multimedia learning: A meta-analysis and two meta-regression analyses

PubMed Central

Hao, Yanbin; Chen, Jiaxue; An, Jing; Wang, Yuxin; Liu, Huashan

2017-01-01

Cueing facilitates retention and transfer of multimedia learning. From the perspective of cognitive load theory (CLT), cueing has a positive effect on learning outcomes because of the reduction in total cognitive load and avoidance of cognitive overload. However, this has not been systematically evaluated. Moreover, what remains ambiguous is the direct relationship between the cue-related cognitive load and learning outcomes. A meta-analysis and two subsequent meta-regression analyses were conducted to explore these issues. Subjective total cognitive load (SCL) and scores on a retention test and transfer test were selected as dependent variables. Through a systematic literature search, 32 eligible articles encompassing 3,597 participants were included in the SCL-related meta-analysis. Among them, 25 articles containing 2,910 participants were included in the retention-related meta-analysis and the following retention-related meta-regression, while there were 29 articles containing 3,204 participants included in the transfer-related meta-analysis and the transfer-related meta-regression. The meta-analysis revealed a statistically significant cueing effect on subjective ratings of cognitive load (d = −0.11, 95% CI = [−0.19, −0.02], p < 0.05), retention performance (d = 0.27, 95% CI = [0.08, 0.46], p < 0.01), and transfer performance (d = 0.34, 95% CI = [0.12, 0.56], p < 0.01). The subsequent meta-regression analyses showed that dSCL for cueing significantly predicted dretention for cueing (β = −0.70, 95% CI = [−1.02, −0.38], p < 0.001), as well as dtransfer for cueing (β = −0.60, 95% CI = [−0.92, −0.28], p < 0.001). Thus in line with CLT, adding cues in multimedia materials can indeed reduce SCL and promote learning outcomes, and the more SCL is reduced by cues, the better retention and transfer of multimedia learning. PMID:28854205

STA-2A NDT testing

NASA Technical Reports Server (NTRS)

Lewis, T. J.

1987-01-01

The nondestructive testing (NDT) on the Space Shuttle Solid Rocket Booster (SRB) filament wound case (FWC) short stact structural test articles 2 (STA-2A) during test of phases 1B-9C is described. The primary objective of this testing was to verify the structural integrity of the SRB-FWC for critical design loads. Another objective was to quantify the effect of load distributions in the aft skirt. The NDT objectives were to determine the acoustic emission characteristics of the FWC-SRB and to identify possible design deficiencies or defect growth. The results from the posttest inspection of the samples shows the depth measurements taken were accurate until exceeding .260 inches thickness. The data then show that pulse echo measurements exceeded actual part thickness by 10 to 14 percent. The mapping of forward boundaries of delaminations proved to be within the tolerance of the equipment. Using the ZIP probe, the maximum difference between the pulse echo boundary and the visual boundary was expected to be no greater than one half the diameter of the probe. The NDT performance on STA-2A shows how NDT can be used to assist design engineering in evaluating the structural integrity of composite test articles.

Longitudinally Jointed Edge-wise Compression Honeycomb Composite Sandwich Coupon Testing and FE Analysis: Three Methods of Strain Measurement, and Comparison

NASA Technical Reports Server (NTRS)

Farrokh, Babak; AbdulRahim, Nur Aida; Segal, Ken; Fan, Terry; Jones, Justin; Hodges, Ken; Mashni, Noah; Garg, Naman; Sang, Alex; Gifford, Dawn;

Analysis of open loop higher harmonic control at high airspeeds on a modern four-bladed articulated rotor

NASA Technical Reports Server (NTRS)

Kottapalli, Sesi; Leyland, Jane

1991-01-01

The effects of open loop higher harmonic control (HHC) on rotor hub loads, performance, and push rod loads of a Sikorsky S-76 helicopter rotor at high airspeeds (up to 200 knots) and moderate lift (10,000 lbs) were studied analytically. The analysis was performed as part of a wind tunnel pre-test prediction and preparation procedure, as well as to provide analytical results for post-test correlation efforts. The test associated with this study is to be concluded in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex (NFAC) at the NASA Ames Research Center. The results from this analytical study show that benefits from HHC can be achieved at high airspeeds. These results clear the way for conducting (with the requirement of safe pushrod loads) an open loop HHC test a high airspeeds in the 40- by 80-Foot Wind Tunnel using an S-76 rotor as the test article.

An Extended IEEE 118-Bus Test System With High Renewable Penetration

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

Pena, Ivonne; Martinez-Anido, Carlo Brancucci; Hodge, Bri-Mathias

This article describes a new publicly available version of the IEEE 118-bus test system, named NREL-118. The database is based on the transmission representation (buses and lines) of the IEEE 118-bus test system, with a reconfigured generation representation using three regions of the US Western Interconnection from the latest Western Electricity Coordination Council (WECC) 2024 Common Case [1]. Time-synchronous hourly load, wind, and solar time series are provided for over one year (8784 hours). The public database presented and described in this manuscript will allow researchers to model a test power system using detailed transmission, generation, load, wind, and solarmore » data. This database includes key additional features that add to the current IEEE 118-bus test model, such as: the inclusion of 10 generation technologies with different heat rate functions, minimum stable levels and ramping rates, GHG emissions rates, regulation and contingency reserves, and hourly time series data for one full year for load, wind and solar generation.« less

Using Item Response Theory to Describe the Nonverbal Literacy Assessment (NVLA)

ERIC Educational Resources Information Center

Fleming, Danielle; Wilson, Mark; Ahlgrim-Delzell, Lynn

2018-01-01

The Nonverbal Literacy Assessment (NVLA) is a literacy assessment designed for students with significant intellectual disabilities. The 218-item test was initially examined using confirmatory factor analysis. This method showed that the test worked as expected, but the items loaded onto a single factor. This article uses item response theory to…

Failure mechanism characterization of platinum alloy

NASA Technical Reports Server (NTRS)

Rosen, J. M.; Mcfarlen, W. T.

1986-01-01

This article describes procedures and results of testing performed on a platinum/10-percent rhodium, thin-wall tubular product. The purpose of the testing was to develop exemplar SEM fractographs to be used to characterize failures under various environmental conditions. Conditions evaluated for the platinum alloys included high temperature, hydrogen environment, braze metal contamination, and cyclic loading.

Testing of a Stitched Composite Large-Scale Multi-Bay Pressure Box

NASA Technical Reports Server (NTRS)

Jegley, Dawn; Rouse, Marshall; Przekop, Adam; Lovejoy, Andrew

2016-01-01

NASA has created the Environmentally Responsible Aviation (ERA) Project to develop technologies to reduce aviation's impact on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe to enable the introduction of unconventional aircraft configurations. NASA and The Boeing Company have worked together to develop a structural concept that is lightweight and an advancement beyond state-of-the-art composite structures. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is an integrally stiffened panel design where elements are stitched together. The PRSEUS concept is designed to maintain residual load carrying capabilities under a variety of damage scenarios. A series of building block tests were evaluated to explore the fundamental assumptions related to the capability and advantages of PRSEUS panels. The final step in the building block series is an 80%-scale pressure box representing a portion of the center section of a Hybrid Wing Body (HWB) transport aircraft. The testing of this article under maneuver load and internal pressure load conditions is the subject of this paper. The experimental evaluation of this article, along with the other building block tests and the accompanying analyses, has demonstrated the viability of a PRSEUS center body for the HWB vehicle. Additionally, much of the development effort is also applicable to traditional tube-and-wing aircraft, advanced aircraft configurations, and other structures where weight and through-the-thickness strength are design considerations.

Field investigation of low-temperature cracking and stiffness moduli on selected roads with conventional and high modulus asphalt concrete

NASA Astrophysics Data System (ADS)

Judycki, Józef; Jaczewski, Mariusz; Ryś, Dawid; Pszczoła, Marek; Jaskuła, Piotr; Glinicki, Adam

2017-09-01

High Modulus Asphalt Concrete (HMAC) was introduced in Poland as a one of the solutions to the problem of rutting, type of deterioration common in the 1990s. After first encouraging trials in 2002 HMAC was widely used for heavily loaded national roads and motorways. However some concerns were raised about low-temperature cracking of HMAC. This was the main reason of the studies presented in this article were started. The article presents the comparison of performance of pavements constructed in typical contract conditions with the road bases made of HMAC and conventional asphalt concrete (AC). The field investigation was focused on the number of low-temperature cracks, bearing capacity (based on FWD test) of road sections localized in coldest region of Poland. Also load transfer efficiency of selected low-temperature cracks was assessed. FWD test confirmed lower deflections of pavements with HMAC and two times higher stiffness modulus of asphalt courses in comparison to pavements constructed with conventional AC mixtures. Relation of stiffness of asphalt layers and amount of low-temperature cracks showed that the higher stiffness modulus of asphalt layers could lead to increase of the number of low-temperature cracks. FWD test results showed that the load transfer efficiency of low-temperature cracks on pavements with HMAC presents very low values, very close to lack of load transfer. It was surprising as section with HMAC road base were aged from 2 to 5 years and presented very good bearing capacity.

Initial Evaluation of Acoustic Emission SHM of PRSEUS Multi-bay Box Tests

NASA Technical Reports Server (NTRS)

Horne, Michael R.; Madaras, Eric I.

2016-01-01

A series of tests of the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) HWB Multi-Bay Test Article were conducted during the second quarter of 2015 at NASA Langley Research Center (LaRC) in the Combined Loads Test facility (COLTS). This report documents the Acoustic Emission (AE) data collected during those tests along with an initial analysis of the data. A more detailed analysis will be presented in future publications.

Derivation of the Data Reduction Equations for the Calibration of the Six-component Thrust Stand in the CE-22 Advanced Nozzle Test Facility

NASA Technical Reports Server (NTRS)

Wong, Kin C.

2003-01-01

This paper documents the derivation of the data reduction equations for the calibration of the six-component thrust stand located in the CE-22 Advanced Nozzle Test Facility. The purpose of the calibration is to determine the first-order interactions between the axial, lateral, and vertical load cells (second-order interactions are assumed to be negligible). In an ideal system, the measurements made by the thrust stand along the three coordinate axes should be independent. For example, when a test article applies an axial force on the thrust stand, the axial load cells should measure the full magnitude of the force, while the off-axis load cells (lateral and vertical) should read zero. Likewise, if a lateral force is applied, the lateral load cells should measure the entire force, while the axial and vertical load cells should read zero. However, in real-world systems, there may be interactions between the load cells. Through proper design of the thrust stand, these interactions can be minimized, but are hard to eliminate entirely. Therefore, the purpose of the thrust stand calibration is to account for these interactions, so that necessary corrections can be made during testing. These corrections can be expressed in the form of an interaction matrix, and this paper shows the derivation of the equations used to obtain the coefficients in this matrix.

Instrumentation for the Characterization of Inflatable Structures

NASA Technical Reports Server (NTRS)

Swanson, Gregory T.; Cassell, Alan M.; Johnson, R. Keith

2012-01-01

Current entry, descent, and landing technologies are not practical for heavy payloads due to mass and volume constraints dictated by limitations imposed by launch vehicle fairings. Therefore, new technologies are now being explored to provide a mass- and volume-efficient solution for heavy payload capabilities, including Inflatable Aerodynamic Decelerators (IAD) [1]. Consideration of IADs for space applications has prompted the development of instrumentation systems for integration with flexible structures to characterize system response to flight-like environment testing. This development opportunity faces many challenges specific to inflatable structures in extreme environments, including but not limited to physical flexibility, packaging, temperature, structural integration and data acquisition [2]. In the spring of 2012, two large scale Hypersonic Inflatable Aerodynamic Decelerators (HIAD) will be tested in the National Full-Scale Aerodynamics Complex s 40 by 80 wind tunnel at NASA Ames Research Center. The test series will characterize the performance of a 3.0 m and 6.0 m HIAD at various angles of attack and levels of inflation during flight-like loading. To analyze the performance of these inflatable test articles as they undergo aerodynamic loading, many instrumentation systems have been researched and developed. These systems will utilize new experimental sensing systems developed by the HIAD ground test campaign instrumentation team, in addition to traditional wind tunnel sensing techniques in an effort to improve test article characterization and model validation. During the 2012 test series the instrumentation systems will target inflatable aeroshell static and dynamic deformation, structural strap loading, surface pressure distribution, localized skin deflection, and torus inflation pressure. This paper will offer an overview of inflatable structure instrumentation, and provide detail into the design and implementation of the sensors systems that will be utilized during the 2012 HIAD ground test campaign.

Genetic Testing for Deafness--GJB2 and SLC26A4 as Causes of Deafness.

ERIC Educational Resources Information Center

Smith, Richard J. H.; Robin, Nathaniel H.

2002-01-01

This article introduces the concept of genetic testing for deafness. Two genes that make appreciable contributions to the autosomal recessive non-syndromic deafness (ARNSD) genetic load are reviewed, GJB2 and SLC26A4. In addition, the unique aspects of genetic counseling for deafness and recurrence chance estimates are explained. (Contains…

Vibroacoustic Response of Pad Structures to Space Shuttle Launch Acoustic Loads

NASA Technical Reports Server (NTRS)

Margasahayam, R. N.; Caimi, Raoul E.

1995-01-01

This paper presents a deterministic theory for the random vibration problem for predicting the response of structures in the low-frequency range (0 to 20 hertz) of launch transients. Also presented are some innovative ways to characterize noise and highlights of ongoing test-analysis correlation efforts titled the Verification Test Article (VETA) project.

14 CFR Appendix H to Part 25 - Instructions for Continued Airworthiness

Code of Federal Regulations, 2013 CFR

2013-01-01

..., approved under § 25.571. Until the full-scale fatigue testing is completed and the FAA has approved the LOV... accumulated on the fatigue test article. (b) If the Instructions for Continued Airworthiness consist of... identifying any changes to EWIS under § 25.1711. (5) Electrical load data and instructions for updating that...

14 CFR Appendix H to Part 25 - Instructions for Continued Airworthiness

Code of Federal Regulations, 2014 CFR

2014-01-01

..., approved under § 25.571. Until the full-scale fatigue testing is completed and the FAA has approved the LOV... accumulated on the fatigue test article. (b) If the Instructions for Continued Airworthiness consist of... identifying any changes to EWIS under § 25.1711. (5) Electrical load data and instructions for updating that...

14 CFR Appendix H to Part 25 - Instructions for Continued Airworthiness

Code of Federal Regulations, 2012 CFR

2012-01-01

..., approved under § 25.571. Until the full-scale fatigue testing is completed and the FAA has approved the LOV... accumulated on the fatigue test article. (b) If the Instructions for Continued Airworthiness consist of... identifying any changes to EWIS under § 25.1711. (5) Electrical load data and instructions for updating that...

Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure. Part 1; Ultimate Design Loads

NASA Technical Reports Server (NTRS)

Przekop, Adam; Jegley, Dawn C.; Lovejoy, Andrew E.; Rouse, Marshall; Wu, Hsi-Yung T.

2016-01-01

The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses finite element analysis and testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part I of the paper considers the five most critical load conditions, which are internal pressure only and positive and negative g-loads with and without internal pressure. Analysis results are compared with measurements acquired during testing. Performance of the test article is found to be closely aligned with predictions and, consequently, able to support the hybrid wing body design loads in pristine and barely visible impact damage conditions.

Ground test article for deployable space structure systems

NASA Technical Reports Server (NTRS)

Malloy, G. D.

1984-01-01

The ground test article fabrication and assembly plan was completed by Santek Engineering, Inc. The plan was reviewed and accepted by Rockwell during an on-site visit to the Santek facility. Raw material and hardware orders were placed by Santek in July. Approximately 98% of the raw materials and 10% of the hardware deliveries have been completed. Several material and hardware substitutions were requested by Santek due to no-bid responses from suppliers or excessive costs for limited quantity items. These substitutions were evaluated and approved by Rockwell Engineering and Material and Process and are being incorporated into the drawing package. Santek started fabrication of detail parts in mid-August. Their current resource utilization is at approximately 50% of the planned eventual commitment and is increasing at a rate commensurate with the fabrication and assembly plan. At this writing, Santek's estimate of completion is 03%. During verification testing of the diagonal member joint, in a program funded by Rockwell discretionary funds, the axial load to unlock the joint was found to increase significantly after a few cycles of operation. This was attributed to galling, poor lubrication, and locking pin geometry. A change of materials, lubricant, and modification of the pin geometry reduced the unlocking load and provided repeatability after 50 cycles of operation. This new design is being implemented into the ground test article.

Ultrasonic Nondestructive Evaluation of PRSEUS Pressure Cube Article in Support of Load Test to Failure

NASA Technical Reports Server (NTRS)

Johnston, Patrick H.

2013-01-01

The PRSEUS Pressure Cube Test was a joint development effort between the Boeing Company and NASA Langley Research Center, sponsored in part by the Environmentally Responsible Aviation Project and Boeing internal R&D. This Technical Memorandum presents the results of ultrasonic inspections in support of the PRSEUS Pressure Cube Test, and is a companion document with the NASA test report and a report on the acoustic emission measurements made during the test.

Thermal coupon testing of Load-Bearing Multilayer Insulation

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Heckle, K. W.; Hurd, J.

2014-01-01

Advanced liquid hydrogen storage concepts being considered for long duration space travel incorporate refrigeration systems and cryocoolers to lower the heat load. Using a refrigeration loop to intercept the energy flowing through MLI to a liquid hydrogen tank at a temperature between the environment and the liquid hydrogen can lower the heat load on the propellant system by as much as 50%. However, the refrigeration loop requires structural integration into the MLI. Use of a more traditional concept of MLI underneath this refrigeration loop requires that a structural system be put in place to support the loop. Such structures, even when thermally optimized, present a relatively large parasitic heat load into the tank. Through NASA small business innovation research funding, Quest Thermal Group and Ball Aerospace have been developing a structural MLI based insulation system. These systems are designed with discrete polymeric spacers between reflective layers instead of either dacron or silk netting. The spacers (or posts) have an intrinsic structural capability that is beyond that of just supporting the internal insulation mechanical loads. This new MLI variant called Load Bearing MLI (LB-MLI) has been developed specifically for the application of supporting thermal shields within the insulation system. Test articles (coupons) of the new LB-MLI product were fabricated for thermal performance testing using liquid nitrogen at Kennedy Space Center (KSC) and using cryocooler based calorimetry at Florida State University. The test results and analysis are presented. Thermal models developed for correlation with the thermal testing results both at KSC and testing that was performed at Florida State University are also discussed.

Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices

PubMed Central

MacLeod, A.; Simpson, A. H. R. W.

2018-01-01

Objectives Secondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs. Methods Synthetic composite bones were used to evaluate experimentally the influence of four different methods of loading and restraining specimens, all used in recent previous studies. Two plate types and three screw arrangements were also evaluated for each loading scenario. Computational models were also developed and validated using the experimental tests. Results The method of loading was found to affect the gap stiffness strongly (by up to six times) but also the magnitude of the plate stress and the location and magnitude of strains at the bone-screw interface. Conclusions This study demonstrates that the method of loading is responsible for much of the difference in reported stiffness values in the literature. It also shows that previous contradictory findings, such as the influence of working length and very large differences in failure loads, can be readily explained by the choice of loading condition. Cite this article: A. MacLeod, A. H. R. W. Simpson, P. Pankaj. Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices. Bone Joint Res 2018;7:111–120. DOI: 10.1302/2046-3758.71.BJR-2017-0074.R2. PMID:29363522

A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

NASA Astrophysics Data System (ADS)

Szumigała, Ewa; Szumigała, Maciej; Polus, Łukasz

2015-03-01

The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

Thermodynamic performance testing of the orbiter flash evaporator system

NASA Technical Reports Server (NTRS)

Jaax, J. R.; Melgares, M. A.; Frahm, J. P.

1980-01-01

System level testing of the space shuttle orbiter's development flash evaporator system (FES) was performed in a thermal vacuum chamber capable of simulating ambient ascent, orbital, and entry temperature and pressure profiles. The test article included the evaporator assembly, high load and topping exhaust duct and nozzle assemblies, and feedwater supply assembly. Steady state and transient heat load, water pressure/temperature and ambient pressure/temperature profiles were imposed by especially designed supporting test hardware. Testing in 1978 verified evaporator and duct heater thermal design, determined FES performance boundaries, and assessed topping evaporator plume characteristics. Testing in 1979 combined the FES with the other systems in the orbiter active thermal control subsystem (ATCS). The FES met or exceeded all nominal and contingency performance requirements during operation with the integrated ATCS. During both tests stability problems were encountered during steady state operations which resulted in subsequent design changes to the water spray nozzle and valve plate assemblies.

Development of a clinically validated bulk failure test for ceramic crowns.

PubMed

Kelly, J Robert; Rungruanganunt, Patchnee; Hunter, Ben; Vailati, Francesca

2010-10-01

Traditional testing of ceramic crowns creates a stress state and damage modes that differ greatly from those seen clinically. There is a need to develop and communicate an in vitro testing protocol that is clinically valid. The purpose of this study was to develop an in vitro failure test for ceramic single-unit prostheses that duplicates the failure mechanism and stress state observed in clinically failed prostheses. This article first compares characteristics of traditional load-to-failure tests of ceramic crowns with the growing body of evidence regarding failure origins and stress states at failure from the examination of clinically failed crowns, finite element analysis (FEA), and data from clinical studies. Based on this analysis, an experimental technique was systematically developed and test materials were identified to recreate key aspects of clinical failure in vitro. One potential dentin analog material (an epoxy filled with woven glass fibers; NEMA grade G10) was evaluated for elastic modulus in blunt contact and for bond strength to resin cement as compared to hydrated dentin. Two bases with different elastic moduli (nickel chrome and resin-based composite) were tested for influence on failure loads. The influence of water during storage and loading (both monotonic and cyclic) was examined. Loading piston materials (G10, aluminum, stainless steel) and piston designs were varied to eliminate Hertzian cracking and to improve performance. Testing was extended from a monolayer ceramic (leucite-filled glass) to a bilayer ceramic system (glass-infiltrated alumina). The influence of cyclic rate on mean failure loads was examined (2 Hz, 10 Hz, 20 Hz) with the extremes compared statistically (t test; α=.05). Failure loads were highly influenced by base elastic modulus (t test; P<.001). Cyclic loading while in water significantly decreased mean failure loads (1-way ANOVA; P=.003) versus wet storage/dry cycling (350 N vs. 1270 N). G10 was not significantly different from hydrated dentin in terms of blunt contact elastic behavior or resin cement bond strength. Testing was successful with the bilayered ceramic, and the cycling rate altered mean failure loads only slightly (approximately 5%). Test methods and materials were developed to validly simulate many aspects of clinical failure. Copyright © 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Simulation of Cold Flow in a Truncated Ideal Nozzle with Film Cooling

NASA Technical Reports Server (NTRS)

Braman, Kalen; Ruf, Joseph

2015-01-01

Flow transients during rocket start-up and shut-down can lead to significant side loads on rocket nozzles. The capability to estimate these side loads computationally can streamline the nozzle design process. Towards this goal, the flow in a truncated ideal contour (TIC) nozzle has been simulated for a range of nozzle pressure ratios (NPRs) aimed to match a series of cold flow experiments performed at the NASA MSFC Nozzle Test Facility. These simulations were performed with varying turbulence model choices and with four different versions of the TIC nozzle model geometry, each of which was created with a different simplification to the test article geometry.

Dynamic cone penetration tests in granular media: Determination of the tip's dynamic load-penetration curve

NASA Astrophysics Data System (ADS)

Escobar, E.; Benz, M.; Gourvès, R.; Breul, P.

2013-06-01

In this article a two-dimensional discrete numerical model, realized in PFC2D, is presented. This model is used in the dynamic penetration tests in a granular medium. Its objective being the validation of the measurement technique offered by Panda 3® (Benz et al. 2011) which is designed to calculate the tip's load-penetration curve for each impact in the soil where different parameters are used. To do so, we have compared the results obtained by calculation during the impacts to those measured directly in the model of a penetrometer through the installation of the gauges at the cone.

Tests of Low-Noise MMIC Amplifier Module at 290 to 340 GHz

NASA Technical Reports Server (NTRS)

Gaier, Todd; Samoska, Lorene; Fung, King Man; Deal, William; Mei, Xiaobing; Lai, Richard

2009-01-01

A document presents data from tests of a low-noise amplifier module operating in the frequency range from 290 to 340 GHz said to be the highest-frequency low-noise, solid-state amplifier ever developed. The module comprised a three-stage monolithic microwave integrated circuit (MMIC) amplifier integrated with radial probe MMIC/waveguide transitions and contained in a compact waveguide package, all according to the concepts described in the immediately preceding article and in the referenced prior article, "Integrated Radial Probe Transition From MMIC to Waveguide" (NPO-43957), NASA Tech Briefs Vol. 31, No. 5 (May 2007), page 38. The tests included measurements by the Y-factor method, in which noise figures are measured repeatedly with an input noise source alternating between an "on" (hot-load) condition and an "off" (cold-load) condition. (The Y factor is defined as the ratio between the "on" and "off" noise power levels.) The test results showed that, among other things, the module exhibited a minimum noise figure of about 8.7 dB at 325 GHz and that the gain at that frequency under the bias conditions that produced the minimum noise figure was between about 9 and 10 dB.

A pulse-shaping technique to investigate the behaviour of brittle materials subjected to plate-impact tests.

PubMed

Forquin, Pascal; Zinszner, Jean-Luc

2017-01-28

Owing to their significant hardness and compressive strengths, ceramic materials are widely employed for use with protective systems subjected to high-velocity impact loadings. Therefore, their mechanical behaviour along with damage mechanisms need to be significantly investigated as a function of loading rates. However, the classical plate-impact testing procedures produce shock loadings in the brittle sample material which cause unrealistic levels of loading rates. Additionally, high-pulsed power techniques and/or functionally graded materials used as flyer plates to smooth the loading pulse remain costly, and are generally difficult to implement. In this study, a shockless plate-impact technique based on the use of either a wavy-machined flyer plate or buffer plate that can be produced by chip-forming is proposed. A series of numerical simulations using an explicit transient dynamic finite-element code have been performed to design and validate the experimental testing configuration. The calculations, conducted in two-dimensional (2D) plane-strain or in 2D axisymmetric modes, prove that the 'wavy' contact surface will produce a pulse-shaping effect, whereas the buffer plate will produce a homogenizing effect of the stress field along the transverse direction of the sample. In addition, 'wavy-shape' geometries of different sizes provide an easy way to change the level of loading rate and rise time in an experimentally tested ceramic specimen. Finally, when a shockless compression loading method is applied to the sample, a Lagrangian analysis of data is made possible by considering an assemblage of ceramic plates of different thicknesses in the target, so the axial stress-strain response of the brittle sample material can be provided.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. © 2016 The Author(s).

A pulse-shaping technique to investigate the behaviour of brittle materials subjected to plate-impact tests

NASA Astrophysics Data System (ADS)

Forquin, Pascal; Zinszner, Jean-Luc

2017-01-01

Owing to their significant hardness and compressive strengths, ceramic materials are widely employed for use with protective systems subjected to high-velocity impact loadings. Therefore, their mechanical behaviour along with damage mechanisms need to be significantly investigated as a function of loading rates. However, the classical plate-impact testing procedures produce shock loadings in the brittle sample material which cause unrealistic levels of loading rates. Additionally, high-pulsed power techniques and/or functionally graded materials used as flyer plates to smooth the loading pulse remain costly, and are generally difficult to implement. In this study, a shockless plate-impact technique based on the use of either a wavy-machined flyer plate or buffer plate that can be produced by chip-forming is proposed. A series of numerical simulations using an explicit transient dynamic finite-element code have been performed to design and validate the experimental testing configuration. The calculations, conducted in two-dimensional (2D) plane-strain or in 2D axisymmetric modes, prove that the `wavy' contact surface will produce a pulse-shaping effect, whereas the buffer plate will produce a homogenizing effect of the stress field along the transverse direction of the sample. In addition, `wavy-shape' geometries of different sizes provide an easy way to change the level of loading rate and rise time in an experimentally tested ceramic specimen. Finally, when a shockless compression loading method is applied to the sample, a Lagrangian analysis of data is made possible by considering an assemblage of ceramic plates of different thicknesses in the target, so the axial stress-strain response of the brittle sample material can be provided. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

High Fidelity Simulations for Unsteady Flow Through the Orbiter LH2 Feedline Flowliner

NASA Technical Reports Server (NTRS)

Kiris, Cetin C.; Kwak, Dochan; Chan, William; Housman, Jeffrey

2005-01-01

High fidelity computations were carried out to analyze the orbiter M2 feedline flowliner. Various computational models were used to characterize the unsteady flow features in the turbopump, including the orbiter Low-Pressure-Fuel-Turbopump (LPFTP) inducer, the orbiter manifold and a test article used to represent the manifold. Unsteady flow originating from the orbiter LPFTP inducer is one of the major contributors to the high frequency cyclic loading that results in high cycle fatigue damage to the gimbal flowliners just upstream of the LPFTP. The flow fields for the orbiter manifold and representative test article are computed and analyzed for similarities and differences. An incompressible Navier-Stokes flow solver INS3D, based on the artificial compressibility method, was used to compute the flow of liquid hydrogen in each test article.

Application of Fracture Mechanics to Specify the Proof Load Factor for Clamp Band Systems of Launch Vehicles

NASA Astrophysics Data System (ADS)

Singaravelu, J.; Sundaresan, S.; Nageswara Rao, B.

2013-04-01

This article presents a methodology for evaluation of the proof load factor (PLF) for clamp band system (CBS) made of M250 Maraging steel following fracture mechanics principles.CBS is most widely used as a structural element and as a separation system. Using Taguchi's design of experiments and the response surface method (RSM) the compact tension specimens were tested to establish an empirical relation for the failure load ( P max) in terms of the ultimate strength, width, thickness, and initial crack length. The test results of P max closely matched with the developed RSM empirical relation. Crack growth rates of the maraging steel in different environments were examined. Fracture strength (σf) of center surface cracks and through-crack tension specimens are evaluated utilizing the fracture toughness ( K IC). Stress induced in merman band at flight loading conditions is evaluated to estimate the higher load factor and PLF. Statistical safety factor and reliability assessments were made for the specified flaw sizes useful in the development of fracture control plan for CBS of launch vehicles.

Edgewise Compression Testing of STIPS-0 (Structurally Integrated Thermal Protection System)

NASA Technical Reports Server (NTRS)

Brewer, Amy R.

2011-01-01

The Structurally Integrated Thermal Protection System (SITPS) task was initiated by the NASA Hypersonics Project under the Fundamental Aeronautics Program to develop a structural load-carrying thermal protection system for use in aerospace applications. The initial NASA concept for SITPS consists of high-temperature composite facesheets (outer and inner mold lines) with a light-weight insulated structural core. An edgewise compression test was performed on the SITPS-0 test article at room temperature using conventional instrumentation and methods in order to obtain panel-level mechanical properties and behavior of the panel. Three compression loadings (10, 20 and 37 kips) were applied to the SITPS-0 panel. The panel behavior was monitored using standard techniques and non-destructive evaluation methods such as photogrammetry and acoustic emission. The elastic modulus of the SITPS-0 panel was determined to be 1.146x106 psi with a proportional limit at 1039 psi. Barrel-shaped bending of the panel and partial delamination of the IML occurred under the final loading.

Advanced recovery systems wind tunnel test report

NASA Technical Reports Server (NTRS)

Geiger, R. H.; Wailes, W. K.

1990-01-01

Pioneer Aerospace Corporation (PAC) conducted parafoil wind tunnel testing in the NASA-Ames 80 by 120 test sections of the National Full-Scale Aerodynamic Complex, Moffett Field, CA. The investigation was conducted to determine the aerodynamic characteristics of two scale ram air wings in support of air drop testing and full scale development of Advanced Recovery Systems for the Next Generation Space Transportation System. Two models were tested during this investigation. Both the primary test article, a 1/9 geometric scale model with wing area of 1200 square feet and secondary test article, a 1/36 geometric scale model with wing area of 300 square feet, had an aspect ratio of 3. The test results show that both models were statically stable about a model reference point at angles of attack from 2 to 10 degrees. The maximum lift-drag ratio varied between 2.9 and 2.4 for increasing wing loading.

Composite Testing

DTIC Science & Technology

2007-01-01

characterising the behaviour and ultimate load capacity of adhesively bonded joints for both composite-to-composite and composite-to-metal hybrid systems...novel hybrid joint details one of which involved perforations in the steel. The second detail employed bonding and bolting. The detail performed well...will be fabricated by four teams (3TEX, Space Micro, Tech Partnership, and Beltran) as part of the STTR Hybrid Joints Test Articles Program. Each

Subscale and Full-Scale Testing of Buckling-Critical Launch Vehicle Shell Structures

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Haynie, Waddy T.; Lovejoy, Andrew E.; Roberts, Michael G.; Norris, Jeffery P.; Waters, W. Allen; Herring, Helen M.

2012-01-01

New analysis-based shell buckling design factors (aka knockdown factors), along with associated design and analysis technologies, are being developed by NASA for the design of launch vehicle structures. Preliminary design studies indicate that implementation of these new knockdown factors can enable significant reductions in mass and mass-growth in these vehicles and can help mitigate some of NASA s launch vehicle development and performance risks by reducing the reliance on testing, providing high-fidelity estimates of structural performance, reliability, robustness, and enable increased payload capability. However, in order to validate any new analysis-based design data or methods, a series of carefully designed and executed structural tests are required at both the subscale and full-scale level. This paper describes recent buckling test efforts at NASA on two different orthogrid-stiffened metallic cylindrical shell test articles. One of the test articles was an 8-ft-diameter orthogrid-stiffened cylinder and was subjected to an axial compression load. The second test article was a 27.5-ft-diameter Space Shuttle External Tank-derived cylinder and was subjected to combined internal pressure and axial compression.

Further Testing of an Amine-based Pressure-Swing System for Carbon Dioxide and Humidity Control

NASA Technical Reports Server (NTRS)

Lin, Amy; Smith, Frederick; Sweterlitsch, Jeffrey; Nalette, Tim A.; Papale, William

2008-01-01

In a crewed spacecraft environment, atmospheric carbon dioxide (CO2) and moisture control are crucial. Hamilton Sundstrand has developed a stable and efficient amine-based CO2 and water vapor sorbent, SA9T, that is well suited for use in a spacecraft environment. The sorbent is efficiently packaged in pressure-swing regenerable beds that are thermally linked to improve removal efficiency and minimize vehicle thermal loads. Flows are all controlled with a single spool valve. This technology has been baselined for the new Orion spacecraft. However, more data was needed on the operational characteristics of the package in a simulated spacecraft environment. A unit was therefore tested with simulated metabolic loads in a closed chamber at Johnson Space Center during the last third of 2006. Those test results were reported in a 2007 ICES paper. A second test article was incorporated for a third phase of testing, and that test article was modified to allow pressurized gas purge regeneration on the launch pad in addition to the standard vacuum regeneration in space. Metabolic rates and chamber volumes were also adjusted to reflect current programmatic standards. The third phase of tests was performed during the spring and summer of 2007. Tests were run with a range of operating conditions, varying: cycle time, vacuum pressure (or purge gas flow rate), air flow rate, and crew activity levels. Results of this testing are presented and potential flight operational strategies discussed.

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

James Schondel; Henry S. Chu

Lightweight panels have been designed to protect buildings and vehicles from blast pressures by activating energy dissipation mechanisms under the influence of blast loading. Panels were fabricated which featured a variety of granular materials and hydraulic dissipative deformation mechanisms and the test articles were subjected to full-scale blast loading. The force time-histories transmitted by each technology were measured by a novel method that utilized inexpensive custom-designed force sensors. The array of tests revealed that granular materials can effectively dissipate blast energy if they are employed in a way that they easily crush and rearrange. Similarly, hydraulic dissipation can effectively dissipatemore » energy if the panel features a high fraction of porosity and the panel encasement features low compressive stiffness.« less

Embedded electronics for intelligent structures

NASA Astrophysics Data System (ADS)

Warkentin, David J.; Crawley, Edward F.

The signal, power, and communications provisions for the distributed control processing, sensing, and actuation of an intelligent structure could benefit from a method of physically embedding some electronic components. The preliminary feasibility of embedding electronic components in load-bearing intelligent composite structures is addressed. A technique for embedding integrated circuits on silicon chips within graphite/epoxy composite structures is presented which addresses the problems of electrical, mechanical, and chemical isolation. The mechanical and chemical isolation of test articles manufactured by this technique are tested by subjecting them to static and cyclic mechanical loads and a temperature/humidity/bias environment. The likely failure modes under these conditions are identified, and suggestions for further improvements in the technique are discussed.

Manipulation of cognitive load variables and impact on auscultation test performance.

PubMed

Chen, Ruth; Grierson, Lawrence; Norman, Geoffrey

2015-10-01

Health profession educators have identified auscultation skill as a learning need for health professional students. This article explores the application of cognitive load theory (CLT) to designing cardiac and respiratory auscultation skill instruction for senior-level undergraduate nursing students. Three experiments assessed student auscultation performance following instructional manipulations of the three primary components of cognitive load: intrinsic, extraneous, and germane load. Study 1 evaluated the impact of intrinsic cognitive load by varying the number of diagnoses learned in one instruction session; Study 2 evaluated the impact of extraneous cognitive load by providing students with single or multiple examples of diagnoses during instruction; and Study 3 evaluated the impact of germane cognitive load by employing mixed or blocked sequences of diagnostic examples to students. Each of the three studies presents results that support CLT as explaining the influence of different types of cognitive processing on auscultation skill acquisition. We conclude with a discussion regarding CLT's usefulness as a framework for education and education research in the health professions.

Space Shuttle Projects

NASA Image and Video Library

1988-03-21

The Marshall Space Flight Center (MSFC) successfully test fired the third in a series of Transient Pressure Test Articles (TPTA) in its east test area. The test article was a short-stack solid rocket motor 52-feet long and 12-feet in diameter. The TPTA tests were designed to evaluate the effects of temperature, pressure and external loads encountered by the SRM, primarily during ignition transients. Instrumentation on the motor recorded approximately 1,000 charnels of data to verify the structural performance, thermal response, sealing capability of the redesign field, and case-to-nozzle joints. The TPTA test stand, 14-feet wide by 26-feet long by 33-feet high, was built in 1987. The TPTA series was a joint effort among Morton Thiokol, Inc., United Space Boosters, Inc., Wyle Laboratories, and MSFC. Wyle Laboratories conducted the tests for the MSFC, which manages the redesigned SRM program for NASA.

High Fidelity Simulations of Unsteady Flow through Turbopumps and Flowliners

NASA Technical Reports Server (NTRS)

Kiris, Cetin C.; Kwak, dochan; Chan, William; Housman, Jeff

2006-01-01

High fidelity computations were carried out to analyze the orbiter LH2 feedline flowliner. Computations were performed on the Columbia platform which is a 10,240-processor supercluster consisting of 20 Altix nodes with 512 processor each. Various computational models were used to characterize the unsteady flow features in the turbopump, including the orbiter Low-Pressure-Fuel-Turbopump (LPFTP) inducer, the orbiter manifold and a test article used to represent the manifold. Unsteady flow originating from the orbiter LPFTP inducer is one of the major contributors to the high frequency cyclic loading that results in high cycle fatigue damage to the gimbal flowliners just upstream of the LPFTP. The flow fields for the orbiter manifold and representative test article are computed and analyzed for similarities and differences. The incompressible Navier-Stokes flow solver INS3D, based on the artificial compressibility method, was used to compute the flow of liquid hydrogen in each test article.

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.

Longitudinally Jointed Edge-Wise Compression HoneyComb Composite Sandwich Coupon Testing And Fe Analysis: Three Methods of Strain Measurement, And Comparison

NASA Technical Reports Server (NTRS)

Farrokh, Babak; Rahim, Nur Aida Abul; Segal, Ken; Fan, Terry; Jones, Justin; Hodges, Ken; Mashni, Noah; Garg, Naman; Sang, Alex

2013-01-01

Three distinct strain measurement methods (i.e., foil resistance strain gages, fiber optic strain sensors, and a three-dimensional digital image photogrammetry that gives full field strain and displacement measurements) were implemented to measure strains on the back and front surfaces of a longitudinally jointed curved test article subjected to edge-wise compression testing, at NASA Goddard Space Flight Center, according to ASTM C364. The pre-test finite element analysis (FEA) was conducted to assess ultimate failure load and predict strain distribution pattern throughout the test coupon. The predicted strain pattern contours were then utilized as guidelines for installing the strain measurement instrumentations. The foil resistance strain gages and fiber optic strain sensors were bonded on the specimen at locations with nearly the same analytically predicted strain values, and as close as possible to each other, so that, comparisons between the measured strains by strain gages and fiber optic sensors, as well as the three-dimensional digital image photogrammetric system are relevant. The test article was loaded to failure (at 167 kN), at the compressive strain value of 10,000 micro epsilon. As a part of this study, the validity of the measured strains by fiber optic sensors is examined against the foil resistance strain gages and the three-dimensional digital image photogrammetric data, and comprehensive comparisons are made with FEA predictions.

New method of determination of spot welding-adhesive joint fatigue life using full field strain evolution

NASA Astrophysics Data System (ADS)

Sadowski, T.; Kneć, M.

2016-04-01

Fatigue tests were conducted since more than two hundred years ago. Despite this long period, as fatigue phenomena are very complex, assessment of fatigue response of standard materials or composites still requires a long time. Quite precise way to estimate fatigue parameters is to test at least 30 standardized specimens for the analysed material and further statistical post processing is required. In case of structural elements analysis like hybrid joints (Figure 1), the situation is much more complex as more factors influence the fatigue load capacity due to much more complicated structure of the joint in comparison to standard materials specimen, i.e. occurrence of: welded hot spots or rivets, adhesive layers, local notches creating the stress concentrations, etc. In order to shorten testing time some rapid methods are known: Locati's method [1] - step by step load increments up to failure, Prot's method [2] - constant increase of the load amplitude up to failure; Lehr's method [2] - seeking for the point during regular fatigue loading when an increase of temperature or strains become non-linear. The present article proposes new method of the fatigue response assessment - combination of the Locati's and Lehr's method.

The Load-Bearing Capacity of Timber-Glass Composite I-Beams Made with Polyurethane Adhesives

NASA Astrophysics Data System (ADS)

Rodacki, Konrad

2017-12-01

This article discusses the issue of composite timber-glass I-beams, which are an interesting alternative for load-bearing beams of ceilings and roofs. The reasoning behind the use of timber-glass I-beams is the combination of the best features of both materials - this enables the creation of particularly safe beams with regard to structural stability and post-breakage load capacity. Due to the significant differences between the bonding surfaces of timber and glass, a study on the adhesion of various adhesives to both surfaces is presented at the beginning of the paper. After examination, two adhesives were selected for offering the best performance when used with composite beams. The beams were investigated using a four-point bending test under quasi-static loading.

SIRTF primary mirror design, analysis, and testing

NASA Technical Reports Server (NTRS)

Sarver, George L., III; Maa, Scott; Chang, LI

1990-01-01

The primary mirror assembly (PMA) requirements and concepts for the Space Infrared Telescope Facility (SIRTF) program are discussed. The PMA studies at NASA/ARC resulted in the design of two engineering test articles, the development of a mirror mount cryogenic static load testing system, and the procurement and partial testing of a full scale spherical mirror mounting system. Preliminary analysis and testing of the single arch mirror with conical mount design and the structured mirror with the spherical mount design indicate that the designs will meet all figure and environmental requirements of the SIRTF program.

Analysis of particulate contamination on tape lift samples from the VETA optical surfaces

NASA Technical Reports Server (NTRS)

Germani, Mark S.

1992-01-01

Particulate contamination analysis was carried out on samples taken from the Verification Engineering Test Article (VETA) x-ray detection system. A total of eighteen tape lift samples were taken from the VETA optical surfaces. Initially, the samples were tested using a scanning electron microscope. Additionally, particle composition was determined by energy dispersive x-ray spectrometry. Results are presented in terms of particle loading per sample.

Cognitive Load Theory: New Conceptualizations, Specifications, and Integrated Research Perspectives

ERIC Educational Resources Information Center

Paas, Fred; van Gog, Tamara; Sweller, John

2010-01-01

Over the last few years, cognitive load theory has progressed and advanced rapidly. The articles in this special issue, which document those advances, are based on contributions to the 3rd International Cognitive Load Theory Conference (2009), Heerlen, The Netherlands. The articles of this special issue on cognitive load theory discuss new…

Test and Analyses of a Composite Multi-Bay Fuselage Panel Under Uni-Axial Compression

NASA Technical Reports Server (NTRS)

Li, Jian; Baker, Donald J.

2004-01-01

A composite panel containing three stringers and two frames cut from a vacuum-assisted resin transfer molded (VaRTM) stitched fuselage article was tested under uni-axial compression loading. The stringers and frames divided the panel into six bays with two columns of three bays each along the compressive loading direction. The two frames were supported at the ends with pins to restrict the out-of-plane translation. The free edges of the panel were constrained by knife-edges. The panel was modeled with shell finite elements and analyzed with ABAQUS nonlinear solver. The nonlinear predictions were compared with the test results in out-of-plane displacements, back-to-back surface strains on stringer flanges and back-to-back surface strains at the centers of the skin-bays. The analysis predictions were in good agreement with the test data up to post-buckling.

Analysis of rock mass dynamic impact influence on the operation of a powered roof support control system

NASA Astrophysics Data System (ADS)

Szurgacz, Dawid; Brodny, Jaroław

2018-01-01

A powered roof support is a machine responsible for protection of an underground excavation against deformation generated by rock mass. In the case of dynamic impact of rock mass, the proper level of protection is hard to achieve. Therefore, the units of the roof support and its components are subject to detailed tests aimed at acquiring greater reliability, efficiency and efficacy. In the course of such test, however, it is not always possible to foresee values of load that may occur in actual conditions. The article presents a case of a dynamic load impacting the powered roof support during a high-energy tremor in an underground hard coal mine. The authors discuss the method for selecting powered roof support units proper for specific forecasted load conditions. The method takes into account the construction of the support and mining and geological conditions of an excavation. Moreover, the paper includes tests carried out on hydraulic legs and yield valves which were responsible for additional yielding of the support. Real loads impacting the support unit during tremors are analysed. The results indicated that the real registered values of the load were significantly greater than the forecasted values. The analysis results of roof support operation during dynamic impact generated by the rock mass (real life conditions) prompted the authors to develop a set of recommendations for manufacturers and users of powered roof supports. These include, inter alia, the need for innovative solutions for testing hydraulic section systems.

Thermal performance evaluation of Solar Energy Products Company (SEPCO) 'Soloron' collector tested outdoors

NASA Technical Reports Server (NTRS)

Chiou, J., Sr.

1977-01-01

The test article, Model EF-212, Serial Nr. 002, is a single glazed collector with a nonselective absorber plate, using flowing air as the heat transfer medium. The absorber plate and box frame are aluminum and the insulation is one inch isocyanurate foam board with thermal conductivity of 0.11 (BTU/sq ft Hr0/ft.) The tests included the following. (1) time constant test, (2) collector efficiency test, (3) collector stagnation test, (4) incident angle modifier test, (5) load test, (6) weathering test, and (7) absorber plate optical properties test. The results of these tests are tabulated, graphed, or otherwise recorded.

Comparison of Numerical Analyses with a Static Load Test of a Continuous Flight Auger Pile

NASA Astrophysics Data System (ADS)

Hoľko, Michal; Stacho, Jakub

2014-12-01

The article deals with numerical analyses of a Continuous Flight Auger (CFA) pile. The analyses include a comparison of calculated and measured load-settlement curves as well as a comparison of the load distribution over a pile's length. The numerical analyses were executed using two types of software, i.e., Ansys and Plaxis, which are based on FEM calculations. Both types of software are different from each other in the way they create numerical models, model the interface between the pile and soil, and use constitutive material models. The analyses have been prepared in the form of a parametric study, where the method of modelling the interface and the material models of the soil are compared and analysed. Our analyses show that both types of software permit the modelling of pile foundations. The Plaxis software uses advanced material models as well as the modelling of the impact of groundwater or overconsolidation. The load-settlement curve calculated using Plaxis is equal to the results of a static load test with a more than 95 % degree of accuracy. In comparison, the load-settlement curve calculated using Ansys allows for the obtaining of only an approximate estimate, but the software allows for the common modelling of large structure systems together with a foundation system.

Model Development and Experimental Validation of the Fusible Heat Sink Design for Exploration Vehicles

NASA Technical Reports Server (NTRS)

Cognata, Thomas J.; Leimkuehler, Thomas O.; Sheth, Rubik B.; Le,Hung

2012-01-01

The Fusible Heat Sink is a novel vehicle heat rejection technology which combines a flow through radiator with a phase change material. The combined technologies create a multi-function device able to shield crew members against Solar Particle Events (SPE), reduce radiator extent by permitting sizing to the average vehicle heat load rather than to the peak vehicle heat load, and to substantially absorb heat load excursions from the average while constantly maintaining thermal control system setpoints. This multi-function technology provides great flexibility for mission planning, making it possible to operate a vehicle in hot or cold environments and under high or low heat load conditions for extended periods of time. This paper describes the model development and experimental validation of the Fusible Heat Sink technology. The model developed was intended to meet the radiation and heat rejection requirements of a nominal MMSEV mission. Development parameters and results, including sizing and model performance will be discussed. From this flight-sized model, a scaled test-article design was modeled, designed, and fabricated for experimental validation of the technology at Johnson Space Center thermal vacuum chamber facilities. Testing showed performance comparable to the model at nominal loads and the capability to maintain heat loads substantially greater than nominal for extended periods of time.

Model Development and Experimental Validation of the Fusible Heat Sink Design for Exploration Vehicles

NASA Technical Reports Server (NTRS)

Cognata, Thomas J.; Leimkuehler, Thomas; Sheth, Rubik; Le, Hung

2013-01-01

The Fusible Heat Sink is a novel vehicle heat rejection technology which combines a flow through radiator with a phase change material. The combined technologies create a multi-function device able to shield crew members against Solar Particle Events (SPE), reduce radiator extent by permitting sizing to the average vehicle heat load rather than to the peak vehicle heat load, and to substantially absorb heat load excursions from the average while constantly maintaining thermal control system setpoints. This multi-function technology provides great flexibility for mission planning, making it possible to operate a vehicle in hot or cold environments and under high or low heat load conditions for extended periods of time. This paper describes the modeling and experimental validation of the Fusible Heat Sink technology. The model developed was intended to meet the radiation and heat rejection requirements of a nominal MMSEV mission. Development parameters and results, including sizing and model performance will be discussed. From this flight-sized model, a scaled test-article design was modeled, designed, and fabricated for experimental validation of the technology at Johnson Space Center thermal vacuum chamber facilities. Testing showed performance comparable to the model at nominal loads and the capability to maintain heat loads substantially greater than nominal for extended periods of time.

Orion EFT-1 Heat Shield Move from LASF to VAB Highbay 2

NASA Image and Video Library

2017-04-26

Inside the Launch Abort System Facility at NASA's Kennedy Space Center in Florida, the Orion heat shield from Exploration Flight Test-1 is being loaded onto a transporter for its move to the Vehicle Assembly Building (VAB). The heat shield is being transferred from the Orion Program to the Ground Systems Development and Operations Program, Landing and Recovery Operations. In the VAB, the heat shield will be integrated with the Orion ground test article and used for future underway recovery testing.

An improved method of crafting a multi-electrode spiral cuff for the selective.

PubMed

Rozman, Janez; Pečlin, Polona; Ribarič, Samo; Godec, Matjaž; Burja, Jaka

2018-01-17

This article reviews an improved methodology and technology for crafting a multi-electrode spiral cuff for the selective activation of nerve fibres in particular superficial regions of a peripheral nerve. The analysis, structural and mechanical properties of the spot welds used for the interconnections between the stimulating electrodes and stainless-steel lead wires are presented. The cuff consisted of 33 platinum electrodes embedded within a self-curling 17-mm-long silicone spiral sheet with a nominal internal diameter of 2.5 mm. The weld was analyzed using scanning electron microscopy and nanohardness tests, while the interconnection was investigated using destructive load tests. The functionality of the cuff was tested in an isolated porcine vagus nerve. The results of the scanning electron microscopy show good alloying and none of the typical welding defects that occur between the wire and the platinum foil. The results of the destructive load tests show that the breaking loads were between 3.22 and 5 N. The results of the nanohardness testing show that the hardness of the weld was different for the particular sites on the weld sample. Finally, the results of the functional testing show that for different stimulation intensities both the compound action potential deflection and the shape are modulated.

Design and Fabrication of a Tank-Applied Broad Area Cooling Shield Coupon

NASA Technical Reports Server (NTRS)

Wood, J. J.; Middlemas, M. R.

2012-01-01

The small-scale broad area cooling (BAC) shield test panel represents a section of the cryogenic propellant storage and transfer ground test article, a flight-like cryogenic propellant storage tank. The test panel design includes an aluminum tank shell, primer, spray-on foam insulation, multilayer insulation (MLI), and BAC shield hardware. This assembly was sized to accurately represent the character of the MLI/BAC shield system, be quickly and inexpensively assembled, and be tested in the Marshall Space Flight Center Acoustic Test Facility. Investigating the BAC shield response to a worst-case launch dynamic load was the key purpose for developing the test article and performing the test. A preliminary method for structurally supporting the BAC shield using low-conductivity standoffs was designed, manufactured, and evaluated as part of the test. The BAC tube-standoff interface and unsupported BAC tube lengths were key parameters for evaluation. No noticeable damage to any system hardware element was observed after acoustic testing.

Apparatus and method for skin packaging articles

NASA Technical Reports Server (NTRS)

Madsen, B.; Pozsony, E. R.; Collin, E. E. (Inventor)

1973-01-01

A system for skin packaging articles including a loading zone for positioning articles to be packaged upon a substrate, a thermoplastic film heating and vacuum operated skin packaging zone for covering the articles with film laminated to the substrate and a slitting zone for separating and trimming the individual skin packaged articles. The articles are passed to the successive zones. The loading zone may be adapted for conveyorized instead of hand loading. In some cases, where only transverse cutting of the film web is necessary, it may be desirable to eliminate the slitting zone and remove the skin packaged article or articles directly from the packaging zone. A conveniently located operating panel contains controls for effecting automatic, semiautomatic or manual operation of the entire system of any portions in any manner desired.

Forward Skirt Structural Testing on the Space Launch System (SLS) Program

NASA Technical Reports Server (NTRS)

Lohrer, J. D.; Wright, R. D.

2016-01-01

Structural testing was performed to evaluate heritage forward skirts from the Space Shuttle program for use on the Space Launch System (SLS) program. One forward skirt is located in each solid rocket booster. Heritage forward skirts are aluminum 2219 welded structures. Loads are applied at the forward skirt thrust post and ball assembly. Testing was needed because SLS ascent loads are roughly 40% higher than Space Shuttle loads. Testing objectives were to determine margins of safety, demonstrate reliability, and validate analytical models. Two forward skirts were structurally tested using the test configuration. The test stand applied loads to the thrust post. Four hydraulic actuators were used to apply axial load and two hydraulic actuators were used to apply radial and tangential loads. The first test was referred to as FSTA-1 (Forward Skirt Structural Test Article) and was performed in April/May 2014. The purpose of FSTA-1 was to verify the ultimate capability of the forward skirt subjected to ascent ultimate loads. Testing consisted of two liftoff load cases taken to 100% limit load followed by an ascent load case taken to 110% limit load. The forward skirt was unloaded to no load after each test case. Lastly, the forward skirt was tested to 140% limit and then to failure using the ascent loads. The second test was referred to as FSTA-2 and performed in July/August of 2014. The purpose of FSTA-2 was to verify the ultimate capability of the forward skirt subjected to liftoff ultimate loads. Testing consisted of six liftoff load cases taken to 100% limit load followed by the six liftoff cases taken to 140% limit load. Two ascent load cases were then tested to 100% limit load. The forward skirt was unloaded to no load after each test case. Lastly, the forward skirt was tested to 140% limit and then to failure using the ascent loads. The forward skirts on FSTA-1 and FSTA-2 successfully carried all applied liftoff and ascent load cases. Both FSTA-1 and FSTA-2 were tested to failure by increasing the ascent loads. Failure occurred in the forward skirt thrust post radius. The forward skirts on FSTA-1 and FSTA-2 had nearly identical failure modes. FSTA-1 failed at 1.72 times limit load and FSTA-2 failed at 1.62 times limit load. This difference is primarily attributed to variation in material properties in the thrust post region. Test data were obtained from strain gages, deflection gages, ARAMIS digital strain measurement, acoustic emissions, and high-speed video. Strain gage data and ARAMIS strain were compared to finite element (FE) analysis predictions. Both the forward skirt and tooling were modeled. This allows the analysis to simulate the loading as close as possible to actual test configuration. FSTA-1 and FSTA-2 were instrumented with over 200 strain gages to ensure all possible failure modes could be captured. However, it turned out that three gages provided critical strain data. One was located in the post bore and two on the post radius. More gages were not specified due to space limitations and the desire to not interfere with the use of the ARAMIS system on the post radius. Measured strains were compared to analysis results for the load cycle to failure. Note that FSTA-1 gages were lost before failure was reached. FSTA-2 gages made it to the failure load but one of the radius gages was lost before testing began. This gage was not replaced because of the time and cost associated with disassembly of the test structure. Correlation to analysis was excellent for FSTA-1. FSTA-2 was not quite as good because there was more residual strain from previous load cycles. FSTA-2 was loaded and unloaded with 12 liftoff cases and two ascent cases before taking the skirt to failure. FSTA-1 only had two liftoff cases and one ascent case before taking the skirt to failure. The ARAMIS system was used to determine strain at the post radius by processing digital images of a speckled paint pattern. Digital cameras recorded images of the speckled paint pattern. ARAMIS strain results for FSTA-2 just prior to failure. Note a high strain location develops near the left side. This high strain compares well to analysis prediction for both FSTA-1 and FSTA-2. The strain at this location was also plotted versus limit load. Both FSTA-1 and FSTA-2 had excellent correlation between ARAMIS and analysis strains. Acoustic emission (AE) sensors were used to monitor for damage formation that may occur during testing (e.g., crack formation and growth or propagation). AE was very important because after disassembly of FSTA-1, a crack was observed in the ball fitting radius. The ball fitting did not crack on FSTA-2. AE data was used to reconstruct when the crack occurred. The AE energy versus time plot for FSTA. The energy increased considerably at 850 seconds (152% limit load), indicating a crack could have formed at this point. The only visual evidence found that could have corresponded to this was the crack that initiated in the ball fitting. The cracks in the forward skirt aluminum structures would likely have been lower energy due to a lower modulus and all that were found after failure correlated to occurring after the initial crack in the post radius. This was verified by high-speed cameras used to record the failure.

Measured and predicted structural behavior of the HiMAT tailored composite wing

NASA Technical Reports Server (NTRS)

Nelson, Lawrence H.

1987-01-01

A series of load tests was conducted on the HiMAT tailored composite wing. Coupon tests were also run on a series of unbalanced laminates, including the ply configuration of the wing, the purpose of which was to compare the measured and predicted behavior of unbalanced laminates, including - in the case of the wing - a comparison between the behavior of the full scale structure and coupon tests. Both linear and nonlinear finite element (NASTRAN) analyses were carried out on the wing. Both linear and nonlinear point-stress analyses were performed on the coupons. All test articles were instrumented with strain gages, and wing deflections measured. The leading and trailing edges were found to have no effect on the response of the wing to applied loads. A decrease in the stiffness of the wing box was evident over the 27-test program. The measured load-strain behavior of the wing was found to be linear, in contrast to coupon tests of the same laminate, which were nonlinear. A linear NASTRAN analysis of the wing generally correlated more favorably with measurements than did a nonlinear analysis. An examination of the predicted deflections in the wing root region revealed an anomalous behavior of the structural model that cannot be explained. Both hysteresis and creep appear to be less significant in the wing tests than in the corresponding laminate coupon tests.

Structural Testing at the NWTC Helps Improve Blade Design and Increase System Reliability; NREL (National Renewable Energy Laboratory)

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

None

2015-08-01

Since 1990, the National Renewable Energy Laboratory’s (NREL's) National Wind Technology Center (NWTC) has tested more than 150 wind turbine blades. NWTC researchers can test full-scale and subcomponent articles, conduct data analyses, and provide engineering expertise on best design practices. Structural testing of wind turbine blades enables designers, manufacturers, and owners to validate designs and assess structural performance to specific load conditions. Rigorous structural testing can reveal design and manufacturing problems at an early stage of development that can lead to overall improvements in design and increase system reliability.

Damage Tolerance Testing of a NASA TransHab Derivative Woven Inflatable Module

NASA Technical Reports Server (NTRS)

Edgecombe, John; delaFuente, Horacio; Valle, Gerard

2009-01-01

Current options for Lunar habitat architecture include inflatable habitats and airlocks. Inflatable structures can have mass and volume advantages over conventional structures. However, inflatable structures carry different inherent risks and are at a lower Technical Readiness Level (TRL) than more conventional metallic structures. One of the risks associated with inflatable structures is in understanding the tolerance to induced damage. The Damage Tolerance Test (DTT) is designed to study the structural integrity of an expandable structure. TransHab (Figure 1) was an experimental inflatable module developed at the NASA/Johnson Space Center in the 1990 s. The TransHab design was originally envisioned for use in Mars Transits but was also studied as a potential habitat for the International Space Station (ISS). The design of the TransHab module was based on a woven design using an Aramid fabric. Testing of this design demonstrated a high level of predictability and repeatability with analytical predictions of stresses and deflections. Based on JSC s experience with the design and analysis of woven inflatable structures, the Damage Tolerance Test article was designed and fabricated using a woven design. The DTT article was inflated to 45 psig, representing 25% of the ultimate burst pressure, and one of the one-inch wide longitudinal structural members was severed by initiating a Linear Shaped Charge (LSC). Strain gage measurements, at the interface between the expandable elements (straps) and the nonexpandable metallic elements for pre-selected longitudinal straps, were taken throughout pressurization of the module and strap separation. Strain gage measurements show no change in longitudinal strap loading at the bulkhead interface after strap separation indicating loads in the restraint layer were re-distributed local to the damaged area due to the effects of friction under high internal pressure loading. The test completed all primary objectives with better than expected results. This paper will discuss space inflatable structures, damage tolerance analysis, test results, and applicability to the Lunar architecture.

Cognitive Spare Capacity as an Index of Listening Effort.

PubMed

Rudner, Mary

2016-01-01

Everyday listening may be experienced as effortful, especially by individuals with hearing loss. This may be due to internal factors, such as cognitive load, and external factors, such as noise. Even when speech is audible, internal and external factors may combine to reduce cognitive spare capacity, or the ability to engage in cognitive processing of spoken information. A better understanding of cognitive spare capacity and how it can be optimally allocated may guide new approaches to rehabilitation and ultimately improve outcomes. This article presents results of three tests of cognitive spare capacity:1. Sentence-final Word Identification and Recall (SWIR) test2. Cognitive Spare Capacity Test (CSCT)3. Auditory Inference Span Test (AIST)Results show that noise reduces cognitive spare capacity even when speech intelligibility is retained. In addition, SWIR results show that hearing aid signal processing can increase cognitive spare capacity, and CSCT and AIST results show that increasing load reduces cognitive spare capacity. Correlational evidence suggests that while the effect of noise on cognitive spare capacity is related to working memory capacity, the effect of load is related to executive function. Future studies should continue to investigate how hearing aid signal processing can mitigate the effect of load on cognitive spare capacity, and whether such effects can be enhanced by developing executive skills through training. The mechanisms modulating cognitive spare capacity should be investigated by studying their neural correlates, and tests of cognitive spare capacity should be developed for clinical use in conjunction with developing new approaches to rehabilitation.

High-Temperature Modal Survey of a Hot-Structure Control Surface

NASA Technical Reports Server (NTRS)

Spivey, Natalie D.

2011-01-01

Ground vibration tests are routinely conducted for supporting flutter analysis for subsonic and supersonic vehicles; however, for hypersonic vehicles, thermoelastic vibration testing techniques are neither well established nor routinely performed. New high-temperature material systems, fabrication technologies and high-temperature sensors expand the opportunities to develop advanced techniques for performing ground vibration tests at elevated temperatures. When high-temperature materials, which increase in stiffness when heated, are incorporated into a hot-structure that contains metallic components that decrease in stiffness when heated, the interaction between those materials can affect the hypersonic flutter analysis. A high-temperature modal survey will expand the research database for hypersonics and improve the understanding of this dual-material interaction. This report discusses the vibration testing of the carbon-silicon carbide Ruddervator Subcomponent Test Article, which is a truncated version of a full-scale hot-structure control surface. Two series of room-temperature modal test configurations were performed in order to define the modal characteristics of the test article during the elevated-temperature modal survey: one with the test article suspended from a bungee cord (free-free) and the second with it mounted on the strongback (fixed boundary). Testing was performed in the NASA Dryden Flight Research Center Flight Loads Laboratory Large Nitrogen Test Chamber.

Composite Bending Box Section Modal Vibration Fault Detection

NASA Technical Reports Server (NTRS)

Werlink, Rudy

2002-01-01

One of the primary concerns with Composite construction in critical structures such as wings and stabilizers is that hidden faults and cracks can develop operationally. In the real world, catastrophic sudden failure can result from these undetected faults in composite structures. Vibration data incorporating a broad frequency modal approach, could detect significant changes prior to failure. The purpose of this report is to investigate the usefulness of frequency mode testing before and after bending and torsion loading on a composite bending Box Test section. This test article is representative of construction techniques being developed for the recent NASA Blended Wing Body Low Speed Vehicle Project. The Box section represents the construction technique on the proposed blended wing aircraft. Modal testing using an impact hammer provides an frequency fingerprint before and after bending and torsional loading. If a significant structural discontinuity develops, the vibration response is expected to change. The limitations of the data will be evaluated for future use as a non-destructive in-situ method of assessing hidden damage in similarly constructed composite wing assemblies. Modal vibration fault detection sensitivity to band-width, location and axis will be investigated. Do the sensor accelerometers need to be near the fault and or in the same axis? The response data used in this report was recorded at 17 locations using tri-axial accelerometers. The modal tests were conducted following 5 independent loading conditions before load to failure and 2 following load to failure over a period of 6 weeks. Redundant data was used to minimize effects from uncontrolled variables which could lead to incorrect interpretations. It will be shown that vibrational modes detected failure at many locations when skin de-bonding failures occurred near the center section. Important considerations are the axis selected and frequency range.

Training Load and Fatigue Marker Associations with Injury and Illness: A Systematic Review of Longitudinal Studies.

PubMed

Jones, Christopher M; Griffiths, Peter C; Mellalieu, Stephen D

2017-05-01

Coaches, sport scientists, clinicians and medical personnel face a constant challenge to prescribe sufficient training load to produce training adaption while minimising fatigue, performance inhibition and risk of injury/illness. The aim of this review was to investigate the relationship between injury and illness and longitudinal training load and fatigue markers in sporting populations. Systematic searches of the Web of Science and PubMed online databases to August 2015 were conducted for articles reporting relationships between training load/fatigue measures and injury/illness in athlete populations. From the initial 5943 articles identified, 2863 duplicates were removed, followed by a further 2833 articles from title and abstract selection. Manual searching of the reference lists of the remaining 247 articles, together with use of the Google Scholar 'cited by' tool, yielded 205 extra articles deemed worthy of assessment. Sixty-eight studies were subsequently selected for inclusion in this study, of which 45 investigated injury only, 17 investigated illness only, and 6 investigated both injury and illness. This systematic review highlighted a number of key findings, including disparity within the literature regarding the use of various terminologies such as training load, fatigue, injury and illness. Athletes are at an increased risk of injury/illness at key stages in their training and competition, including periods of training load intensification and periods of accumulated training loads. Further investigation of individual athlete characteristics is required due to their impact on internal training load and, therefore, susceptibility to injury/illness.

Fiber Optic Rosette Strain Gauge Development and Application on a Large-Scale Composite Structure

NASA Technical Reports Server (NTRS)

Moore, Jason P.; Przekop, Adam; Juarez, Peter D.; Roth, Mark C.

2015-01-01

A detailed description of the construction, application, and measurement of 196 FO rosette strain gauges that measured multi-axis strain across the outside upper surface of the forward bulkhead component of a multibay composite fuselage test article is presented. A background of the FO strain gauge and the FO measurement system as utilized in this application is given and results for the higher load cases of the testing sequence are shown.

Evaluation of Rock Bolt Support for Polish Hard Rock Mines

NASA Astrophysics Data System (ADS)

Skrzypkowski, Krzysztof

2018-03-01

The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead "Olkusz - Pomorzany" mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt "Olkusz - 20A" is able to overcome the load.The second purpose of the study was to obtain load - displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.

Advancing Lie Detection by Inducing Cognitive Load on Liars: A Review of Relevant Theories and Techniques Guided by Lessons from Polygraph-Based Approaches

PubMed Central

Walczyk, Jeffrey J.; Igou, Frank P.; Dixon, Alexa P.; Tcholakian, Talar

2013-01-01

This article critically reviews techniques and theories relevant to the emerging field of “lie detection by inducing cognitive load selectively on liars.” To help these techniques benefit from past mistakes, we start with a summary of the polygraph-based Controlled Question Technique (CQT) and the major criticisms of it made by the National Research Council (2003), including that it not based on a validated theory and administration procedures have not been standardized. Lessons from the more successful Guilty Knowledge Test are also considered. The critical review that follows starts with the presentation of models and theories offering insights for cognitive lie detection that can undergird theoretically load-inducing approaches. This is followed by evaluation of specific research-based, load-inducing proposals, especially for their susceptibility to rehearsal and other countermeasures. To help organize these proposals and suggest new direction for innovation and refinement, a theoretical taxonomy is presented based on the type of cognitive load induced in examinees (intrinsic or extraneous) and how open-ended the responses to test items are. Finally, four recommendations are proffered that can help researchers and practitioners to avert the corresponding mistakes with the CQT and yield new, valid cognitive lie detection technologies. PMID:23378840

Corner Wrinkling at a Square Membrane Due to Symmetric Mechanical Loads

NASA Technical Reports Server (NTRS)

Blandino, Joseph R.; Johnston, John D.; Dharamsi, Urmil K.; Brodeur, Stephen J. (Technical Monitor)

2001-01-01

Thin-film membrane structures are under consideration for use in many future gossamer spacecraft systems. Examples include sunshields for large aperture telescopes, solar sails, and membrane optics. The development of capabilities for testing and analyzing pre-tensioned, thin film membrane structures is an important and challenging aspect of gossamer spacecraft technology development. This paper presents results from experimental and computational studies performed to characterize the wrinkling behavior of thin-fi[m membranes under mechanical loading. The test article is a 500 mm square membrane subjected to symmetric comer loads. Data is presented for loads ranging from 0.49 N to 4.91 N. The experimental results show that as the load increases the number of wrinkles increases, while the wrinkle amplitude decreases. The computational model uses a finite element implementation of Stein-Hedgepeth membrane wrinkling theory to predict the behavior of the membrane. Comparisons were made with experimental results for the wrinkle angle and wrinkled region. There was reasonably good agreement between the measured wrinkle angle and the predicted directions of the major principle stresses. The shape of the wrinkle region predicted by the finite element model matches that observed in the experiments; however, the size of the predicted region is smaller than that determined in the experiments.

The use of 3d scanner for testing changes in shape of human limbs under the influence of external mechanical load

NASA Astrophysics Data System (ADS)

Kasperska, Kamila; Wieczorowski, Michał; Krolczyk, Jolanta B.

2017-10-01

Three-dimensional scanning is used in many fields: medicine, architecture, industry, reverse engineering. The aim of the article was to analyze the changes in the shape of the limbs under the influence of a mechanical external load using the method of three-dimensional scanner uses white light technology. The paper presents a system of human movement, passive part - skeleton and active part - the muscles, and principles of their interaction, which results in a change of the position of the body. Furthermore, by using the 3D scan, the differences in appearance of the arm and leg depending on the size of the external load in different positions have been presented. The paper shows that with increasing load, which muscles must prevent, increases the volume of certain parts of the legs, while another parts of them will be reduced. Results of the research using three-dimensional scanner allow determining what impact on changing the legs shape has an external mechanical load.

Brittle materials at high-loading rates: an open area of research

NASA Astrophysics Data System (ADS)

Forquin, Pascal

2017-01-01

Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

Brittle materials at high-loading rates: an open area of research

PubMed Central

2017-01-01

Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’. PMID:27956517

Brittle materials at high-loading rates: an open area of research.

PubMed

Forquin, Pascal

2017-01-28

Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. © 2016 The Author(s).

Pegasus delivers SLS engine section

NASA Image and Video Library

2017-03-03

NASA engineers install test hardware for the agency's new heavy lift rocket, the Space Launch System, into a newly constructed 50-foot structural test stand at NASA's Marshall Space Flight Center. In the stand, hydraulic cylinders will be electronically controlled to push, pull, twist and bend the test article with millions of pounds of force. Engineers will record and analyze over 3,000 channels of data for each test case to verify the capabilities of the engine section and validate that the design and analysis models accurately predict the amount of loads the core stage can withstand during launch and ascent. The engine section, recently delivered via NASA's barge Pegasus from NASA's Michoud Assembly Facility, is the first of four core stage structural test articles scheduled to be delivered to Marshall for testing. The engine section, located at the bottom of SLS's massive core stage, will house the rocket's four RS-25 engines and be an attachment point for the two solid rocket boosters.

Pegasus delivers SLS engine section

NASA Image and Video Library

2017-05-18

NASA engineers install test hardware for the agency's new heavy lift rocket, the Space Launch System, into a newly constructed 50-foot structural test stand at NASA's Marshall Space Flight Center. In the stand, hydraulic cylinders will be electronically controlled to push, pull, twist and bend the test article with millions of pounds of force. Engineers will record and analyze over 3,000 channels of data for each test case to verify the capabilities of the engine section and validate that the design and analysis models accurately predict the amount of loads the core stage can withstand during launch and ascent. The engine section, recently delivered via NASA's barge Pegasus from NASA's Michoud Assembly Facility, is the first of four core stage structural test articles scheduled to be delivered to Marshall for testing. The engine section, located at the bottom of SLS's massive core stage, will house the rocket's four RS-25 engines and be an attachment point for the two solid rocket boosters.

Static behavior of the weld in the joint of the steel support element using experiment and numerical modeling

NASA Astrophysics Data System (ADS)

Krejsa, M.; Brozovsky, J.; Mikolasek, D.; Parenica, P.; Koubova, L.

2018-04-01

The paper is focused on the numerical modeling of welded steel bearing elements using commercial software system ANSYS, which is based on the finite element method - FEM. It is important to check and compare the results of FEM analysis with the results of physical verification test, in which the real behavior of the bearing element can be observed. The results of the comparison can be used for calibration of the computational model. The article deals with the physical test of steel supporting elements, whose main purpose is obtaining of material, geometry and strength characteristics of the fillet and butt welds including heat affected zone in the basic material of welded steel bearing element. The pressure test was performed during the experiment, wherein the total load value and the corresponding deformation of the specimens under the load was monitored. Obtained data were used for the calibration of numerical models of test samples and they are necessary for further stress and strain analysis of steel supporting elements.

Technical details in the structural development of Rohrbach seaplanes

NASA Technical Reports Server (NTRS)

Mathias, Gotthold; Holzapfel, Adolf

1929-01-01

The recent trial flights and acceptance tests of the Rohrbach "Romar," the largest seaplane in the world, have yielded results fully confirming the principles followed in its development. Its take-off weight of 19,000 kg, its beating the world record for raising the greatest useful load to 2000 m by almost 2500 kg and its remarkable showing in the seaworthiness tests are the results of intelligent researches, the guiding principles of which are briefly set forth in this article.

Cognitive Load Theory and the Role of Learner Experience: An Abbreviated Review for Educational Practitioners

ERIC Educational Resources Information Center

Artino, Anthony R., Jr.

2008-01-01

The purpose of this review is to provide educational practitioners with a brief overview of cognitive load theory (CLT) and its major implications for learning. To achieve this objective, the article includes a short description of human cognitive architecture as conceived by cognitive load theorists. Following this overview, the article provides…

Rotation Criteria and Hypothesis Testing for Exploratory Factor Analysis: Implications for Factor Pattern Loadings and Interfactor Correlations

ERIC Educational Resources Information Center

Schmitt, Thomas A.; Sass, Daniel A.

2011-01-01

Exploratory factor analysis (EFA) has long been used in the social sciences to depict the relationships between variables/items and latent traits. Researchers face many choices when using EFA, including the choice of rotation criterion, which can be difficult given that few research articles have discussed and/or demonstrated their differences.…

Rapid Dynamic Assessment of Expertise to Improve the Efficiency of Adaptive Elearning

ERIC Educational Resources Information Center

Kalyuga, Slava; Sweller, John

2005-01-01

In this article we suggest a method of evaluating learner expertise based on assessment of the content of working memory and the extent to which cognitive load has been reduced by knowledge retrieved from long-term memory. The method was tested in an experiment with an elementary algebra tutor using a yoked control design. In the learner-adapted…

Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

NASA Astrophysics Data System (ADS)

Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

2015-01-01

Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

Assembly Test Article (ATA)

NASA Technical Reports Server (NTRS)

Ricks, Glen A.

1988-01-01

The assembly test article (ATA) consisted of two live loaded redesigned solid rocket motor (RSRM) segments which were assembled and disassembled to simulate the actual flight segment stacking process. The test assembly joint was flight RSRM design, which included the J-joint insulation design and metal capture feature. The ATA test was performed mid-November through 24 December 1987, at Kennedy Space Center (KSC), Florida. The purpose of the test was: certification that vertical RSRM segment mating and separation could be accomplished without any damage; verification and modification of the procedures in the segment stacking/destacking documents; and certification of various GSE to be used for flight assembly and inspection. The RSRM vertical segment assembly/disassembly is possible without any damage to the insulation, metal parts, or seals. The insulation J-joint contact area was very close to the predicted values. Numerous deviations and changes to the planning documents were made to ensure the flight segments are effectively and correctly stacked. Various GSE were also certified for use on flight segments, and are discussed in detail.

Cognitive Load Theory: How Many Types of Load Does It Really Need?

ERIC Educational Resources Information Center

Kalyuga, Slava

2011-01-01

Cognitive load theory has been traditionally described as involving three separate and additive types of load. Germane load is considered as a learning-relevant load complementing extraneous and intrinsic load. This article argues that, in its traditional treatment, germane load is essentially indistinguishable from intrinsic load, and therefore…

Synthesis and characterization of poly(3-sulfopropylmethacrylate) brushes for potential antibacterial applications.

PubMed

Ramstedt, Madeleine; Cheng, Nan; Azzaroni, Omar; Mossialos, Dimitris; Mathieu, Hans Jörg; Huck, Wilhelm T S

2007-03-13

This article describes the aqueous atom transfer radical polymerization synthesis of poly(3-sulfopropylmethacrylate) brushes onto gold and Si/SiO2 surfaces in a controlled manner. The effect of Cu(I)/Cu(II) ratio was examined, and a quartz crystal microbalance was used to study the kinetics of the brush synthesis. The synthesized brushes displayed a thickness from a few nanometers to several hundred nanometers and were characterized using atomic force microscopy, ellipsometry, Fourier transform infrared spectroscopy (FTIR), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). The as-synthesized sulfonate brushes had very good ion-exchange properties for the ions tested in this study, i.e., Na+, K+, Cu2+, and Ag+. FTIR and XPS show that the metal ions are coordinating to sulfonate moieties inside the brushes. The brushes were easily loaded with silver ions, and the effect of silver ion concentration on silver loading of the brush was examined. The silver-loaded brushes were shown to be antibacterial toward both gram negative and gram positive bacteria. The silver leaching was studied through leaching experiments into water, NaNO3, and NaCl (physiological medium). The results from these leaching experiments are compared and discussed in the article.

Clinical Utility of Viral Load in Management of Cytomegalovirus Infection after Solid Organ Transplantation

PubMed Central

2013-01-01

SUMMARY The negative impact of cytomegalovirus (CMV) infection on transplant outcomes warrants efforts toward improving its prevention, diagnosis, and treatment. During the last 2 decades, significant breakthroughs in diagnostic virology have facilitated remarkable improvements in CMV disease management. During this period, CMV nucleic acid amplification testing (NAT) evolved to become one of the most commonly performed tests in clinical virology laboratories. NAT provides a means for rapid and sensitive diagnosis of CMV infection in transplant recipients. Viral quantification also introduced several principles of CMV disease management. Specifically, viral load has been utilized (i) for prognostication of CMV disease, (ii) to guide preemptive therapy, (iii) to assess the efficacy of antiviral treatment, (iv) to guide the duration of treatment, and (v) to indicate the risk of clinical relapse or antiviral drug resistance. However, there remain important limitations that require further optimization, including the interassay variability in viral load reporting, which has limited the generation of standardized viral load thresholds for various clinical indications. The recent introduction of an international reference standard should advance the major goal of uniform viral load reporting and interpretation. However, it has also become apparent that other aspects of NAT should be standardized, including sample selection, nucleic acid extraction, amplification, detection, and calibration, among others. This review article synthesizes the vast amount of information on CMV NAT and provides a timely review of the clinical utility of viral load testing in the management of CMV in solid organ transplant recipients. Current limitations are highlighted, and avenues for further research are suggested to optimize the clinical application of NAT in the management of CMV after transplantation. PMID:24092851

Experimental Analysis of Dynamic Effects of FRP Reinforced Masonry Vaults.

PubMed

Corradi, Marco; Borri, Antonio; Castori, Giulio; Coventry, Kathryn

2015-11-27

An increasing interest in the preservation of historic structures has produced a need for new methods for reinforcing curved masonry structures, such as arches and vaults. These structures are generally very ancient, have geometries and materials which are poorly defined and have been exposed to long-term historical movements and actions. Consequently, they are often in need of repair or reinforcement. This article presents the results of an experimental study carried out in the laboratory and during on-site testing to investigate the behaviour of brick masonry vaults under dynamic loading strengthened with FRPs (Fiber Reinforced Polymers). For the laboratory tests, the brick vaults were built with solid sanded clay bricks and weak mortar and were tested under dynamic loading. The experimental tests were designed to facilitate analysis of the dynamic behaviour of undamaged, damaged and reinforced vaulted structures. On-site tests were carried out on an earthquake-damaged thin brick vault of an 18th century aristocratic residence in the city of L'Aquila, Italy. The provision of FRP reinforcement is shown to re-establish elastic behavior previously compromised by time induced damage in the vaults.

Experimental Analysis of Dynamic Effects of FRP Reinforced Masonry Vaults

PubMed Central

Corradi, Marco; Borri, Antonio; Castori, Giulio; Coventry, Kathryn

2015-01-01

An increasing interest in the preservation of historic structures has produced a need for new methods for reinforcing curved masonry structures, such as arches and vaults. These structures are generally very ancient, have geometries and materials which are poorly defined and have been exposed to long-term historical movements and actions. Consequently, they are often in need of repair or reinforcement. This article presents the results of an experimental study carried out in the laboratory and during on-site testing to investigate the behaviour of brick masonry vaults under dynamic loading strengthened with FRPs (Fiber Reinforced Polymers). For the laboratory tests, the brick vaults were built with solid sanded clay bricks and weak mortar and were tested under dynamic loading. The experimental tests were designed to facilitate analysis of the dynamic behaviour of undamaged, damaged and reinforced vaulted structures. On-site tests were carried out on an earthquake-damaged thin brick vault of an 18th century aristocratic residence in the city of L’Aquila, Italy. The provision of FRP reinforcement is shown to re-establish elastic behavior previously compromised by time induced damage in the vaults. PMID:28793697

Extraction-Separation Performance and Dynamic Modeling of Orion Test Vehicles with Adams Simulation: 2nd Edition

NASA Technical Reports Server (NTRS)

Fraire, Usbaldo, Jr.; Anderson, Keith; Varela, Jose G.; Bernatovich, Michael A.

2015-01-01

NASA's Orion Capsule Parachute Assembly System (CPAS) project has advanced into the third generation of its parachute test campaign and requires technically comprehensive modeling capabilities to simulate multi-body dynamics (MBD) of test articles released from a C-17. Safely extracting a 30,000 lbm mated test article from a C-17 and performing stable mid-air separation maneuvers requires an understanding of the interaction between elements in the test configuration and how they are influenced by extraction parachute performance, aircraft dynamics, aerodynamics, separation dynamics, and kinetic energy experienced by the system. During the real-time extraction and deployment sequences, these influences can be highly unsteady and difficult to bound. An avionics logic window based on time, pitch, and pitch rate is used to account for these effects and target a favorable separation state in real time. The Adams simulation has been employed to fine-tune this window, as well as predict and reconstruct the coupled dynamics of the Parachute Test Vehicle (PTV) and Cradle Platform Separation System (CPSS) from aircraft extraction through the mid-air separation event. The test-technique for the extraction of CPAS test articles has evolved with increased complexity and requires new modeling concepts to ensure the test article is delivered to a stable test condition for the programmer phase. Prompted by unexpected dynamics and hardware malfunctions in drop tests, these modeling improvements provide a more accurate loads prediction by incorporating a spring-damper line-model derived from the material properties. The qualification phase of CPAS testing is on the horizon and modeling increasingly complex test-techniques with Adams is vital to successfully qualify the Orion parachute system for human spaceflight.

The Relationship Between Training Load and Injury in Athletes: A Systematic Review.

PubMed

Eckard, Timothy G; Padua, Darin A; Hearn, Darren W; Pexa, Brett S; Frank, Barnett S

2018-06-26

The relationship between training load and musculoskeletal injury is a rapidly advancing area of research in need of an updated systematic review. This systematic review examined the evidence for the relationship between training load and musculoskeletal injury risk in athlete, military, and first responder (i.e. law enforcement, firefighting, rescue service) populations. The CINAHL, EMBASE, MEDLINE, SportDISCUS, and SCOPUS databases were searched using a comprehensive strategy. Studies published prior to July 2017 were included if they prospectively examined the relationship between training load and injury risk. Study quality was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS) and Oxford Centre for Evidence-Based Medicine levels of evidence. A narrative synthesis of findings was conducted. A total of 2047 articles were examined for potential inclusion. Forty-six met the inclusion criteria and 11 known to the authors but not found in the search were added, for a total of 57 articles. Overall, 47 studies had at least partially statistically significant results, demonstrating a relationship between training load and injury risk. Included articles were rated as poor (n = 15), fair (n = 6), and good (n = 36) based on NOS score. Articles assessed as 'good' were considered level 2b evidence on the Oxford Centre for Evidence-Based Medicine Model, and articles assessed as 'fair' or 'poor' were considered level 4 evidence. Our results demonstrate that the existence of a relationship between training load and injury continues to be well supported in the literature and is strongest for subjective internal training load. The directionality of this relationship appears to depend on the type and timeframe of load measured.

Clinical evaluation of Roche COBAS® AmpliPrep/COBAS® TaqMan® CMV Test using non-plasma samples.

PubMed

Hildenbrand, Cynthia; Wedekind, Laura; Li, Ge; vonRentzell, Jeanne E; Shah, Krunal; Rooney, Paul; Harrington, Amanda T; Zhao, Richard Y

2018-05-24

Cytomegalovirus (CMV) infection is a leading cause of loss of hearing, vision, and mental retardation in congenitally infected children. It is also associated with complications of organ-transplant and opportunistic HIV co-infection. The Roche COBAS ® AmpliPrep/COBAS ® TaqMan ® CMV Test is a FDA-approved test that measures CMV DNA viral load in plasma for the diagnosis and management of patients at risk for CMV-associated diseases. Besides plasma, CMV is often found in bronchoalveolar lavage (BAL), cerebrospinal fluid (CSF) and urine. Thus, monitoring of CMV for critical care of patients in these non-plasma samples becomes necessary. The objective of this study was to conduct an analytic and clinical feasibility study of the Roche CMV Test in BAL, CSF, and urine. The lower limit of detection (LOD), analytic measurement range (AMR), assay sensitivity, specificity, and precision were determined. Results of this study showed the LODs were 50, 100 and 300 IU/mL for BAL, CSF, or urine, respectively. The AMRs were from log 10 2.48 to log 10 5.48. The assay specificity was 94.4% for BAL, and 100% for CSF and urine. The assay precision was all within the acceptable range. The performance of Roche test was further compared with two comparators including the RealTime CMV Assay (Abbott Molecular) and a CMV Quantitative PCR Test (Vela Diagnostics). There was a general positive correlation between the Roche method and the Abbott or the Vela method. Overall, this study suggests the Roche CMV Test is suitable for the quantification of CMV viral load DNA in the described non-plasma samples. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Survival Model for Foot and Leg High Rate Axial Impact Injury Data.

PubMed

Bailey, Ann M; McMurry, Timothy L; Poplin, Gerald S; Salzar, Robert S; Crandall, Jeff R

2015-01-01

Understanding how lower extremity injuries from automotive intrusion and underbody blast (UBB) differ is of key importance when determining whether automotive injury criteria can be applied to blast rate scenarios. This article provides a review of existing injury risk analyses and outlines an approach to improve injury prediction for an expanded range of loading rates. This analysis will address issues with existing injury risk functions including inaccuracies due to inertial and potential viscous resistance at higher loading rates. This survival analysis attempts to minimize these errors by considering injury location statistics and a predictor variable selection process dependent upon failure mechanisms of bone. Distribution of foot/ankle/leg injuries induced by axial impact loading at rates characteristic of UBB as well as automotive intrusion was studied and calcaneus injuries were found to be the most common injury; thus, footplate force was chosen as the main predictor variable because of its proximity to injury location to prevent inaccuracies associated with inertial differences due to loading rate. A survival analysis was then performed with age, sex, dorsiflexion angle, and mass as covariates. This statistical analysis uses data from previous axial postmortem human surrogate (PMHS) component leg tests to provide perspectives on how proximal boundary conditions and loading rate affect injury probability in the foot/ankle/leg (n = 82). Tibia force-at-fracture proved to be up to 20% inaccurate in previous analyses because of viscous resistance and inertial effects within the data set used, suggesting that previous injury criteria are accurate only for specific rates of loading and boundary conditions. The statistical model presented in this article predicts 50% probability of injury for a plantar force of 10.2 kN for a 50th percentile male with a neutral ankle position. Force rate was found to be an insignificant covariate because of the limited range of loading rate differences within the data set; however, compensation for inertial effects caused by measuring the force-at-fracture in a location closer to expected injury location improved the model's predictive capabilities for the entire data set. This study provides better injury prediction capabilities for both automotive and blast rates because of reduced sensitivity to inertial effects and tibia-fibula load sharing. Further, a framework is provided for future injury criteria generation for high rate loading scenarios. This analysis also suggests key improvements to be made to existing anthropomorphic test device (ATD) lower extremities to provide accurate injury prediction for high rate applications such as UBB.

Solid Rocket Booster Structural Test Article

NASA Technical Reports Server (NTRS)

1978-01-01

The structural test article to be used in the solid rocket booster (SRB) structural and load verification tests is being assembled in a high bay building of the Marshall Space Flight Center (MSFC). The Shuttle's two SRB's are the largest solids ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the solid rocket motors (SRM's) were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. At burnout, the boosters separate from the external tank and drop by parachute to the ocean for recovery and subsequent refurbishment.

Predicting the Reliability of Brittle Material Structures Subjected to Transient Proof Test and Service Loading

NASA Astrophysics Data System (ADS)

Nemeth, Noel N.; Jadaan, Osama M.; Palfi, Tamas; Baker, Eric H.

Brittle materials today are being used, or considered, for a wide variety of high tech applications that operate in harsh environments, including static and rotating turbine parts, thermal protection systems, dental prosthetics, fuel cells, oxygen transport membranes, radomes, and MEMS. Designing brittle material components to sustain repeated load without fracturing while using the minimum amount of material requires the use of a probabilistic design methodology. The NASA CARES/Life 1 (Ceramic Analysis and Reliability Evaluation of Structure/Life) code provides a general-purpose analysis tool that predicts the probability of failure of a ceramic component as a function of its time in service. This capability includes predicting the time-dependent failure probability of ceramic components against catastrophic rupture when subjected to transient thermomechanical loads (including cyclic loads). The developed methodology allows for changes in material response that can occur with temperature or time (i.e. changing fatigue and Weibull parameters with temperature or time). For this article an overview of the transient reliability methodology and how this methodology is extended to account for proof testing is described. The CARES/Life code has been modified to have the ability to interface with commercially available finite element analysis (FEA) codes executed for transient load histories. Examples are provided to demonstrate the features of the methodology as implemented in the CARES/Life program.

Implementation of Statistical Process Control: Evaluating the Mechanical Performance of a Candidate Silicone Elastomer Docking Seal

NASA Technical Reports Server (NTRS)

Oravec, Heather Ann; Daniels, Christopher C.

2014-01-01

The National Aeronautics and Space Administration has been developing a novel docking system to meet the requirements of future exploration missions to low-Earth orbit and beyond. A dynamic gas pressure seal is located at the main interface between the active and passive mating components of the new docking system. This seal is designed to operate in the harsh space environment, but is also to perform within strict loading requirements while maintaining an acceptable level of leak rate. In this study, a candidate silicone elastomer seal was designed, and multiple subscale test articles were manufactured for evaluation purposes. The force required to fully compress each test article at room temperature was quantified and found to be below the maximum allowable load for the docking system. However, a significant amount of scatter was observed in the test results. Due to the stochastic nature of the mechanical performance of this candidate docking seal, a statistical process control technique was implemented to isolate unusual compression behavior from typical mechanical performance. The results of this statistical analysis indicated a lack of process control, suggesting a variation in the manufacturing phase of the process. Further investigation revealed that changes in the manufacturing molding process had occurred which may have influenced the mechanical performance of the seal. This knowledge improves the chance of this and future space seals to satisfy or exceed design specifications.

An Architecture for Real-Time Interpretation and Visualization of Structural Sensor Data in a Laboratory Environment

NASA Technical Reports Server (NTRS)

Doggett, William; Vazquez, Sixto

2000-01-01

A visualization system is being developed out of the need to monitor, interpret, and make decisions based on the information from several thousand sensors during experimental testing to facilitate development and validation of structural health monitoring algorithms. As an added benefit the system will enable complete real-time sensor assessment of complex test specimens. Complex structural specimens are routinely tested that have hundreds or thousands of sensors. During a test, it is impossible for a single researcher to effectively monitor all the sensors and subsequently interesting phenomena occur that are not recognized until post-test analysis. The ability to detect and alert the researcher to these unexpected phenomena as the test progresses will significantly enhance the understanding and utilization of complex test articles. Utilization is increased by the ability to halt a test when the health monitoring algorithm response is not satisfactory or when an unexpected phenomenon occurs, enabling focused investigation potentially through the installation of additional sensors. Often if the test continues, structural changes make it impossible to reproduce the conditions that exhibited the phenomena. The prohibitive time and costs associated with fabrication, sensoring, and subsequent testing of additional test articles generally makes it impossible to further investigate the phenomena. A scalable architecture is described to address the complex computational demands of structural health monitoring algorithm development and laboratory experimental test monitoring. The researcher monitors the test using a photographic quality 3D graphical model with actual sensor locations identified. In addition, researchers can quickly activate plots displaying time or load versus selected sensor response along with the expected values and predefined limits. The architecture has several key features. First, distributed dissimilar computers may be seamlessly integrated into the information flow. Second, virtual sensors may be defined that are complex functions of existing sensors or other virtual sensors. Virtual sensors represent a calculated value not directly measured by particular physical instrument. They can be used, for example, to represent the maximum difference in a range of sensors or the calculated buckling load based on the current strains. Third, the architecture enables autonomous response to preconceived events, where by the system can be configured to suspend or abort a test if a failure is detected in the load introduction system. Fourth, the architecture is designed to allow cooperative monitoring and control of the test progression from multiple stations both remote and local to the test system. To illustrate the architecture, a preliminary implementation is described monitoring the Stitched Composite Wing recently tested at LaRC.

Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum

NASA Technical Reports Server (NTRS)

Brady, David; White, Harold G.; March, Paul; Lawrence, James T.; Davies, Frank J.

2014-01-01

This paper describes the eight-day August 2013 test campaign designed to investigate and demonstrate viability of using classical magnetoplasmadynamics to obtain a propulsive momentum transfer via the quantum vacuum virtual plasma. This paper will not address the physics of the quantum vacuum plasma thruster, but instead will describe the test integration, test operations, and the results obtained from the test campaign. Approximately 30-50 micro-Newtons of thrust were recorded from an electric propulsion test article consisting primarily of a radio frequency (RF) resonant cavity excited at approximately 935 megahertz. Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure. Several different test configurations were used, including two different test articles as well as a reversal of the test article orientation. In addition, the test article was replaced by an RF load to verify that the force was not being generated by effects not associated with the test article. The two test articles were designed by Cannae LLC of Doylestown, Pennsylvania. The torsion pendulum was designed, built, and operated by Eagleworks Laboratories at the NASA Johnson Space Center of Houston, Texas. Approximately six days of test integration were required, followed by two days of test operations, during which, technical issues were discovered and resolved. Integration of the two test articles and their supporting equipment was performed in an iterative fashion between the test bench and the vacuum chamber. In other words, the test article was tested on the bench, then moved to the chamber, then moved back as needed to resolve issues. Manual frequency control was required throughout the test. Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article). Test data gathered includes torsion pendulum displacement measurements which are used to calculate generated force, still imagery in the visible spectrum to document the physical configuration, still imagery in the infrared spectrum to characterize the thermal environment, and video imagery. Post-test data includes static and animated graphics produced during RF resonant cavity characterization using the COMSOL Multiphysics® software application. Excerpts from all of the above are included and discussed in this paper. Lessons learned from test integration and operations include identification of the need to replace manual control of the resonant cavity target frequency with an automated frequency control capability. Future test plans include the development of an automatic frequency control circuit. Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma. Future test plans include independent verification and validation at other test facilities.

Design of a 3T preamplifier which stability is insensitive to coil loading

NASA Astrophysics Data System (ADS)

Cao, Xueming; Fischer, Elmar; Korvink, Jan G.; Gruschke, Oliver; Hennig, Jürgen; Zaitsev, Maxim

2016-04-01

In MRI (magnetic resonance imaging), preamplifiers are needed to amplify signals obtained from MRI receiver coils. Under various loading conditions of the corresponding receiver coils, preamplifiers see different source impedance at their input and may become unstable. Therefore preamplifiers which stability is not sensitive to coil loading are desirable. In this article, a coil-loading-insensitive preamplifier for MRI is presented, derived from an unstable preamplifier. Different approaches to improve stability were used during this derivation. Since a very low noise factor is essential for MRI preamplifiers, noise contributions from passive components in the MRI preamplifier have to be considered during the stabilization process. As a result, the initially unstable preamplifier became stable with regard to coil loading, while other MRI requirements, as the extremely low noise factor, were still fulfilled. The newly designed preamplifier was manufactured, characterized and tested in the MRI spectrometer. Compared to a commercially available preamplifier, the newly designed preamplifier has similar imaging performance but other advantages like smaller size and better stability. Furthermore, presented stabilization approaches can be generalized to stabilize other unstable low-noise amplifiers.

Overview of the Acoustic Testing of the European Service Module Structural Test Article (E-STA)

NASA Technical Reports Server (NTRS)

Hughes, William; Fogt, Vince; Le Plenier, Cyprien; Duval, Francois; Durand, Jean-Francois; Staab, Lucas D.; Hozman, Aron; Mcnelis, Anne; Bittinger, Samantha; Thirkettle, Anthony;

Overview of the Acoustic Testing of the European Service Module Structural Test Article (E-STA)

NASA Technical Reports Server (NTRS)

Hughes, William; Le Plenier, Cyprien; Duval, Francois; Staab, Lucas; Hozman, Aron; Thirkettle, Anthony; Fogt, Vincent; Durand, Jean-Francois; McNelis, Anne; Bittinger, Samantha;

Determination of Offgassed Products

NASA Technical Reports Server (NTRS)

1997-01-01

A technician at Marshall Space Flight Center's Materials Combustion Research Facility begins the Determination of Offgassed Products Test to determine the identity and quantity of volatile offgassed products from materials and assembled articles. Materials are measured, weighed, and loaded into a clean toxicity chamber (pictured). The chamber is purged with high-purity air and loaded into an oven where it will be held at 120 degrees Fahrenheit (48.9 degrees Celsius) for 72 hours. At the end of the 72-hour period, the chamber is removed and allowed to cool to room temperature. Gas samples are taken from the chamber and analyzed using gas chromatography and mass spectrometry. From this, the quantity of the material that may be used safely in habitable areas of spacecraft is determined. This test also determines whether a flight hardware item may be flown safely in a crew compartment. Everything going into space with the astronauts is tested prior to flight to ensure the health and safety of the crew members.

Test and Analysis Correlation of a Large-Scale, Orthogrid-Stiffened Metallic Cylinder without Weld Lands

NASA Technical Reports Server (NTRS)

Rudd, Michelle T.; Hilburger, Mark W.; Lovejoy, Andrew E.; Lindell, Michael C.; Gardner, Nathaniel W.; Schultz, Marc R.

2018-01-01

The NASA Engineering Safety Center (NESC) Shell Buckling Knockdown Factor Project (SBKF) was established in 2007 by the NESC with the primary objective to develop analysis-based buckling design factors and guidelines for metallic and composite launch-vehicle structures.1 A secondary objective of the project is to advance technologies that have the potential to increase the structural efficiency of launch-vehicles. The SBKF Project has determined that weld-land stiffness discontinuities can significantly reduce the buckling load of a cylinder. In addition, the welding process can introduce localized geometric imperfections that can further exacerbate the inherent buckling imperfection sensitivity of the cylinder. Therefore, single-piece barrel fabrication technologies can improve structural efficiency by eliminating these weld-land issues. As part of this effort, SBKF partnered with the Advanced Materials and Processing Branch (AMPB) at NASA Langley Research Center (LaRC), the Mechanical and Fabrication Branch at NASA Marshall Space Flight Center (MSFC), and ATI Forged Products to design and fabricate an 8-ft-diameter orthogrid-stiffened seamless metallic cylinder. The cylinder was subjected to seven subcritical load sequences (load levels that are not intended to induce test article buckling or material failure) and one load sequence to failure. The purpose of this test effort was to demonstrate the potential benefits of building cylindrical structures with no weld lands using the flow-formed manufacturing process. This seamless barrel is the ninth 8-ft-diameter metallic barrel and the first single-piece metallic structure to be tested under this program.

High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield

NASA Technical Reports Server (NTRS)

Kerslake, Thomas W.; Mason, Lee S.; Strumpf, Hal J.

1997-01-01

As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near equilibrium temperature of 2072 K was achieved. The aperture shield sustained no visible damage as a result of the exposures. This paper describes the aperture shield thermal-vacuum qualification test program including the test article, test facility, procedures, data collection, test success criteria, results and conclusions.

Correlation of Structural Analysis and Test Results for the McDonnell Douglas Stitched/RFI All-Composite Wing Stub Box

NASA Technical Reports Server (NTRS)

Wang, John T.; Jegley, Dawn C.; Bush, Harold G.; Hinrichs, Stephen C.

1996-01-01

The analytical and experimental results of an all-composite wing stub box are presented in this report. The wing stub box, which is representative of an inboard portion of a commercial transport high-aspect-ratio wing, was fabricated from stitched graphite-epoxy material with a Resin Film Infusion manufacturing process. The wing stub box was designed and constructed by the McDonnell Douglas Aerospace Company as part of the NASA Advanced Composites Technology program. The test article contained metallic load-introduction structures on the inboard and outboard ends of the graphite-epoxy wing stub box. The root end of the inboard load introduction structure was attached to a vertical reaction structure, and an upward load was applied to the outermost tip of the outboard load introduction structure to induce bending of the wing stub box. A finite element model was created in which the center portion of the wing-stub-box upper cover panel was modeled with a refined mesh. The refined mesh was required to represent properly the geometrically nonlinear structural behavior of the upper cover panel and to predict accurately the strains in the stringer webs of the stiffened upper cover panel. The analytical and experimental results for deflections and strains are in good agreement.

Numerical Analyses of Subsoil-structure Interaction in Original Non-commercial Software based on FEM

NASA Astrophysics Data System (ADS)

Cajka, R.; Vaskova, J.; Vasek, J.

2018-04-01

For decades attention has been paid to interaction of foundation structures and subsoil and development of interaction models. Given that analytical solutions of subsoil-structure interaction could be deduced only for some simple shapes of load, analytical solutions are increasingly being replaced by numerical solutions (eg. FEM – Finite element method). Numerical analyses provides greater possibilities for taking into account the real factors involved in the subsoil-structure interaction and was also used in this article. This makes it possible to design the foundation structures more efficiently and still reliably and securely. Currently there are several software that, can deal with the interaction of foundations and subsoil. It has been demonstrated that non-commercial software called MKPINTER (created by Cajka) provides appropriately results close to actual measured values. In MKPINTER software stress-strain analysis of elastic half-space by means of Gauss numerical integration and Jacobean of transformation is done. Input data for numerical analysis were observed by experimental loading test of concrete slab. The loading was performed using unique experimental equipment which was constructed in the area Faculty of Civil Engineering, VŠB-TU Ostrava. The purpose of this paper is to compare resulting deformation of the slab with values observed during experimental loading test.

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.

Coupled Facility/Payload Vibration Modeling Improvements

NASA Technical Reports Server (NTRS)

Carnahan, Timothy M.; Kaiser, Michael

2015-01-01

A major phase of aerospace hardware verification is vibration testing. The standard approach for such testing is to use a shaker to induce loads into the payload. In preparation for vibration testing at NASA/GSFC there is an analysis to assess the responses of the payload. A new method of modeling the test is presented that takes into account dynamic interactions between the facility and the payload. This dynamic interaction has affected testing in the past, but been ignored or adjusted for during testing. By modeling the combination of the facility and test article (payload) it is possible to improve the prediction of hardware responses. Many aerospace test facilities work in similar way to those at NASA Goddard Space Flight Center. Lessons learned here should be applicable to other test facilities with similar setups.

Simulation of Cold Flow in a Truncated Ideal Nozzle with Film Cooling

NASA Technical Reports Server (NTRS)

Braman, K. E.; Ruf, J. H.

2015-01-01

Flow transients during rocket start-up and shut-down can lead to significant side loads on rocket nozzles. The capability to estimate these side loads computationally can streamline the nozzle design process. Towards this goal, the flow in a truncated ideal contour (TIC) nozzle has been simulated using RANS and URANS for a range of nozzle pressure ratios (NPRs) aimed to match a series of cold flow experiments performed at the NASA MSFC Nozzle Test Facility. These simulations were performed with varying turbulence model choices and for four approximations of the supersonic film injection geometry, each of which was created with a different simplification of the test article geometry. The results show that although a reasonable match to experiment can be obtained with varying levels of geometric fidelity, the modeling choices made do not fully represent the physics of flow separation in a TIC nozzle with film cooling.

Monitoring of a micro-smart grid: Power consumption data of some machineries of an agro-industrial test site.

PubMed

Fabrizio, Enrico; Biglia, Alessandro; Branciforti, Valeria; Filippi, Marco; Barbero, Silvia; Tecco, Giuseppe; Mollo, Paolo; Molino, Andrea

2017-02-01

For the management of a (micro)-smart grid it is important to know the patters of the load profiles and of the generators. In this article the power consumption data obtained through a monitoring activity developed on a micro-smart grid in an agro-industrial test-site are presented. In particular, this reports the synthesis of the monitoring results of 5 loads (5 industrial machineries for crop micronization, corncob crashing and other similar processes). How these data were used within a monitoring and managing scheme of a micro-smart grid can be found in (E. Fabrizio, V. Branciforti, A. Costantino, M. Filippi, S. Barbero, G. Tecco, P. Mollo, A. Molino, 2017) [1]. The data can be useful for other researchers in order to create benchmarks of energy use input appropriate energy demand values in optimization tools for the industrial sector.

High-Temperature Modal Survey of a Hot-Structure Control Surface

NASA Technical Reports Server (NTRS)

Spivey, Natalie Dawn

2010-01-01

Ground vibration tests or modal surveys are routinely conducted for supporting flutter analysis for subsonic and supersonic vehicles; however, for hypersonic vehicle applications, thermoelastic vibration testing techniques are not well established and are not routinely performed for supporting hypersonic flutter analysis. New high-temperature material systems, fabrication technologies and high-temperature sensors expand the opportunities to develop advanced techniques for performing ground vibration tests at elevated temperatures. High-temperature materials have the unique property of increasing in stiffness when heated. When these materials are incorporated into a hot-structure, which includes metallic components that decrease in stiffness with increasing temperature, the interaction between the two materials systems needs to be understood because that interaction could ultimately affect the hypersonic flutter analysis. Performing a high-temperature modal survey will expand the research database for hypersonics and will help build upon the understanding of the dual material interaction. This paper will discuss the vibration testing of the Carbon-Silicon Carbide Ruddervator Subcomponent Test Article which is a truncated version of the full-scale X-37 hot-structure control surface. In order to define the modal characteristics of the test article during the elevated-temperature modal survey, two series of room-temperature modal test configurations had to be performed. The room-temperature test series included one with the test article suspended from a bungee cord (free-free) and the second with it mounted on the strongback (fixed boundary condition) in NASA Dryden's Flight Loads Lab large nitrogen test chamber.

Interaction of gelatin with polyenes modulates antifungal activity and biocompatibility of electrospun fiber mats

PubMed Central

Lakshminarayanan, Rajamani; Sridhar, Radhakrishnan; Loh, Xian Jun; Nandhakumar, Muruganantham; Barathi, Veluchamy Amutha; Kalaipriya, Madhaiyan; Kwan, Jia Lin; Liu, Shou Ping; Beuerman, Roger Wilmer; Ramakrishna, Seeram

2014-01-01

Topical application of antifungals does not have predictable or well-controlled release characteristics and requires reapplication to achieve therapeutic local concentration in a reasonable time period. In this article, the efficacy of five different US Food and Drug Administration-approved antifungal-loaded (amphotericin B, natamycin, terbinafine, fluconazole, and itraconazole) electrospun gelatin fiber mats were compared. Morphological studies show that incorporation of polyenes resulted in a two-fold increase in fiber diameter and the mats inhibit the growth of yeasts and filamentous fungal pathogens. Terbinafine-loaded mats were effective against three filamentous fungal species. Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains. However, activity loss was observed for fluconazole-loaded mats against all of the test organisms. The polyene-loaded mats displayed rapid candidacidal activities as well. Biophysical and rheological measurements indicate strong interactions between polyene antifungals and gelatin matrix. As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes. The polyene-loaded fiber mats were noncytotoxic to primary human corneal and sclera fibroblasts. The reduction of toxicity with complete retention of activity of the polyene antifungal-loaded gelatin fiber mats can provide new opportunities in the management of superficial skin infections. PMID:24920895

Thermal tests of the SGT5-4000F gas-turbine plant of the PGU-420T power-generating unit at Combined Heat And Power Plant 16 of Mosenergo

NASA Astrophysics Data System (ADS)

Teplov, B. D.; Radin, Yu. A.; Filin, A. A.; Rudenko, D. V.

2016-08-01

In December 2014, the PGU-420T power-generating unit was put into operation at the Combined Heat and Power Plant 16, an affiliated company of PAO Mosenergo. In 2014-2015, thermal tests of the SGT5- 4000F gas-turbine plant (GTP) integrated into the power-generating unit were carried out. In the article, the test conditions are described and the test results are presented and analyzed. During the tests, 92 operating modes within a wide range of electrical loads and ambient air temperatures and operating conditions of the GTP when fired with fuel oil were investigated. In the tests, an authorized automated measuring system was applied. The experimental data were processed according to ISO 2314:2009 "Gas turbines—Acceptance tests" standard. The available capacity and the GTP efficiency vary from 266 MW and 38.8% to 302 MW and 39.8%, respectively, within the ambient air temperature range from +24 to-12°C, while the turbine inlet temperature decreases from 1200 to 1250°C. The switch to firing fuel oil results in a reduction in the turbine inlet temperature and the capacity of the GTP. With the full load and a reduction in the ambient temperature from +24 to-12°C, the compressor efficiency decreases from 89.6 to 86.4%. The turbine efficiency is approximately 89-91%. Within the investigated range of power output, the emissions of nitrogen oxides do not exceed 35 ppm for the gas-fired plant and 65 ppm for the fuel-oil-fired plant. Within the range of the GTP power output from 50 to 100% of the rated output, the combustion chamber operates without underburning and with hardly any CO being formed. At low loads close to the no-load operation mode, the CO emissions drastically increase.

A Large Motion Suspension System for Simulation of Orbital Deployment

NASA Technical Reports Server (NTRS)

Straube, T. M.; Peterson, L. D.

1994-01-01

This paper describes the design and implementation of a vertical degree of freedom suspension system which provides a constant force off-load condition to counter gravity over large displacements. By accommodating motions up to one meter for structures weighing up to 100 pounds, the system is useful for experiments which simulate the on-orbit deployment of spacecraft components. A unique aspect of this system is the combination of a large stroke passive off-load device augmented by electromotive torque actuated force feedback. The active force feedback has the effect of reducing breakaway friction by an order of magnitude over the passive system alone. The paper describes the development of the suspension hardware and the feedback control algorithm. Experiments were performed to verify the suspensions system's ability to provide a gravity off-load as well as its effect on the modal characteristics of a test article.

Underway Recovery Test 6 (URT-6) - Day 2 Activites

NASA Image and Video Library

2018-01-18

As part of Underway Recovery Test 6, the Orion test article is pulled in by a winch line at the rear of the USS Anchorage’s well deck that brings the capsule into the ship, along with four manned LLAMAs (Line Load Attenuation Mechanism Assembly) that control the capsule’s side-to-side movement and a tending line attached to a rigid hull inflatable boat for controlling Orion’s movement behind the ship. The testing with Kennedy Space Center's NASA Recovery Team and the U.S. Navy will provide important data that is being used to improve recovery procedures and hardware ahead of Orion's next flight, Exploration Mission-1, when it splashes down in the Pacific Ocean.

Element Interactivity and Intrinsic, Extraneous, and Germane Cognitive Load

ERIC Educational Resources Information Center

Sweller, John

2010-01-01

In cognitive load theory, element interactivity has been used as the basic, defining mechanism of intrinsic cognitive load for many years. In this article, it is suggested that element interactivity underlies extraneous cognitive load as well. By defining extraneous cognitive load in terms of element interactivity, a distinct relation between…

The Fatigue Behavior of Built-Up Welded Beams of Commercially Pure Titanium

NASA Astrophysics Data System (ADS)

Patnaik, Anil; Poondla, Narendra; Bathini, Udaykar; Srivatsan, T. S.

2011-10-01

In this article, the results of a recent study aimed at evaluating, understanding, and rationalizing the extrinsic influence of fatigue loading on the response characteristics of built-up welded beams made from commercially pure titanium (Grade 2) are presented and discussed. The beams were made from welding plates and sheets of titanium using the pulsed gas metal arc welding technique to form a structural beam having an I-shaped cross section. The welds made for the test beams of the chosen metal were fillet welds using a matching titanium filler metal wire. The maximum and minimum load values at which the built-up beams were cyclically deformed were chosen to be within the range of 22-45% of the maximum predicted flexural static load. The beams were deformed in fatigue at a stress ratio of 0.1 and constant frequency of 5 Hz. The influence of the ratio of maximum load with respect to the ultimate failure load on fatigue performance, quantified in terms of fatigue life, was examined. The percentage of maximum load to ultimate load that resulted in run-out of one million cycles was established. The overall fracture behavior of the failed beam sample was characterized by scanning electron microscopy observations to establish the conjoint influence of load severity, intrinsic microstructural effects, and intrinsic fracture surface features in governing failure by fracture.

Pre-Test Analysis Predictions for the Shell Buckling Knockdown Factor Checkout Tests - TA01 and TA02

NASA Technical Reports Server (NTRS)

Thornburgh, Robert P.; Hilburger, Mark W.

2011-01-01

This report summarizes the pre-test analysis predictions for the SBKF-P2-CYL-TA01 and SBKF-P2-CYL-TA02 shell buckling tests conducted at the Marshall Space Flight Center (MSFC) in support of the Shell Buckling Knockdown Factor (SBKF) Project, NASA Engineering and Safety Center (NESC) Assessment. The test article (TA) is an 8-foot-diameter aluminum-lithium (Al-Li) orthogrid cylindrical shell with similar design features as that of the proposed Ares-I and Ares-V barrel structures. In support of the testing effort, detailed structural analyses were conducted and the results were used to monitor the behavior of the TA during the testing. A summary of predicted results for each of the five load sequences is presented herein.

CM-2 Environmental / Modal Testing of Spacehab Racks

NASA Technical Reports Server (NTRS)

McNelis, Mark E.; Goodnight, Thomas W.; Farkas, Michael A.

2001-01-01

Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS 107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the Shuttle.

Factor structure and invariance test of the alcohol use disorder identification test (AUDIT): Comparison and further validation in a U.S. and Philippines college student sample.

PubMed

Tuliao, Antover P; Landoy, Bernice Vania N; McChargue, Dennis E

2016-01-01

The Alcohol Use Disorder Identification Test's factor structure varies depending on population and culture. Because of this inconsistency, this article examined the factor structure of the test and conducted a factorial invariance test between a U.S. and a Philippines college sample. Confirmatory factor analyses indicated that a three-factor solution outperforms the one- and two-factor solution in both samples. Factorial invariance analyses further supports the confirmatory findings by showing that factor loadings were generally invariant across groups; however, item intercepts show non-invariance. Country differences between factors show that Filipino consumption factor mean scores were significantly lower than their U.S. counterparts.

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.

Fabrication and testing of microchannel heat exchangers

NASA Astrophysics Data System (ADS)

Cuta, Judith M.; Bennett, Wendy D.; McDonald, Carolyn E.; Ravigururajan, T. S.

1995-09-01

Micro-channel heat-exchanger test articles were fabricated and performance tested. The heat exchangers are being developed for innovative applications, and have been shown to be capable of handling heat loads of up to 100 W/cm2. The test articles were fabricated to represent two different designs for the micro-channel portion of the heat exchanger. One design consists of 166 micro-channels etched in silicon substrate, and a second design consists of 54 micro-channels machined in copper substrate. The devices were tested in an experimental loop designed for performance testing in single- and two-phase flow with water and R124. Pressure and liquid subcooling can be regulated over the range of interest, and a secondary heat removal loop provides stable loop performance for steady-state tests. The selected operating pressures are approximately 0.344 MPa for distilled water and 0.689 MPa for R124. The temperature ranges are 15.5 to 138 C for distilled water and 15.5 to 46 C for R-124. The mass flow range 7.6 X 10-8 to 7.6 X 10MIN5 kg/min for both distilled water and R124.

Maximum acceptable weight of lift reflects peak lumbosacral extension moments in a functional capacity evaluation test using free style, stoop and squat lifting.

PubMed

Kuijer, P P F M; van Oostrom, S H; Duijzer, K; van Dieën, J H

2012-01-01

It is unclear whether the maximum acceptable weight of lift (MAWL), a common psychophysical method, reflects joint kinetics when different lifting techniques are employed. In a within-participants study (n = 12), participants performed three lifting techniques--free style, stoop and squat lifting from knee to waist level--using the same dynamic functional capacity evaluation lifting test to assess MAWL and to calculate low back and knee kinetics. We assessed which knee and back kinetic parameters increased with the load mass lifted, and whether the magnitudes of the kinetic parameters were consistent across techniques when lifting MAWL. MAWL was significantly different between techniques (p = 0.03). The peak lumbosacral extension moment met both criteria: it had the highest association with the load masses lifted (r > 0.9) and was most consistent between the three techniques when lifting MAWL (ICC = 0.87). In conclusion, MAWL reflects the lumbosacral extension moment across free style, stoop and squat lifting in healthy young males, but the relation between the load mass lifted and lumbosacral extension moment is different between techniques. Tests of maximum acceptable weight of lift (MAWL) from knee to waist height are used to assess work capacity of individuals with low-back disorders. This article shows that the MAWL reflects the lumbosacral extension moment across free style, stoop and squat lifting in healthy young males, but the relation between the load mass lifted and lumbosacral extension moment is different between techniques. This suggests that standardisation of lifting technique used in tests of the MAWL would be indicated if the aim is to assess the capacity of the low back.

Should we be testing for urogenital Mycoplasma hominis, Ureaplasma parvum and U. urealyticum in men and women? - a Position Statement from the European STI Guidelines Editorial Board.

PubMed

Horner, P; Donders, G; Cusini, M; Gomberg, M; Jensen, J S; Unemo, M

2018-06-20

At present, we have no evidence that we are doing more good than harm detecting and subsequently treating Mycoplasma hominis, Ureaplasma parvum and Ureaplasma urealyticum colonisations/infections. Consequently, routine testing and treatment of asymptomatic or symptomatic men and women for M. hominis, U. urealyticum, and U. parvum is not recommended. Asymptomatic carriage of these bacteria is common and the majority of individuals do not develop disease. Although U. urealyticum has been associated with urethritis in men, it is probably not causal unless a high load is present (likely carriage in 40-80% of detected cases). The extensive testing, detection and subsequent antimicrobial treatment of these bacteria performed in some settings may result in selection of antimicrobial resistance, in these bacteria, "true" STI agents, as well as in the general microbiota, and substantial economic cost for society and individuals, particularly women. The commercialisation of many particularly multiplex PCR assays detecting traditional non-viral STIs together with M. hominis, U. parvum and/or U. urealyticum have worsened this situation. Thus, routine screening of asymptomatic men and women or routine testing of symptomatic individuals for M. hominis, U. urealyticum, and U. parvum is not recommended. If testing of men with symptomatic urethritis is undertaken, traditional STI urethritis agents such as Neisseria gonorrhoeae, Chlamydia trachomatis, M. genitalium and, in settings where relevant, Trichomonas vaginalis should be excluded prior to U. urealyticum testing and quantitative species-specific molecular diagnostic tests should be used. Only men with high U. urealyticum load should be considered for treatment, however, appropriate evidence for effective treatment regimens is lacking. In symptomatic women, bacterial vaginosis (BV) should always be tested for and treated if detected. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Coupled Facility-Payload Vibration Modeling Improvements

NASA Technical Reports Server (NTRS)

Carnahan, Timothy M.; Kaiser, Michael A.

2015-01-01

A major phase of aerospace hardware verification is vibration testing. The standard approach for such testing is to use a shaker to induce loads into the payload. In preparation for vibration testing at National Aeronautics and Space Administration/Goddard Space Flight Center an analysis is performed to assess the responses of the payload. A new method of modeling the test is presented that takes into account dynamic interactions between the facility and the payload. This dynamic interaction has affected testing in the past, but been ignored or adjusted for during testing. By modeling the combined dynamics of the facility and test article (payload) it is possible to improve the prediction of hardware responses. Many aerospace test facilities work in similar way to those at NASA/Goddard Space Flight Center. Lessons learned here should be applicable to other test facilities with similar setups.

Structural Qualification Testing of the WindSat Payload Using Sine Bursts Near Structural Resonance

NASA Technical Reports Server (NTRS)

Pontius, Jim; Barnes, Donald; Broduer, Steve (Technical Monitor)

2001-01-01

Sine burst tests are often used for structural qualification of space flight hardware. In most instances, the driving frequency of the shaker is specified far below the structure's first resonant mode, such that the entire test article sees uniform acceleration. For large structures, this limits qualification testing to lower parts of the structure, or else it over-tests the lower structure to achieve qualification of the upper structure. The WindSat payload, a 10.5 foot tall graphite/epoxy, titanium, and aluminum radiometer, experiences accelerations at the six foot diameter reflector nearly four times that at the spacecraft interface. Due to size of the payload, the number of bonded joints, and the lightweight reflector support structure design and construction, using static pull testing to qualify all of the bonded joints in the upper structure would result in large, expensive, and extensive test fixturing. Sine burst testing near the first two structural resonant modes was performed on the WindSat payload to achieve the correct load factor distribution up the stack for structural qualification. In this presentation, how finite element method (FEM) sine burst predictions were used in conjunction with low level random and sine burst tests to achieve correct qualification test load factor distribution on the WindSat payload is discussed. Also presented is the risk mitigation approach for using the uncorrelated FEM in this procedure.

Global and Local Stress Analyses of McDonnell Douglas Stitched/RFI Composite Wing Stub Box

NASA Technical Reports Server (NTRS)

Wang, John T.

1996-01-01

This report contains results of structural analyses performed in support of the NASA structural testing of an all-composite stitched/RFI (resin film infusion) wing stub box. McDonnell Douglas Aerospace Company designed and fabricated the wing stub box. The analyses used a global/local approach. The global model contains the entire test article. It includes the all-composite stub box, a metallic load-transition box and a metallic wing-tip extension box. The two metallic boxes are connected to the inboard and outboard ends of the composite wing stub box, respectively. The load-transition box was attached to a steel and concrete vertical reaction structure and a load was applied at the tip of the extension box to bend the wing stub box upward. The local model contains an upper cover region surrounding three stringer runouts. In that region, a large nonlinear deformation was identified by the global analyses. A more detailed mesh was used for the local model to obtain more accurate analysis results near stringer runouts. Numerous analysis results such as deformed shapes, displacements at selected locations, and strains at critical locations are included in this report.

Mechatronical system for testing small diameter drills

NASA Astrophysics Data System (ADS)

Vekteris, Vladas; Jurevichius, Mindaugas; Daktariunas, Algis

2008-08-01

This paper describes a technique and mechatronical system for testing drills of a small diameter at different stages of production. The goal is to realize a system for drill testing which automatically increases the load applied to a drill under testing conditions and measure the drill's breaking torsion moment and deflection angle before a break occurs. The system's apparatus part and algorithms for the control of actuators and data acquisition from sensors are explained in the article. Also, a testing technique was applied in theoretical investigations to define the stress concentrations in dangerous places of the drill. The proposed technique and system have been verified by testing the drills of a small diameter at different stages of production—after thermal, mechanical treatment, and for quality control of the finished product.

Extraction-Separation Performance and Dynamic Modeling of Orion Test Vehicles with Adams Simulation: 3rd Edition

NASA Technical Reports Server (NTRS)

Varela, Jose G.; Reddy, Satish; Moeller, Enrique; Anderson, Keith

2017-01-01

NASA's Orion Capsule Parachute Assembly System (CPAS) Project is now in the qualification phase of testing, and the Adams simulation has continued to evolve to model the complex dynamics experienced during the test article extraction and separation phases of flight. The ability to initiate tests near the upper altitude limit of the Orion parachute deployment envelope requires extractions from the aircraft at 35,000 ft-MSL. Engineering development phase testing of the Parachute Test Vehicle (PTV) carried by the Carriage Platform Separation System (CPSS) at altitude resulted in test support equipment hardware failures due to increased energy caused by higher true airspeeds. As a result, hardware modifications became a necessity requiring ground static testing of the textile components to be conducted and a new ground dynamic test of the extraction system to be devised. Force-displacement curves from static tests were incorporated into the Adams simulations, allowing prediction of loads, velocities and margins encountered during both flight and ground dynamic tests. The Adams simulation was then further refined by fine tuning the damping terms to match the peak loads recorded in the ground dynamic tests. The failure observed in flight testing was successfully replicated in ground testing and true safety margins of the textile components were revealed. A multi-loop energy modulator was then incorporated into the system level Adams simulation model and the effect on improving test margins be properly evaluated leading to high confidence ground verification testing of the final design solution.

Pulse-Echo Phased Array Ultrasonic Inspection of Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS)

NASA Technical Reports Server (NTRS)

Johnston, Pat H.

2010-01-01

A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading. Keywords: Phased Array, Ultrasonics, Composites, Out-of-Autoclave

Walking Robot Locomotion System Conception

NASA Astrophysics Data System (ADS)

Ignatova, D.; Abadjieva, E.; Abadjiev, V.; Vatzkitchev, Al.

2014-09-01

This work is a brief analysis on the application and perspective of using the walking robots in different areas in practice. The most common characteristics of walking four legs robots are presented here. The specific features of the applied actuators in walking mechanisms are also shown in the article. The experience of Institute of Mechanics - BAS is illustrated in creation of Spiroid and Helicon1 gears and their assembly in actuation of studied robots. Loading on joints reductors of robot legs is modelled, when the geometrical and the walking parameters of the studied robot are preliminary defined. The obtained results are purposed for designing the control of the loading of reductor type Helicon in the legs of the robot, when it is experimentally tested.

Qualification Motor no. 8 (QM-8), volume 1

NASA Technical Reports Server (NTRS)

Garecht, D. M.

1989-01-01

All inspection and instrumentation data indicate that the QM-8 static test firing conducted 20 January 1989 was successful. Ambient temperature at T-0 was 28 F. With two flights successfully accomplished, this final test in the redesigned solid rocket motor (RSRM) program certified that the design meets motor performance requirements under extreme cold conditions. This test was a prerequisite to the third flight. The entire test article was cold conditioned at 20 to 25 F for approximately 31 days to assure a maximum propellant mean bulk temperature (PMBT) of 40 F, making it the lowest PMBT in the history of the program. This extreme condition also presented the opportunity to certify critical components at low temperatures. Certification of field joint and igniter heaters, adhesive bondline integrity, flex bearing performance, flight instrumentation performance, RSRM seal performance, and LSC and nozzle plug performance was accomplished. Prior to motor ignition, the field joints were maintained between 75 to 130 F, the igniter-to-case joint was maintained between 75 to 123 F, and the case-to-nozzle joint was maintained between 75 to 120 F. QM-8 was tested with induced side loads to simulate the strut loads experienced during ignition and maximum aerodynamic loading conditions. The ability of the safe and arm device to change position from safe-to-arm and arm-to-safe was certified. Ballistics performance was certified at the lower limits. Values were within specification requirements. Nozzle performance was nominal with typical erosion. The use of Fiberite carbon-cloth phenolic was certified. The water deluge system, CO2 quench, and other test equipment performed as planned during all required test operations.

Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifting Philosophy

NASA Technical Reports Server (NTRS)

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.

2009-01-01

The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle s Kevlar-49 (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed nonconservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23 percent lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy

NASA Technical Reports Server (NTRS)

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

2007-01-01

The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

Reusable LH2 tank technology demonstration through ground test

NASA Technical Reports Server (NTRS)

Bianca, C.; Greenberg, H. S.; Johnson, S. E.

1995-01-01

The paper presents the project plan to demonstrate, by March 1997, the reusability of an integrated composite LH2 tank structure, cryogenic insulation, and thermal protection system (TPS). The plan includes establishment of design requirements and a comprehensive trade study to select the most suitable Reusable Hydrogen Composite Tank system (RHCTS) within the most suitable of 4 candidate structural configurations. The 4 vehicles are winged body with the capability to deliver 25,000 lbs of payload to a circular 220 nm, 51.6 degree inclined orbit (also 40,000 lbs to a 28.5 inclined 150 nm orbit). A prototype design of the selected RHCTS is established to identify the construction, fabrication, and stress simulation and test requirements necessary in an 8 foot diameter tank structure/insulation/TPS test article. A comprehensive development test program supports the 8 foot test article development and involves the composite tank itself, cryogenic insulation, and integrated tank/insulation/TPS designs. The 8 foot diameter tank will contain the integrated cryogenic insulation and TPS designs resulting from this development and that of the concurrent lightweight durable TPS program. Tank ground testing will include 330 cycles of LH2 filling, pressurization, body loading, depressurization, draining, and entry heating.

Stress Behaviour in Compression of Contact-Monolithic Joint of Self-Supporting Wall of Large Panel Multi-Storey Building

NASA Astrophysics Data System (ADS)

Derbentsev, I.; Karyakin, A. A.; Volodin, A.

2017-11-01

The article deals with the behaviour of a contact-monolithic joint of large-panel buildings under compression. It gives a detailed analysis and the descriptions of the stages of such joints failure based on the results of the tests and computational modelling. The article is of interest to specialists who deal with computational modelling or the research of large-panel multi-storey buildings. The text gives a valuable information on the values of their bearing capacity and flexibility, the eccentricity of load transfer from upper panel to lower, the value of thrust passed to a ceiling panel. Recommendations are given to estimate all the above-listed parameters.

Simulation Study of Stress and Deformation Behaviour of Debonded Laminated Structure

NASA Astrophysics Data System (ADS)

Hirwani, C. K.; Mittal, H.; Panda, S. K.; Mahapatra, S. S.; Mandal, S. K.; De, A. K.

2017-02-01

The bending strength and deformation characteristics of the debonded laminated plate under the uniformly distributed loading (UDL) have been investigated in this research article. For the simulation study, an internally damaged laminated plate structure model has been developed in ANSYS based on the first-order shear deformable kinematic theory via ANSYS parametric design language (APDL) code. The internal debonding within the laminated structure is incorporated using two sub-laminate approach. Further, the convergence (different mesh densities), as well as the validity (comparing the responses with published results) of the present simulation model, have been performed by solving the deflection responses under the influence of transversely loaded layered structure. Also, to show the coherence of the simulation analysis the results are compared with the experimental bending results of the homemade Glass/Epoxy composite with artificial delamination. For the experimental analysis, Glass/Epoxy laminated composite seeded with delamination at the central mid-plane of the laminate is fabricated using an open mould hand lay-up composites fabrication technique. For the computational purpose, the necessary material properties of fabricated composite plate evaluated experimentally via uniaxial tensile test (Universal Testing Machine INSTRON-1195). Further, the bending (three-point bend test) test is conducted with the help of Universal Testing Machine INSTRON-5967. Finally, the effect different geometrical and material parameters (thickness ratio, modular ratio, constraint conditions) and magnitude of the loading on the static deflection and stress behaviour of the delaminated composite plate are investigated thoroughly by solving different kinds of numerical illustrations and discussed in detail.

Stress-strain time-dependent behavior of A356.0 aluminum alloy subjected to cyclic thermal and mechanical loadings

NASA Astrophysics Data System (ADS)

Farrahi, G. H.; Ghodrati, M.; Azadi, M.; Rezvani Rad, M.

2014-08-01

This article presents the cyclic behavior of the A356.0 aluminum alloy under low-cycle fatigue (or isothermal) and thermo-mechanical fatigue loadings. Since the thermo-mechanical fatigue (TMF) test is time consuming and has high costs in comparison to low-cycle fatigue (LCF) tests, the purpose of this research is to use LCF test results to predict the TMF behavior of the material. A time-independent model, considering the combined nonlinear isotropic/kinematic hardening law, was used to predict the TMF behavior of the material. Material constants of this model were calibrated based on room-temperature and high-temperature low-cycle fatigue tests. The nonlinear isotropic/kinematic hardening law could accurately estimate the stress-strain hysteresis loop for the LCF condition; however, for the out-of-phase TMF, the condition could not predict properly the stress value due to the strain rate effect. Therefore, a two-layer visco-plastic model and also the Johnson-Cook law were applied to improve the estimation of the stress-strain hysteresis loop. Related finite element results based on the two-layer visco-plastic model demonstrated a good agreement with experimental TMF data of the A356.0 alloy.

CM-2 Environmental/Modal Testing of SPACEHAB Racks

NASA Technical Reports Server (NTRS)

McNelis, Mark E.; Goodnight, Thomas W.

2001-01-01

Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that will launch on shuttle mission STS-107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack-level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the shuttles.

Inducer Hydrodynamic Forces in a Cavitating Environment

NASA Technical Reports Server (NTRS)

Skelley, Stephen E.

2004-01-01

Marshall Space Flight Center has developed and demonstrated a measurement device for sensing and resolving the hydrodynamic loads on fluid machinery. The device - a derivative of the six-component wind tunnel balance - senses the forces and moments on the rotating device through a weakened shaft section instrumented with a series of strain gauges. This rotating balance was designed to directly measure the steady and unsteady hydrodynamic loads on an inducer, thereby defining the amplitude and frequency content associated with operating in various cavitation modes. The rotating balance was calibrated statically using a dead-weight load system in order to generate the 6 x 12 calibration matrix later used to convert measured voltages to engineering units. Structural modeling suggested that the rotating assembly first bending mode would be significantly reduced with the balance s inclusion. This reduction in structural stiffness was later confirmed experimentally with a hammer-impact test. This effect, coupled with the relatively large damping associated with the rotating balance waterproofing material, limited the device s bandwidth to approximately 50 Hertz Other pre-test validations included sensing the test article rotating assembly built-in imbalance for two configurations and directly measuring the assembly mass and buoyancy while submerged under water. Both tests matched predictions and confirmed the device s sensitivity while stationary and rotating. The rotating balance was then demonstrated in a water test of a full-scale Space Shuttle Main Engine high-pressure liquid oxygen pump inducer. Experimental data was collected a scaled operating conditions at three flow coefficients across a range of cavitation numbers for the single inducer geometry and radial clearance. Two distinct cavitation modes were observed symmetric tip vortex cavitation and alternate-blade cavitation. Although previous experimental tests on the same inducer demonstrated two additional cavitation modes at lower inlet pressures, these conditions proved unreachable with the rotating balance installed due to the intense dynamic environment. The sensed radial load was less influenced by flow coefficient than by cavitation number or cavitation mode although the flow coefficient range was relatively narrow. Transition from symmetric tip vortex to alternate-blade cavitation corresponded to changes in both radial load magnitude and radial load orientation relative to the inducer. Sensed moments indicated that the effective load center moved downstream during this change in cavitation mode. An occurrence of "higher+rdex cavitation" was also detected in both the stationary pressures and the rotating balance data although the frequency of the phenomena was well above the reliable bandwidth of the rotating balance. In summary the experimental tests proved both the concept and device s capability despite the limitations and confirmed that hydrodynamically-induced forces and moments develop in response to the unbalanced pressure field, which is, in turn, a product of the cavitation environment.

Compression Behavior of Fluted-Core Composite Panels

NASA Technical Reports Server (NTRS)

Schultz, Marc R.; Oremont, Leonard; Guzman, J. Carlos; McCarville, Douglas; Rose, Cheryl A.; Hilburger, Mark W.

2011-01-01

In recent years, fiber-reinforced composites have become more accepted for aerospace applications. Specifically, during NASA s recent efforts to develop new launch vehicles, composite materials were considered and baselined for a number of structures. Because of mass and stiffness requirements, sandwich composites are often selected for many applications. However, there are a number of manufacturing and in-service concerns associated with traditional honeycomb-core sandwich composites that in certain instances may be alleviated through the use of other core materials or construction methods. Fluted-core, which consists of integral angled web members with structural radius fillers spaced between laminate face sheets, is one such construction alternative and is considered herein. Two different fluted-core designs were considered: a subscale design and a full-scale design sized for a heavy-lift-launch-vehicle interstage. In particular, axial compression of fluted-core composites was evaluated with experiments and finite-element analyses (FEA); axial compression is the primary loading condition in dry launch-vehicle barrel sections. Detailed finite-element models were developed to represent all components of the fluted-core construction, and geometrically nonlinear analyses were conducted to predict both buckling and material failures. Good agreement was obtained between test data and analyses, for both local buckling and ultimate material failure. Though the local buckling events are not catastrophic, the resulting deformations contribute to material failures. Consequently, an important observation is that the material failure loads and modes would not be captured by either linear analyses or nonlinear smeared-shell analyses. Compression-after-impact (CAI) performance of fluted core composites was also investigated by experimentally testing samples impacted with 6 ft.-lb. impact energies. It was found that such impacts reduced the ultimate load carrying capability by approximately 40% on the subscale test articles and by less than 20% on the full-scale test articles. Nondestructive inspection of the damage zones indicated that the detectable damage was limited to no more than one flute on either side of any given impact. More study is needed, but this may indicate that an inherent damage-arrest capability of fluted core could provide benefits over traditional sandwich designs in certain weight-critical applications.

A research on motion design for APP's loading pages based on time perception

NASA Astrophysics Data System (ADS)

Cao, Huai; Hu, Xiaoyun

2018-04-01

Due to restrictions caused by objective reasons like network bandwidth, hardware performance and etc., waiting is still an inevitable phenomenon that appears in our using mobile-terminal products. Relevant researches show that users' feelings in a waiting scenario can affect their evaluations on the whole product and services the product provides. With the development of user experience and inter-facial design subjects, the role of motion effect in the interface design has attracted more and more scholars' attention. In the current studies, the research theory of motion design in a waiting scenario is imperfect. This article will use the basic theory and experimental research methods of cognitive psychology to explore the motion design's impact on user's time perception when users are waiting for loading APP pages. Firstly, the article analyzes the factors that affect waiting experience of loading APP pages based on the theory of time perception, and then discusses motion design's impact on the level of time-perception when loading pages and its design strategy. Moreover, by the operation analysis of existing loading motion designs, the article classifies the existing loading motions and designs an experiment to verify the impact of different types of motions on the user's time perception. The result shows that the waiting time perception of mobile's terminals' APPs is related to the loading motion types, the combination type of loading motions can effectively shorten the waiting time perception as it scores a higher mean value in the length of time perception.

Analysis and Test Correlation of Proof of Concept Box for Blended Wing Body-Low Speed Vehicle

NASA Technical Reports Server (NTRS)

Spellman, Regina L.

2003-01-01

The Low Speed Vehicle (LSV) is a 14.2% scale remotely piloted vehicle of the revolutionary Blended Wing Body concept. The design of the LSV includes an all composite airframe. Due to internal manufacturing capability restrictions, room temperature layups were necessary. An extensive materials testing and manufacturing process development effort was underwent to establish a process that would achieve the high modulus/low weight properties required to meet the design requirements. The analysis process involved a loads development effort that incorporated aero loads to determine internal forces that could be applied to a traditional FEM of the vehicle and to conduct detailed component analyses. A new tool, Hypersizer, was added to the design process to address various composite failure modes and to optimize the skin panel thickness of the upper and lower skins for the vehicle. The analysis required an iterative approach as material properties were continually changing. As a part of the material characterization effort, test articles, including a proof of concept wing box and a full-scale wing, were fabricated. The proof of concept box was fabricated based on very preliminary material studies and tested in bending, torsion, and shear. The box was then tested to failure under shear. The proof of concept box was also analyzed using Nastran and Hypersizer. The results of both analyses were scaled to determine the predicted failure load. The test results were compared to both the Nastran and Hypersizer analytical predictions. The actual failure occurred at 899 lbs. The failure was predicted at 1167 lbs based on the Nastran analysis. The Hypersizer analysis predicted a lower failure load of 960 lbs. The Nastran analysis alone was not sufficient to predict the failure load because it does not identify local composite failure modes. This analysis has traditionally been done using closed form solutions. Although Hypersizer is typically used as an optimizer for the design process, the failure prediction was used to help gain acceptance and confidence in this new tool. The correlated models and process were to be used to analyze the full BWB-LSV airframe design. The analysis and correlation with test results of the proof of concept box is presented here, including the comparison of the Nastran and Hypersizer results.

Load reduction test method of similarity theory and BP neural networks of large cranes

NASA Astrophysics Data System (ADS)

Yang, Ruigang; Duan, Zhibin; Lu, Yi; Wang, Lei; Xu, Gening

2016-01-01

Static load tests are an important means of supervising and detecting a crane's lift capacity. Due to space restrictions, however, there are difficulties and potential danger when testing large bridge cranes. To solve the loading problems of large-tonnage cranes during testing, an equivalency test is proposed based on the similarity theory and BP neural networks. The maximum stress and displacement of a large bridge crane is tested in small loads, combined with the training neural network of a similar structure crane through stress and displacement data which is collected by a physics simulation progressively loaded to a static load test load within the material scope of work. The maximum stress and displacement of a crane under a static load test load can be predicted through the relationship of stress, displacement, and load. By measuring the stress and displacement of small tonnage weights, the stress and displacement of large loads can be predicted, such as the maximum load capacity, which is 1.25 times the rated capacity. Experimental study shows that the load reduction test method can reflect the lift capacity of large bridge cranes. The load shedding predictive analysis for Sanxia 1200 t bridge crane test data indicates that when the load is 1.25 times the rated lifting capacity, the predicted displacement and actual displacement error is zero. The method solves the problem that lifting capacities are difficult to obtain and testing accidents are easily possible when 1.25 times related weight loads are tested for large tonnage cranes.

NDE evidence for the damage arrestment performance of PRSEUS composite cube during high-pressure load test

NASA Astrophysics Data System (ADS)

Johnston, Patrick H.; Parker, F. Raymond

2014-02-01

As an approach to light-weight, cost-effective and manufacturable structures required to enable the hybrid wing body aircraft, The Boeing Company, Inc. and NASA have developed the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept. A PRSEUS pressure cube was developed as a risk reduction test article to examine a new integral cap joint concept as part of a building block approach for technology development of the PRSEUS concept. The overall specimen strength exceeded the 18.4 psi load requirement as testing resulted in the cube reaching a final pressure load of around 48 psi prior to catastrophic failure. The cube pressure test verified that the joints and structure were capable of sustaining the required loads, and represented the first testing of joined PRSEUS structure. This paper will address the damage arrestment performance of the stitched PRSEUS structure. Following catastrophic failure of the cube, ultrasonic pulse-echo inspection found that the localized damage, surrounding a barely-visible impact damage site, did not change noticeably between just after impact and catastrophic failure of the cube, and did not play a role in the catastrophic failure event. Ultrasonic inspection of the remaining intact cube panels presented three basic types of indications: delaminations between laminae parallel to the face sheets, lying between face sheet and tear strap layers, or between tear strap and flange layers; delaminations above the noodles of stringers, frames or integral caps, lying within face sheet or tear strap layers; and delaminations between the laminae in the inner fillets of the integral caps, where pulloff stresses were expected to be highest. Delaminations of all three types were predominantly contained by the first row of stitches encountered. For the small fraction of delaminations extending beyond the first row of stitches, all were contained by the second stitch row.

NDE Evidence for the Damage Arrestment Performance of PRSEUS Composite Cube During High-Pressure Load Test

NASA Technical Reports Server (NTRS)

Johnston, Patrick H.; Parker, F. Raymond

2013-01-01

As an approach to light-weight, cost-effective and manufacturable structures required to enable the hybrid wing body aircraft, The Boeing Company, Inc. and NASA have developed the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept. A PRSEUS pressure cube was developed as a risk reduction test article to examine a new integral cap joint concept as part of a building block approach for technology development of the PRSEUS concept. The overall specimen strength exceeded the 18.4 psi load requirement as testing resulted in the cube reaching a final pressure load of around 48 psi prior to catastrophic failure. The cube pressure test verified that the joints and structure were capable of sustaining the required loads, and represented the first testing of joined PRSEUS structure. This paper will address the damage arrestment performance of the stitched PRSEUS structure. Following catastrophic failure of the cube, ultrasonic pulse-echo inspection found that the localized damage, surrounding a barely-visible impact damage site, did not change noticeably between just after impact and catastrophic failure of the cube, and did not play a role in the catastrophic failure event. Ultrasonic inspection of the remaining intact cube panels presented three basic types of indications: delaminations between laminae parallel to the face sheets, lying between face sheet and tear strap layers, or between tear strap and flange layers; delaminations above the noodles of stringers, frames or integral caps, lying within face sheet or tear strap layers; and delaminations between the laminae in the inner fillets of the integral caps, where pulloff stresses were expected to be highest. Delaminations of all three types were predominantly contained by the first row of stitches encountered. For the small fraction of delaminations extending beyond the first row of stitches, all were contained by the second stitch row.

Monitoring system of hydraulic lifting device based on the fiber optic sensors

NASA Astrophysics Data System (ADS)

Fajkus, Marcel; Nedoma, Jan; Novak, Martin; Martinek, Radek; Vanus, Jan; Mec, Pavel; Vasinek, Vladimir

2017-10-01

This article deals with the description of the monitoring system of hydraulic lifting device based on the fiber-optic sensors. For minimize the financial costs of the proposed monitoring system, the power evaluation of measured signal has been chosen. The solution is based on an evaluation of the signal obtained using the single point optic fiber sensors with overlapping reflective spectra. For encapsulation of the sensors was used polydimethylsiloxane (PDMS) polymer. To obtain a information of loading is uses the action of deformation of the lifting device on the pair single point optic fiber sensors mounted on the lifting device of the tested car. According to the proposed algorithm is determined information of pressure with an accuracy of +/- 5 %. Verification of the proposed system was realized on the various types of the tested car with different loading. The original contribution of the paper is to verify the new low-cost system for monitoring the hydraulic lifting device based on the fiber-optic sensors.

Liquid Oxygen Propellant Densification Production and Performance Test Results With a Large-Scale Flight-Weight Propellant Tank for the X33 RLV

NASA Technical Reports Server (NTRS)

Tomsik, Thomas M.; Meyer, Michael L.

2010-01-01

This paper describes in-detail a test program that was initiated at the Glenn Research Center (GRC) involving the cryogenic densification of liquid oxygen (LO2). A large scale LO2 propellant densification system rated for 200 gpm and sized for the X-33 LO2 propellant tank, was designed, fabricated and tested at the GRC. Multiple objectives of the test program included validation of LO2 production unit hardware and characterization of densifier performance at design and transient conditions. First, performance data is presented for an initial series of LO2 densifier screening and check-out tests using densified liquid nitrogen. The second series of tests show performance data collected during LO2 densifier test operations with liquid oxygen as the densified product fluid. An overview of LO2 X-33 tanking operations and load tests with the 20,000 gallon Structural Test Article (STA) are described. Tank loading testing and the thermal stratification that occurs inside of a flight-weight launch vehicle propellant tank were investigated. These operations involved a closed-loop recirculation process of LO2 flow through the densifier and then back into the STA. Finally, in excess of 200,000 gallons of densified LO2 at 120 oR was produced with the propellant densification unit during the demonstration program, an achievement that s never been done before in the realm of large-scale cryogenic tests.

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.

Recent Enhancements to the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility

NASA Technical Reports Server (NTRS)

Rizzi, Stephen A.; Cabell, Randolph H.; Allen, Albert R.

2013-01-01

The Structural Acoustics Loads and Transmission (SALT) facility at the NASA Langley Research Center is comprised of an anechoic room and a reverberant room, and may act as a transmission loss suite when test articles are mounted in a window connecting the two rooms. In the latter configuration, the reverberant room acts as the noise source side and the anechoic room as the receiver side. The noise generation system used for qualification testing in the reverberant room was previously shown to achieve a maximum overall sound pressure level of 141 dB. This is considered to be marginally adequate for generating sound pressure levels typically required for launch vehicle payload qualification testing. Recent enhancements to the noise generation system increased the maximum overall sound pressure level to 154 dB, through the use of two airstream modulators coupled to 35 Hz and 160 Hz horns. This paper documents the acoustic performance of the enhanced noise generation system for a variety of relevant test spectra. Additionally, it demonstrates the capability of the SALT facility to conduct transmission loss and absorption testing in accordance with ASTM and ISO standards, respectively. A few examples of test capabilities are shown and include transmission loss testing of simple unstiffened and built up structures and measurement of the diffuse field absorption coefficient of a fibrous acoustic blanket.

Preventing information overload: cognitive load theory as an instructional framework for teaching pharmacology.

PubMed

Kaylor, Sara K

2014-02-01

Nursing students are challenged by content-laden curricula and learning environments that emphasize testing outcomes. Likewise, educators are challenged to support student-centered learning in a manner that encourages students to connect and act upon their personal motivations. This article describes the use of cognitive load theory (CLT) as an instructional design framework for an undergraduate pharmacology for nursing course. Guided by the principles of CLT, four instructional strategies were used in this course: (a) opening review activities, (b) providing students with lecture notes, (c) a "Top Five" prototype approach, and (d) deciphering "Need to Knows" from "Nice to Knows." Instructional style and strategies received positive student feedback and were found to promote a student-centered environment and active learning. On the basis of this feedback, cognitive load theory may be a successful and effective framework for undergraduate pharmacology and other nursing courses, thus assisting students and educators alike in overcoming obstacles imposed on learning environments. Copyright 2014, SLACK Incorporated.

Effect of filler loading and silane modification on the biodegradability of SBR composites reinforced with peanut shell powder

NASA Astrophysics Data System (ADS)

Shaniba, V.; Balan, Aparna K.; Sreejith, M. P.; Jinitha, T. V.; Subair, N.; Purushothaman, E.

2017-06-01

The development of biocomposites and their applications are important in material science due to environmental and sustainability issues. The extent of degradation depends on the nature of reinforcing filler, particle size and their modification. In this article, we tried to focus on the biodegradation of composites of Styrene Butadiene Rubber (SBR) reinforced with Peanut Shell Powder (PSP) by soil burial test. The composites of SBR with untreated PSP (UPSP) and silane modified PSP (SPSP) of 10 parts per hundred rubber (phr) and 20 phr filler loading in two particle size were buried in the garden soil for six months. The microbial degradation were assessed through the measurement of weight loss, tensile strength and hardness at definite period. The study shows that degradation increases with increase in filler loading and particle size. The chemical treatment of filler has been found to resist the degradation. The analysis of morphological properties by the SEM also confirmed biodegradation process by the microorganism in the soil.

Potential of a precrash lateral occupant movement in side collisions of (electric) minicars.

PubMed

Hierlinger, T; Lienkamp, M; Unger, J; Unselt, T

2015-01-01

In minicars, the survival space between the side structure and occupant is smaller than in conventional cars. This is an issue in side collisions. Therefore, in this article a solution is studied in which a lateral seat movement is imposed in the precrash phase. It generates a pre-acceleration and an initial velocity of the occupant, thus reducing the loads due to the side impact. The assessment of the potential is done by numerical simulations and a full-vehicle crash test. The optimal parameters of the restraint system including the precrash movement, time-to-fire of head and side airbag, etc., are found using metamodel-based optimization methods by minimizing occupant loads according to European New Car Assessment Programme (Euro NCAP). The metamodel-based optimization approach is able to tune the restraint system parameters. The numerical simulations show a significant averaged reduction of 22.3% in occupant loads. The results show that the lateral precrash occupant movement offers better occupant protection in side collisions.

Cost optimization of reinforced concrete cantilever retaining walls under seismic loading using a biogeography-based optimization algorithm with Levy flights

NASA Astrophysics Data System (ADS)

Aydogdu, Ibrahim

2017-03-01

In this article, a new version of a biogeography-based optimization algorithm with Levy flight distribution (LFBBO) is introduced and used for the optimum design of reinforced concrete cantilever retaining walls under seismic loading. The cost of the wall is taken as an objective function, which is minimized under the constraints implemented by the American Concrete Institute (ACI 318-05) design code and geometric limitations. The influence of peak ground acceleration (PGA) on optimal cost is also investigated. The solution of the problem is attained by the LFBBO algorithm, which is developed by adding Levy flight distribution to the mutation part of the biogeography-based optimization (BBO) algorithm. Five design examples, of which two are used in literature studies, are optimized in the study. The results are compared to test the performance of the LFBBO and BBO algorithms, to determine the influence of the seismic load and PGA on the optimal cost of the wall.

Beam-energy-spread minimization using cell-timing optimization

NASA Astrophysics Data System (ADS)

Rose, C. R.; Ekdahl, C.; Schulze, M.

2012-04-01

Beam energy spread, and related beam motion, increase the difficulty in tuning for multipulse radiographic experiments at the dual-axis radiographic hydrodynamic test facility’s axis-II linear induction accelerator (LIA). In this article, we describe an optimization method to reduce the energy spread by adjusting the timing of the cell voltages (both unloaded and loaded), either advancing or retarding, such that the injector voltage and summed cell voltages in the LIA result in a flatter energy profile. We developed a nonlinear optimization routine which accepts as inputs the 74 cell-voltage, injector voltage, and beam current waveforms. It optimizes cell timing per user-selected groups of cells and outputs timing adjustments, one for each of the selected groups. To verify the theory, we acquired and present data for both unloaded and loaded cell-timing optimizations. For the unloaded cells, the preoptimization baseline energy spread was reduced by 34% and 31% for two shots as compared to baseline. For the loaded-cell case, the measured energy spread was reduced by 49% compared to baseline.

Biomechanics and Mechanobiology of Trabecular Bone: A Review

PubMed Central

Oftadeh, Ramin; Perez-Viloria, Miguel; Villa-Camacho, Juan C.; Vaziri, Ashkan; Nazarian, Ara

2015-01-01

Trabecular bone is a highly porous, heterogeneous, and anisotropic material which can be found at the epiphyses of long bones and in the vertebral bodies. Studying the mechanical properties of trabecular bone is important, since trabecular bone is the main load bearing bone in vertebral bodies and also transfers the load from joints to the compact bone of the cortex of long bones. This review article highlights the high dependency of the mechanical properties of trabecular bone on species, age, anatomic site, loading direction, and size of the sample under consideration. In recent years, high resolution micro finite element methods have been extensively used to specifically address the mechanical properties of the trabecular bone and provide unique tools to interpret and model the mechanical testing experiments. The aims of the current work are to first review the mechanobiology of trabecular bone and then present classical and new approaches for modeling and analyzing the trabecular bone microstructure and macrostructure and corresponding mechanical properties such as elastic properties and strength. PMID:25412137

Trace Contaminant Testing with the Orion Atmosphere Revitalization Technology

NASA Technical Reports Server (NTRS)

Button, Amy B.; Sweterlitsch, Jeffrey J.; Broerman, Craig D.; Campbell, Melissa L.

2010-01-01

Every spacecraft atmosphere contains trace contaminants resulting from offgassing by cabin materials and human passengers. An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). Part of the risk mitigation effort for this new technology is the study of how atmospheric trace contaminants will affect and be affected by the technology. One particular area of concern is ammonia, which, in addition to the normal spacecraft sources, can also be offgassed by the amine-based sorbent. In the spring of 2009, tests were performed at Johnson Space Center (JSC) with typical cabin atmosphere levels of five of the most common trace gases, most of which had not yet been tested with this technology. A subscale sample of the sorbent was exposed to each of the chemicals mixed into a stream of moist, CO2-laden air, and the CO2 adsorption capacity of the sorbent was compared before and after the exposure. After these typical-concentration chemicals were proven to have negligible effect on the subscale sample, tests proceeded on a full-scale test article in a sealed chamber with a suite of eleven contaminants. To isolate the effects of various test rig components, several extended-duration tests were run: without injection or scrubbing, with injection and without scrubbing, with injection of both contaminants and metabolic CO2 and water vapor loads and scrubbing by both the test article and dedicated trace contaminant filters, and with the same injections and scrubbing by only the test article. The high-level results of both the subscale and full-scale tests are examined in this paper.

The study of fix composite panel and steel plates on testing stand

NASA Astrophysics Data System (ADS)

Wróbel, A.; Płaczek, M.; Wachna, M.

2016-08-01

In this paper the practical possibilities of strength verification analysis of composite materials used in the manufacture of selected components of railway wagons are presented. Real laboratory stand for measurements in a scale controlled by PLC controller were made. The study of different types of connections of composite materials with sheet metal is presented. In one of the chapter of this paper principles construction of testing stand with pneumatic cylinder were presented. Mainly checking of displacements and stresses generated on the sheet as a result of pneumatic actuators load for composite boards was carried out. The use of the controller with operating panel allows to easy programming testing cycle. The user can define the force generated by the actuator by change of air pressure in cylinder. Additionally the location of acting cylinders and their jump can be changed by operator. The examination of the volume displacements was done by displacement sensor, and the tensile strain gauge. All parameters are written in CatmanEasy - data acquisition software. This article presents the study of stresses and displacements in the composite plates joined with sheet metal, in summary of this article, the authors compare the obtained results with the computer simulation results in the article: "Simulation of stresses in an innovative combination of composite with sheet".

Effects of the Physical Environment on Cognitive Load and Learning: Towards a New Model of Cognitive Load

ERIC Educational Resources Information Center

Choi, Hwan-Hee; van Merriënboer, Jeroen J. G.; Paas, Fred

2014-01-01

Although the theoretical framework of cognitive load theory has acknowledged a role for the learning environment, the specific characteristics of the physical learning environment that could affect cognitive load have never been considered, neither theoretically nor empirically. In this article, we argue that the physical learning environment, and…

Development of composite carrythrough bulkhead

NASA Technical Reports Server (NTRS)

Ehlen, R. J.; Libeskind, M.

1992-01-01

A structural development program was recently completed in which the weight and fatigue advantages of an all composite major load carrying bulkhead was successfully demonstrated. Fabrication of a full scale article, including static and fatigue testing of the carry-through beam portion verified the producibility, strength and durability of this design, thereby presenting the opportunity for use on aircraft upgrades and new aircraft. A 15% weight saving is achievable and, more importantly, the fatigue problems that normally plague metal bulkheads are virtually eliminated.

Spectrum Savings from High Performance Recording and Playback Onboard the Test Article

DTIC Science & Technology

2013-02-20

execute within a Windows 7 environment, and data is recorded on SSDs. The underlying database is implemented using MySQL . Figure 1 illustrates the... MySQL database. This is effectively the time at which the recorded data are available for retransmission. CPU and Memory utilization were collected...17.7% MySQL avg. 3.9% EQDR Total avg. 21.6% Table 1 CPU Utilization with260 Mbits/sec Load The difference between the total System CPU (27.8

Skin mechanical properties and modeling: A review.

PubMed

Joodaki, Hamed; Panzer, Matthew B

2018-04-01

The mechanical properties of the skin are important for various applications. Numerous tests have been conducted to characterize the mechanical behavior of this tissue, and this article presents a review on different experimental methods used. A discussion on the general mechanical behavior of the skin, including nonlinearity, viscoelasticity, anisotropy, loading history dependency, failure properties, and aging effects, is presented. Finally, commonly used constitutive models for simulating the mechanical response of skin are discussed in the context of representing the empirically observed behavior.

Lightweight design and analysis of automobile wheel based on bending and radial loads

NASA Astrophysics Data System (ADS)

Jiang, X.; Lyu, R.; Fukushima, Y.; Otake, M.; Ju, D. Y.

2018-06-01

Lightweighting of automobile vehicle is a significant application trends, using magnesium alloy wheels is a valuable way. This article discusses design of a new model of automobile wheel. Then bending test and radial test finite element model were established. Considering three different materials namely magnesium alloy, aluminium alloy and steel, the stress and strain performances of each material can be obtained. Through evaluating and analyzing model in bending test and radial test, we obtained the reasonable and superior results for magnesium alloy wheel. The results of the equivalent stress and deformation were compared, the magnesium alloy wheel practicality has been confirmed. This research predicts the reliability of the structural design, some valuable references are provided for the design and development of magnesium alloy wheel.

Underway Recovery Test 6 (URT-6) - Day 2 Activites

NASA Image and Video Library

2018-01-18

Off the rear of the USS Anchorage, the Orion test article is pulled in by a winch line at the rear of the USS Anchorage’s well deck that brings the capsule into the ship, along with four manned LLAMAs (Line Load Attenuation Mechanism Assembly) that control the capsule’s side-to-side movement and a tending line attached to a rigid hull inflatable boat for controlling Orion’s movement behind the ship. The Underway Recovery Test 6 (URT-6) is spearheaded by Kennedy Space Center's NASA Recovery Team. In partnership with the U.S. Navy, the testing will provide important data that is being used to improve recovery procedures and hardware ahead of Orion's next flight, Exploration Mission-1, when it splashes down in the Pacific Ocean.

Outage management and health physics issue, 2009

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

Agnihotri, Newal

2009-05-15

The focus of the May-June issue is on outage management and health physics. Major articles include the following: Planning and scheduling to minimize refueling outage, by Pat McKenna, AmerenUE; Prioritizing safety, quality and schedule, by Tom Sharkey, Dominion; Benchmarking to high standards, by Margie Jepson, Energy Nuclear; Benchmarking against U.S. standards, by Magnox North, United Kingdom; Enabling suppliers for new build activity, by Marcus Harrington, GE Hitachi Nuclear Energy; Identifying, cultivating and qualifying suppliers, by Thomas E. Silva, AREVA NP; Creating new U.S. jobs, by Francois Martineau, Areva NP. Industry innovation articles include: MSL Acoustic source load reduction, by Amirmore » Shahkarami, Exelon Nuclear; Dual Methodology NDE of CRDM nozzles, by Michael Stark, Dominion Nuclear; and Electronic circuit board testing, by James Amundsen, FirstEnergy Nuclear Operating Company. The plant profile article is titled The future is now, by Julia Milstead, Progress Energy Service Company, LLC.« less

Concepts of skin protection: considerations for the evaluation and terminology of the performance of skin protective equipment.

PubMed

Brouwer, Derk H; Aitken, Robert J; Oppl, Reinhard; Cherrie, John W

2005-09-01

This article proposes a common language for better understanding processes involved in dermal exposure and skin protection. A conceptual model has been developed that systematically describes the transport of agent mass from sources, eventually resulting in "loading" of the skin surface or the skin contaminant layer. In view of a harmonized glossary of exposure terminology this is considered the exposure surface. Loading is defined as agent mass present in this layer divided by the exposure surface area. Skin protective equipment (SPE) is meant to reduce uptake, that is, an agent crosses the absorption barrier of the skin, by intervening in the processes of loading the exposure surface; however, the design of the equipment may fail to cover skin surface entirely. In addition, part of the mass intercepted by the SPE may reach the skin surface either by permeation, penetration, or by transfer when touching the contaminated exterior of the SPE. Evaluation of SPE performance has earlier focused on chemical resistance performance testing for permeation, penetration, or degradation of SPE-materials. In use-scenario practice, however, all processes will occur concurrently. Thus, SPE field performance evaluation including user-SPE interaction complementary to material testing is warranted. Results of laboratory testing for SPE-materials are reported as substance-specific breakthrough times and permeation rates. SPE field performance should be evaluated for reduction of either uptake or parameters that reflect the outcome of dermal exposure. Ideally, this should be based on the results of intervention-type workplace studies, for (e.g., assessment of exposure loading). The level of reduction can be expressed as a protection factor (ratio without/with SPE) for different parameters of dermal exposure or uptake. It is concluded that for evaluation of SPE-type performance, generic protection factors can be derived for substance-independent processes (e.g., reduction of exposure loading) but not for substance-specific reduction of uptake.

Satisfaction with and benefits of a psych-social club: development of a mixed method evaluation instrument.

PubMed

Labun, Evelyn; Yurkovich, Eleanor; Ide, Bette A

2012-12-01

There are no instruments for validation or evaluation of a member's satisfaction of and benefits with psych-social clubs. This article reports on the development and testing of the mixed-method instrument entitled Benefits and Satisfaction Tool for Members of a Psych-social Club (B&ST-MPC), which evolved from findings of a qualitative research study. The alpha reliability coefficient was .92. The Kaiser-Meyer-Olkin Test yielded a value of .812. The items loaded on 3 factors. Utilization of B&ST-MPC supports development of services for rural communities through feedback from consumers. Further testing of the B&ST-MPC in settings with diverse populations is recommended. Copyright © 2012 Elsevier Inc. All rights reserved.

40 CFR 53.65 - Test procedure: Loading test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Test procedure: Loading test. 53.65... Characteristics of Class II Equivalent Methods for PM 2.5 § 53.65 Test procedure: Loading test. (a) Overview. (1) The loading tests are designed to quantify any appreciable changes in a candidate method sampler's...

40 CFR 53.65 - Test procedure: Loading test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Test procedure: Loading test. 53.65... Characteristics of Class II Equivalent Methods for PM2.5 § 53.65 Test procedure: Loading test. (a) Overview. (1) The loading tests are designed to quantify any appreciable changes in a candidate method sampler's...

40 CFR 53.65 - Test procedure: Loading test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Test procedure: Loading test. 53.65... Characteristics of Class II Equivalent Methods for PM2.5 § 53.65 Test procedure: Loading test. (a) Overview. (1) The loading tests are designed to quantify any appreciable changes in a candidate method sampler's...

40 CFR 53.65 - Test procedure: Loading test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Test procedure: Loading test. 53.65... Characteristics of Class II Equivalent Methods for PM2.5 § 53.65 Test procedure: Loading test. (a) Overview. (1) The loading tests are designed to quantify any appreciable changes in a candidate method sampler's...

Comparisons Between Pretest Prediction and Flight Test Data of Aerodynamic Loading for EFT-1

NASA Technical Reports Server (NTRS)

Schwing, Alan M.

2016-01-01

Exploration Flight Test One (EFT-1) was an incredible milestone in the development NASA's Orion spacecraft. It incorporated hundreds of articles of flight test instrumentation and returned with a wealth of data. Aerodynamic surface pressures were collected during launch vehicle ascent and capsule reentry and descent. These discrete surface pressure measurements enable comparisons to computational results and ground test data. This paper details the comparisons between pre-test predictions and flight test data for the Orion MPCV Crew Module (CM) and Launch Abort Tower (LAT) during all phases of flight. Regions with strong comparisons, poor predictions, and lessons learned are discussed. 38 pressure measurements were made on the LAT during ascent. Nine of the gauges were Honeywell PPTs and the remainder were Kulite pressure transducers. In order to address bias in the Kulites, a two-point linear calibration was used and the details are discussed. Results from the flight are compared to existing database products. 44 pressure measurements were made on the CM during reentry and descent. Nine of the gauges were Honeywell PPTs and the remainder were Kulite pressure transducers. In order to address bias in the Kulites, a tare was made against the vacuum measurements as described below. Once the bias was removed from the gauges, comparisons between predicted loading and the measured results are compared.

Reponse dynamique des structures sous charges de vent

NASA Astrophysics Data System (ADS)

Gani, Ferawati

The main purpose of this research is to assemble numerical tools that allows realistic dynamic study of structures under wind loading. The availability of such numerical tools is becoming more important for the industry, following previous experiences in structural damages after extreme wind events. The methodology of the present study involves two main steps: (i) preparing the wind loading according to its spatial and temporal correlations by using digitally generated wind or real measured wind; (ii) preparing the numerical model that captures the characteristics of the real structures and respects all the necessary numerical requirements to pursue transient dynamic analyses. The thesis is presented as an ensemble of four articles written for refereed journals and conferences that showcase the contributions of the present study to the advancement of transient dynamic study of structures under wind loading, on the wind model itself (the first article) and on the application of the wind study on complex structures (the next three articles). The articles presented are as follows: (a) the evaluation of three-dimensional correlations of wind, an important issue for more precise prediction of wind loading for flexible and line-like structures, the results presented in this first article helps design engineers to choose a more suitable models to define three-dimensional wind loading; (b) the refinement of design for solar photovoltaic concentrator-tracker structure developed for utility scale, this study addressed concerns related strict operational criteria and fatigue under wind load for a large parabolic truss structure; (c) the study of guyed towers for TLs, the applicability of the static-equivalent method from the current industry documents for the design of this type of flexible TL support was questioned, a simplified method to improve the wind design was proposed; (d) the fundamental issue of nonlinear behaviour under extreme wind loading for single-degree-of-freedom systems is evaluated here, the use of real measured hurricane and winter storm have highlighted the possible interest of taking into account the ductility in the extreme wind loading design. The present research project has shown the versatility of the use of the developed wind study methodology to solve concerns related to different type of complex structures. In addition, this study proposes simplified methods that are useful for practical engineers when there is the need to solve similar problems. Key words: nonlinear, dynamic, wind, guyed tower, parabolic structure, ductility.

Prevalence of Trichomonas vaginalis infection and protozoan load in South African women: a cross-sectional study.

PubMed

de Waaij, Dewi J; Dubbink, Jan Henk; Ouburg, Sander; Peters, Remco P H; Morré, Servaas A

2017-10-08

Trichomonas vaginalis is thought to be the most common non-viral sexually transmitted infection worldwide. We investigated the prevalence, risk factors and protozoan load of T. vaginalis infection in South African women. A cross-sectional study of 604 women was conducted at 25 primary healthcare facilities in rural South Africa (Mopani district). T. vaginalis DNA was detected in vaginal and rectal swabs. In univariate and multivariate analyses, the T. vaginalis infection was investigated in relation to demographic characteristics, medical history and behavioural factors. The T. vaginalis load was determined as the logarithm of DNA copies per microlitre sample solution. Collected vaginal and rectal swabs were tested for T. vaginalis DNA. Prevalence of vaginal T. vaginalis was 20% (95% CI 17.0% to 23.4%) and rectal 1.2% (95% CI 0.6% to 2.4%). Most women (66%) with a vaginal infection were asymptomatic. Factors associated with T. vaginalis infection were a relationship status of single (OR 2.4; 95% CI 1.5 to 4.0; p<0.001) and HIV positive infection (OR 1.6; 95% CI 1.0 to 2.6; p=0.041). Women with vaginal T. vaginalis infection were more likely to have concurrent Chlamydia trachomatis rectal infection than those without vaginal infection (12%vs3%; p<0.001; OR 4.1). A higher median T. vaginalis load was observed among women with observed vaginal discharge compared with those without vaginal discharge (p=0.025). Vaginal trichomoniasis is highly prevalent in rural South Africa, especially among single women and those with HIV infection, and often presents without symptoms. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Strength evaluation of prosthetic check sockets, copolymer sockets, and definitive laminated sockets.

PubMed

Gerschutz, Maria J; Haynes, Michael L; Nixon, Derek; Colvin, James M

2012-01-01

A prosthesis encounters loading through forces and torques exerted by the person with amputation. International Organization for Standardization (ISO) standard 10328 was designed to test most lower-limb prosthetic components. However, this standard does not include prosthetic sockets. We measured static failure loads of prosthetic sockets using a modified ISO 10328 and then compared them with the criteria set by this standard for other components. Check socket (CS) strengths were influenced by thickness, material choice, and fabrication method. Copolymer socket (CP) strengths depended on thickness and fabrication methods. A majority of the CSs and all of the CPs failed to pass the ISO 10328 ductile loading criterion. In contrast, the strengths of definitive laminated sockets (DLs) were influenced more by construction material and technique. A majority of the DLs failed to pass the ISO 10328 brittle loading criterion. Analyzing prosthetic sockets from a variety of facilities demonstrated that socket performance varies considerably between and within facilities. The results from this article provide a foundation for understanding the quality of prosthetic sockets, some insight into possible routes for improving the current care delivered to patients, and a comparative basis for future technology.

Improving the Quality of Online Discussion: The Effects of Strategies Designed Based on Cognitive Load Theory Principles

ERIC Educational Resources Information Center

Darabi, Aubteen; Jin, Li

2013-01-01

This article focuses on heavy cognitive load as the reason for the lack of quality associated with conventional online discussion. Using the principles of cognitive load theory, four online discussion strategies were designed specifically aiming at reducing the discussants' cognitive load and thus enhancing the quality of their online discussion.…

Structural Analysis and Test Comparison of a 20-Meter Inflation-Deployed Solar Sail

NASA Technical Reports Server (NTRS)

Sleight, David W.; Mann, Troy; Lichodziejewski, David; Derbes, Billy

2006-01-01

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive test program was implemented to advance the technology readiness level of the solar sail design. These tests consisted of solar sail component, subsystem, and sub-scale system ground tests that simulated the aspects of the space environment such as vacuum and thermal conditions. In July 2005, a 20-m four-quadrant solar sail system test article was tested in the NASA Glenn Research Center s Space Power Facility to measure its static and dynamic structural responses. Key to the maturation of solar sail technology is the development of validated finite element analysis (FEA) models that can be used for design and analysis of solar sails. A major objective of the program was to utilize the test data to validate the FEA models simulating the solar sail ground tests. The FEA software, ABAQUS, was used to perform the structural analyses to simulate the ground tests performed on the 20-m solar sail test article. This paper presents the details of the FEA modeling, the structural analyses simulating the ground tests, and a comparison of the pretest and post-test analysis predictions with the ground test results for the 20-m solar sail system test article. The structural responses that are compared in the paper include load-deflection curves and natural frequencies for the beam structural assembly and static shape, natural frequencies, and mode shapes for the solar sail membrane. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were unmeasured initial conditions in the test set-up.

Knotless anchors with sutures external to the anchor body may be at risk for suture cutting through osteopenic bone

PubMed Central

Ono, Y.; Woodmass, J. M.; Nelson, A. A.; Boorman, R. S.; Thornton, G. M.

2016-01-01

Objectives This study evaluated the mechanical performance, under low-load cyclic loading, of two different knotless suture anchor designs: sutures completely internal to the anchor body (SpeedScrew) and sutures external to the anchor body and adjacent to bone (MultiFIX P). Methods Using standard suture loops pulled in-line with the rotator cuff (approximately 60°), anchors were tested in cadaveric bone and foam blocks representing normal to osteopenic bone. Mechanical testing included preloading to 10 N and cyclic loading for 500 cycles from 10 N to 60 N at 60 mm/min. The parameters evaluated were initial displacement, cyclic displacement and number of cycles and load at 3 mm displacement relative to preload. Video recording throughout testing documented the predominant source of suture displacement and the distance of ‘suture cutting through bone’. Results In cadaveric bone and foam blocks, MultiFIX P anchors had significantly greater initial displacement, and lower number of cycles and lower load at 3 mm displacement than SpeedScrew anchors. Video analysis revealed ‘suture cutting through bone’ as the predominant source of suture displacement in cadaveric bone (qualitative) and greater ‘suture cutting through bone’ comparing MultiFIX P with SpeedScrew anchors in foam blocks (quantitative). The greater suture displacement in MultiFIX P anchors was predominantly from suture cutting through bone, which was enhanced in an osteopenic bone model. Conclusions Anchors with sutures external to the anchor body are at risk for suture cutting through bone since the suture eyelet is at the distal tip of the implant and the suture directly abrades against the bone edge during cyclic loading. Suture cutting through bone may be a significant source of fixation failure, particularly in osteopenic bone. Cite this article: Y. Ono, J. M. Woodmass, A. A. Nelson, R. S. Boorman, G. M. Thornton, I. K. Y. Lo. Knotless anchors with sutures external to the anchor body may be at risk for suture cutting through osteopenic bone. Bone Joint Res 2016;5:269–275. DOI: 10.1302/2046-3758.56.2000535. PMID:27357383

Fracture toughness of titanium-cement interfaces: effects of fibers and loading angles.

PubMed

Khandaker, Morshed; Utsaha, Khatri Chhetri; Morris, Tracy

2014-01-01

Ideal implant-cement or implant-bone interfaces are required for implant fixation and the filling of tissue defects created by disease. Micron- to nanosize osseointegrated features, such as surface roughness, fibers, porosity, and particles, have been fused with implants for improving the osseointegration of an implant with the host tissue in orthopedics and dentistry. The effects of fibers and loading angles on the interface fracture toughness of implant-cement specimens with and without fibers at the interface are not yet known. Such studies are important for the design of a long-lasting implant for orthopedic applications. The goal of this study was to improve the fracture toughness of an implant-cement interface by deposition of micron- to nanosize fibers on an implant surface. There were two objectives in the study: 1) to evaluate the influence of fibers on the fracture toughness of implant-cement interfaces with and without fibers at the interfaces, and 2) to evaluate the influence of loading angles on implant-cement interfaces with and without fibers at the interfaces. This study used titanium as the implant, poly(methyl methacrylate) (PMMA) as cement, and polycaprolactone (PCL) as fiber materials. An electrospinning unit was fabricated for the deposition of PCL unidirectional fibers on titanium (Ti) plates. The Evex tensile test stage was used to determine the interface fracture toughness (KC) of Ti-PMMA with and without PCL fibers at 0°, 45°, and 90° loading angles, referred to in this article as tension, mixed, and shear tests. The study did not find any significant interaction between fiber and loading angles (P>0.05), although there was a significant difference in the KC means of Ti-PMMA samples for the loading angles (P<0.05). The study also found a significant difference in the KC means of Ti-PMMA samples with and without fibers (P<0.05). The results showed that the addition of the micron- to nanosize PCL fibers on Ti improved the quality of the Ti-PMMA union. The results of the study are essential for fatigue testing and finite-element analysis of implant-cement interfaces to evaluate the performance of orthopedic and orthodontic implants.

Fracture toughness of titanium–cement interfaces: effects of fibers and loading angles

PubMed Central

Khandaker, Morshed; Utsaha, Khatri Chhetri; Morris, Tracy

2014-01-01

Ideal implant–cement or implant–bone interfaces are required for implant fixation and the filling of tissue defects created by disease. Micron- to nanosize osseointegrated features, such as surface roughness, fibers, porosity, and particles, have been fused with implants for improving the osseointegration of an implant with the host tissue in orthopedics and dentistry. The effects of fibers and loading angles on the interface fracture toughness of implant–cement specimens with and without fibers at the interface are not yet known. Such studies are important for the design of a long-lasting implant for orthopedic applications. The goal of this study was to improve the fracture toughness of an implant–cement interface by deposition of micron- to nanosize fibers on an implant surface. There were two objectives in the study: 1) to evaluate the influence of fibers on the fracture toughness of implant–cement interfaces with and without fibers at the interfaces, and 2) to evaluate the influence of loading angles on implant–cement interfaces with and without fibers at the interfaces. This study used titanium as the implant, poly(methyl methacrylate) (PMMA) as cement, and polycaprolactone (PCL) as fiber materials. An electrospinning unit was fabricated for the deposition of PCL unidirectional fibers on titanium (Ti) plates. The Evex tensile test stage was used to determine the interface fracture toughness (KC) of Ti–PMMA with and without PCL fibers at 0°, 45°, and 90° loading angles, referred to in this article as tension, mixed, and shear tests. The study did not find any significant interaction between fiber and loading angles (P>0.05), although there was a significant difference in the KC means of Ti–PMMA samples for the loading angles (P<0.05). The study also found a significant difference in the KC means of Ti–PMMA samples with and without fibers (P<0.05). The results showed that the addition of the micron- to nanosize PCL fibers on Ti improved the quality of the Ti–PMMA union. The results of the study are essential for fatigue testing and finite-element analysis of implant–cement interfaces to evaluate the performance of orthopedic and orthodontic implants. PMID:24729704

Knotless anchors with sutures external to the anchor body may be at risk for suture cutting through osteopenic bone.

PubMed

Ono, Y; Woodmass, J M; Nelson, A A; Boorman, R S; Thornton, G M; Lo, I K Y

2016-06-01

This study evaluated the mechanical performance, under low-load cyclic loading, of two different knotless suture anchor designs: sutures completely internal to the anchor body (SpeedScrew) and sutures external to the anchor body and adjacent to bone (MultiFIX P). Using standard suture loops pulled in-line with the rotator cuff (approximately 60°), anchors were tested in cadaveric bone and foam blocks representing normal to osteopenic bone. Mechanical testing included preloading to 10 N and cyclic loading for 500 cycles from 10 N to 60 N at 60 mm/min. The parameters evaluated were initial displacement, cyclic displacement and number of cycles and load at 3 mm displacement relative to preload. Video recording throughout testing documented the predominant source of suture displacement and the distance of 'suture cutting through bone'. In cadaveric bone and foam blocks, MultiFIX P anchors had significantly greater initial displacement, and lower number of cycles and lower load at 3 mm displacement than SpeedScrew anchors. Video analysis revealed 'suture cutting through bone' as the predominant source of suture displacement in cadaveric bone (qualitative) and greater 'suture cutting through bone' comparing MultiFIX P with SpeedScrew anchors in foam blocks (quantitative). The greater suture displacement in MultiFIX P anchors was predominantly from suture cutting through bone, which was enhanced in an osteopenic bone model. Anchors with sutures external to the anchor body are at risk for suture cutting through bone since the suture eyelet is at the distal tip of the implant and the suture directly abrades against the bone edge during cyclic loading. Suture cutting through bone may be a significant source of fixation failure, particularly in osteopenic bone.Cite this article: Y. Ono, J. M. Woodmass, A. A. Nelson, R. S. Boorman, G. M. Thornton, I. K. Y. Lo. Knotless anchors with sutures external to the anchor body may be at risk for suture cutting through osteopenic bone. Bone Joint Res 2016;5:269-275. DOI: 10.1302/2046-3758.56.2000535. © 2016 Lo et al.

The Behavior of a Stitched Composite Large-Scale Multi-Bay Pressure Box

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Rouse, Marshall; Przekop, Adam; Lovejoy, Andrew E.

2016-01-01

NASA has created the Environmentally Responsible Aviation (ERA) Project to develop technologies to reduce impact of aviation on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe to enable the introduction of unconventional aircraft configurations. NASA and The Boeing Company have worked together to develop a structural concept that is lightweight and an advancement beyond state-of-the-art composite structures. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is an integrally stiffened panel design where elements are stitched together and designed to maintain residual load-carrying capabilities under a variety of damage scenarios. With the PRSEUS concept, through-the-thickness stitches are applied through dry fabric prior to resin infusion, and replace fasteners throughout each integral panel. Through-the-thickness reinforcement at discontinuities, such as along flange edges, has been shown to suppress delamination and turn cracks, which expands the design space and leads to lighter designs. The pultruded rod provides stiffening away from the more vulnerable skin surface and improves bending stiffness. A series of building block tests were evaluated to explore the fundamental assumptions related to the capability and advantages of PRSEUS panels. The final step in the building block series of tests is an 80%-scale pressure box representing a portion of the center section of a Hybrid Wing Body (HWB) transport aircraft. The testing of this test article under maneuver and internal pressure loading conditions is the subject of this paper. The experimental evaluation of this article, along with the other building block tests and the accompanying analyses, has demonstrated the viability of a PRSEUS center body for the HWB vehicle. Additionally, much of the development effort is also applicable to traditional tube-and-wing aircraft, advanced aircraft configurations, and other structures where weight and through-the-thickness strength are design considerations.

PRSEUS Pressure Cube Test Data and Response

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.

2013-01-01

NASA s Environmentally Responsible Aviation (ERA) Program is examining the hybrid wing body (HWB) aircraft, among others, in an effort to increase the fuel efficiency of commercial aircraft. The HWB design combines features of a flying wing with features of conventional transport aircraft, and has the advantage of simultaneously increasing both fuel efficiency and payload. Recent years have seen an increased focus on the structural performance of the HWB. The key structural challenge of a HWB airframe is the ability to create a cost and weight efficient, non-circular, pressurized shell. Conventional round fuselage sections react cabin pressure by hoop tension. However, the structural configuration of the HWB subjects the majority of the structural panels to bi-axial, in-plane loads in addition to the internal cabin pressure, which requires more thorough examination and analysis than conventional transport aircraft components having traditional and less complex load paths. To address this issue, while keeping structural weights low, extensive use of advanced composite materials is made. This report presents the test data and preliminary conclusions for a pressurized cube test article that utilizes Boeing's Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), and which is part of the building block approach used for HWB development.

Novel platens to measure the hardness of a pentagonal shaped tablet.

PubMed

Malladi, Jaya; Sidik, Kurex; Wu, Sutan; McCann, Ryan; Dougherty, Jeffrey; Parab, Prakash; Carragher, Thomas

2017-03-01

Tablet hardness, a measure of the breaking force of a tablet, is based on numerous factors. These include the shape of the tablet and the mode of the application of force. For instance, when a pentagonal-shaped tablet was tested with a traditional hardness tester with flat platens, there was a large variation in hardness measurements. This was due to the propensity of vertices of the tablet to crush, referred to as an "improper break". This article describes a novel approach to measure the hardness of pentagonal-shaped tablets using modified platens. The modified platens have more uniform loading than flat platens. This is because they reduce loading on the vertex of the pentagon and apply forces on tablet edges to generate reproducible tablet fracture. The robustness of modified platens was assessed using a series of studies, which included feasibility and Gauge Repeatability & Reproducibility (R&R) studies. A key finding was that improper breaks, generated frequently with a traditional hardness tester using flat platens, were eliminated. The Gauge R&R study revealed that the tablets tested with novel platens generated consistent values in hardness measurements, independent of batch, hardness level, and day of testing, operator and tablet dosage strength.

Optical Fiber Distributed Sensing Structural Health Monitoring (SHM) Strain Measurements Taken During Cryotank Y-Joint Test Article Load Cycling at Liquid Helium Temperatures

NASA Technical Reports Server (NTRS)

Allison, Sidney G.; Prosser, William H.; Hare, David A.; Moore, Thomas C.; Kenner, Winfred S.

2007-01-01

This paper outlines cryogenic Y-joint testing at Langley Research Center (LaRC) to validate the performance of optical fiber Bragg grating strain sensors for measuring strain at liquid helium temperature (-240 C). This testing also verified survivability of fiber sensors after experiencing 10 thermal cool-down, warm-up cycles and 400 limit load cycles. Graphite composite skins bonded to a honeycomb substrate in a sandwich configuration comprised the Y-joint specimens. To enable SHM of composite cryotanks for consideration to future spacecraft, a light-weight, durable monitoring technology is needed. The fiber optic distributed Bragg grating strain sensing system developed at LaRC is a viable substitute for conventional strain gauges which are not practical for SHM. This distributed sensing technology uses an Optical Frequency Domain Reflectometer (OFDR). This measurement approach has the advantage that it can measure hundreds of Bragg grating sensors per fiber and the sensors are all written at one frequency, greatly simplifying fiber manufacturing. Fiber optic strain measurements compared well to conventional strain gauge measurements obtained during these tests. These results demonstrated a high potential for a successful implementation of a SHM system incorporating LaRC's fiber optic sensing system on the composite cryotank and other future cryogenic applications.

Strain Gage Load Calibration of the Wing Interface Fittings for the Adaptive Compliant Trailing Edge Flap Flight Test

NASA Technical Reports Server (NTRS)

Miller, Eric J.; Holguin, Andrew C.; Cruz, Josue; Lokos, William A.

2014-01-01

The safety-of-flight parameters for the Adaptive Compliant Trailing Edge (ACTE) flap experiment require that flap-to-wing interface loads be sensed and monitored in real time to ensure that the structural load limits of the wing are not exceeded. This paper discusses the strain gage load calibration testing and load equation derivation methodology for the ACTE interface fittings. Both the left and right wing flap interfaces were monitored; each contained four uniquely designed and instrumented flap interface fittings. The interface hardware design and instrumentation layout are discussed. Twenty-one applied test load cases were developed using the predicted in-flight loads. Pre-test predictions of strain gage responses were produced using finite element method models of the interface fittings. Predicted and measured test strains are presented. A load testing rig and three hydraulic jacks were used to apply combinations of shear, bending, and axial loads to the interface fittings. Hardware deflections under load were measured using photogrammetry and transducers. Due to deflections in the interface fitting hardware and test rig, finite element model techniques were used to calculate the reaction loads throughout the applied load range, taking into account the elastically-deformed geometry. The primary load equations were selected based on multiple calibration metrics. An independent set of validation cases was used to validate each derived equation. The 2-sigma residual errors for the shear loads were less than eight percent of the full-scale calibration load; the 2-sigma residual errors for the bending moment loads were less than three percent of the full-scale calibration load. The derived load equations for shear, bending, and axial loads are presented, with the calculated errors for both the calibration cases and the independent validation load cases.

Simulation of a 5MW wind turbine in an atmospheric boundary layer

NASA Astrophysics Data System (ADS)

Meister, Konrad; Lutz, Thorsten; Krämer, Ewald

2014-12-01

This article presents detached eddy simulation (DES) results of a 5MW wind turbine in an unsteady atmospheric boundary layer. The evaluation performed in this article focuses on turbine blade loads as well as on the influence of atmospheric turbulence and tower on blade loads. Therefore, the turbulence transport of the atmospheric boundary layer to the turbine position is analyzed. To determine the influence of atmospheric turbulence on wind turbines the blade load spectrum is evaluated and compared to wind turbine simulation results with uniform inflow. Moreover, the influences of different frequency regimes and the tower on the blade loads are discussed. Finally, the normal force coefficient spectrum is analyzed at three different radial positions and the influence of tower and atmospheric turbulence is shown.

Self-aligning biaxial load frame

DOEpatents

Ward, M.B.; Epstein, J.S.; Lloyd, W.R.

1994-01-18

An self-aligning biaxial loading apparatus for use in testing the strength of specimens while maintaining a constant specimen centroid during the loading operation. The self-aligning biaxial loading apparatus consists of a load frame and two load assemblies for imparting two independent perpendicular forces upon a test specimen. The constant test specimen centroid is maintained by providing elements for linear motion of the load frame relative to a fixed cross head, and by alignment and linear motion elements of one load assembly relative to the load frame. 3 figures.

Self-aligning biaxial load frame

DOEpatents

Ward, Michael B.; Epstein, Jonathan S.; Lloyd, W. Randolph

1994-01-01

An self-aligning biaxial loading apparatus for use in testing the strength of specimens while maintaining a constant specimen centroid during the loading operation. The self-aligning biaxial loading apparatus consists of a load frame and two load assemblies for imparting two independent perpendicular forces upon a test specimen. The constant test specimen centroid is maintained by providing elements for linear motion of the load frame relative to a fixed crosshead, and by alignment and linear motion elements of one load assembly relative to the load frame.

Long Duration Exposure Facility (LDEF) structural verification test report

NASA Technical Reports Server (NTRS)

Jones, T. C.; Lucy, M. H.; Shearer, R. L.

1983-01-01

Structural load tests on the Long Duration Exposure Facility's (LDEF) primary structure were conducted. These tests had three purposes: (1) demonstrate structural adequacy of the assembled LDEF primary structure when subjected to anticipated flight loads; (2) verify analytical models and methods used in loads and stress analysis; and (3) perform tests to comply with the Space Transportation System (STS) requirements. Test loads were based on predicted limit loads which consider all flight events. Good agreement is shown between predicted and observed load, strain, and deflection data. Test data show that the LDEF structure was subjected to 1.2 times limit load to meet the STS requirements. The structural adequacy of the LDEF is demonstrated.

Development of load spectra for Airbus A330/A340 full scale fatigue tests

NASA Technical Reports Server (NTRS)

Schmidt, H.-J.; Nielsen, Thomas

1994-01-01

For substantiation of the recently certified medium range Airbus A330 and long range A340 the full scale fatigue tests are in progress. The airframe structures of both aircraft types are tested by one set of A340 specimens. The development of the fatigue test spectra for the two major test specimens which are the center fuselage and wing test and the rear fuselage test is described. The applied test load spectra allow a realistic simulation of flight, ground and pressurization loads and the finalization of the tests within the pre-defined test period. The paper contains details about the 1 g and incremental flight and ground loads and the establishment of the flight-by-flight test program, i.e., the definition of flight types, distribution of loads within the flights and randomization of flight types in repeated blocks. Special attention is given to procedures applied for acceleration of the tests, e.g. omission of lower spectrum loads and a general increase of all loads by ten percent.

Approach to osteomyelitis treatment with antibiotic loaded PMMA.

PubMed

Wentao, Zhang; Lei, Guangyu; Liu, Yang; Wang, Wei; Song, Tao; Fan, Jinzhu

2017-01-01

To reduce the incidence of osteomyelitis infection, local antibiotic impregnated delivery systems are commonly used as a promising and effective approach to deliver high antibiotic concentrations at the infection site. The objective of this review was to provide a literature review regarding approach to osteomyelitis treatment with antibiotic loaded PMMA. Literature study regarding osteomyelitis treatment with antibiotic loaded carriers using key terms Antibiotic, osteomyelitis, biodegradable PMMA through published articles. Hands searching of bibliographies of identified articles were also undertaken. We concluded that Antibiotic-impregnated PMMA beads are useful options for the treatment of osteomyelitis for prolonged drug therapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intelligent Distribution Voltage Control with Distributed Generation =

NASA Astrophysics Data System (ADS)

Castro Mendieta, Jose

In this thesis, three methods for the optimal participation of the reactive power of distributed generations (DGs) in unbalanced distributed network have been proposed, developed, and tested. These new methods were developed with the objectives of maintain voltage within permissible limits and reduce losses. The first method proposes an optimal participation of reactive power of all devices available in the network. The propose approach is validated by comparing the results with other methods reported in the literature. The proposed method was implemented using Simulink of Matlab and OpenDSS. Optimization techniques and the presentation of results are from Matlab. The co-simulation of Electric Power Research Institute's (EPRI) OpenDSS program solves a three-phase optimal power flow problem in the unbalanced IEEE 13 and 34-node test feeders. The results from this work showed a better loss reduction compared to the Coordinated Voltage Control (CVC) method. The second method aims to minimize the voltage variation on the pilot bus on distribution network using DGs. It uses Pareto and Fuzzy-PID logic to reduce the voltage variation. Results indicate that the proposed method reduces the voltage variation more than the other methods. Simulink of Matlab and OpenDSS is used in the development of the proposed approach. The performance of the method is evaluated on IEEE 13-node test feeder with one and three DGs. Variables and unbalanced loads are used, based on real consumption data, over a time window of 48 hours. The third method aims to minimize the reactive losses using DGs on distribution networks. This method analyzes the problem using the IEEE 13-node test feeder with three different loads and the IEEE 123-node test feeder with four DGs. The DGs can be fixed or variables. Results indicate that integration of DGs to optimize the reactive power of the network helps to maintain the voltage within the allowed limits and to reduce the reactive power losses. The thesis is presented in the form of the three articles. The first article is published in the journal Electrical Power and Energy System, the second is published in the international journal Energies and the third was submitted to the journal Electrical Power and Energy System. Two other articles have been published in conferences with reviewing committee. This work is based on six chapters, which are detailed in the various sections of the thesis.

Critical joints in large composite primary aircraft structures. Volume 2: Technology demonstration test report

NASA Technical Reports Server (NTRS)

Bunin, Bruce L.

1985-01-01

A program was conducted to develop the technology for critical structural joints in composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. The results of four large composite multirow bolted joint tests are presented. The tests were conducted to demonstrate the technology for critical joints in highly loaded composite structure and to verify the analytical methods that were developed throughout the program. The test consisted of a wing skin-stringer transition specimen representing a stringer runout and skin splice on the wing lower surface at the side of the fuselage attachment. All tests were static tension tests. The composite material was Toray T-300 fiber with Ciba-Geigy 914 resin in 10 mil tape form. The splice members were metallic, using combinations of aluminum and titanium. Discussions are given of the test article, instrumentation, test setup, test procedures, and test results for each of the four specimens. Some of the analytical predictions are also included.

Room Temperature and Elevated Temperature Composite Sandwich Joint Testing

NASA Technical Reports Server (NTRS)

Walker, Sandra P.

1998-01-01

Testing of composite sandwich joint elements has been completed to verify the strength capacity of joints designed to carry specified running loads representative of a high speed civil transport wing. Static tension testing at both room and an elevated temperature of 350 F and fatigue testing at room temperature were conducted to determine strength capacity, fatigue life, and failure modes. Static tension test results yielded failure loads above the design loads for the room temperature tests, confirming the ability of the joint concepts tested to carry their design loads. However, strength reductions as large as 30% were observed at the elevated test temperature, where all failure loads were below the room temperature design loads for the specific joint designs tested. Fatigue testing resulted in lower than predicted fatigue lives.

Nondestructive Evaluation Methods for the Ares I Common Bulkhead

NASA Technical Reports Server (NTRS)

Walker, James

2010-01-01

A large scale bonding demonstration test article was fabricated to prove out manufacturing techniques for the current design of the NASA Ares I Upper Stage common bulkhead. The common bulkhead serves as the single interface between the liquid hydrogen and liquid oxygen portions of the Upper Stage propellant tank. The bulkhead consists of spin-formed aluminum domes friction stir welded to Y-rings and bonded to a perforated phenolic honeycomb core. Nondestructive evaluation methods are being developed for assessing core integrity and the core-to-dome bond line of the common bulkhead. Detection of manufacturing defects such as delaminations between the core and face sheets as well as service life defects such as crushed or sheared core resulting from impact loading are all of interest. The focus of this work will be on the application of thermographic, shearographic, and phased array ultrasonic methods to the bonding demonstration article as well as various smaller test panels featuring design specific defect types and geometric features.

Inspection and monitoring of wind turbine blade-embedded wave defects during fatigue testing

DOE PAGES

Niezrecki, Christopher; Avitabile, Peter; Chen, Julie; ...

2014-05-20

The research we present in this article focuses on a 9-m CX-100 wind turbine blade, designed by a team led by Sandia National Laboratories and manufactured by TPI Composites Inc. The key difference between the 9-m blade and baseline CX-100 blades is that this blade contains fabric wave defects of controlled geometry inserted at specified locations along the blade length. The defect blade was tested at the National Wind Technology Center at the National Renewable Energy Laboratory using a schedule of cycles at increasing load level until failure was detected. Our researchers used digital image correlation, shearography, acoustic emission, fiber-opticmore » strain sensing, thermal imaging, and piezoelectric sensing as structural health monitoring techniques. Furthermore, this article provides a comparison of the sensing results of these different structural health monitoring approaches to detect the defects and track the resultant damage from the initial fatigue cycle to final failure.« less

Application of Novel Lateral Tire Force Sensors to Vehicle Parameter Estimation of Electric Vehicles.

PubMed

Nam, Kanghyun

2015-11-11

This article presents methods for estimating lateral vehicle velocity and tire cornering stiffness, which are key parameters in vehicle dynamics control, using lateral tire force measurements. Lateral tire forces acting on each tire are directly measured by load-sensing hub bearings that were invented and further developed by NSK Ltd. For estimating the lateral vehicle velocity, tire force models considering lateral load transfer effects are used, and a recursive least square algorithm is adapted to identify the lateral vehicle velocity as an unknown parameter. Using the estimated lateral vehicle velocity, tire cornering stiffness, which is an important tire parameter dominating the vehicle's cornering responses, is estimated. For the practical implementation, the cornering stiffness estimation algorithm based on a simple bicycle model is developed and discussed. Finally, proposed estimation algorithms were evaluated using experimental test data.

Implementation of Fiber Optic Sensing System on Sandwich Composite Cylinder Buckling Test

NASA Technical Reports Server (NTRS)

Pena, Francisco; Richards, W. Lance; Parker, Allen R.; Piazza, Anthony; Schultz, Marc R.; Rudd, Michelle T.; Gardner, Nathaniel W.; Hilburger, Mark W.

2018-01-01

The National Aeronautics and Space Administration (NASA) Engineering and Safety Center Shell Buckling Knockdown Factor Project is a multicenter project tasked with developing new analysis-based shell buckling design guidelines and design factors (i.e., knockdown factors) through high-fidelity buckling simulations and advanced test technologies. To validate these new buckling knockdown factors for future launch vehicles, the Shell Buckling Knockdown Factor Project is carrying out structural testing on a series of large-scale metallic and composite cylindrical shells at the NASA Marshall Space Flight Center (Marshall Space Flight Center, Alabama). A fiber optic sensor system was used to measure strain on a large-scale sandwich composite cylinder that was tested under multiple axial compressive loads up to more than 850,000 lb, and equivalent bending loads over 22 million in-lb. During the structural testing of the composite cylinder, strain data were collected from optical cables containing distributed fiber Bragg gratings using a custom fiber optic sensor system interrogator developed at the NASA Armstrong Flight Research Center. A total of 16 fiber-optic strands, each containing nearly 1,000 fiber Bragg gratings, measuring strain, were installed on the inner and outer cylinder surfaces to monitor the test article global structural response through high-density real-time and post test strain measurements. The distributed sensing system provided evidence of local epoxy failure at the attachment-ring-to-barrel interface that would not have been detected with conventional instrumentation. Results from the fiber optic sensor system were used to further refine and validate structural models for buckling of the large-scale composite structures. This paper discusses the techniques employed for real-time structural monitoring of the composite cylinder for structural load introduction and distributed bending-strain measurements over a large section of the cylinder by utilizing unique sensing capabilities of fiber optic sensors.

Users manual for the Texas quick-load method for foundation load testing.

DOT National Transportation Integrated Search

1976-12-01

The Texas State Department of Highways and Public Transportation has developed and implemented a "quick-load" method for load testing piling and drilled shafts. Using this method a load test can be completed in a relatively short time of one to two...

Ergonomics assessment of composite ballistic inserts for bullet- and fragment-proof vests.

PubMed

Majchrzycka, Katarzyna; Brochocka, Agnieszka; Luczak, Anna; Lężak, Krzysztof

2013-01-01

Personal protective equipment worn by uniformed services (e.g., the police and the military) must ensure protection against bodily injuries. However, a high degree of protection is always associated with significant discomfort. This article presents the results of an assessment of the ergonomics parameters of new special purpose products, ballistic inserts with improved ballistic resistance, and an assessment of the impact of the burden related to their use on the psychomotor performance of the subjects. An obstacle course and subjective ergonomics assessment questionnaires were used in tests. Thermal discomfort was also assessed. Psychological testing included tests enabling an assessment of the subjects' cognitive and psychomotor performance, and a subjective assessment of mental load. The tests did not show any decrease in the comfort of use of the new inserts with improved ballistic resistance compared to the inserts currently used.

Stability of the anterior arm of three different Hyrax hybrid expanders: an in vitro study

PubMed Central

de la Iglesia, Gonzalo; Walter, André; de la Iglesia, Fernando; Winsauer, Heinz; Puigdollers, Andreu

2018-01-01

ABSTRACT Introduction: The force applied to the teeth by fixed orthopaedic expanders has previously been studied, but not the force applied to the orthodontic mini-implant (OMI) used to expand the maxilla with Hyrax hybrid expanders (HHE). Objective: The aim of this article was to evaluate the clinical safety of the components (OMI, abutment and double wire arms) of three different force-transmitting systems (FTS) for conducting orthopaedic maxillary expansion: Jeil Medical & Tiger Dental™, Microdent™ and Ortholox™. Methods: For the realization of this in vitro study of the resistance to mechanical load, three different abutment types (bonded, screwed on, and coupling) and three different OMIs’ diameters (Jeil™ 2.5 mm, Microdent™ 1.6 mm and Ortholox™ 2.2 mm) were used. Ten tests for each of these three FTS were carried out in a static lateral load in artificial bone blocks (Sawbones™) by a Galdabini universal testing machine, then comparing its performance. Comparisons of loads, deformations and fractures were carried out by means of radiographs of FTS components in each case. Results: At 1- mm load and within the elastic deformation, FTS values ranged from 67 ± 13 N to 183 ± 48 N. Under great deformations, Jeil & Tiger™ was the one who withstood the greatest loads, with an average 378 ± 22 N; followed by Microdent™, with 201 ± 18 N, and Ortholox™, with 103 ± 10 N. At 3 mm load, the OMIs shaft bends and deforms when the diameter is smaller than 2.5 mm. The abutment fixation is crucial to transmit forces and moments. Conclusions: The present study shows the importance of a rigid design of the different components of HHEs, and also that HHEs would be suitable for maxillary expansion in adolescents and young adults, since its mean expansion forces exceed 120N. Furthermore, early abutment detachment or smaller mini-implants diameter would only be appropriate for children. PMID:29791684

76 FR 4300 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-25

.... Some of the initial eighteen piles will be removed and re-driven as part of lateral load and tension tests. A total of eleven piles will be installed to perform lateral load and tension load tests. All... substrate. Additionally, three lateral load and two tension load tests will be performed. The lateral load...

The sheltered genetic load linked to the s locus in plants: new insights from theoretical and empirical approaches in sporophytic self-incompatibility.

PubMed

Llaurens, Violaine; Gonthier, Lucy; Billiard, Sylvain

2009-11-01

Inbreeding depression and mating systems evolution are closely linked, because the purging of deleterious mutations and the fitness of individuals may depend on outcrossing vs. selfing rates. Further, the accumulation of deleterious mutations may vary among genomic regions, especially for genes closely linked to loci under balancing selection. Sporophytic self-incompatibility (SSI) is a common genetic mechanism in angiosperm that enables hermaphrodite plants to avoid selfing and promote outcrossing. The SSI phenotype is determined by the S locus and may depend on dominance relationships among alleles. Since most individuals are heterozygous at the S locus and recombination is suppressed in the S-locus region, it has been suggested that deleterious mutations could accumulate at genes linked to the S locus, generating a "sheltered load." In this article, we first theoretically investigate the conditions generating sheltered load in SSI. We show that deleterious mutations can accumulate in linkage with specific S alleles, and particularly if those S alleles are dominant. Second, we looked for the presence of sheltered load in Arabidopsis halleri using CO(2) gas treatment to overcome self-incompatibility. By examining the segregation of S alleles and measuring the relative fitness of progeny, we found significant sheltered load associated with the most dominant S allele (S15) of three S alleles tested. This sheltered load seems to be expressed at several stages of the life cycle and to have a larger effect than genomic inbreeding depression.

Symplasmic transport and phloem loading in gymnosperm leaves

PubMed Central

Liesche, Johannes; Martens, Helle Juel

2010-01-01

Despite more than 130 years of research, phloem loading is far from being understood in gymnosperms. In part this is due to the special architecture of their leaves. They differ from angiosperm leaves among others by having a transfusion tissue between bundle sheath and the axial vascular elements. This article reviews the somewhat inaccessible and/or neglected literature and identifies the key points for pre-phloem transport and loading of photoassimilates. The pre-phloem pathway of assimilates is structurally characterized by a high number of plasmodesmata between all cell types starting in the mesophyll and continuing via bundle sheath, transfusion parenchyma, Strasburger cells up to the sieve elements. Occurrence of median cavities and branching indicates that primary plasmodesmata get secondarily modified and multiplied during expansion growth. Only functional tests can elucidate whether this symplasmic pathway is indeed continuous for assimilates, and if phloem loading in gymnosperms is comparable with the symplasmic loading mode in many angiosperm trees. In contrast to angiosperms, the bundle sheath has properties of an endodermis and is equipped with Casparian strips or other wall modifications that form a domain border for any apoplasmic transport. It constitutes a key point of control for nutrient transport, where the opposing flow of mineral nutrients and photoassimilates has to be accommodated in each single cell, bringing to mind the principle of a revolving door. The review lists a number of experiments needed to elucidate the mode of phloem loading in gymnosperms. PMID:21107620

Appropriate Mechanochemical Conditions for Corrosion-Fatigue Testing of Magnesium Alloys for Temporary Bioimplant Applications

NASA Astrophysics Data System (ADS)

Harandi, Shervin Eslami; Singh Raman, R. K.

2015-05-01

Magnesium (Mg) alloys possess great potential as bioimplants. A temporary implant employed as support for the repair of a fractured bone must possess sufficient strength to maintain their mechanical integrity for the required duration of healing. However, Mg alloys are susceptible to sudden cracking or fracture under the simultaneous action of cyclic loading and the corrosive physiological environment, i.e., corrosion fatigue (CF). Investigations of such fracture should be performed under appropriate mechanochemical conditions that appropriately simulate the actual human body conditions. This article reviews the existing knowledge on CF of Mg alloys in simulated body fluid and describes a relatively more accurate testing procedure developed in the authors' laboratory.

Ultrasonic Characterization of Fatigue Cracks in Composite Materials

NASA Technical Reports Server (NTRS)

Workman, Gary L.; Watson, Jason; Johnson, Devin; Walker, James; Russell, Sam; Thom, Robert (Technical Monitor)

2002-01-01

Microcracking in composite structures due to combined fatigue and cryogenic loading can cause leakage and failure of the structure and can be difficult to detect in-service. In aerospace systems, these leaks may lead to loss of pressure/propellant, increased risk of explosion and possible cryo-pumping. The success of nondestructive evaluation to detect intra-ply microcracking in unlined pressure vessels fabricated from composite materials is critical to the use of composite structures in future space systems. The work presented herein characterizes measurements of intraply fatigue cracking through the thickness of laminated composite material by means of correlation with ultrasonic resonance. Resonant ultrasound spectroscopy provides measurements which are sensitive to both the microscopic and macroscopic properties of the test article. Elastic moduli, acoustic attenuation, and geometry can all be probed. The approach is based on the premise of half-wavelength resonance. The method injects a broadband ultrasonic wave into the test structure using a swept frequency technique. This method provides dramatically increased energy input into the test article, as compared to conventional pulsed ultrasonics. This relative energy increase improves the ability to measure finer details in the materials characterization, such as microcracking and porosity. As the microcrack density increases, more interactions occur with the higher frequency (small wavelength) components of the signal train causing the spectrum to shift toward lower frequencies. Several methods are under investigation to correlate the degree of microcracking from resonance ultrasound measurements on composite test articles including self organizing neural networks, chemometric techniques used in optical spectroscopy and other clustering algorithms.

Research on light rail electric load forecasting based on ARMA model

NASA Astrophysics Data System (ADS)

Huang, Yifan

2018-04-01

The article compares a variety of time series models and combines the characteristics of power load forecasting. Then, a light load forecasting model based on ARMA model is established. Based on this model, a light rail system is forecasted. The prediction results show that the accuracy of the model prediction is high.

MEMS resonant load cells for micro-mechanical test frames: feasibility study and optimal design

NASA Astrophysics Data System (ADS)

Torrents, A.; Azgin, K.; Godfrey, S. W.; Topalli, E. S.; Akin, T.; Valdevit, L.

2010-12-01

This paper presents the design, optimization and manufacturing of a novel micro-fabricated load cell based on a double-ended tuning fork. The device geometry and operating voltages are optimized for maximum force resolution and range, subject to a number of manufacturing and electromechanical constraints. All optimizations are enabled by analytical modeling (verified by selected finite elements analyses) coupled with an efficient C++ code based on the particle swarm optimization algorithm. This assessment indicates that force resolutions of ~0.5-10 nN are feasible in vacuum (~1-50 mTorr), with force ranges as large as 1 N. Importantly, the optimal design for vacuum operation is independent of the desired range, ensuring versatility. Experimental verifications on a sub-optimal device fabricated using silicon-on-glass technology demonstrate a resolution of ~23 nN at a vacuum level of ~50 mTorr. The device demonstrated in this article will be integrated in a hybrid micro-mechanical test frame for unprecedented combinations of force resolution and range, displacement resolution and range, optical (or SEM) access to the sample, versatility and cost.

Launch Vehicle Base Buffeting- Recent Experimental And Numerical Investigations

NASA Astrophysics Data System (ADS)

Hannemann, K.; Ludeke, H.; Pallegoix, J.-F.; Ollivier, A.; Lambare, H.; Maseland, J. E. J.; Geurts, E. G. M.; Frey, M.; Deck, S.; Schrijer, F. F. J.; Scarano, F.; Schwane, R.

2011-05-01

During atmospheric ascent of launcher configurations, a massively separated flow environment in the base region of the launcher can generate strong low frequency wall pressure fluctuations. The nozzle structure can be subjected to dynamic loads resulting from these pressure fluctuations. The loads are usually most severe during the high dynamic pressure phase of flight at transonic speeds and the aerodynamic excitation can induce a response of the structural modes called buffeting. In order to obtain a deeper insight into base buffeting related to the Ariane 5 launch vehicle, a set of experiments was performed in the DNW HST wind tunnel in close cooperation with the utilization of modern CFD tools (hybrid RANS/LES). During the test campaign a 1/60 scale Ariane 5 launcher test article was utilized, and detailed unsteady pressure measurements in the base region of the model were for the first time performed in conjunction with time resolved velocity field measurements using PIV. The work was performed in the framework of the ESA TRP “Unsteady Subscale Force Measurements within a Launch Vehicle Base Buffeting Environment”.

Wavelet Analysis of Acoustic Emissions during Tensile Test of Carbon Fibre Reinforced Polymer Composites

NASA Astrophysics Data System (ADS)

Świt, Grzegorz; Adamczak, Anna; Krampikowska, Aleksandra

2017-10-01

The increase of the interest in polymer composites in technology and in people’s everyday lives has been noticed in the recent years. Producing new materials with polymer matrix of particular properties that cannot be achieved by traditional construction materials contributed to high interest in fibre composite materials. However, a wider use of these materials is limited because of the lack of detailed knowledge about their properties and behaviour in various conditions of exposure under load. Mechanical degradation of polymer composites, which is caused by prolonged permanent loads, is connected with the changes of the material structure that are local or that include the whole volume of the element’s body. These changes are in the form of various types of discontinuity, including: deboning, matrix and fibers cracks and delamination. The article presents the example of the application of acoustic emission method based on the analysis of the waves through the use of wavelet analysis for the evaluation of the progress of the destructive processes and the level of the degradation of composite tapes that were subject to tensile testing.

Analysis characteristics determination of electrohydraulic control system operation to reduce the operation time of a powered roof support

NASA Astrophysics Data System (ADS)

Szurgacz, Dawid

2018-01-01

The article discusses basic functions of a powered roof support in a longwall unit. The support function is to provide safety by protecting mine workings against uncontrolled falling of rocks. The subject of the research includes the measures to shorten the time of roof support shifting. The roof support is adapted to transfer, in hazard conditions of rock mass tremors, dynamic loads caused by mining exploitation. The article presents preliminary research results on the time reduction of the unit advance to increase the extraction process and thus reduce operating costs. Conducted stand tests showed the ability to increase the flow for 3/2-way valve cartridges. The level of fluid flowing through the cartridges is adequate to control individual actuators.

The effect of cognitive load and patient race on physicians' decisions to prescribe opioids for chronic low back pain: a randomized trial.

PubMed

Burgess, Diana J; Phelan, Sean; Workman, Michael; Hagel, Emily; Nelson, David B; Fu, Steven S; Widome, Rachel; van Ryn, Michelle

2014-06-01

To test the hypothesis that racial biases in opioid prescribing would be more likely under high levels of cognitive load, defined as the amount of mental activity imposed on working memory, which may come from environmental factors such as stressful conditions, chaotic workplace, staffing insufficiency, and competing demands, one's own psychological or physiological state, as well as from demands inherent in the task at hand. Two (patient race: White vs Black) by two (cognitive load: low vs high) between-subjects factorial design. Ninety-eight primary care physicians from the Veterans Affairs Healthcare System. Web-based experimental study. Physicians were randomly assigned to read vignettes about either a Black or White patient, under low vs high cognitive load, and to indicate their likelihood of prescribing opioids. High cognitive load was induced by having physicians perform a concurrent task under time pressure. There was a three-way interaction between patient race, cognitive load, and physician gender on prescribing decisions (P = 0.034). Hypotheses were partially confirmed. Male physicians were less likely to prescribe opioids for Black than White patients under high cognitive load (12.5% vs 30.0%) and were more likely to prescribe opioids for Black than White patients under low cognitive load (30.8% vs 10.5%). By contrast, female physicians were more likely to prescribe opioids for Black than White patients in both conditions, with greater racial differences under high (39.1% vs 15.8%) vs low cognitive load (28.6% vs 21.7%). Physician gender affected the way in which patient race and cognitive load influenced decisions to prescribe opioids for chronic pain. Future research is needed to further explore the potential effects of physician gender on racial biases in pain treatment, and the effects of physician cognitive load on pain treatment. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

In situ observation of fracture processes in high-strength concretes and limestone using high-speed X-ray phase-contrast imaging

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

Parab, Niranjan D.; Guo, Zherui; Hudspeth, Matthew

The mechanical properties and fracture mechanisms of geomaterials and construction materials such as concrete are reported to be dependent on the loading rates. However, the in situ cracking inside such specimens cannot be visualized using traditional optical imaging methods since the materials are opaque. In this study, the in situ sub-surface failure/damage mechanisms in Cor-Tuf (a reactive powder concrete), a high-strength concrete (HSC) and Indiana limestone under dynamic loading were investigated using high-speed synchrotron X-ray phase-contrast imaging. Dynamic compressive loading was applied using a modified Kolsky bar and fracture images were recorded using a synchronized high-speed synchrotron X-ray imaging set-up.more » Three-dimensional synchrotron X-ray tomography was also performed to record the microstructure of the specimens before dynamic loading. In the Cor-Tuf and HSC specimens, two different modes of cracking were observed: straight cracking or angular cracking with respect to the direction of loading. In limestone, cracks followed the grain boundaries and voids, ultimately fracturing the specimen. Cracks in HSC were more tortuous than the cracks in Cor-Tuf specimens. The effects of the microstructure on the observed cracking behaviour are discussed. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.« less

Aircraft Survivability: Rotorcraft Survivability. Summer 2010

DTIC Science & Technology

2010-01-01

Loading of the shafts was conducted using two techniques. The first tech- nique applied a torsion load up to the design limit load after the article...show the ballistic impact and impact damage. Figure 11 shows a 45-degree shaft failure, a common failure type, when loaded to design limit after...SUMMER 2010 ROTORCRAFT Survivability STUDY ON ROTORCRAFT SURVIVABILITY V-22 INTEGRATED SURVIVABILITY DESIGN CH-53K HEAVY LIFT HELICOPTER 9 20 25

Slow Crack Growth Analysis of Advanced Structural Ceramics Under Combined Loading Conditions: Damage Assessment in Life Prediction Testing

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Gyekenyesi, John P.

2000-01-01

Slow crack growth analysis was performed with three different loading histories including constant stress-rate/constant stress-rate testing (Case 1 loading), constant stress/constant stress-rate testing (Case 2 loading), and cyclic stress/constant stress-rate testing (Case 2 loading). Strength degradation due to slow crack growth and/or damage accumulation was determined numerically as a function of percentage of interruption time between the two loading sequences for a given loading history. The numerical solutions were examined with the experimental data determined at elevated temperatures using four different advanced ceramic materials, two silicon nitrides, one silicon carbide and one alumina for the Case 1 loading history, and alumina for the Case 3 loading history. The numerical solutions were in reasonable agreement with the experimental data, indicating that notwithstanding some degree of creep deformation presented for some test materials slow crack growth was a governing mechanism associated with failure for all the test materials.

Slow Crack Growth Analysis of Advanced Structural Ceramics Under Combined Loading Conditions: Damage Assessment in Life Prediction Testing

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Gyekenyesi, John P.

2000-01-01

Slow crack growth analysis was performed with three different loading histories including constant stress-rate/constant stress-rate testing (Case I loading), constant stress/constant stress-rate testing (Case II loading), and cyclic stress/constant stress-rate testing (Case III loading). Strength degradation due to slow crack growth arid/or damage accumulation was determined numerically as a Function of percentage of interruption time between the two loading sequences for a given loading history. The numerical solutions were examined with the experimental data determined at elevated temperatures using four different advanced ceramic materials, two silicon nitrides, one silicon carbide and one alumina for the Case I loading history, and alumina for the Case II loading history. The numerical solutions were in reasonable agreement with the experimental data, indicating that notwithstanding some degree of creep deformation presented for some test materials slow crack growth was a governing mechanism associated with failure for all the test material&

Testing Machine for Biaxial Loading

NASA Technical Reports Server (NTRS)

Demonet, R. J.; Reeves, R. D.

1985-01-01

Standard tensile-testing machine applies bending and tension simultaneously. Biaxial-loading test machine created by adding two test fixtures to commercial tensile-testing machine. Bending moment applied by substrate-deformation fixture comprising yoke and anvil block. Pneumatic tension-load fixture pulls up on bracket attached to top surface of specimen. Tension and deflection measured with transducers. Modified test apparatus originally developed to load-test Space Shuttle surface-insulation tiles and particuarly important for composite structures.

Track-train dynamic analysis and test program, truck static test

NASA Technical Reports Server (NTRS)

Nemes, A. G.

1974-01-01

A series of tests were conducted to define the characteristics of an ASF 11 Ride Truck Assembly including joint slop, friction and stiffness. Loading to the truck assembly included vertical load to simulate the car/pool loading combined with lateral or moment loading that resulted in desired truck deflections for the various phases of testing. All seven test conditions were successfully completed with load and deflection data being collected. No attempt is made to reduce the applicable data other than to provide computer plots.

AXAF-I Low Intensity-Low Temperature (LILT) Testing of the Development Verification Test (DVT) Solar Panel

NASA Technical Reports Server (NTRS)

Alexander, Doug; Edge, Ted; Willowby, Doug

1998-01-01

The planned orbit of the AXAF-I spacecraft will subject the spacecraft to both short, less than 30 minutes for solar and less than 2 hours for lunar, and long earth eclipses and lunar eclipses with combined conjunctive duration of up to 3 to 4 hours. Lack of proper Electrical Power System (EPS) conditioning prior to eclipse may cause loss of mission. To avoid this problem, for short eclipses, it is necessary to off-point the solar array prior to or at the beginning of the eclipse to reduce the battery state of charge (SOC). This yields less overcharge during the high charge currents at sun entry. For long lunar eclipses, solar array pointing and load scheduling must be tailored for the profile of the eclipse. The battery SOC, loads, and solar array current-voltage (I-V) must be known or predictable to maintain the bus voltage within acceptable range. To address engineering concerns about the electrical performance of the AXAF-I solar array under Low Intensity and Low Temperature (LILT) conditions, Marshall Space Flight Center (MSFC) engineers undertook special testing of the AXAF-I Development Verification Test (DVT) solar panel in September-November 1997. In the test the DVT test panel was installed in a thermal vacuum chamber with a large view window with a mechanical "flapper door". The DVT test panel was "flash" tested with a Large Area Pulse Solar Simulator (LAPSS) at various fractional sun intensities and panel (solar cell) temperatures. The testing was unique with regards to the large size of the test article and type of testing performed. The test setup, results, and lessons learned from the testing will be presented.

Passive Orbital Disconnect Strut (PODS 3) structural test program

NASA Technical Reports Server (NTRS)

Parmley, R. T.

1985-01-01

A passive orbital disconnect strut (PODS-3) was analyzed structurally and thermally. Development tests on a graphite/epoxy orbit tube and S glass epoxy launch tube provided the needed data to finalize the design. A detailed assembly procedure was prepared. One strut was fabricated. Shorting loads in both the axial and lateral direction (vs. load angle and location) were measured. The strut was taken to design limit loads at both ambient and 78 K (cold end only). One million fatigue cycles were performed at predicted STS loads (half in tension, half in compression) with the cold end at 78 K. The fatigue test was repeated at design limit loads. Six struts were then fabricated and tested as a system. Axial loads, side loads, and simulated asymmetric loads due to temperature gradients around the vacuum shell were applied. Shorting loads were measured for all tests.

Watch 60-Seconds of Major SLS Hardware Being Moved and Put in the Test Stand at NASA Marshall

NASA Image and Video Library

2016-10-13

A test version of the launch vehicle stage adapter (LVSA) for NASA’s new rocket, the Space Launch System, is moved to a 65-foot-tall test stand at the agency’s Marshall Space Flight Center in Huntsville, Alabama. The test version LVSA will be stacked with other test pieces of the upper part of the SLS rocket and pushed, pulled and twisted as part of an upcoming test series to ensure each structure can withstand the incredible stresses of launch. The LVSA joins the core stage simulator, which was loaded into the test stand Sept. 21. The other three qualification articles and the Orion simulator will complete the stack later this fall. SLS will be the world’s most powerful rocket, and with the Orion spacecraft, take astronauts to deep-space destinations, including the Journey to Mars. More information on the upcoming test series can be found here: http://go.nasa.gov/2dS8yXB

SLS Rocket Hardware Moved to NASA Marshall Stand for Upcoming Test Series (30-second timelapse)

NASA Image and Video Library

2016-10-13

A test version of the launch vehicle stage adapter (LVSA) for NASA’s new rocket, the Space Launch System, is moved to a 65-foot-tall test stand at the agency’s Marshall Space Flight Center in Huntsville, Alabama. The test version LVSA will be stacked with other test pieces of the upper part of the SLS rocket and pushed, pulled and twisted as part of an upcoming test series to ensure each structure can withstand the incredible stresses of launch. The LVSA joins the core stage simulator, which was loaded into the test stand Sept. 21. The other three qualification articles and the Orion simulator will complete the stack later this fall. SLS will be the world’s most powerful rocket, and with the Orion spacecraft, take astronauts to deep-space destinations, including the Journey to Mars. More information on the upcoming test series can be found here: http://go.nasa.gov/2dS8yXB

Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy.

PubMed

Hermannsdörfer, Justus; de Jonge, Niels

2017-02-05

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline.

Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

PubMed Central

Hermannsdörfer, Justus; de Jonge, Niels

2017-01-01

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline. PMID:28190028

Researches on ailerons and especially on the test loads to which they should be subjected

NASA Technical Reports Server (NTRS)

Sabatier, J

1927-01-01

Aileron calculations have hitherto given greatly differing results according to different authors. It seems to be the general opinion that it is only necessary to give the ailerons such dimensions that the airplane can maneuver well, that the stresses they must undergo are relatively small, and that they are strong enough if their framework is of the order of strength as the wings to which they are attached. This article will show that the problem is really quite complex and that it should receive more attention.

Generating Researcher Networks with Identified Persons on a Semantic Service Platform

NASA Astrophysics Data System (ADS)

Jung, Hanmin; Lee, Mikyoung; Kim, Pyung; Lee, Seungwoo

This paper describes a Semantic Web-based method to acquire researcher networks by means of identification scheme, ontology, and reasoning. Three steps are required to realize it; resolving co-references, finding experts, and generating researcher networks. We adopt OntoFrame as an underlying semantic service platform and apply reasoning to make direct relations between far-off classes in ontology schema. 453,124 Elsevier journal articles with metadata and full-text documents in information technology and biomedical domains have been loaded and served on the platform as a test set.

New control center for EPM in Medellin, Columbia

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

Gomez, H.C.; Zadeh, K.N.; Meyer, R.C.

1989-07-01

The municipal electric utility of Empresas Publicas de Medellin (EPM) in Medellin, Colombia, has completed the installation and testing of their new control center. These facilities, which include all the functions expected from a modern control center, were implemented through carefully monitored and executed project stages, which are described in this article. EPM generates and transmits 1400 MW of exclusively hydroelectric energy to their service territory of the city of Medellin and nine neighboring cities and 77 smaller cities. The EPM system load ranges from 400 MW to 1200 MW.

First Article Testing of the USMC Container Consolidation Pallet Manufactured by Grate Pallet Solutions

DTIC Science & Technology

2009-05-28

posts use a small sliding “ latch ” to insure they remain in place (Appendix 2, Figure 4). AFPTEF Report No. 09-R-02 USMC CCP AFPTEF Project No. 09...A total of 8 inflated air bladders, measuring 30 in. x 30 in. before inflation, shall be wedged between the end panel and each shelf load, and the...sliding “ latch ”. AFPTEF Report No. 09-R-02 USMC CCP AFPTEF Project No. 09-P-104 25 Figure 5. Corner post indexing tab and lockable slide

Round Heat-treated Chromium-molybdenum-steel Tubing Under Combined Loads

NASA Technical Reports Server (NTRS)

Osgood, William R

1943-01-01

The results of tests of round heat-treated chromium-molybdenum-steel tubing are presented. Tests were made on tubing under axial load, bending load, torsional load, combined bending and axial load, combined bending and torsional load, and combined axial, bending, and torsional load. Tensile and compressive tests were made to determine the properties of the material. Formulas are given for the evaluation of the maximum strength of this steel tubing under individual or combined loads. The solution of an example is included to show the procedure to be followed in designing a tubular cantilever member to carry combined loads.

40 CFR 201.23 - Test site, weather conditions and background noise criteria for measurement at a 30 meter (100...

Code of Federal Regulations, 2010 CFR

2010-07-01

... rail car operations and locomotive load cell test stands. 201.23 Section 201.23 Protection of... locomotive and rail car operations and locomotive load cell test stands. (a) The standard test site shall be... contribution from the operation of the load cell, if any, including load cell contribution during test. (h...

40 CFR 201.16 - Standard for locomotive load cell test stands.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Standard for locomotive load cell test... Interstate Rail Carrier Operations Standards § 201.16 Standard for locomotive load cell test stands. (a) Effective January 15, 1984, no carrier subject to this reguation shall operate locomotive load cell test...

40 CFR 201.16 - Standard for locomotive load cell test stands.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Standard for locomotive load cell test... Interstate Rail Carrier Operations Standards § 201.16 Standard for locomotive load cell test stands. (a) Effective January 15, 1984, no carrier subject to this reguation shall operate locomotive load cell test...

40 CFR 201.16 - Standard for locomotive load cell test stands.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Standard for locomotive load cell test... Interstate Rail Carrier Operations Standards § 201.16 Standard for locomotive load cell test stands. (a) Effective January 15, 1984, no carrier subject to this reguation shall operate locomotive load cell test...

40 CFR 201.16 - Standard for locomotive load cell test stands.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Standard for locomotive load cell test... Interstate Rail Carrier Operations Standards § 201.16 Standard for locomotive load cell test stands. (a) Effective January 15, 1984, no carrier subject to this reguation shall operate locomotive load cell test...

40 CFR 201.16 - Standard for locomotive load cell test stands.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Standard for locomotive load cell test... Interstate Rail Carrier Operations Standards § 201.16 Standard for locomotive load cell test stands. (a) Effective January 15, 1984, no carrier subject to this reguation shall operate locomotive load cell test...

The Critical Compression Load for a Universal Testing Machine When the Specimen Is Loaded Through Knife Edges

NASA Technical Reports Server (NTRS)

Lundquist, Eugene E; Schwartz, Edward B

1942-01-01

The results of a theoretical and experimental investigation to determine the critical compression load for a universal testing machine are presented for specimens loaded through knife edges. The critical load for the testing machine is the load at which one of the loading heads becomes laterally instable in relation to the other. For very short specimens the critical load was found to be less than the rated capacity given by the manufacturer for the machine. A load-length diagram is proposed for defining the safe limits of the test region for the machine. Although this report is particularly concerned with a universal testing machine of a certain type, the basic theory which led to the derivation of the general equation for the critical load, P (sub cr) = alpha L can be applied to any testing machine operated in compression where the specimen is loaded through knife edges. In this equation, L is the length of the specimen between knife edges and alpha is the force necessary to displace the upper end of the specimen unit horizontal distance relative to the lower end of the specimen in a direction normal to the knife edges through which the specimen is loaded.

Whole bone mechanics and bone quality.

PubMed

Cole, Jacqueline H; van der Meulen, Marjolein C H

2011-08-01

The skeleton plays a critical structural role in bearing functional loads, and failure to do so results in fracture. As we evaluate new therapeutics and consider treatments to prevent skeletal fractures, understanding the basic mechanics underlying whole bone testing and the key principles and characteristics contributing to the structural strength of a bone is critical. We therefore asked: (1) How are whole bone mechanical tests performed and what are the key outcomes measured? (2) How do the intrinsic characteristics of bone tissue contribute to the mechanical properties of a whole bone? (3) What are the effects of extrinsic characteristics on whole bone mechanical behavior? (4) Do environmental factors affect whole bone mechanical properties? We conducted a PubMed search using specific search terms and limiting our included articles to those related to in vitro testing of whole bones. Basic solid mechanics concepts are summarized in the context of whole bone testing and the determinants of whole bone behavior. Whole bone mechanical tests measure structural stiffness and strength from load-deformation data. Whole bone stiffness and strength are a function of total bone mass and the tissue geometric distribution and material properties. Age, sex, genetics, diet, and activity contribute to bone structural performance and affect the incidence of skeletal fractures. Understanding and preventing skeletal fractures is clinically important. Laboratory tests of whole bone strength are currently the only measures for in vivo fracture prediction. In the future, combined imaging and engineering models may be able to predict whole bone strength noninvasively.

Mechanical Characterization of Bone: State of the Art in Experimental Approaches-What Types of Experiments Do People Do and How Does One Interpret the Results?

PubMed

Bailey, Stacyann; Vashishth, Deepak

2018-06-18

The mechanical integrity of bone is determined by the direct measurement of bone mechanical properties. This article presents an overview of the current, most common, and new and upcoming experimental approaches for the mechanical characterization of bone. The key outcome variables of mechanical testing, as well as interpretations of the results in the context of bone structure and biology are also discussed. Quasi-static tests are the most commonly used for determining the resistance to structural failure by a single load at the organ (whole bone) level. The resistance to crack initiation or growth by fracture toughness testing and fatigue loading offers additional and more direct characterization of tissue material properties. Non-traditional indentation techniques and in situ testing are being increasingly used to probe the material properties of bone ultrastructure. Destructive ex vivo testing or clinical surrogate measures are considered to be the gold standard for estimating fracture risk. The type of mechanical test used for a particular investigation depends on the length scale of interest, where the outcome variables are influenced by the interrelationship between bone structure and composition. Advancement in the sensitivity of mechanical characterization techniques to detect changes in bone at the levels subjected to modifications by aging, disease, and/or pharmaceutical treatment is required. As such, a number of techniques are now available to aid our understanding of the factors that contribute to fracture risk.

Live load testing and load rating of five reinforced concrete bridges.

DOT National Transportation Integrated Search

2014-10-01

Five cast-in-place concrete T-beam bridges Eustis #5341, Whitefield #3831, Cambridge #3291, Eddington #5107, : and Albion #2832 were live load tested. Revised load ratings were computed either using test data or detailed : analysis when possi...

Crippling load test of Budd Pioneer Car 244, test 3.

DOT National Transportation Integrated Search

2013-04-01

This report summarizes Test 3, a crippling load test on Budd Pioneer Car 244, conducted on June 28, 2011. Before the crippling load test, Transportation Technology Center, Inc., conducted two 800,000-pound (lb) quasi-static tests on Car 244 in accord...

Load apparatus and method for bolt-loaded compact tension test specimen

DOEpatents

Buescher, B.J. Jr.; Lloyd, W.R.; Ward, M.B.; Epstein, J.S.

1997-02-04

A bolt-loaded compact tension test specimen load apparatus includes: (a) a body having first and second opposing longitudinal ends, the first end comprising an externally threaded portion sized to be threadedly received within the test specimen threaded opening; (b) a longitudinal loading rod having first and second opposing longitudinal ends, the loading rod being slidably received in a longitudinal direction within the body internally through the externally threaded portion and slidably extending longitudinally outward of the body first longitudinal end; (c) a force sensitive transducer slidably received within the body and positioned to engage relative to the loading rod second longitudinal end; and (d) a loading bolt threadedly received relative to the body, the loading bolt having a bearing end surface and being positioned to bear against the transducer to forcibly sandwich the transducer between the loading bolt and loading rod. Also disclosed is a method of in situ determining applied force during crack propagation in a bolt-loaded compact tension test specimen. 6 figs.

Load apparatus and method for bolt-loaded compact tension test specimen

DOEpatents

Buescher, Jr., Brent J.; Lloyd, W. Randolph; Ward, Michael B.; Epstein, Jonathan S.

1997-01-01

A bolt-loaded compact tension test specimen load apparatus includes: a) a body having first and second opposing longitudinal ends, the first end comprising an externally threaded portion sized to be threadedly received within the test specimen threaded opening; b) a longitudinal loading rod having first and second opposing longitudinal ends, the loading rod being slidably received in a longitudinal direction within the body internally through the externally threaded portion and slidably extending longitudinally outward of the body first longitudinal end; c) a force sensitive transducer slidably received within the body and positioned to engage relative to the loading rod second longitudinal end; and d) a loading bolt threadedly received relative to the body, the loading bolt having a bearing end surface and being positioned to bear against the transducer to forcibly sandwich the transducer between the loading bolt and loading rod. Also disclosed is a method of in situ determining applied force during crack propagation in a bolt-loaded compact tension test specimen.

Opening Loads Analyses for Various Disk-Gap-Band Parachutes

NASA Technical Reports Server (NTRS)

Cruz, J. R.; Kandis, M.; Witkowski, A.

2003-01-01

Detailed opening loads data is presented for 18 tests of Disk-Gap-Band (DGB) parachutes of varying geometry with nominal diameters ranging from 43.2 to 50.1 ft. All of the test parachutes were deployed from a mortar. Six of these tests were conducted via drop testing with drop test vehicles weighing approximately 3,000 or 8,000 lb. Twelve tests were conducted in the National Full-Scale Aerodynamics Complex 80- by 120-foot wind tunnel at the NASA Ames Research Center. The purpose of these tests was to structurally qualify the parachute for the Mars Exploration Rover mission. A key requirement of all tests was that peak parachute load had to be reached at full inflation to more closely simulate the load profile encountered during operation at Mars. Peak loads measured during the tests were in the range from 12,889 to 30,027 lb. Of the two test methods, the wind tunnel tests yielded more accurate and repeatable data. Application of an apparent mass model to the opening loads data yielded insights into the nature of these loads. Although the apparent mass model could reconstruct specific tests with reasonable accuracy, the use of this model for predictive analyses was not accurate enough to set test conditions for either the drop or wind tunnel tests. A simpler empirical model was found to be suitable for predicting opening loads for the wind tunnel tests to a satisfactory level of accuracy. However, this simple empirical model is not applicable to the drop tests.

The signatures of acoustic emission waveforms from fatigue crack advancing in thin metallic plates

NASA Astrophysics Data System (ADS)

Yeasin Bhuiyan, Md; Giurgiutiu, Victor

2018-01-01

The acoustic emission (AE) waveforms from a fatigue crack advancing in a thin metallic plate possess diverse and complex spectral signatures. In this article, we analyze these waveform signatures in coordination with the load level during cyclic fatigue. The advancing fatigue crack may generate numerous AE hits while it grows under fatigue loading. We found that these AE hits can be sorted into various groups based on their AE waveform signatures. Each waveform group has a particular time-domain signal pattern and a specific frequency spectrum. This indicates that each group represents a certain AE event related to the fatigue crack growth behavior. In situ AE-fatigue experiments were conducted to monitor the fatigue crack growth with simultaneous measurement of AE signals, fatigue loading, and optical crack growth measurement. An in situ microscope was installed in the load-frame of the mechanical testing system (MTS) to optically monitor the fatigue crack growth and relate the AE signals with the crack growth measurement. We found the AE signal groups at higher load levels (75%-85% of maximum load) were different from the AE signal groups that happened at lower load levels (below 60% of load level). These AE waveform groups are highly related to the fatigue crack-related AE events. These AE signals mostly contain the higher frequency peaks (100 kHz, 230 kHz, 450 kHz, 550 kHz). Some AE signal groups happened as a clustered form that relates a sequence of small AE events within the fatigue crack. They happened at relatively lower load level (50%-60% of the maximum load). These AE signal groups may be related to crack friction and micro-fracture during the friction process. These AE signals mostly contain the lower frequency peaks (60 kHz, 100 kHz, 200 kHz). The AE waveform based analysis may give us comprehensive information of the metal fatigue.

A Methodology for Flight-Time Identification of Helicopter-Slung Load Frequency Response Characteristics Using CIFER

NASA Technical Reports Server (NTRS)

Sahai, Ranjana; Pierce, Larry; Cicolani, Luigi; Tischler, Mark

1998-01-01

Helicopter slung load operations are common in both military and civil contexts. The slung load adds load rigid body modes, sling stretching, and load aerodynamics to the system dynamics, which can degrade system stability and handling qualities, and reduce the operating envelope of the combined system below that of the helicopter alone. Further, the effects of the load on system dynamics vary significantly among the large range of loads, slings, and flight conditions that a utility helicopter will encounter in its operating life. In this context, military helicopters and loads are often qualified for slung load operations via flight tests which can be time consuming and expensive. One way to reduce the cost and time required to carry out these tests and generate quantitative data more readily is to provide an efficient method for analysis during the flight, so that numerous test points can be evaluated in a single flight test, with evaluations performed in near real time following each test point and prior to clearing the aircraft to the next point. Methodology for this was implemented at Ames and demonstrated in slung load flight tests in 1997 and was improved for additional flight tests in 1999. The parameters of interest for the slung load tests are aircraft handling qualities parameters (bandwidth and phase delay), stability margins (gain and phase margin), and load pendulum roots (damping and natural frequency). A procedure for the identification of these parameters from frequency sweep data was defined using the CIFER software package. CIFER is a comprehensive interactive package of utilities for frequency domain analysis previously developed at Ames for aeronautical flight test applications. It has been widely used in the US on a variety of aircraft, including some primitive flight time analysis applications.

40 CFR 201.27 - Procedures for: (1) Determining applicability of the locomotive load cell test stand standard and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... applicability of the locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving property; (2) measurement of locomotive load cell test stands more than 120 meters... locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving...

40 CFR 201.27 - Procedures for: (1) Determining applicability of the locomotive load cell test stand standard and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... applicability of the locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving property; (2) measurement of locomotive load cell test stands more than 120 meters... locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving...

40 CFR 201.27 - Procedures for: (1) Determining applicability of the locomotive load cell test stand standard and...

Code of Federal Regulations, 2012 CFR

2012-07-01

... applicability of the locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving property; (2) measurement of locomotive load cell test stands more than 120 meters... locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving...

40 CFR 201.27 - Procedures for: (1) Determining applicability of the locomotive load cell test stand standard and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... applicability of the locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving property; (2) measurement of locomotive load cell test stands more than 120 meters... locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving...

40 CFR 201.27 - Procedures for: (1) Determining applicability of the locomotive load cell test stand standard and...

Code of Federal Regulations, 2013 CFR

2013-07-01

... applicability of the locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving property; (2) measurement of locomotive load cell test stands more than 120 meters... locomotive load cell test stand standard and switcher locomotive standard by noise measurement on a receiving...

Effect of training with and without a load on military fitness tests and marksmanship.

PubMed

Swain, David P; Ringleb, Stacie I; Naik, Dayanand N; Butowicz, Courtney M

2011-07-01

The purpose of this study was to determine whether military-style training performed while carrying a weighted vest and backpack (Load condition) resulted in superior training adaptations (specifically, changes in military fitness and marksmanship) than did more conventional training (No-Load condition). A total of 33 college-aged men and women (16 Load, 17 No-Load) completed all testing and 9 weeks of training (1 h·d, 4 d·wk). No-Load training consisted of military calisthenics, sprints, agility drills, and running. Load training was similar except that running was replaced with stair climbing, and Load increased across the 9 weeks to 20 kg for women and 30 kg for men. Pretraining and posttraining, all subjects performed an uphill treadmill test with full load to determine peak oxygen consumption (VO(2)peak), the marine physical fitness test (PFT) and combat fitness test (CFT) without load, other fitness tests, and an indoor marksmanship test using a laser-fitted carbine. The marksmanship test was performed with full load and done before and immediately after a 200-m shuttle run performed in 60 seconds. Both groups significantly improved their VO(2)peak, PFT, and CFT scores by similar amounts. Pretraining, shooting score decreased significantly after the 200-m run and then rapidly recovered, with no difference between groups. A similar, but nonsignificant, pattern in shooting scores was seen in both groups posttraining. In conclusion, loaded training did not produce measurable advantages compared with unloaded training in this population. A strenuous anaerobic challenge caused a temporary reduction in marksmanship.

Structural qualification testing and operational loading on a fiberglass rotor blade for the Mod-OA wind turbine

NASA Technical Reports Server (NTRS)

Sullivan, T. L.

1983-01-01

Fatigue tests were performed on full- and half-scale root end sections, first to qualify the root retention design, and second to induce failure. Test methodology and results are presented. Two operational blades were proof tested to design limit load to ascertain buckling resistance. Measurements of natural frequency, damping ratio, and deflection under load made on the operational blades are documented. The tests showed that all structural design requirements were met or exceeded. Blade loads measured during 3000 hr of field operation were close to those expected. The measured loads validated the loads used in the fatigue tests and gave high confidence in the ability of the blades to achieve design life.

Field Test of Driven Pile Group under Lateral Loading

NASA Astrophysics Data System (ADS)

Gorska, Karolina; Rybak, Jaroslaw; Wyjadlowski, Marek

2017-12-01

All the geotechnical works need to be tested because the diversity of soil parameters is much higher than in other fields of construction. Horizontal load tests are necessary to determine the lateral capacity of driven piles subject to lateral load. Various load tests were carried out altogether on the test field in Kutno (Poland). While selecting the piles for load tests, different load combinations were taken into account. The piles with diverse length were chosen, on the basis of the previous tests of their length and integrity. The subsoil around the piles consisted of mineral soils: clays and medium compacted sands with the density index ID>0.50. The pile heads were free. The points of support of the “base” to which the dial gauges (displacement sensors) were fastened were located at the distance of 0.7 m from the side surface of the pile loaded laterally. In order to assure the independence of measurement, additional control (verifying) geodetic survey of the displacement of the piles subject to the load tests was carried out (by means of the alignment method). The trial load was imposed in stages by means of a hydraulic jack. The oil pressure in the actuator was corrected by means of a manual pump in order to ensure the constant value of the load in the on-going process of the displacement of the pile under test. On the basis of the obtained results it is possible to verify the numerical simulations of the behaviour of piles loaded by a lateral force.

Monitoring Workload in Throwing-Dominant Sports: A Systematic Review.

PubMed

Black, Georgia M; Gabbett, Tim J; Cole, Michael H; Naughton, Geraldine

2016-10-01

The ability to monitor training load accurately in professional sports is proving vital for athlete preparedness and injury prevention. While numerous monitoring techniques have been developed to assess the running demands of many team sports, these methods are not well suited to throwing-dominant sports that are infrequently linked to high running volumes. Therefore, other techniques are required to monitor the differing demands of these sports to ensure athletes are adequately prepared for competition. To investigate the different methodologies used to quantitatively monitor training load in throwing-dominant sports. A systematic review of the methods used to monitor training load in throwing-dominant sports was conducted using variations of terms that described different load-monitoring techniques and different sports. Studies included in this review were published prior to June 2015 and were identified through a systematic search of four electronic databases including Academic Search Complete, CINAHL, Medline and SPORTDiscus. Only full-length peer-reviewed articles investigating workload monitoring in throwing-dominant sports were selected for review. A total of 8098 studies were initially retrieved from the four databases and 7334 results were removed as they were either duplicates, review articles, non-peer-reviewed articles, conference abstracts or articles written in languages other than English. After screening the titles and abstracts of the remaining papers, 28 full-text papers were reviewed, resulting in the identification of 20 articles meeting the inclusion criteria for monitoring workloads in throwing-dominant sports. Reference lists of selected articles were then scanned to identify other potential articles, which yielded one additional article. Ten articles investigated workload monitoring in cricket, while baseball provided eight results, and handball, softball and water polo each contributed one article. Results demonstrated varying techniques used to monitor workload and purposes for monitoring workload, encompassing the relationship between workload and injury, individual responses to workloads, the effect of workload on subsequent performance and the future directions of workload-monitoring techniques. This systematic review highlighted a number of simple and effective workload-monitoring techniques implemented across a variety of throwing-dominant sports. The current literature placed an emphasis on the relationship between workload and injury. However, due to differences in chronological and training age, inconsistent injury definitions and time frames used for monitoring, injury thresholds remain unclear in throwing-dominant sports. Furthermore, although research has examined total workload, the intensity of workload is often neglected. Additional research on the reliability of self-reported workload data is also required to validate existing relationships between workload and injury. Considering the existing disparity within the literature, it is likely that throwing-dominant sports would benefit from the development of an automated monitoring tool to objectively assess throwing-related workloads in conjunction with well-established internal measures of load in athletes.

Demonstration of load rating capabilities through physical load testing : Sioux County bridge case study.

DOT National Transportation Integrated Search

2013-08-01

The objective of this work, Pilot Project - Demonstration of Capabilities and Benefits of Bridge Load Rating through Physical Testing, was to demonstrate the capabilities for load testing and rating bridges in Iowa, study the economic benefit of perf...

Demonstration of load rating capabilities through physical load testing : Ida County bridge case study.

DOT National Transportation Integrated Search

2013-08-01

The objective of this work, Pilot Project - Demonstration of Capabilities and Benefits of Bridge Load Rating through Physical Testing, was to demonstrate the capabilities for load testing and rating bridges in Iowa, study the economic benefit of perf...

Demonstration of load rating capabilities through physical load testing : Johnson County bridge case study.

DOT National Transportation Integrated Search

2013-08-01

The objective of this work, Pilot Project - Demonstration of Capabilities and Benefits of Bridge Load Rating through Physical Testing, was to demonstrate the capabilities for load testing and rating bridges in Iowa, study the economic benefit of perf...

Simulation of Laboratory Tests of Steel Arch Support

NASA Astrophysics Data System (ADS)

Horyl, Petr; Šňupárek, Richard; Maršálek, Pavel; Pacześniowski, Krzysztof

2017-03-01

The total load-bearing capacity of steel arch yielding roadways supports is among their most important characteristics. These values can be obtained in two ways: experimental measurements in a specialized laboratory or computer modelling by FEM. Experimental measurements are significantly more expensive and more time-consuming. However, for proper tuning, a computer model is very valuable and can provide the necessary verification by experiment. In the cooperating workplaces of GIG Katowice, VSB-Technical University of Ostrava and the Institute of Geonics ASCR this verification was successful. The present article discusses the conditions and results of this verification for static problems. The output is a tuned computer model, which may be used for other calculations to obtain the load-bearing capacity of other types of steel arch supports. Changes in other parameters such as the material properties of steel, size torques, friction coefficient values etc. can be determined relatively quickly by changing the properties of the investigated steel arch supports.

Characterisation of a hybrid, fuel-cell-based propulsion system for small unmanned aircraft

NASA Astrophysics Data System (ADS)

Verstraete, D.; Lehmkuehler, K.; Gong, A.; Harvey, J. R.; Brian, G.; Palmer, J. L.

2014-03-01

Advanced hybrid powerplants combining a fuel cell and battery can enable significantly higher endurance for small, electrically powered unmanned aircraft systems, compared with batteries alone. However, detailed investigations of the static and dynamic performance of such systems are required to address integration challenges. This article describes a series of tests used to characterise the Horizon Energy Systems' AeroStack hybrid, fuel-cell-based powertrain. The results demonstrate that a significant difference can exist between the dynamic performance of the fuel-cell system and its static polarisation curve, confirming the need for detailed measurements. The results also confirm that the AeroStack's lithium-polymer battery plays a crucial role in its response to dynamic load changes and protects the fuel cell from membrane dehydration and fuel starvation. At low static loads, the AeroStack fuel cell recharges the battery with currents up to 1 A, which leads to further differences with the polarisation curve.

A Three-Parameter Model for Predicting Fatigue Life of Ductile Metals Under Constant Amplitude Multiaxial Loading

NASA Astrophysics Data System (ADS)

Liu, Jia; Li, Jing; Zhang, Zhong-ping

2013-04-01

In this article, a fatigue damage parameter is proposed to assess the multiaxial fatigue lives of ductile metals based on the critical plane concept: Fatigue crack initiation is controlled by the maximum shear strain, and the other important effect in the fatigue damage process is the normal strain and stress. This fatigue damage parameter introduces a stress-correlated factor, which describes the degree of the non-proportional cyclic hardening. Besides, a three-parameter multiaxial fatigue criterion is used to correlate the fatigue lifetime of metallic materials with the proposed damage parameter. Under the uniaxial loading, this three-parameter model reduces to the recently developed Zhang's model for predicting the uniaxial fatigue crack initiation life. The accuracy and reliability of this three-parameter model are checked against the experimental data found in literature through testing six different ductile metals under various strain paths with zero/non-zero mean stress.

Application of Novel Lateral Tire Force Sensors to Vehicle Parameter Estimation of Electric Vehicles

PubMed Central

Nam, Kanghyun

2015-01-01

This article presents methods for estimating lateral vehicle velocity and tire cornering stiffness, which are key parameters in vehicle dynamics control, using lateral tire force measurements. Lateral tire forces acting on each tire are directly measured by load-sensing hub bearings that were invented and further developed by NSK Ltd. For estimating the lateral vehicle velocity, tire force models considering lateral load transfer effects are used, and a recursive least square algorithm is adapted to identify the lateral vehicle velocity as an unknown parameter. Using the estimated lateral vehicle velocity, tire cornering stiffness, which is an important tire parameter dominating the vehicle’s cornering responses, is estimated. For the practical implementation, the cornering stiffness estimation algorithm based on a simple bicycle model is developed and discussed. Finally, proposed estimation algorithms were evaluated using experimental test data. PMID:26569246

Design automation of load-bearing arched structures of roofs of tall buildings

NASA Astrophysics Data System (ADS)

Kulikov, Vladimir

2018-03-01

The article considers aspects of the possible use of arched roofs in the construction of skyscrapers. Tall buildings experience large load from various environmental factors. Skyscrapers are subject to various and complex types of deformation of its structural elements. The paper discusses issues related to the aerodynamics of various structural elements of tall buildings. The technique of solving systems of equations state method of Simpson. The article describes the optimization of geometric parameters of bearing elements of the arched roofs of skyscrapers.

Using Maximal Isometric Force to Determine the Optimal Load for Measuring Dynamic Muscle Power

NASA Technical Reports Server (NTRS)

Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason R.; Nash, Roxanne E.; Sinka, Joseph; Bloomberg, Jacob J.

2009-01-01

Maximal power output occurs when subjects perform ballistic exercises using loads of 30-50% of one-repetition maximum (1-RM). However, performing 1-RM testing prior to power measurement requires considerable time, especially when testing involves multiple exercises. Maximal isometric force (MIF), which requires substantially less time to measure than 1-RM, might be an acceptable alternative for determining the optimal load for power testing. PURPOSE: To determine the optimal load based on MIF for maximizing dynamic power output during leg press and bench press exercises. METHODS: Twenty healthy volunteers (12 men and 8 women; mean +/- SD age: 31+/-6 y; body mass: 72 +/- 15 kg) performed isometric leg press and bench press movements, during which MIF was measured using force plates. Subsequently, subjects performed ballistic leg press and bench press exercises using loads corresponding to 20%, 30%, 40%, 50%, and 60% of MIF presented in randomized order. Maximal instantaneous power was calculated during the ballistic exercise tests using force plates and position transducers. Repeated-measures ANOVA and Fisher LSD post hoc tests were used to determine the load(s) that elicited maximal power output. RESULTS: For the leg press power test, six subjects were unable to be tested at 20% and 30% MIF because these loads were less than the lightest possible load (i.e., the weight of the unloaded leg press sled assembly [31.4 kg]). For the bench press power test, five subjects were unable to be tested at 20% MIF because these loads were less than the weight of the unloaded aluminum bar (i.e., 11.4 kg). Therefore, these loads were excluded from analysis. A trend (p = 0.07) for a main effect of load existed for the leg press exercise, indicating that the 40% MIF load tended to elicit greater power output than the 60% MIF load (effect size = 0.38). A significant (p . 0.05) main effect of load existed for the bench press exercise; post hoc analysis indicated that the effect of load on power output was: 30% > 40% > 50% = 60%. CONCLUSION: Loads of 40% and 30% of MIF elicit maximal power output during dynamic leg presses and bench presses, respectively. These findings are similar to those obtained when loading is based on 1-RM.

Performance deterioration due to acceptance testing and flight loads; JT90 jet engine diagnostic program

NASA Technical Reports Server (NTRS)

Olsson, W. J.

1982-01-01

The results of a flight loads test of the JT9D-7 engine are presented. The goals of this test program were to: measure aerodynamic and inertia loads on the engine during flight, explore the effects of airplane gross weight and typical maneuvers on these flight loads, simultaneously measure the changes in engine running clearances and performance resulting from the maneuvers, make refinements of engine performance deterioration prediction models based on analytical results of the tests, and make recommendations to improve propulsion system performance retention. The test program included a typical production airplane acceptance test plus additional flights and maneuvers to encompass the range of flight loads in revenue service. The test results indicated that aerodynamic loads, primarily at take-off, were the major cause of rub-indicated that aerodynamic loads, primarily at take-off, were the major cause of rub-induced deterioration in the cold sectin of the engine. Differential thermal expansion between rotating and static parts plus aerodynamic loads combined to cause blade-to-seal rubs in the turbine.

Vibration Testing of Electrical Cables to Quantify Loads at Tie-Down Locations

NASA Technical Reports Server (NTRS)

Dutson, Joseph D.

2013-01-01

The standard method for defining static equivalent structural load factors for components is based on Mile s equation. Unless test data is available, 5% critical damping is assumed for all components when calculating loads. Application of this method to electrical cable tie-down hardware often results in high loads, which often exceed the capability of typical tie-down options such as cable ties and P-clamps. Random vibration testing of electrical cables was used to better understand the factors that influence component loads: natural frequency, damping, and mass participation. An initial round of vibration testing successfully identified variables of interest, checked out the test fixture and instrumentation, and provided justification for removing some conservatism in the standard method. Additional testing is planned that will include a larger range of cable sizes for the most significant contributors to load as variables to further refine loads at cable tie-down points. Completed testing has provided justification to reduce loads at cable tie-downs by 45% with additional refinement based on measured cable natural frequencies.

Slow Crack Growth Analysis of Advanced Structural Ceramics Under Combined Loading Conditions: Damage Assessment in Life Prediction Testing

NASA Technical Reports Server (NTRS)

Choi, S. R.; Gyekenyesi, J. P.

2001-01-01

Slow crack growth analysis was performed with three different loading histories including constant stress- rate/constant stress-rate testing (Case I loading), constant stress/constant stress-rate testing (Case II loading), and cyclic stress/constant stress-rate testing (Case III loading). Strength degradation due to slow crack growth and/or damage accumulation was determined numerically as a function of percentage of interruption time between the two loading sequences for a given loading history. The numerical solutions were examined with the experimental data determined at elevated temperatures using four different advanced ceramic materials, two silicon nitrides, one silicon carbide and one alumina for the Case I loading history, and alumina for the Case II loading history. The numerical solutions were in reasonable agreement with the experimental data, indicating that notwithstanding some degree of creep deformation presented for some test materials slow crack growth was a governing mechanism associated with failure for all the rest materials.

Combined Loads Test Fixture for Thermal-Structural Testing Aerospace Vehicle Panel Concepts

NASA Technical Reports Server (NTRS)

Fields, Roger A.; Richards, W. Lance; DeAngelis, Michael V.

2004-01-01

A structural test requirement of the National Aero-Space Plane (NASP) program has resulted in the design, fabrication, and implementation of a combined loads test fixture. Principal requirements for the fixture are testing a 4- by 4-ft hat-stiffened panel with combined axial (either tension or compression) and shear load at temperatures ranging from room temperature to 915 F, keeping the test panel stresses caused by the mechanical loads uniform, and thermal stresses caused by non-uniform panel temperatures minimized. The panel represents the side fuselage skin of an experimental aerospace vehicle, and was produced for the NASP program. A comprehensive mechanical loads test program using the new test fixture has been conducted on this panel from room temperature to 500 F. Measured data have been compared with finite-element analyses predictions, verifying that uniform load distributions were achieved by the fixture. The overall correlation of test data with analysis is excellent. The panel stress distributions and temperature distributions are very uniform and fulfill program requirements. This report provides details of an analytical and experimental validation of the combined loads test fixture. Because of its simple design, this unique test fixture can accommodate panels from a variety of aerospace vehicle designs.

Progress in the Phase 0 Model Development of a STAR Concept for Dynamics and Control Testing

NASA Technical Reports Server (NTRS)

Woods-Vedeler, Jessica A.; Armand, Sasan C.

2003-01-01

The paper describes progress in the development of a lightweight, deployable passive Synthetic Thinned Aperture Radiometer (STAR). The spacecraft concept presented will enable the realization of 10 km resolution global soil moisture and ocean salinity measurements at 1.41 GHz. The focus of this work was on definition of an approximately 1/3-scaled, 5-meter Phase 0 test article for concept demonstration and dynamics and control testing. Design requirements, parameters and a multi-parameter, hybrid scaling approach for the dynamically scaled test model were established. The El Scaling Approach that was established allows designers freedom to define the cross section of scaled, lightweight structural components that is most convenient for manufacturing when the mass of the component is small compared to the overall system mass. Static and dynamic response analysis was conducted on analytical models to evaluate system level performance and to optimize panel geometry for optimal tension load distribution.

Experimental Performance Evaluation of a Supersonic Turbine for Rocket Engine Applications

NASA Technical Reports Server (NTRS)

Snellgrove, Lauren M.; Griffin, Lisa W.; Sieja, James P.; Huber, Frank W.

2003-01-01

In order to mitigate the risk of rocket propulsion development, efficient, accurate, detailed fluid dynamics analysis and testing of the turbomachinery is necessary. To support this requirement, a task was developed at NASA Marshall Space Flight Center (MSFC) to improve turbine aerodynamic performance through the application of advanced design and analysis tools. These tools were applied to optimize a supersonic turbine design suitable for a reusable launch vehicle (RLV). The hot gas path and blading were redesigned-to obtain an increased efficiency. The goal of the demonstration was to increase the total-to- static efficiency of the turbine by eight points over the baseline design. A sub-scale, cold flow test article modeling the final optimized turbine was designed, manufactured, and tested in air at MSFC s Turbine Airflow Facility. Extensive on- and off- design point performance data, steady-state data, and unsteady blade loading data were collected during testing.

Performance of the Xpert HIV-1 Viral Load Assay: a Systematic Review and Meta-analysis

PubMed Central

Nash, Madlen; Huddart, Sophie; Badar, Sayema; Baliga, Shrikala; Saravu, Kavitha

2018-01-01

ABSTRACT Viral load (VL) is the preferred treatment-monitoring approach for HIV-positive patients. However, more rapid, near-patient, and low-complexity assays are needed to scale up VL testing. The Xpert HIV-1 VL assay (Cepheid, Sunnyvale, CA) is a new, automated molecular test, and it can leverage the GeneXpert systems that are being used widely for tuberculosis diagnosis. We systematically reviewed the evidence on the performance of this new tool in comparison to established reference standards. A total of 12 articles (13 studies) in which HIV patient VLs were compared between Xpert HIV VL assay and a reference standard VL assay were identified. Study quality was generally high, but substantial variability was observed in the number and type of agreement measures reported. Correlation coefficients between Xpert and reference assays were high, with a pooled Pearson correlation (n = 8) of 0.94 (95% confidence interval [CI], 0.89, 0.97) and Spearman correlation (n = 3) of 0.96 (95% CI, 0.86, 0.99). Bland-Altman metrics (n = 11) all were within 0.35 log copies/ml of perfect agreement. Overall, Xpert HIV-1 VL performed well compared to current reference tests. The minimal training and infrastructure requirements for the Xpert HIV-1 VL assay make it attractive for use in resource-constrained settings, where point-of-care VL testing is most needed. PMID:29386266

Performance of the Xpert HIV-1 Viral Load Assay: a Systematic Review and Meta-analysis.

PubMed

Nash, Madlen; Huddart, Sophie; Badar, Sayema; Baliga, Shrikala; Saravu, Kavitha; Pai, Madhukar

2018-04-01

Viral load (VL) is the preferred treatment-monitoring approach for HIV-positive patients. However, more rapid, near-patient, and low-complexity assays are needed to scale up VL testing. The Xpert HIV-1 VL assay (Cepheid, Sunnyvale, CA) is a new, automated molecular test, and it can leverage the GeneXpert systems that are being used widely for tuberculosis diagnosis. We systematically reviewed the evidence on the performance of this new tool in comparison to established reference standards. A total of 12 articles (13 studies) in which HIV patient VLs were compared between Xpert HIV VL assay and a reference standard VL assay were identified. Study quality was generally high, but substantial variability was observed in the number and type of agreement measures reported. Correlation coefficients between Xpert and reference assays were high, with a pooled Pearson correlation ( n = 8) of 0.94 (95% confidence interval [CI], 0.89, 0.97) and Spearman correlation ( n = 3) of 0.96 (95% CI, 0.86, 0.99). Bland-Altman metrics ( n = 11) all were within 0.35 log copies/ml of perfect agreement. Overall, Xpert HIV-1 VL performed well compared to current reference tests. The minimal training and infrastructure requirements for the Xpert HIV-1 VL assay make it attractive for use in resource-constrained settings, where point-of-care VL testing is most needed. Copyright © 2018 Nash et al.

Combined experimental and numerical evaluation of a prototype nano-PCM enhanced wallboard

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

Biswas, Kaushik; LuPh.D., Jue; Soroushian, Parviz

2014-01-01

In the United States, forty-eight (48) percent of the residential end-use energy consumption is spent on space heating and air conditioning. Reducing envelope-generated heating and cooling loads through application of phase change material (PCM)-enhanced building envelopes can facilitate maximizing the energy efficiency of buildings. Combined experimental testing and numerical modeling of PCM-enhanced envelope components are two important aspects of the evaluation of their energy benefits. An innovative phase change material (nano-PCM) was developed with PCM encapsulated with expanded graphite (interconnected) nanosheets, which is highly conductive for enhanced thermal storage and energy distribution, and is shape-stable for convenient incorporation into lightweightmore » building components. A wall with cellulose cavity insulation and prototype PCM-enhanced interior wallboards was built and tested in a natural exposure test (NET) facility in a hot-humid climate location. The test wall contained PCM wallboards and regular gypsum wallboard, for a side-by-side annual comparison study. Further, numerical modeling of the walls containing the nano-PCM wallboard was performed to determine its actual impact on wall-generated heating and cooling loads. The model was first validated using experimental data, and then used for annual simulations using Typical Meteorological Year (TMY3) weather data. This article presents the measured performance and numerical analysis evaluating the energy-saving potential of the nano-PCM-enhanced wallboard.« less

A structured analysis of in vitro failure loads and failure modes of fiber, metal, and ceramic post-and-core systems.

PubMed

Fokkinga, Wietske A; Kreulen, Cees M; Vallittu, Pekka K; Creugers, Nico H J

2004-01-01

This study sought to aggregate literature data on in vitro failure loads and failure modes of prefabricated fiber-reinforced composite (FRC) post systems and to compare them to those of prefabricated metal, custom-cast, and ceramic post systems. The literature was searched using MEDLINE from 1984 to 2003 for dental articles in English. Keywords used were (post or core or buildup or dowel) and (teeth or tooth). Additional inclusion/exclusion steps were conducted, each step by two independent readers: (1) Abstracts describing post-and-core techniques to reconstruct endodontically treated teeth and their mechanical and physical characteristics were included (descriptive studies or reviews were excluded); (2) articles that included FRC post systems were selected; (3) in vitro studies, single-rooted human teeth, prefabricated FRC posts, and composite as the core material were the selection criteria; and (4) failure loads and modes were extracted from the selected papers, and failure modes were dichotomized (distinction was made between "favorable failures," defined as reparable failures, and "unfavorable failures,"defined as irreparable [root] fractures). The literature search revealed 1,984 abstracts. Included were 244, 42, and 12 articles in the first, second, and third selection steps, respectively. Custom-cast post systems showed higher failure loads than prefabricated FRC post systems, whereas ceramic showed lower failure loads. Significantly more favorable failures occurred with prefabricated FRC post systems than with prefabricated and custom-cast metal post systems. The variable "post system" had a significant effect on mean failure loads. FRC post systems more frequently showed favorable failure modes than did metal post systems.

Torsional Vibration in the National Wind Technology Center’s 2.5-Megawatt Dynamometer

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

Sethuraman, Latha; Keller, Jonathan; Wallen, Robb

2016-08-31

This report documents the torsional drivetrain dynamics of the NWTC's 2.5-megawatt dynamometer as identified experimentally and as calculated using lumped parameter models using known inertia and stiffness parameters. The report is presented in two parts beginning with the identification of the primary torsional modes followed by the investigation of approaches to damp the torsional vibrations. The key mechanical parameters for the lumped parameter models and justification for the element grouping used in the derivation of the torsional modes are presented. The sensitivities of the torsional modes to different test article properties are discussed. The oscillations observed from the low-speed andmore » generator torque measurements were used to identify the extent of damping inherently achieved through active and passive compensation techniques. A simplified Simulink model of the dynamometer test article integrating the electro-mechanical power conversion and control features was established to emulate the torque behavior that was observed during testing. The torque response in the high-speed, low-speed, and generator shafts were tested and validated against experimental measurements involving step changes in load with the dynamometer operating under speed-regulation mode. The Simulink model serves as a ready reference to identify the torque sensitivities to various system parameters and to explore opportunities to improve torsional damping under different conditions.« less

Study on load test of 100m cross-reinforced deck type concrete box arch bridge

NASA Astrophysics Data System (ADS)

Shi, Jing Xian; Cheng, Ying Jie

2018-06-01

Found in the routine quality inspection of highway bridge that many vertical fractures on the main beam (10mT beam) of the steel reinforced concrete arch bridge near the hydropower station. In order to grasp the bearing capacity of this bridge under working conditions with cracks, the static load and dynamic load test of box arch bridge are carried out. The Midas civil theory is calculated by using the special plate trailer - 300 as the calculation load, and the deflection and stress of the critical section are tested by the equivalent cloth load in the test vehicle. The pulsation test, obstacles and no obstacle driving test were carried out. Experimental results show that the bridge under the condition of the test loads is in safe condition, main bearing component of the strength and stiffness meet the design requirements, the crack width does not increase, in the process of loading bridge overall work performance is good.

Water Based Phase Change Material Heat Exchanger Development

NASA Technical Reports Server (NTRS)

Hansen, Scott W.; Sheth, Ribik B.; Atwell, Matt; Cheek, Ann; Agarwal, Muskan; Hong, Steven; Patel, Aashini,; Nguyen, Lisa; Posada, Luciano

2014-01-01

In a cyclical heat load environment such as low Lunar orbit, a spacecraft’s radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a “topper” to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. Studies conducted in this paper investigate utilizing water’s high latent heat of formation as a PCM, as opposed to traditional waxes, and corresponding complications surrounding freezing water in an enclosed volume. Work highlighted in this study is primarily visual and includes understanding ice formation, freeze front propagation, and the solidification process of water/ice. Various test coupons were constructed of copper to emulate the interstitial pin configuration (to aid in conduction) of the proposed water PCM HX design. Construction of a prototypic HX was also completed in which a flexible bladder material and interstitial pin configurations were tested. Additionally, a microgravity flight was conducted where three copper test articles were frozen continuously during microgravity and 2-g periods and individual water droplets were frozen during microgravity.

Material fatigue data obtained by card-programmed hydraulic loading system

NASA Technical Reports Server (NTRS)

Davis, W. T.

1967-01-01

Fatigue tests using load distributions from actual loading histories encountered in flight are programmed on punched electronic accounting machine cards. With this hydraulic loading system, airframe designers can apply up to 55 load levels to a test specimen.

Influence of load type on power factor and harmonic composition of three-phase rectifier current

NASA Astrophysics Data System (ADS)

Nikolayzin, N. V.; Vstavskaya, E. V.; Konstantinov, V. I.; Konstantinova, O. V.

2018-05-01

This article is devoted to research of the harmonic composition of the three-phase rectifier current consumed when it operates with different types of load. The results are compared with Standard requirements.

Evaluation of the base/subgrade soil under repeated loading : phase II, in-box and ALF cyclic plate load tests.

DOT National Transportation Integrated Search

2012-03-01

This research study aims at evaluating the performance of base and subgrade soil in flexible pavements under repeated loading test conditions. For this purpose, an indoor cyclic plate load testing equipment was developed and used to conduct a series ...

14 CFR 23.726 - Ground load dynamic tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground load dynamic tests. 23.726 Section 23.726 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Landing Gear § 23.726 Ground load dynamic tests. (a) If compliance with the ground load requirements of...

14 CFR 23.726 - Ground load dynamic tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ground load dynamic tests. 23.726 Section 23.726 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Landing Gear § 23.726 Ground load dynamic tests. (a) If compliance with the ground load requirements of...

Embryonic genetic load in coastal Douglas-fir, Pseudotsuga menziesii var. menziesii.

Treesearch

Frank C. Sorensen

1969-01-01

Genetic load has been estimated for a number of outcrossing organisms, for example, Drosophila (Malogolowkin-Cohen et al. 1964), Tribolium (Levene et al. 1965), and man (Morton, Crow, and Muller 1956). However, little informaiton about load of deleterious genes in higher plants has been published. The purpose of this article is to provide some data on plants by...

Study of a High Voltage Ion Engine Power Supply

NASA Technical Reports Server (NTRS)

Stuart, Thomas A.; King, Roger J.; Mayer, Eric

1996-01-01

A complete laboratory breadboard version of a ion engine power converter was built and tested. This prototype operated on a line voltage of 80-120 Vdc, and provided output ratings of 1100 V at 1.8 kW, and 250 V at 20 mA. The high-voltage (HV) output voltage rating was revised from the original value of 1350 V at the beginning of the project. The LV output was designed to hold up during a 1-A surge current lasting up to 1 second. The prototype power converter included a internal housekeeping power supply which also operated from the line input. The power consumed in housekeeping was included in the overall energy budget presented for the ion engine converter. HV and LV output voltage setpoints were commanded through potentiometers. The HV converter itself reached its highest power efficiency of slightly over 93% at low line and maximum output. This would dip below 90% at high line. The no-load (rated output voltages, zero load current) power consumption of the entire system was less than 13 W. A careful loss breakdown shows that converter losses are predominately Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) conduction losses and HV rectifier snubbing losses, with the rectifier snubbing losses becoming predominant at high line. This suggests that further improvements in power efficiency could best be obtained by either developing a rectifier that was adequately protected against voltage overshoot with less snubbing, or by developing a pre-regulator to reduced the range of line voltage on the converter. The transient testing showed the converter to be fully protected against load faults, including a direct short-circuit from the HV output to the LV output terminals. Two currents sensors were used: one to directly detect any core ratcheting on the output transformer and re-initiate a soft start, and the other to directly detect a load fault and quickly shut down the converter for load protection. The finished converter has been extensively fault tested without failure. The finished converter has been packaged suitable for use as a laboratory prototype for further testing. The finished converter is readily transportable. An article on design issues for high voltage converters for ion engines is included as an attachement.

Load-bearing capacity of all-ceramic posterior inlay-retained fixed dental prostheses.

PubMed

Puschmann, Djamila; Wolfart, Stefan; Ludwig, Klaus; Kern, Matthias

2009-06-01

The purpose of this in vitro study was to compare the quasi-static load-bearing capacity of all-ceramic resin-bonded three-unit inlay-retained fixed dental prostheses (IRFDPs) made from computer-aided design/computer-aided manufacturing (CAD/CAM)-manufactured yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) frameworks with two different connector dimensions, with and without fatigue loading. Twelve IRFDPs each were made with connector dimensions 3 x 3 mm(2) (width x height) (control group) and 3 x 2 mm(2) (test group). Inlay-retained fixed dental prostheses were adhesively cemented on identical metal-models using composite resin cement. Subgroups of six specimens each were fatigued with maximal 1,200,000 loading cycles in a chewing simulator with a weight load of 25 kg and a load frequency of 1.5 Hz. The load-bearing capacity was tested in a universal testing machine for IRFDPs without fatigue loading and for IRFDPs that had not already fractured during fatigue loading. During fatigue testing one IRFDP (17%) of the test group failed. Under both loading conditions, IRFDPs of the control group exhibited statistically significantly higher load-bearing capacities than the test group. Fatigue loading reduced the load-bearing capacity in both groups. Considering the maximum chewing forces in the molar region, it seems possible to use zirconia ceramic as a core material for IRFDPs with a minimum connector dimension of 9 mm(2). A further reduction of the connector dimensions to 6 mm(2) results in a significant reduction of the load-bearing capacity.

Interaction of threat and verbal working memory in adolescents.

PubMed

Patel, Nilam; Vytal, Katherine; Pavletic, Nevia; Stoodley, Catherine; Pine, Daniel S; Grillon, Christian; Ernst, Monique

2016-04-01

Threat induces a state of sustained anxiety that can disrupt cognitive processing, and, reciprocally, cognitive processing can modulate an anxiety response to threat. These effects depend on the level of cognitive engagement, which itself varies as a function of task difficulty. In adults, we recently showed that induced anxiety impaired working memory accuracy at low and medium but not high load. Conversely, increasing the task load reduced the physiological correlates of anxiety (anxiety-potentiated startle). The present work examines such threat-cognition interactions as a function of age. We expected threat to more strongly impact working memory in younger individuals by virtue of putatively restricted cognitive resources and weaker emotion regulation. This was tested by examining the influence of age on the interaction of anxiety and working memory in 25 adolescents (10 to 17 years) and 25 adults (22 to 46 years). Working memory load was manipulated using a verbal n-back task. Anxiety was induced using the threat of an aversive loud scream and measured via eyeblink startle. Findings revealed that, in both age groups, accuracy was lower during threat than safe conditions at low and medium but not high load, and reaction times were faster during threat than safe conditions at high load but did not differ at other loads. Additionally, anxiety-potentiated startle was greater during low and medium than high load. Thus, the interactions of anxiety with working memory appear similar in adolescents and adults. Whether these similarities reflect common neural mechanisms would need to be assessed using functional neuroimaging. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Towards scalable Byzantine fault-tolerant replication

NASA Astrophysics Data System (ADS)

Zbierski, Maciej

2017-08-01

Byzantine fault-tolerant (BFT) replication is a powerful technique, enabling distributed systems to remain available and correct even in the presence of arbitrary faults. Unfortunately, existing BFT replication protocols are mostly load-unscalable, i.e. they fail to respond with adequate performance increase whenever new computational resources are introduced into the system. This article proposes a universal architecture facilitating the creation of load-scalable distributed services based on BFT replication. The suggested approach exploits parallel request processing to fully utilize the available resources, and uses a load balancer module to dynamically adapt to the properties of the observed client workload. The article additionally provides a discussion on selected deployment scenarios, and explains how the proposed architecture could be used to increase the dependability of contemporary large-scale distributed systems.

Paramagnetic liposomes as innovative contrast agents for magnetic resonance (MR) molecular imaging applications.

PubMed

Terreno, Enzo; Delli Castelli, Daniela; Cabella, Claudia; Dastrù, Walter; Sanino, Alberto; Stancanello, Joseph; Tei, Lorenzo; Aime, Silvio

2008-10-01

This article illustrates some innovative applications of liposomes loaded with paramagnetic lanthanide-based complexes in MR molecular imaging field. When a relatively high amount of a Gd(III) chelate is encapsulated in the vesicle, the nanosystem can simultaneously affect both the longitudinal (R(1)) and the transverse (R(2)) relaxation rate of the bulk H2O H-atoms, and this finding can be exploited to design improved thermosensitive liposomes whose MRI response is not longer dependent on the concentration of the probe. The observation that the liposome compartmentalization of a paramagnetic Ln(III) complex induce a significant R(2) enhancement, primarily caused by magnetic susceptibility effects, prompted us to test the potential of such agents in cell-targeting MR experiments. The results obtained indicated that these nanoprobes may have a great potential for the MR visualization of cellular targets (like the glutamine membrane transporters) overexpressing in tumor cells. Liposomes loaded with paramagnetic complexes acting as NMR shift reagents have been recently proposed as highly sensitive CEST MRI agents. The main peculiarity of CEST probes is to allow the MR visualization of different agents present in the same region of interest, and this article provides an illustrative example of the in vivo potential of liposome-based CEST agents.

24 CFR 3280.402 - Test procedure for roof trusses.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) Nondestructive test procedure—(1) Dead load plus live load. (i) Noting figure A-1, measure and record initial... the truss equal to the full dead load of roof and ceiling. Measure and record deflections. (iii) Maintaining the dead load, add live load in approximate 1/4 design live load increments. Measure the...

24 CFR 3280.402 - Test procedure for roof trusses.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) Nondestructive test procedure—(1) Dead load plus live load. (i) Noting figure A-1, measure and record initial... the truss equal to the full dead load of roof and ceiling. Measure and record deflections. (iii) Maintaining the dead load, add live load in approximate 1/4 design live load increments. Measure the...

Twenty years of load theory-Where are we now, and where should we go next?

PubMed

Murphy, Gillian; Groeger, John A; Greene, Ciara M

2016-10-01

Selective attention allows us to ignore what is task-irrelevant and focus on what is task-relevant. The cognitive and neural mechanisms that underlie this process are key topics of investigation in cognitive psychology. One of the more prominent theories of attention is perceptual load theory, which suggests that the efficiency of selective attention is dependent on both perceptual and cognitive load. It is now more than 20 years since the proposal of load theory, and it is a good time to evaluate the evidence in support of this influential model. The present article supplements and extends previous reviews (Lavie, Trends in Cognitive Sciences, 9, 75-82. doi: 10.1016/j.tics.2004.12.004 , 2005, Current Directions in Psychological Science, 19, 143-148. doi: 10.1177/0963721410370295 , 2010) by examining more recent research in what appears to be a rapidly expanding area. The article comprises five parts, examining (1) evidence for the effects of perceptual load on attention, (2) cognitive load, (3) individual differences under load, (4) alternative theories and criticisms, and (5) the future of load theory. We argue that the key next step for load theory will be the application of the model to real-world tasks. The potential benefits of applied attention research are numerous, and there is tentative evidence that applied research would provide strong support for the theory itself, as well as real-world benefits related to activities in which attention is crucial, such as driving and education.

Effect of simulated sampling disturbance on creep behaviour of rock salt

NASA Astrophysics Data System (ADS)

Guessous, Z.; Gill, D. E.; Ladanyi, B.

1987-10-01

This article presents the results of an experimental study of creep behaviour of a rock salt under uniaxial compression as a function of prestrain, simulating sampling disturbance. The prestrain was produced by radial compressive loading of the specimens prior to creep testing. The tests were conducted on an artifical salt to avoid excessive scattering of the results. The results obtained from several series of single-stage creep tests show that, at short-term, the creep response of salt is strongly affected by the preloading history of samples. The nature of this effect depends upon the intensity of radial compressive preloading, and its magnitude is a function of the creep stress level. The effect, however, decreases with increasing plastic deformation, indicating that large creep strains may eventually lead to a complete loss of preloading memory.

Data collection and analysis software development for rotor dynamics testing in spin laboratory

NASA Astrophysics Data System (ADS)

Abdul-Aziz, Ali; Arble, Daniel; Woike, Mark

2017-04-01

Gas turbine engine components undergo high rotational loading another complex environmental conditions. Such operating environment leads these components to experience damages and cracks that can cause catastrophic failure during flights. There are traditional crack detections and health monitoring methodologies currently being used which rely on periodic routine maintenances, nondestructive inspections that often times involve engine and components dis-assemblies. These methods do not also offer adequate information about the faults, especially, if these faults at subsurface or not clearly evident. At NASA Glenn research center, the rotor dynamics laboratory is presently involved in developing newer techniques that are highly dependent on sensor technology to enable health monitoring and prediction of damage and cracks in rotor disks. These approaches are noninvasive and relatively economical. Spin tests are performed using a subscale test article mimicking turbine rotor disk undergoing rotational load. Non-contact instruments such as capacitive and microwave sensors are used to measure the blade tip gap displacement and blade vibrations characteristics in an attempt develop a physics based model to assess/predict the faults in the rotor disk. Data collection is a major component in this experimental-analytical procedure and as a result, an upgrade to an older version of the data acquisition software which is based on LabVIEW program has been implemented to support efficiently running tests and analyze the results. Outcomes obtained from the tests data and related experimental and analytical rotor dynamics modeling including key features of the updated software are presented and discussed.

QM-8 final performance evaluation report: SEALS, volume 4

NASA Technical Reports Server (NTRS)

Nelsen, L. V.

1989-01-01

The Space Shuttle Redesigned Solid Rocket Motor (RSRM) static test of Qualification Motor-8 (QM-8) was conducted. The QM-8 test article was the fifth full-scale, full-duration test, and the third qualification motor to incorporate the redesigned case field joint and nozzle-to-case joint. This was the second static test conducted in the T-97 test facility, which is equipped with actuators for inducing external side loads to a 360 degree external tank (ET) attach ring during test motor operation, and permits heating/cooling of an entire motor. The QM-8 motor was cooled to a temperature which ensured that the maximum propellant mean bulk temperature (PMBT) of 40 F was achieved at firing. All test results are not included, but rather, the performance of the metal case, field joints, and nozzle-to-case joint is addressed. The involvement is studied of the Structural Applications and Structural Design Groups with the QM-8 test which includes: assembly procedures of the field and nozzle-to-case joints, joint leak check results, structural test results, and post-test inspection evaluations.

Piezocomposite Actuator Arrays for Correcting and Controlling Wavefront Error in Reflectors

NASA Technical Reports Server (NTRS)

Bradford, Samuel Case; Peterson, Lee D.; Ohara, Catherine M.; Shi, Fang; Agnes, Greg S.; Hoffman, Samuel M.; Wilkie, William Keats

2012-01-01

Three reflectors have been developed and tested to assess the performance of a distributed network of piezocomposite actuators for correcting thermal deformations and total wave-front error. The primary testbed article is an active composite reflector, composed of a spherically curved panel with a graphite face sheet and aluminum honeycomb core composite, and then augmented with a network of 90 distributed piezoelectric composite actuators. The piezoelectric actuator system may be used for correcting as-built residual shape errors, and for controlling low-order, thermally-induced quasi-static distortions of the panel. In this study, thermally-induced surface deformations of 1 to 5 microns were deliberately introduced onto the reflector, then measured using a speckle holography interferometer system. The reflector surface figure was subsequently corrected to a tolerance of 50 nm using the actuators embedded in the reflector's back face sheet. Two additional test articles were constructed: a borosilicate at window at 150 mm diameter with 18 actuators bonded to the back surface; and a direct metal laser sintered reflector with spherical curvature, 230 mm diameter, and 12 actuators bonded to the back surface. In the case of the glass reflector, absolute measurements were performed with an interferometer and the absolute surface was corrected. These test articles were evaluated to determine their absolute surface control capabilities, as well as to assess a multiphysics modeling effort developed under this program for the prediction of active reflector response. This paper will describe the design, construction, and testing of active reflector systems under thermal loads, and subsequent correction of surface shape via distributed peizeoelctric actuation.

Freezable Radiator Coupon Testing and Full Scale Radiator Design

NASA Technical Reports Server (NTRS)

Lillibridge, Sean T.; Guinn, John; Cognata, Thomas; Navarro, Moses

2009-01-01

Freezable radiators offer an attractive solution to the issue of thermal control system scalability. As thermal environments change, a freezable radiator will effectively scale the total heat rejection it is capable of as a function of the thermal environment and flow rate through the radiator. Scalable thermal control systems are a critical technology for spacecraft that will endure missions with widely varying thermal requirements. These changing requirements are a result of the space craft s surroundings and because of different thermal loads during different mission phases. However, freezing and thawing (recovering) a radiator is a process that has historically proven very difficult to predict through modeling, resulting in highly inaccurate predictions of recovery time. This paper summarizes tests on three test articles that were performed to further empirically quantify the behavior of a simple freezable radiator, and the culmination of those tests into a full scale design. Each test article explored the bounds of freezing and recovery behavior, as well as providing thermo-physical data of the working fluid, a 50-50 mixture of DowFrost HD and water. These results were then used as a tool for developing correlated thermal model in Thermal Desktop which could be used for modeling the behavior of a full scale thermal control system for a lunar mission. The final design of a thermal control system for a lunar mission is also documented in this paper.

Development and Realization of a Shock Wave Test on Expert Flap Qualification Model

NASA Astrophysics Data System (ADS)

De Fruytier, C.; Dell'Orco, F.; Ullio, R.; Gomiero, F.

2012-07-01

This paper presents the methodology and the results of the shock test campaign conducted by TAS-I and TAS ETCA to qualify the EXPERT Flap in regards of shock wave and acoustic load generated by pyrocord detonation at stages 2/3 separation phase of the EXPERT vehicle. The design concept of the open flap (manufactured by MT AEROSPACE) is a fully integral manufactured, four sided control surface, with an additional stiffening rib and flanges to meet the first eigenfrequency and the allowable deformation requirement with a minimum necessary mass. The objectives were to reproduce equivalent loading at test article level in terms of pulse duration, front pressure, front velocity and acoustic emission. The Thales Alenia Space ETCA pyrotechnic shock test device is usually used to produce high level shocks by performing a shock on a test fixture supporting the unit under test. In this case, the facility has been used to produce a shock wave, with different requested physical characteristics, directed to the unit under test. Different configurations have been tried on a dummy of the unit to test, following an empirical process. This unusual work has lead to the definition of a nominal set- up meeting the requested physical parameters. Two blast sensors have been placed to acquire the pressure around the flap. The distance between the two sensors has allowed estimating the front pressure velocity. Then, several locations have been selected to acquire the acceleration responses on the unit when it was submitted to this environment. Additionally, a “standard” shock test has been performed on this model. The qualification of the flap, in regards of shock environment, has been successfully conducted.

The European Spacelab structural design evolution

NASA Technical Reports Server (NTRS)

Thirkettle, A. J.

1982-01-01

Spacelab is a manned, reusable laboratory which is being developed for the European Space Agency (ESA). In its working mode it will fly in low earth orbit in the cargo bay of the Shuttle Transportation System (STS) Orbiter. A description is presented of the structural development of the various features of Spacelab. System requirements are considered along with structural requirements, quasi-static loads, acoustic loads, pressure loads, crash loads, ground loads, and the fatigue profile. Aspects of thermal environment generation are discussed, and questions regarding the design evolution of the pallet structure are examined. Details of pallet structure testing are reported, taking into account static strength tests, acoustic tests, the modal survey test, crash tests, and fatigue/fracture mechanics testing.

Milestone 4: Test plan for Reusable Hydrogen Composite Tank System (RHCTS). Task 3: Composite tank materials

NASA Technical Reports Server (NTRS)

Greenberg, H. S.

1994-01-01

This document is the detailed test plan for the series of tests enumerated in the preceding section. The purpose of this plan is to present the test objectives, test parameters and procedures, expected performance and data analysis plans, criteria for success, test schedules, and related safety provisions and to describe the test articles, test instrumentation, and test facility requirements. Initial testing will be performed to screen four composite materials for suitability for SSTO LH2 tank loads and environmental conditions. The laminates for this testing will be fabricated by fiber placement, which is the manufacturing approach identified as baseline for the tank wall. Even though hand layup will be involved in fabricating many of the internal structural members of the tank, no hand-layup laminates will be evaluated in the screening or subsequent characterization testing. This decision is based on the understanding that mechanical properties measured for hand-layup material should be at least equivalent to properties measured for fiber-placed material, so that the latter should provide no less than a conservative approximation of the former. A single material will be downselected from these screening tests. This material will be subsequently characterized for impact-damage tolerance and durability under conditions of mechanical and thermal cycling, and to establish a preliminary design database to support ongoing analysis. Next, testing will be performed on critical structural elements fabricated from the selected material. Finally, the 8-foot diameter tank article, containing the critical structural features of the full-scale tank, will be fabricated by fiber placement and tested to verify its structural integrity and LH2 containment.

Flight Test Identification and Simulation of a UH-60A Helicopter and Slung Load

NASA Technical Reports Server (NTRS)

Cicolani, Luigi S.; Sahai, Ranjana; Tucker, George E.; McCoy, Allen H.; Tyson, Peter H.; Tischler, Mark B.; Rosen, Aviv

2001-01-01

Helicopter slung-load operations are common in both military and civil contexts. Helicopters and loads are often qualified for these operations by means of flight tests, which can be expensive and time consuming. There is significant potential to reduce such costs both through revisions in flight-test methods and by using validated simulation models. To these ends, flight tests were conducted at Moffett Field to demonstrate the identification of key dynamic parameters during flight tests (aircraft stability margins and handling-qualities parameters, and load pendulum stability), and to accumulate a data base for simulation development and validation. The test aircraft was a UH-60A Black Hawk, and the primary test load was an instrumented 8- by 6- by 6-ft cargo container. Tests were focused on the lateral and longitudinal axes, which are the axes most affected by the load pendulum modes in the frequency range of interest for handling qualities; tests were conducted at airspeeds from hover to 80 knots. Using telemetered data, the dynamic parameters were evaluated in near real time after each test airspeed and before clearing the aircraft to the next test point. These computations were completed in under 1 min. A simulation model was implemented by integrating an advanced model of the UH-60A aerodynamics, dynamic equations for the two-body slung-load system, and load static aerodynamics obtained from wind-tunnel measurements. Comparisons with flight data for the helicopter alone and with a slung load showed good overall agreement for all parameters and test points; however, unmodeled secondary dynamic losses around 2 Hz were found in the helicopter model and they resulted in conservative stability margin estimates.

Structural strength assessment of the reconstructed road structure in terms of the loading time and yield criterion

NASA Astrophysics Data System (ADS)

Mazurek, Grzegorz; Iwański, Marek

2018-05-01

This article reports the results of numerical simulations of the stress-strain states in the rebuilt road structure compared to the solutions contained in the Polish Catalogue, with the true characteristics of the layer materials taken into account. In the case analysed, a cold-recycled base layer with foamed bitumen as a recycling agent was used. The presented analysis is complementary to the mandatory in Poland procedure of mechanistic pavement design based on a linear elastic model. The temperature distribution in the road structure was analysed at the reference temperature of 40°C on the asphalt layer surface. The loading time was included in the computer simulations through the use of the classic generalized Maxwell model and thus the stiffness-time history of the layers had to be determined. For this purpose, the dynamic modulus E* tests of the loading time frequency from 0.1 Hz to 20 Hz were carried out, and the yield point was modelled using the Coulomb-Mohr failure criterion calculated on the basis of triaxial compression tests. The analytical solution to the problem was found with ABAQUS. The results demonstrate that the high temperature of asphalt layers and long loading time noticeably reduces the stiffness modulus in those layers. That reduction changes the principal stress levels, which significantly influences the shear stress both in the recycled base layer and in the subgrade soil. Should the yield point be exceeded rapidly in the recycled layer, the horizontal stresses in the asphalt layers will increase and adversely affect the durability of the reconstructed road pavement structure, especially in the zones of slow heavy vehicle traffic.

Wear behavior of pressable lithium disilicate glass ceramic.

PubMed

Peng, Zhongxiao; Izzat Abdul Rahman, Muhammad; Zhang, Yu; Yin, Ling

2016-07-01

This article reports effects of surface preparation and contact loads on abrasive wear properties of highly aesthetic and high-strength pressable lithium disilicate glass-ceramics (LDGC). Abrasive wear testing was performed using a pin-on-disk device in which LDGC disks prepared with different surface finishes were against alumina pins at different contact loads. Coefficients of friction and wear volumes were measured as functions of initial surface finishes and contact loads. Wear-induced surface morphology changes in both LDGC disks and alumina pins were characterized using three-dimensional laser scanning microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results show that initial surface finishes of LDGC specimens and contact loads significantly affected the friction coefficients, wear volumes and wear-induced surface roughness changes of the material. Both wear volumes and friction coefficients of LDGC increased as the load increased while surface roughness effects were complicated. For rough LDGC surfaces, three-body wear was dominant while for fine LDGC surfaces, two-body abrasive wear played a key role. Delamination, plastic deformation, and brittle fracture were observed on worn LDGC surfaces. The adhesion of LDGC matrix materials to alumina pins was also discovered. This research has advanced our understanding of the abrasive wear behavior of LDGC and will provide guidelines for better utilization and preparation of the material for long-term success in dental restorations. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 968-978, 2016. © 2015 Wiley Periodicals, Inc.

The influence of schizotypal traits on attention under high perceptual load.

PubMed

Stotesbury, Hanne; Gaigg, Sebastian B; Kirhan, Saim; Haenschel, Corinna

2018-03-01

Schizophrenia Spectrum Disorders (SSD) are known to be characterised by abnormalities in attentional processes, but there are inconsistencies in the literature that remain unresolved. This article considers whether perceptual resource limitations play a role in moderating attentional abnormalities in SSD. According to perceptual load theory, perceptual resource limitations can lead to attenuated or superior performance on dual-task paradigms depending on whether participants are required to process, or attempt to ignore, secondary stimuli. If SSD is associated with perceptual resource limitations, and if it represents the extreme end of an otherwise normally distributed neuropsychological phenotype, schizotypal traits in the general population should lead to disproportionate performance costs on dual-task paradigms as a function of the perceptual task demands. To test this prediction, schizotypal traits were quantified via the Schizotypal Personality Questionnaire (SPQ) in 74 healthy volunteers, who also completed a dual-task signal detection paradigm that required participants to detect central and peripheral stimuli across conditions that varied in the overall number of stimuli presented. The results confirmed decreasing performance as the perceptual load of the task increased. More importantly, significant correlations between SPQ scores and task performance confirmed that increased schizotypal traits, particularly in the cognitive-perceptual domain, are associated with greater performance decrements under increasing perceptual load. These results confirm that attentional difficulties associated with SSD extend sub-clinically into the general population and suggest that cognitive-perceptual schizotypal traits may represent a risk factor for difficulties in the regulation of attention under increasing perceptual load.

Maximum and minimum return losses from a passive two-port network terminated with a mismatched load

NASA Technical Reports Server (NTRS)

Otoshi, T. Y.

1993-01-01

This article presents an analytical method for determining the exact distance a load is required to be offset from a passive two-port network to obtain maximum or minimum return losses from the terminated two-port network. Equations are derived in terms of two-port network S-parameters and load reflection coefficient. The equations are useful for predicting worst-case performances of some types of networks that are terminated with offset short-circuit loads.

Multi-Objective Differential Evolution for Voltage Security Constrained Optimal Power Flow in Deregulated Power Systems

NASA Astrophysics Data System (ADS)

Roselyn, J. Preetha; Devaraj, D.; Dash, Subhransu Sekhar

2013-11-01

Voltage stability is an important issue in the planning and operation of deregulated power systems. The voltage stability problems is a most challenging one for the system operators in deregulated power systems because of the intense use of transmission line capabilities and poor regulation in market environment. This article addresses the congestion management problem avoiding offline transmission capacity limits related to voltage stability by considering Voltage Security Constrained Optimal Power Flow (VSCOPF) problem in deregulated environment. This article presents the application of Multi Objective Differential Evolution (MODE) algorithm to solve the VSCOPF problem in new competitive power systems. The maximum of L-index of the load buses is taken as the indicator of voltage stability and is incorporated in the Optimal Power Flow (OPF) problem. The proposed method in hybrid power market which also gives solutions to voltage stability problems by considering the generation rescheduling cost and load shedding cost which relieves the congestion problem in deregulated environment. The buses for load shedding are selected based on the minimum eigen value of Jacobian with respect to the load shed. In the proposed approach, real power settings of generators in base case and contingency cases, generator bus voltage magnitudes, real and reactive power demands of selected load buses using sensitivity analysis are taken as the control variables and are represented as the combination of floating point numbers and integers. DE/randSF/1/bin strategy scheme of differential evolution with self-tuned parameter which employs binomial crossover and difference vector based mutation is used for the VSCOPF problem. A fuzzy based mechanism is employed to get the best compromise solution from the pareto front to aid the decision maker. The proposed VSCOPF planning model is implemented on IEEE 30-bus system, IEEE 57 bus practical system and IEEE 118 bus system. The pareto optimal front obtained from MODE is compared with reference pareto front and the best compromise solution for all the cases are obtained from fuzzy decision making strategy. The performance measures of proposed MODE in two test systems are calculated using suitable performance metrices. The simulation results show that the proposed approach provides considerable improvement in the congestion management by generation rescheduling and load shedding while enhancing the voltage stability in deregulated power system.

Loading Patterns of the Posterior Cruciate Ligament in the Healthy Knee: A Systematic Review

PubMed Central

List, Renate; Oberhofer, Katja; Fucentese, Sandro F.; Snedeker, Jess G.; Taylor, William R.

2016-01-01

Background The posterior cruciate ligament (PCL) is the strongest ligament of the knee, serving as one of the major passive stabilizers of the tibio-femoral joint. However, despite a number of experimental and modelling approaches to understand the kinematics and kinetics of the ligament, the normal loading conditions of the PCL and its functional bundles are still controversially discussed. Objectives This study aimed to generate science-based evidence for understanding the functional loading of the PCL, including the anterolateral and posteromedial bundles, in the healthy knee joint through systematic review and statistical analysis of the literature. Data sources MEDLINE, EMBASE and CENTRAL Eligibility criteria for selecting studies Databases were searched for articles containing any numerical strain or force data on the healthy PCL and its functional bundles. Studied activities were as follows: passive flexion, flexion under 100N and 134N posterior tibial load, walking, stair ascent and descent, body-weight squatting and forward lunge. Method Statistical analysis was performed on the reported load data, which was weighted according to the number of knees tested to extract average strain and force trends of the PCL and identify deviations from the norms. Results From the 3577 articles retrieved by the initial electronic search, only 66 met all inclusion criteria. The results obtained by aggregating data reported in the eligible studies indicate that the loading patterns of the PCL vary with activity type, knee flexion angle, but importantly also the technique used for assessment. Moreover, different fibres of the PCL exhibit different strain patterns during knee flexion, with higher strain magnitudes reported in the anterolateral bundle. While during passive flexion the posteromedial bundle is either lax or very slightly elongated, it experiences higher strain levels during forward lunge and has a synergetic relationship with the anterolateral bundle. The strain patterns obtained for virtual fibres that connect the origin and insertion of the bundles in a straight line show similar trends to those of the real bundles but with different magnitudes. Conclusion This review represents what is now the best available understanding of the biomechanics of the PCL, and may help to improve programs for injury prevention, diagnosis methods as well as reconstruction and rehabilitation techniques. PMID:27880849

Space Electronic Test Engineering

NASA Technical Reports Server (NTRS)

Chambers, Rodney D.

2004-01-01

The Space Power and Propulsion Test Engineering Branch at NASA Glenn Research center has the important duty of controlling electronic test engineering services. These services include test planning and early assessment of Space projects, management and/or technical support required to safely and effectively prepare the article and facility for testing, operation of test facilities, and validation/delivery of data to customer. The Space Electronic Test Engineering Branch is assigned electronic test engineering responsibility for the GRC Space Simulation, Microgravity, Cryogenic, and Combustion Test Facilities. While working with the Space Power and Propulsion Test Engineering Branch I am working on several different assignments. My primary assignment deals with an electrical hardware unit known as Sunny Boy. Sunny Boy is a DC load Bank that is designed for solar arrays in which it is used to convert DC power form the solar arrays into AC power at 60 hertz to pump back into the electricity grid. However, there are some researchers who decided that they would like to use the Sunny Boy unit in a space simulation as a DC load bank for a space shuttle or even the International Space Station hardware. In order to do so I must create a communication link between a computer and the Sunny Boy unit so that I can preset a few of the limits (such power, set & constant voltage levels) that Sunny Boy will need to operate using the applied DC load. Apart from this assignment I am also working on a hi-tech circuit that I need to have built at a researcher s request. This is a high voltage analog to digital circuit that will be used to record data from space ion propulsion rocket booster tests. The problem that makes building this circuit so difficult is that it contains high voltage we must find a way to lower the voltage signal before the data is transferred into the computer to be read. The solution to this problem was to transport the signal using infrared light which will lower the voltage signal down low enough so that it is harmless to a computer. Along with my involvement in the Space Power and Propulsion Test Engineering Branch, I am obligated to assist all other members of the branch in their work. This will help me to strengthen and extend my knowledge of Electrical Engineering.

Launch Vehicle Stage Adapter from Start to Stack

NASA Image and Video Library

2016-10-16

See how a test version of the launch vehicle stage adapter (LVSA) for NASA's new rocket, the Space Launch System, is designed, built and stacked in a test stand at the agency's Marshall Space Flight Center in Huntsville, Alabama. The LVSA was moved to a 65-foot-tall test stand Oct. 12 at Marshall. The test version LVSA will be stacked with other test pieces of the upper part of the SLS rocket and pushed, pulled and twisted as part of an upcoming test series to ensure each structure can withstand the incredible stresses of launch. The LVSA joins the core stage simulator, which was loaded into the test stand Sept. 21. The other three qualification articles and the Orion simulator will complete the stack later this fall. Testing is scheduled to begin in early 2017. SLS will be the world’s most powerful rocket, and with the Orion spacecraft, take astronauts to deep-space destinations, including the Journey to Mars. More information on the upcoming test series can be found here: http://go.nasa.gov/2dS8yXB

An Analysis of the Load-Bearing Capacity of Timber-Concrete Composite Beams with Profiled Sheeting

NASA Astrophysics Data System (ADS)

Szumigała, Maciej; Szumigała, Ewa; Polus, Łukasz

2017-12-01

This paper presents an analysis of timber-concrete composite beams. Said composite beams consist of rectangular timber beams and concrete slabs poured into the steel sheeting. The concrete slab is connected with the timber beam using special shear connectors. The authors of this article are trying to patent these connectors. The article contains results from a numerical analysis. It is demonstrated that the type of steel sheeting used as a lost formwork has an influence on the load-bearing capacity and stiffness of the timber-concrete composite beams.

Accceleration of Fatigue Tests of Polymer Composite Materials by Using High-Frequency Loadings

NASA Astrophysics Data System (ADS)

Apinis, R.

2004-03-01

The possibility of using high-frequency loading in fatigue tests of polymer composite materials is discussed. A review of studies on the use of high-frequency loading of organic-, carbon-, and glass-fiber-reinforced plastics is presented. The results obtained are compared with those found in conventional low-frequency loadings. A rig for fatigue tests of rigid materials at loading frequencies to 500 Hz is described, and results for an LM-L1 unidirectional glass-fiber plastic in loadings with frequencies of 17 and 400 Hz are given. These results confirm that it is possible to accelerate the fatigue testing of polymer composite materials by considerably increasing the loading frequency. The necessary condition for using this method is an intense cooling of specimens to prevent them from vibration heating.

[Increasing the safety of ceramic femoral heads for hip prostheses].

PubMed

Willmann, G; Pfaff, H G; Richter, H G

1995-12-01

Since 1974 Biolox ceramic femoral ball heads have been used successfully for artificial modular hip joints. The revision rate due to ball head fracture is lower than 0.02%. This is an extremely low value. In this article it is shown how the safety of a ceramic ball head can be improved using the procedures of HIPing, engraving by laser technique, and 100% proof testing. By applying these means the materials properties density, grain size, grain size distribution, and the strength of the ball head, i.e. the fracture load can be improved significantly.

Development and Application of On-line Monitor for the ZLW-1 Axis Cracks

NASA Astrophysics Data System (ADS)

Shi-jun, Yang; Qian-hui, Yang; Jian-guo, Jin

2018-03-01

This article mainly introduces a method that uses acoustic emission techniques to achieve on-line monitor for the shaft cracks and crack growth. According to this method, axis crack monitor is produced by acoustic emission techniques. This instrument can apply to all the pressure vessels, pipelines and rotor machines that can bear buckling load. It has the online real-time monitoring, automatic recording, printing, sound and light alarm, collecting crack information function. After a series of tests in both laboratory and field, it shows that this instrument is very versatile and possesses broad prospects of development and application.

Load control system. [for space shuttle external tank ground tests

NASA Technical Reports Server (NTRS)

Grosse, J. C.

1977-01-01

The load control system developed for the shuttle external structural tests is described. The system consists of a load programming/display module, and a load control module along with the following hydraulic system components: servo valves, dump valves, hydraulic system components, and servo valve manifold blocks. One load programming/display subsystem can support multiple load control subsystem modules.

Identification of Load Categories in Rotor System Based on Vibration Analysis

PubMed Central

Yang, Zhaojian

2017-01-01

Rotating machinery is often subjected to variable loads during operation. Thus, monitoring and identifying different load types is important. Here, five typical load types have been qualitatively studied for a rotor system. A novel load category identification method for rotor system based on vibration signals is proposed. This method is a combination of ensemble empirical mode decomposition (EEMD), energy feature extraction, and back propagation (BP) neural network. A dedicated load identification test bench for rotor system was developed. According to loads characteristics and test conditions, an experimental plan was formulated, and loading tests for five loads were conducted. Corresponding vibration signals of the rotor system were collected for each load condition via eddy current displacement sensor. Signals were reconstructed using EEMD, and then features were extracted followed by energy calculations. Finally, characteristics were input to the BP neural network, to identify different load types. Comparison and analysis of identifying data and test data revealed a general identification rate of 94.54%, achieving high identification accuracy and good robustness. This shows that the proposed method is feasible. Due to reliable and experimentally validated theoretical results, this method can be applied to load identification and fault diagnosis for rotor equipment used in engineering applications. PMID:28726754

Analysis of Glenoid Fixation with Anatomic Total Shoulder Arthroplasty in an Extreme Cyclic Loading Scenario.

PubMed

Roche, Christopher P; Staunch, Cameron; Hahn, William; Grey, Sean G; Flurin, Pierre-Henri; Wright, Thomas W; Zuckerman, Joseph D

2015-12-01

ASTM F2028-14 was adopted to recom mend a cyclic eccentric glenoid edge loading test that simulates the rocking horse loading mechanism beleived to cause aTSA glenoid loosening. While this method accurately simulates that failure mechanism, the recommended 750 N load may not be sufficient to simulate worst-case loading magnitudes, and the recommended 100,000 cycles may not be sufficient to simulate device fatigue-related failure modes. Finally, if greater loading magnitude or a larger number of cycles is performed, the recommended substrate density may not be sufficiently strong to support the elevated loads and cycles. To this end, a new test method is proposed to supplement ASTM F2028-14. A series of cyclic tests were performed to evaluate the long-term fixation strength of two different hybrid glenoid designs in both low (15 pcf) and high (30 pcf) density polyurethane blocks at elevated loads relative to ASTM F2028-14. To simulate a worst case clinical condition in which the humeral head is superiorly migrated, a cyclic load was applied to the superior glenoid rim to induce a maximum torque on the fixation pegs for three different cyclic loading tests: 1. 1,250 N load for 0.75 M cycles in a 15 pcf block, 2. 1,250 N load for 1.5 M cycles in a 30 pcf block, and 3. 2,000 N load for 0.65 M cycles in a 30 pcf block. All devices completed cyclic loading without failure, fracture, or loss of fixation regardless of glenoid design, polyurethane density, loading magnitude, or cycle length. No significant difference in post-cyclic displacement was noted between designs in any of the three tests. Post-cyclic radiographs demonstrated that each device maintained fixa - tion with the metal pegs within the bone-substitute blocks with no fatigue related failures. These results demonstrate that both cemented hybrid glenoids maintained fixation when tested according to each cyclic loading scenario, with no difference in post-cyclic displacement observed between designs. The lack of fatigue-related failures in these elevated load and high cycle test scenarios are promising, as are the relatively low displacements given the extreme nature of each test. This cyclic loading method is intended to supplement the ASTM F2028-14 standard that adequately simulates the rocking horse loading mechanism but may not adequately simulate the fatigue-related failure modes.

Design of rock socketed drilled shafts

DOT National Transportation Integrated Search

1998-09-01

Three field load tests of drilled shafts socketed in Burlington limestone were conducted using the Osterberg load cell. The objective of these tests was to compare the shaft capacities obtained from the field load tests with capacities predicted usin...

Load-carriage distance run and push-ups tests: no body mass bias and occupationally relevant.

PubMed

Vanderburgh, Paul M; Mickley, Nicholas S; Anloague, Philip A

2011-09-01

Recent research has demonstrated body mass (M) bias in military physical fitness tests favoring lighter, not just leaner, service members. Mathematical modeling predicts that a distance run carrying a backpack of 30 lbs would eliminate M-bias. The purpose of this study was to empirically test this prediction for the U.S. Army push-ups and 2-mile run tests. Two tests were performed for both events for each of 56 university Reserve Officer Training Corps male cadets: with (loaded) and without backpack (unloaded). Results indicated significant M-bias in the unloaded and no M-bias in the loaded condition for both events. Allometrically scaled scores for both events were worse in the loaded vs. unloaded conditions, supporting a hypothesis not previously tested. The loaded push-ups and 2-mile run appear to remove M-bias and are probably more occupationally relevant as military personnel are often expected to carry external loads.

Improving laboratory efficiencies to scale-up HIV viral load testing.

PubMed

Alemnji, George; Onyebujoh, Philip; Nkengasong, John N

2017-03-01

Viral load measurement is a key indicator that determines patients' response to treatment and risk for disease progression. Efforts are ongoing in different countries to scale-up access to viral load testing to meet the Joint United Nations Programme on HIV and AIDS target of achieving 90% viral suppression among HIV-infected patients receiving antiretroviral therapy. However, the impact of these initiatives may be challenged by increased inefficiencies along the viral load testing spectrum. This will translate to increased costs and ineffectiveness of scale-up approaches. This review describes different parameters that could be addressed across the viral load testing spectrum aimed at improving efficiencies and utilizing test results for patient management. Though progress is being made in some countries to scale-up viral load, many others still face numerous challenges that may affect scale-up efficiencies: weak demand creation, ineffective supply chain management systems; poor specimen referral systems; inadequate data and quality management systems; and weak laboratory-clinical interface leading to diminished uptake of test results. In scaling up access to viral load testing, there should be a renewed focus to address efficiencies across the entire spectrum, including factors related to access, uptake, and impact of test results.

Test and evaluation of load converter topologies used in the Space Station Freedom Power Management and distribution DC test bed

NASA Technical Reports Server (NTRS)

Lebron, Ramon C.; Oliver, Angela C.; Bodi, Robert F.

1991-01-01

Power components hardware in support of the Space Station Freedom dc Electrical Power System were tested. One type of breadboard hardware tested is the dc Load Converter Unit, which constitutes the power interface between the electric power system and the actual load. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. Three load converters were tested: a series resonant converter, a series inductor switchmode converter, and a switching full-bridge forward converter. The topology, operation principles, and tests results are described, in general. A comparative analysis of the three units is given with respect to efficiency, regulation, short circuit behavior (protection), and transient characteristics.

Study of Strain-Stress Behavior of Non-Pressure Reinforced Concrete Pipes Used in Road Building

NASA Astrophysics Data System (ADS)

Rakitin, B. A.; Pogorelov, S. N.; Kolmogorova, A. O.

2017-11-01

The article contains the results of the full-scale tests performed for special road products - large-diameter non-pressure concrete pipes reinforced with a single space cylindrical frame manufactured with the technology of high-frequency vertical vibration molding with an immediate demolding. The authors studied the change in the strain-stress behavior of reinforced concrete pipes for underground pipeline laying depending on their laying depth in the trench and the transport load considering the properties of the surrounding ground mass. The strain-stress behavior of the reinforced concrete pipes was evaluated using the strain-gauge method based on the application of active resistance strain gauges. Based on the completed research, the authors made a conclusion on the applicability of a single space frame for reinforcement of large-diameter non-pressure concrete pipes instead of a double frame which allows one to significantly reduce the metal consumption for the production of one item. As a result of the full-scale tests of reinforced concrete pipes manufactured by vertical vibration molding, the authors obtained new data on the deformation of a pipeline cross-section depending on the placement of the transport load with regard to the axis.

Fast Acting Eddy Current Driven Valve for Massive Gas Injection on ITER

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

Lyttle, Mark S; Baylor, Larry R; Carmichael, Justin R

2015-01-01

Tokamak plasma disruptions present a significant challenge to ITER as they can result in intense heat flux, large forces from halo and eddy currents, and potential first-wall damage from the generation of multi-MeV runaway electrons. Massive gas injection (MGI) of high Z material using fast acting valves is being explored on existing tokamaks and is planned for ITER as a method to evenly distribute the thermal load of the plasma to prevent melting, control the rate of the current decay to minimize mechanical loads, and to suppress the generation of runaway electrons. A fast acting valve and accompanying power supplymore » have been designed and first test articles produced to meet the requirements for a disruption mitigation system on ITER. The test valve incorporates a flyer plate actuator similar to designs deployed on TEXTOR, ASDEX upgrade, and JET [1 3] of a size useful for ITER with special considerations to mitigate the high mechanical forces developed during actuation due to high background magnetic fields. The valve includes a tip design and all-metal valve stem sealing for compatibility with tritium and high neutron and gamma fluxes.« less

The Unintentional Memory Load in Tests for Young Children.

ERIC Educational Resources Information Center

Jones, Margaret Hubbard

The validity of certain standardized tests may be affected by the short-term memory load therein and its relation to a child's short-term memory capacity. Factors of testing which increase a test's memory load and consequently interfere with comprehension are discussed. It is hypothesized that a test which strains the short-term memory capacity of…

Locomotive fuel tank structural safety testing program : passenger locomotive fuel tank jackknife derailment load test.

DOT National Transportation Integrated Search

2010-08-01

This report presents the results of a passenger locomotive fuel tank load test simulating jackknife derailment (JD) load. The test is based on FRA requirements for locomotive fuel tanks in the Title 49, Code of Federal Regulations (CFR), Part 238, Ap...

49 CFR 178.1055 - Stacking test.

Code of Federal Regulations, 2014 CFR

2014-10-01

... and no loss of contents during the test or after removal of the test load. ... to a uniformly distributed superimposed test load that is four times the design type maximum gross weight for a period of at least twenty-four hours. (2) For all Flexible Bulk Containers, the load must be...

49 CFR 178.1055 - Stacking test.

Code of Federal Regulations, 2013 CFR

2013-10-01

... and no loss of contents during the test or after removal of the test load. ... to a uniformly distributed superimposed test load that is four times the design type maximum gross weight for a period of at least twenty-four hours. (2) For all Flexible Bulk Containers, the load must be...

Flight Testing and Real-Time System Identification Analysis of a UH-60A Black Hawk Helicopter with an Instrumented External Sling Load

NASA Technical Reports Server (NTRS)

McCoy, Allen H.

1998-01-01

Helicopter external air transportation plays an important role in today's world. For both military and civilian helicopters, external sling load operations offer an efficient and expedient method of handling heavy, oversized cargo. With the ability to reach areas otherwise inaccessible by ground transportation, helicopter external load operations are conducted in industries such as logging, construction, and fire fighting, as well as in support of military tactical transport missions. Historically, helicopter and load combinations have been qualified through flight testing, requiring considerable time and cost. With advancements in simulation and flight test techniques there is potential to substantially reduce costs and increase the safety of helicopter sling load certification. Validated simulation tools make possible accurate prediction of operational flight characteristics before initial flight tests. Real time analysis of test data improves the safety and efficiency of the testing programs. To advance these concepts, the U.S. Army and NASA, in cooperation with the Israeli Air Force and Technion, under a Memorandum of Agreement, seek to develop and validate a numerical model of the UH-60 with sling load and demonstrate a method of near real time flight test analysis. This thesis presents results from flight tests of a U.S. Army Black Hawk helicopter with various external loads. Tests were conducted as the U.S. first phase of this MOA task. The primary load was a container express box (CONEX) which contained a compact instrumentation package. The flights covered the airspeed range from hover to 70 knots. Primary maneuvers were pitch and roll frequency sweeps, steps, and doublets. Results of the test determined the effect of the suspended load on both the aircraft's handling qualities and its control system's stability margins. Included were calculations of the stability characteristics of the load's pendular motion. Utilizing CIFER(R) software, a method for near-real time system identification was also demonstrated during the flight test program.

Response of shallow geothermal energy pile from laboratory model tests

NASA Astrophysics Data System (ADS)

Marto, A.; Amaludin, A.

2015-09-01

In shallow geothermal energy pile systems, the thermal loads from the pile, transferred and stored in the soil will cause thermally induced settlement. This factor must be considered in the geotechnical design process to avoid unexpected hazards. Series of laboratory model tests were carried out to study the behaviour of energy piles installed in kaolin soil, subjected to thermal loads and a combination of axial and thermal loads (henceforth known as thermo-axial loads). Six tests which included two thermal load tests (35°C and 40°C) and four thermo-axial load tests (100 N and 200 N, combined with 35°C and 40°C thermal loads) were conducted. To simulate the behaviour of geothermal energy piles during its operation, the thermo-axial tests were carried out by applying an axial load to the model pile head, and a subsequent application of thermal load. The model soil was compacted at 90% maximum dry density and had an undrained shear strength of 37 kPa, thus classified as having a firm soil consistency. The behaviour of model pile, having the ultimate load capacity of 460 N, was monitored using a linear variable displacement transducer, load cell and wire thermocouple, to measure the pile head settlement, applied axial load and model pile temperature. The acquired data from this study was used to define the thermo-axial response characteristics of the energy pile model. In this study, the limiting settlement was defined as 10% of the model pile diameter. For thermal load tests, higher thermal loads induced higher values of thermal settlement. At 40°C thermal load an irreversible settlement was observed after the heating and cooling cycle was applied to the model pile. Meanwhile, the pile response to thermo-axial loads were attributed to soil consistency and the magnitude of both the axial and thermal loads applied to the pile. The higher the thermoaxial loads, the higher the settlements occurred. A slight hazard on the model pile was detected, since the settlement occurred was greater than the limiting value when the pile was loaded with thermo-axial loads of 40°C and 200 N. It is therefore recommended that the global factor of safety to be applied for energy pile installed in firm soil should be more than 2.3 to prevent any hazard to occur in the future, should the pile also be subjected to thermal load of 40°C or greater.

Fast Response, Open-Celled Porous, Shape Memory Effect Actuators with Integrated Attachments

NASA Technical Reports Server (NTRS)

Jardine, Andrew Peter (Inventor)

2015-01-01

This invention relates to the exploitation of porous foam articles exhibiting the Shape Memory Effect as actuators. Each foam article is composed of a plurality of geometric shapes, such that some geometric shapes can fit snugly into or around rigid mating connectors that attach the Shape Memory foam article intimately into the load path between a static structure and a moveable structure. The foam is open-celled, composed of a plurality of interconnected struts whose mean diameter can vary from approximately 50 to 500 microns. Gases and fluids flowing through the foam transfer heat rapidly with the struts, providing rapid Shape Memory Effect transformations. Embodiments of porous foam articles as torsional actuators and approximately planar structures are disposed. Simple, integral connection systems exploiting the ability to supply large loads to a structure, and that can also supply hot and cold gases and fluids to effect rapid actuation are also disposed.

Determination of current loads of floating platform for special purposes

NASA Astrophysics Data System (ADS)

Ma, Guang-ying; Yao, Yun-long; Zhao, Chen-yao

2017-08-01

This article studied a new floating offshore platform for special purposes, which was assembled by standard floating modules. The environmental load calculation of the platform is an important part of the research of the ocean platform, which has always been paid attention to by engineers. In addition to wave loads, the wind loads and current loads are also important environmental factors that affect the dynamic response of the offshore platform. The current loads on the bottom structure should not be ignored. By Fluent software, the hydrostatic conditions and external current loads of the platform were calculated in this paper. The coefficient which is independent of the current velocity, namely, current force coefficient, can be fitted through current loads, which can be used for the consequent hydrodynamic and mooring analyses.

NCHRP project 20-07/task 361 : hamburg wheel-track test equipment requirements and improvements to AASHTO T 324 : research project capsule.

DOT National Transportation Integrated Search

2015-02-01

The Loaded Wheel Test (LWT) is a laboratory-controlled rut depth test that uses loaded wheel(s) : to apply a moving load on hot-mix and warm-mix asphalt (HMA and WMA) specimens to simulate : tra c load applied on asphalt pavements. In the 1970s He...

Composite Grids for Reinforcement of Concrete Structures.

DTIC Science & Technology

1998-06-01

to greater compressive loads before induced shear failure occurs. Concrete columns were tested in compression to explore alter- native... columns were tested on the same day as the fiber-reinforced concrete columns . Load /deflection readings were taken with the load cell to determine the...ln) Figure 78. Ultimate load vs toughness for the different beam types tested . USACERLTR-98/81 141 £\\

Efficient field testing for load rating railroad bridges

NASA Astrophysics Data System (ADS)

Schulz, Jeffrey L.; Brett C., Commander

1995-06-01

As the condition of our infrastructure continues to deteriorate, and the loads carried by our bridges continue to increase, an ever growing number of railroad and highway bridges require load limits. With safety and transportation costs at both ends of the spectrum. the need for accurate load rating is paramount. This paper describes a method that has been developed for efficient load testing and evaluation of short- and medium-span bridges. Through the use of a specially-designed structural testing system and efficient load test procedures, a typical bridge can be instrumented and tested at 64 points in less than one working day and with minimum impact on rail traffic. Various techniques are available to evaluate structural properties and obtain a realistic model. With field data, a simple finite element model is 'calibrated' and its accuracy is verified. Appropriate design and rating loads are applied to the resulting model and stress predictions are made. This technique has been performed on numerous structures to address specific problems and to provide accurate load ratings. The merits and limitations of this approach are discussed in the context of actual examples of both rail and highway bridges that were tested and evaluated.

Particle loading time and humidity effects on the efficiency of an N95 filtering facepiece respirator model under constant and inhalation cyclic flows.

PubMed

Mahdavi, Alireza; Haghighat, Fariborz; Bahloul, Ali; Brochot, Clothilde; Ostiguy, Claude

2015-06-01

It is necessary to investigate the efficiencies of filtering facepiece respirators (FFRs) exposed to ultrafine particles (UFPs) for long periods of time, since the particle loading time may potentially affect the efficiency of FFRs. This article aims to investigate the filtration efficiency for a model of electrostatic N95 FFRs with constant and 'inhalation-only' cyclic flows, in terms of particle loading time effect, using different humidity conditions. Filters were exposed to generated polydisperse NaCl particles. Experiments were performed mimicking an 'inhalation-only' scenario with a cyclic flow of 85 l min(-1) as the minute volume [or 170 l min(-1) as mean inhalation flow (MIF)] and for two constant flows of 85 and 170 l min(-1), under three relative humidity (RH) levels of 10, 50, and 80%. Each test was performed for loading time periods of 6h and the particle penetration (10-205.4nm in electrical mobility diameter) was measured once every 2h. For a 10% RH, the penetration of smaller size particles (<80nm), including the most penetrating particle size (MPPS), decreased over time for both constant and cyclic flows. For 50 and 80% RH levels, the changes in penetration were typically observed in an opposite direction with less magnitude. The penetrations at MPPS increased with respect to loading time under constant flow conditions (85 and 170 l min(-1)): it did not substantially increase under cyclic flows. The comparison of the cyclic flow (85 l min(-1) as minute volume) and constant flow equal to the cyclic flow minute volume indicated that, for all conditions the penetration was significantly less for the constant flow than that of cyclic flow. The comparison between the cyclic (170 l min(-1) as MIF) and constant flow equal to cyclic flow MIF indicated that, for the initial stage of loading, the penetrations were almost equal, but they were different for the final stages of the loading time. For a 10% RH, the penetration of a wide range of sizes was observed to be higher with the cyclic flow (170 as MIF) than with the equivalent constant flow (170 l min(-1)). For 50 and 80% RH levels, the penetrations were usually greater with a constant flow (170 l min(-1)) than with a cyclic flow (170 l min(-1) as MIF). It is concluded that, for the tested electrostatic N95 filters, the change in penetration as a function of the loading time does not necessarily take place with the same rate under constant (MIF) and cyclic flow. Moreover, for all tested flow rates, the penetration is not only affected by the loading time but also by the RH level. Lower RH levels (10%) have decreasing penetration rates in terms of loading time, while higher RH levels (50 and 80%) have increasing penetration rates. Also, the loading of the filter is normally accompanied with a shift of MPPS towards larger sizes. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

75 FR 34064 - Manufactured Home Construction and Safety Standards, Test Procedures for Roof Trusses

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-16

... dead load, or to 1.75 times the uplift load, minus the dead load in the upright position. [See Figure... 1/32-inch. Dead load must be applied to the top and bottom chord, and live load must be applied to... procedure. (i) Dead load. Measure and record initial elevation of the truss or trusses in the test position...

Reduction of Dynamic Loads in Mine Lifting Installations

NASA Astrophysics Data System (ADS)

Kuznetsov, N. K.; Eliseev, S. V.; Perelygina, A. Yu

2018-01-01

Article is devoted to a problem of decrease in the dynamic loadings arising in transitional operating modes of the mine lifting installations leading to heavy oscillating motions of lifting vessels and decrease in efficiency and reliability of work. The known methods and means of decrease in dynamic loadings and oscillating motions of the similar equipment are analysed. It is shown that an approach based on the concept of the inverse problems of dynamics can be effective method of the solution of this problem. The article describes the design model of a one-ended lifting installation in the form of a two-mass oscillation system, in which the inertial elements are the mass of the lifting vessel and the reduced mass of the engine, reducer, drum and pulley. The simplified mathematical model of this system and results of an efficiency research of an active way of reduction of dynamic loadings of lifting installation on the basis of the concept of the inverse problems of dynamics are given.

Static and dynamic pile testing of reinforced concrete piles with structure integrated fibre optic strain sensors

NASA Astrophysics Data System (ADS)

Schilder, Constanze; Kohlhoff, Harald; Hofmann, Detlef; Basedau, Frank; Habel, Wolfgang R.; Baeßler, Matthias; Niederleithinger, Ernst; Georgi, Steven; Herten, Markus

2013-05-01

Static and dynamic pile tests are carried out to determine the load bearing capacity and the quality of reinforced concrete piles. As part of a round robin test to evaluate dynamic load tests, structure integrated fibre optic strain sensors were used to receive more detailed information about the strains along the pile length compared to conventional measurements at the pile head. This paper shows the instrumentation of the pile with extrinsic Fabry-Perot interferometers sensors and fibre Bragg gratings sensors together with the results of the conducted static load test as well as the dynamic load tests and pile integrity tests.

Development of a biaxial compression device for biological samples: preliminary experimental results for a closed cell foam.

PubMed

Little, J P; Tevelen, G; Adam, C J; Evans, J H; Pearcy, M J

2009-07-01

Biological tissues are subjected to complex loading states in vivo and in order to define constitutive equations that effectively simulate their mechanical behaviour under these loads, it is necessary to obtain data on the tissue's response to multiaxial loading. Single axis and shear testing of biological tissues is often carried out, but biaxial testing is less common. We sought to design and commission a biaxial compression testing device, capable of obtaining repeatable data for biological samples. The apparatus comprised a sealed stainless steel pressure vessel specifically designed such that a state of hydrostatic compression could be created on the test specimen while simultaneously unloading the sample along one axis with an equilibrating tensile pressure. Thus a state of equibiaxial compression was created perpendicular to the long axis of a rectangular sample. For the purpose of calibration and commissioning of the vessel, rectangular samples of closed cell ethylene vinyl acetate (EVA) foam were tested. Each sample was subjected to repeated loading, and nine separate biaxial experiments were carried out to a maximum pressure of 204 kPa (30 psi), with a relaxation time of two hours between them. Calibration testing demonstrated the force applied to the samples had a maximum error of 0.026 N (0.423% of maximum applied force). Under repeated loading, the foam sample demonstrated lower stiffness during the first load cycle. Following this cycle, an increased stiffness, repeatable response was observed with successive loading. While the experimental protocol was developed for EVA foam, preliminary results on this material suggest that this device may be capable of providing test data for biological tissue samples. The load response of the foam was characteristic of closed cell foams, with consolidation during the early loading cycles, then a repeatable load-displacement response upon repeated loading. The repeatability of the test results demonstrated the ability of the test device to provide reproducible test data and the low experimental error in the force demonstrated the reliability of the test data.

Detection of drug resistance mutations at low plasma HIV-1 RNA load in a European multicentre cohort study.

PubMed

Prosperi, Mattia C F; Mackie, Nicola; Di Giambenedetto, Simona; Zazzi, Maurizio; Camacho, Ricardo; Fanti, Iuri; Torti, Carlo; Sönnerborg, Anders; Kaiser, Rolf; Codoñer, Francisco M; Van Laethem, Kristel; Bansi, Loveleen; van de Vijver, David A M C; Geretti, Anna Maria; De Luca, Andrea

2011-08-01

Guidelines indicate a plasma HIV-1 RNA load of 500-1000 copies/mL as the minimal threshold for antiretroviral drug resistance testing. Resistance testing at lower viral load levels may be useful to guide timely treatment switches, although data on the clinical utility of this remain limited. We report here the influence of viral load levels on the probability of detecting drug resistance mutations (DRMs) and other mutations by routine genotypic testing in a large multicentre European cohort, with a focus on tests performed at a viral load <1000 copies/mL. A total of 16 511 HIV-1 reverse transcriptase and protease sequences from 11 492 treatment-experienced patients were identified, and linked to clinical data on viral load, CD4 T cell counts and antiretroviral treatment history. Test results from 3162 treatment-naive patients served as controls. Multivariable analysis was employed to identify predictors of reverse transcriptase and protease DRMs. Overall, 2500/16 511 (15.14%) test results were obtained at a viral load <1000 copies/mL. Individuals with viral load levels of 1000-10000 copies/mL showed the highest probability of drug resistance to any drug class. Independently from other measurable confounders, treatment-experienced patients showed a trend for DRMs and other mutations to decrease at viral load levels <500 copies/mL. Genotypic testing at low viral load may identify emerging antiretroviral drug resistance at an early stage, and thus might be successfully employed in guiding prompt management strategies that may reduce the accumulation of resistance and cross-resistance, viral adaptive changes, and larger viral load increases.

Calculating Nozzle Side Loads using Acceleration Measurements of Test-Based Models

NASA Technical Reports Server (NTRS)

Brown, Andrew M.; Ruf, Joe

2007-01-01

As part of a NASA/MSFC research program to evaluate the effect of different nozzle contours on the well-known but poorly characterized "side load" phenomena, we attempt to back out the net force on a sub-scale nozzle during cold-flow testing using acceleration measurements. Because modeling the test facility dynamics is problematic, new techniques for creating a "pseudo-model" of the facility and nozzle directly from modal test results are applied. Extensive verification procedures were undertaken, resulting in a loading scale factor necessary for agreement between test and model based frequency response functions. Side loads are then obtained by applying a wide-band random load onto the system model, obtaining nozzle response PSD's, and iterating both the amplitude and frequency of the input until a good comparison of the response with the measured response PSD for a specific time point is obtained. The final calculated loading can be used to compare different nozzle profiles for assessment during rocket engine nozzle development and as a basis for accurate design of the nozzle and engine structure to withstand these loads. The techniques applied within this procedure have extensive applicability to timely and accurate characterization of all test fixtures used for modal test.A viewgraph presentation on a model-test based pseudo-model used to calculate side loads on rocket engine nozzles is included. The topics include: 1) Side Loads in Rocket Nozzles; 2) Present Side Loads Research at NASA/MSFC; 3) Structural Dynamic Model Generation; 4) Pseudo-Model Generation; 5) Implementation; 6) Calibration of Pseudo-Model Response; 7) Pseudo-Model Response Verification; 8) Inverse Force Determination; 9) Results; and 10) Recent Work.

Characterization of pediatric wheelchair kinematics and wheelchair tiedown and occupant restraint system loading during rear impact.

PubMed

Fuhrman, Susan I; Karg, Patricia; Bertocci, Gina

2010-04-01

This study characterizes pediatric wheelchair kinematic responses and wheelchair tiedown and occupant restraint system (WTORS) loading during rear impact. It also examines the kinematic and loading effects of wheelchair headrest inclusion in rear impact. In two separate rear-impact test scenarios, identical WC19-compliant manual pediatric wheelchairs were tested using a seated Hybrid III 6-year-old anthropomorphic test device (ATD) to evaluate wheelchair kinematics and WTORS loading. Three wheelchairs included no headrests, and three were equipped with slightly modified wheelchair-mounted headrests. Surrogate WTORS properly secured the wheelchairs; three-point occupant restraints properly restrained the ATD. All tests used a 26km/h, 11g rear-impact test pulse. Headrest presence affected wheelchair kinematics and WTORS loading; headrest-equipped wheelchairs had greater mean seatback deflections, mean peak front and rear tiedown loads and decreased mean lap belt loads. Rear-impact tiedown loads differed from previously measured loads in frontal impact, with comparable tiedown load levels reversed in frontal and rear impacts. The front tiedowns in rear impact had the highest mean peak loads despite lower rear-impact severity. These outcomes have implications for wheelchair and tiedown design, highlighting the need for all four tiedowns to have an equally robust design, and have implications in the development of rear-impact wheelchair transportation safety standards. Copyright 2009 IPEM. Published by Elsevier Ltd. All rights reserved.

Evaluation of Analysis Techniques for Fluted-Core Sandwich Cylinders

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Schultz, Marc R.

2012-01-01

Buckling-critical launch-vehicle structures require structural concepts that have high bending stiffness and low mass. Fluted-core, also known as truss-core, sandwich construction is one such concept. In an effort to identify an analysis method appropriate for the preliminary design of fluted-core cylinders, the current paper presents and compares results from several analysis techniques applied to a specific composite fluted-core test article. The analysis techniques are evaluated in terms of their ease of use and for their appropriateness at certain stages throughout a design analysis cycle (DAC). Current analysis techniques that provide accurate determination of the global buckling load are not readily applicable early in the DAC, such as during preliminary design, because they are too costly to run. An analytical approach that neglects transverse-shear deformation is easily applied during preliminary design, but the lack of transverse-shear deformation results in global buckling load predictions that are significantly higher than those from more detailed analysis methods. The current state of the art is either too complex to be applied for preliminary design, or is incapable of the accuracy required to determine global buckling loads for fluted-core cylinders. Therefore, it is necessary to develop an analytical method for calculating global buckling loads of fluted-core cylinders that includes transverse-shear deformations, and that can be easily incorporated in preliminary design.

Use of microfasteners to produce damage tolerant composite structures

PubMed Central

Hallett, Stephen R.

2016-01-01

The paper concerns the mechanical performance of continuous fibre/thermosetting polymer matrix composites reinforced in the through-thickness direction with fibrous or metallic rods or threads in order to mitigate against low delamination resistance. Specific illustrations of the effects of microfasteners in reducing delamination crack growth are made for Z-pinned and tufted composites. Response to loading in such ‘structured materials’ is subject to multiple parameters defining their in-plane and out-of-plane properties. Single microfastener mechanical tests are well suited to establish the crack bridging laws under a range of loading modes, from simple delamination crack opening to shear, and provide the basis for predicting the corresponding response of microfastener arrays, within a given material environment. The fundamental experiments on microfasteners can be used to derive analytical expressions to describe the crack bridging behaviour in a general sense, to cover all possible loadings. These expressions can be built into cohesive element constitutive laws in a finite-element framework for modelling the effects of microfastener arrays on the out-of-plane mechanical response of reinforced structural elements, including the effects of known manufacturing imperfections. Such predictive behaviour can then be used to assess structural integrity under complex loading, as part of the component design process. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’. PMID:27242299

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2010 CFR

2010-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2013 CFR

2013-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2012 CFR

2012-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2014 CFR

2014-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2011 CFR

2011-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

Investigation of Low-Cycle Bending Fatigue of AISI 9310 Steel Spur Gears

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Krantz, Timothy L.; Lerch, Bradley A.; Burke, Christopher S.

2007-01-01

An investigation of the low-cycle bending fatigue of spur gears made from AISI 9310 gear steel was completed. Tests were conducted using the single-tooth bending method to achieve crack initiation and propagation. Tests were conducted on spur gears in a fatigue test machine using a dedicated gear test fixture. Test loads were applied at the highest point of single tooth contact. Gear bending stresses for a given testing load were calculated using a linear-elastic finite element model. Test data were accumulated from 1/4 cycle to several thousand cycles depending on the test stress level. The relationship of stress and cycles for crack initiation was found to be semi-logarithmic. The relationship of stress and cycles for crack propagation was found to be linear. For the range of loads investigated, the crack propagation phase is related to the level of load being applied. Very high loads have comparable crack initiation and propagation times whereas lower loads can have a much smaller number of cycles for crack propagation cycles as compared to crack initiation.

Investigation of Low-Cycle Bending Fatigue of AISI 9310 Steel Spur Gears

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Krantz, Timothy L.; Lerch, Bradley A.; Burke, Christopher S.

2007-01-01

An investigation of the low-cycle bending fatigue of spur gears made from AISI 9310 gear steel was completed. Tests were conducted using the single-tooth bending method to achieve crack initiation and propagation. Tests were conducted on spur gears in a fatigue test machine using a dedicated gear test fixture. Test loads were applied at the highest point of single tooth contact. Gear bending stresses for a given testing load were calculated using a linear-elastic finite element model. Test data were accumulated from 1/4 cycle to several thousand cycles depending on the test stress level. The relationship of stress and cycles for crack initiation was found to be semilogarithmic. The relationship of stress and cycles for crack propagation was found to be linear. For the range of loads investigated, the crack propagation phase is related to the level of load being applied. Very high loads have comparable crack initiation and propagation times whereas lower loads can have a much smaller number of cycles for crack propagation cycles as compared to crack initiation.

Test and evaluation of load converter topologies used in the Space Station Freedom power management and distribution dc test bed

NASA Technical Reports Server (NTRS)

Lebron, Ramon C.; Oliver, Angela C.; Bodi, Robert F.

1991-01-01

Power components hardware in support of the Space Station freedom dc Electric Power System were tested. One type of breadboard hardware tested is the dc Load Converter Unit, which constitutes the power interface between the electric power system and the actual load. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. Three load converters were tested: a series resonant converter, a series inductor switch-mode converter, and a switching full-bridge forward converter. The topology, operation principles, and test results are described, in general. A comparative analysis of the three units is given with respect to efficiency, regulation, short circuit behavior (protection), and transient characteristics.

Flight-Time Identification of a UH-60A Helicopter and Slung Load

NASA Technical Reports Server (NTRS)

Cicolani, Luigi S.; McCoy, Allen H.; Tischler, Mark B.; Tucker, George E.; Gatenio, Pinhas; Marmar, Dani

1998-01-01

This paper describes a flight test demonstration of a system for identification of the stability and handling qualities parameters of a helicopter-slung load configuration simultaneously with flight testing, and the results obtained.Tests were conducted with a UH-60A Black Hawk at speeds from hover to 80 kts. The principal test load was an instrumented 8 x 6 x 6 ft cargo container. The identification used frequency domain analysis in the frequency range to 2 Hz, and focussed on the longitudinal and lateral control axes since these are the axes most affected by the load pendulum modes in the frequency range of interest for handling qualities. Results were computed for stability margins, handling qualities parameters and load pendulum stability. The computations took an average of 4 minutes before clearing the aircraft to the next test point. Important reductions in handling qualities were computed in some cases, depending, on control axis and load-slung combination. A database, including load dynamics measurements, was accumulated for subsequent simulation development and validation.

Modal Survey of ETM-3, A 5-Segment Derivative of the Space Shuttle Solid Rocket Booster

NASA Technical Reports Server (NTRS)

Nielsen, D.; Townsend, J.; Kappus, K.; Driskill, T.; Torres, I.; Parks, R.

2005-01-01

The complex interactions between internal motor generated pressure oscillations and motor structural vibration modes associated with the static test configuration of a Reusable Solid Rocket Motor have potential to generate significant dynamic thrust loads in the 5-segment configuration (Engineering Test Motor 3). Finite element model load predictions for worst-case conditions were generated based on extrapolation of a previously correlated 4-segment motor model. A modal survey was performed on the largest rocket motor to date, Engineering Test Motor #3 (ETM-3), to provide data for finite element model correlation and validation of model generated design loads. The modal survey preparation included pretest analyses to determine an efficient analysis set selection using the Effective Independence Method and test simulations to assure critical test stand component loads did not exceed design limits. Historical Reusable Solid Rocket Motor modal testing, ETM-3 test analysis model development and pre-test loads analyses, as well as test execution, and a comparison of results to pre-test predictions are discussed.

Deformation and damage mechanisms of zinc coatings on hot-dip galvanized steel sheets: Part II. Damage modes

NASA Astrophysics Data System (ADS)

Parisot, Rodolphe; Forest, Samuel; Pineau, André; Grillon, François; Demonet, Xavier; Mataigne, Jean-Michel

2004-03-01

Zinc-based coatings are widely used for protection against corrosion of steel-sheet products in the automotive industry. The objective of the present article is to investigate the damage modes at work in three different microstructures of a zinc coating on an interstitial-free steel substrate under tension, planestrain tension, and expansion loading. Plastic-deformation mechanisms are addressed in the companion article. Two main fracture mechanisms, namely, intergranular cracking and transgranular cleavage fracture, were identified in an untempered cold-rolled coating, a tempered cold-rolled coating, and a recrystallized coating. No fracture at the interface between the steel and zinc coating was observed that could lead to spalling, in the studied zinc alloy. A complex network of cleavage cracks and their interaction with deformation twinning is shown to develop in the material. An extensive quantitative analysis based on systematic image analysis provides the number and cumulative length of cleavage cracks at different strain levels for the three investigated microstructures and three loading conditions. Grain refinement by recrystallization is shown to lead to an improved cracking resistance of the coating. A model for crystallographic cleavage combining the stress component normal to the basal plane and the amount of plastic slip on the basal slip systems is proposed and identified from equibiaxial tension tests and electron backscattered diffraction (EBSD) analysis of the cracked grains. This analysis requires the computation of the nonlinear stress-strain response of each grain using a crystal-plasticity constitutive model. The model is then applied successfully to other loading conditions and is shown to account for the preferred orientations of damaged grains observed in the case of plane-strain tension.

Load and resistance factor design of drilled shafts in shale for lateral loading.

DOT National Transportation Integrated Search

2014-04-01

A research project involving 32 drilled shaft load tests was undertaken to establish LRFD procedures for : design of drilled shafts subjected to lateral loads. Tests were performed at two Missouri Department of : Transportation (MoDOT) geotechnical r...

14 CFR 27.681 - Limit load static tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Control Systems § 27.681 Limit load... which— (1) The direction of the test loads produces the most severe loading in the control system; and... requirements for control system joints subject to angular motion. ...

Response of Metals and Metallic Structures to Dynamic Loading

DTIC Science & Technology

1978-05-01

materials for service by testing under high rates of loading. Impact tests such as the Charpy test, the drop-weight tear test, and the dynamic tear...have clearly shown this for precracked charpy specimens and for the drop-weight tear test. Hence, there is a strong need for additional dynamic...dynamic fracture resistance ( Charpy , dynamic-tear, drop-weight tear test, etc.), normally assures that fracture in dynamically loaded structures is

Test Plan. GCPS Task 4, subtask 4.2 thrust structure development

NASA Astrophysics Data System (ADS)

Greenberg, H. S.

1994-09-01

The Single Stage To Orbit (SSTO) vehicle is designed to lift off from a vertical position, go into orbit, return to earth for a horizontal landing, and be reusable for the next mission. (NASA baseline only) In order to meet its performance goals, the SSTO relies on light weight structure and the use of 8 tri-propellant engines. These engines are mounted to the thrust structure. This test plan addresses selection of the material for this structure, and the integrity of the design through testing of elements and a full-scale subcomponent. This test plan supports the development of the design for an advanced composite thrust structure for a Single Stage to Orbit manned, heavy launch vehicle. The thrust structure is designed to transmit very high thrust loads from the engines to the rest of the vehicle (see Figure 1 ). The thrust structure will also be used for primary attachment of the twin vertical tails and possibly act as the aft attach point for the wing. The combination of high loading, high vibration, long service life and high acoustic environments will need to be evaluated by tests. To minimize design risk, a building block approach will be used. We will first screen materials to determine which materials show the most promise for this application. Factors in this screening will be the suitability of these materials for chosen design concepts, particularly concerning specific strength, environmental compatibility and applicability to fabrication processes. Next we will characterize two material systems that will be used in the design; the characterization will allow us to generate preliminary design data that will be used for the analysis. Element testing will be performed to evaluate critical structural locations under load. Final testing on the full scale test article will be performed to verify the design and to demonstrate predictability of the analysis. Additionally, risks associated with fabricating full scale thrust structures will be reduced through testing activities. One of the major concerns that stems from full scale fabrication is the realities of size and the associated complexities of handling, manufacturing, and assembly. The need exists to fabricate, assemble and test_representative joint specimens to achieve_confidence in the design and manufacturing technologies being proposed.

Test Plan. GCPS Task 4, subtask 4.2 thrust structure development

NASA Technical Reports Server (NTRS)

Greenberg, H. S.

1994-01-01

The Single Stage To Orbit (SSTO) vehicle is designed to lift off from a vertical position, go into orbit, return to earth for a horizontal landing, and be reusable for the next mission. (NASA baseline only) In order to meet its performance goals, the SSTO relies on light weight structure and the use of 8 tri-propellant engines. These engines are mounted to the thrust structure. This test plan addresses selection of the material for this structure, and the integrity of the design through testing of elements and a full-scale subcomponent. This test plan supports the development of the design for an advanced composite thrust structure for a Single Stage to Orbit manned, heavy launch vehicle. The thrust structure is designed to transmit very high thrust loads from the engines to the rest of the vehicle (see Figure 1 ). The thrust structure will also be used for primary attachment of the twin vertical tails and possibly act as the aft attach point for the wing. The combination of high loading, high vibration, long service life and high acoustic environments will need to be evaluated by tests. To minimize design risk, a building block approach will be used. We will first screen materials to determine which materials show the most promise for this application. Factors in this screening will be the suitability of these materials for chosen design concepts, particularly concerning specific strength, environmental compatibility and applicability to fabrication processes. Next we will characterize two material systems that will be used in the design; the characterization will allow us to generate preliminary design data that will be used for the analysis. Element testing will be performed to evaluate critical structural locations under load. Final testing on the full scale test article will be performed to verify the design and to demonstrate predictability of the analysis. Additionally, risks associated with fabricating full scale thrust structures will be reduced through testing activities. One of the major concerns that stems from full scale fabrication is the realities of size and the associated complexities of handling, manufacturing, and assembly. The need exists to fabricate, assemble and test_representative joint specimens to achieve_confidence in the design and manufacturing technologies being proposed.

Composite Materials and Meta Materials for a New Approach to ITER ICRH Loads

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

Bottollier-Curtet, H.; Argouarch, A.; Vulliez, K.

Preliminary laboratory testing of ICRH antennas is a very useful step before their commissioning. Traditionally, pure water, salt water or baking soda water loads are used. These 'water' loads are convenient but strongly limited in terms of performance testing. We have started two feasibility studies for advanced ICRH loads made of ferroelectric ceramics (passive loads) and meta materials (active loads). Preliminary results are very encouraging.

Space Shuttle Projects

NASA Image and Video Library

1977-12-01

The solid rocket booster (SRB) structural test article is being installed in the Solid Rocket Booster Test Facility for the structural and load verification test at the Marshall Space Flight Center (MSFC). The Shuttle's two SRB's are the largest solids ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the solid rocket motors (SRM's) were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. At burnout, the boosters separate from the external tank and drop by parachute to the ocean for recovery and subsequent refurbishment.

Factor Analysis via Components Analysis

ERIC Educational Resources Information Center

Bentler, Peter M.; de Leeuw, Jan

2011-01-01

When the factor analysis model holds, component loadings are linear combinations of factor loadings, and vice versa. This interrelation permits us to define new optimization criteria and estimation methods for exploratory factor analysis. Although this article is primarily conceptual in nature, an illustrative example and a small simulation show…

In a Concurrent Memory and Auditory Perception Task, the Pupil Dilation Response Is More Sensitive to Memory Load Than to Auditory Stimulus Characteristics.

PubMed

Zekveld, Adriana A; Kramer, Sophia E; Rönnberg, Jerker; Rudner, Mary

2018-06-19

Speech understanding may be cognitively demanding, but it can be enhanced when semantically related text cues precede auditory sentences. The present study aimed to determine whether (a) providing text cues reduces pupil dilation, a measure of cognitive load, during listening to sentences, (b) repeating the sentences aloud affects recall accuracy and pupil dilation during recall of cue words, and (c) semantic relatedness between cues and sentences affects recall accuracy and pupil dilation during recall of cue words. Sentence repetition following text cues and recall of the text cues were tested. Twenty-six participants (mean age, 22 years) with normal hearing listened to masked sentences. On each trial, a set of four-word cues was presented visually as text preceding the auditory presentation of a sentence whose meaning was either related or unrelated to the cues. On each trial, participants first read the cue words, then listened to a sentence. Following this they spoke aloud either the cue words or the sentence, according to instruction, and finally on all trials orally recalled the cues. Peak pupil dilation was measured throughout listening and recall on each trial. Additionally, participants completed a test measuring the ability to perceive degraded verbal text information and three working memory tests (a reading span test, a size-comparison span test, and a test of memory updating). Cue words that were semantically related to the sentence facilitated sentence repetition but did not reduce pupil dilation. Recall was poorer and there were more intrusion errors when the cue words were related to the sentences. Recall was also poorer when sentences were repeated aloud. Both behavioral effects were associated with greater pupil dilation. Larger reading span capacity and smaller size-comparison span were associated with larger peak pupil dilation during listening. Furthermore, larger reading span and greater memory updating ability were both associated with better cue recall overall. Although sentence-related word cues facilitate sentence repetition, our results indicate that they do not reduce cognitive load during listening in noise with a concurrent memory load. As expected, higher working memory capacity was associated with better recall of the cues. Unexpectedly, however, semantic relatedness with the sentence reduced word cue recall accuracy and increased intrusion errors, suggesting an effect of semantic confusion. Further, speaking the sentence aloud also reduced word cue recall accuracy, probably due to articulatory suppression. Importantly, imposing a memory load during listening to sentences resulted in the absence of formerly established strong effects of speech intelligibility on the pupil dilation response. This nullified intelligibility effect demonstrates that the pupil dilation response to a cognitive (memory) task can completely overshadow the effect of perceptual factors on the pupil dilation response. This highlights the importance of taking cognitive task load into account during auditory testing.This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Biomechanical tolerance of whole lumbar spines in straightened posture subjected to axial acceleration.

PubMed

Stemper, Brian D; Chirvi, Sajal; Doan, Ninh; Baisden, Jamie L; Maiman, Dennis J; Curry, William H; Yoganandan, Narayan; Pintar, Frank A; Paskoff, Glenn; Shender, Barry S

2018-06-01

Quantification of biomechanical tolerance is necessary for injury prediction and protection of vehicular occupants. This study experimentally quantified lumbar spine axial tolerance during accelerative environments simulating a variety of military and civilian scenarios. Intact human lumbar spines (T12-L5) were dynamically loaded using a custom-built drop tower. Twenty-three specimens were tested at sub-failure and failure levels consisting of peak axial forces between 2.6 and 7.9 kN and corresponding peak accelerations between 7 and 57 g. Military aircraft ejection and helicopter crashes fall within these high axial acceleration ranges. Testing was stopped following injury detection. Both peak force and acceleration were significant (p < 0.0001) injury predictors. Injury probability curves using parametric survival analysis were created for peak acceleration and peak force. Fifty-percent probability of injury (95%CI) for force and acceleration were 4.5 (3.9-5.2 kN), and 16 (13-19 g). A majority of injuries affected the L1 spinal level. Peak axial forces and accelerations were greater for specimens that sustained multiple injuries or injuries at L2-L5 spinal levels. In general, force-based tolerance was consistent with previous shorter-segment lumbar spine testing (3-5 vertebrae), although studies incorporating isolated vertebral bodies reported higher tolerance attributable to a different injury mechanism involving structural failure of the cortical shell. This study identified novel outcomes with regard to injury patterns, wherein more violent exposures produced more injuries in the caudal lumbar spine. This caudal migration was likely attributable to increased injury tolerance at lower lumbar spinal levels and a faster inertial mass recruitment process for high rate load application. Published 2017. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res 36:1747-1756, 2018. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Resistance of Magnesium Alloys to Corrosion Fatigue for Biodegradable Implant Applications: Current Status and Challenges

PubMed Central

Raman, R. K. Singh; Harandi, Shervin Eslami

2017-01-01

Magnesium (Mg) alloys are attracting increasing interest as the most suitable metallic materials for construction of biodegradable and bio-absorbable temporary implants. However, Mg-alloys can suffer premature and catastrophic fracture under the synergy of cyclic loading and corrosion (i.e., corrosion fatigue (CF)). Though Mg alloys are reported to be susceptible to CF also in the corrosive human body fluid, there are very limited studies on this topic. Furthermore, the in vitro test parameters employed in these investigations have not properly simulated the actual conditions in the human body. This article presents an overview of the findings of available studies on the CF of Mg alloys in pseudo-physiological solutions and the employed testing procedures, as well as identifying the knowledge gap. PMID:29144428

Resistance of Magnesium Alloys to Corrosion Fatigue for Biodegradable Implant Applications: Current Status and Challenges.

PubMed

Raman, R K Singh; Harandi, Shervin Eslami

2017-11-16

Magnesium (Mg) alloys are attracting increasing interest as the most suitable metallic materials for construction of biodegradable and bio-absorbable temporary implants. However, Mg-alloys can suffer premature and catastrophic fracture under the synergy of cyclic loading and corrosion (i.e., corrosion fatigue (CF)). Though Mg alloys are reported to be susceptible to CF also in the corrosive human body fluid, there are very limited studies on this topic. Furthermore, the in vitro test parameters employed in these investigations have not properly simulated the actual conditions in the human body. This article presents an overview of the findings of available studies on the CF of Mg alloys in pseudo-physiological solutions and the employed testing procedures, as well as identifying the knowledge gap.

Fuel cladding behavior under rapid loading conditions

NASA Astrophysics Data System (ADS)

Yueh, K.; Karlsson, J.; Stjärnsäter, J.; Schrire, D.; Ledergerber, G.; Munoz-Reja, C.; Hallstadius, L.

2016-02-01

A modified burst test (MBT) was used in an extensive test program to characterize fuel cladding failure behavior under rapid loading conditions. The MBT differs from a normal burst test with the use of a driver tube to simulate the expansion of a fuel pellet, thereby producing a partial strain driven deformation condition similar to that of a fuel pellet expansion in a reactivity insertion accident (RIA). A piston/cylinder assembly was used to pressurize the driver tube. By controlling the speed and distance the piston travels the loading rate and degree of sample deformation could be controlled. The use of a driver tube with a machined gauge section localizes deformation and allows for continuous monitoring of the test sample diameter change at the location of maximum hoop strain, during each test. Cladding samples from five irradiated fuel rods were tested between 296 and 553 K and loading rates from 1.5 to 3.5/s. The test rods included variations of Zircaloy-2 with different liners and ZIRLO, ranging in burn-up from 41 to 74 GWd/MTU. The test results show cladding ductility is strongly temperature and loading rate dependent. Zircaloy-2 cladding ductility degradation due to operational hydrogen pickup started to recover at approximately 358 K for test condition used in the study. This recovery temperature is strongly loading rate dependent. At 373 K, ductility recovery was small for loading rates less than 8 ms equivalent RIA pulse width, but longer than 8 ms the ductility recovery increased exponentially with increasing pulse width, consistent with literature observations of loading rate dependent brittle-to-ductile (BTD) transition temperature. The cladding ductility was also observed to be strongly loading rate/pulse width dependent for BWR cladding below the BTD temperature and Pressurized Water Reactor (PWR) cladding at both 296 and 553 K.

Application of microtomography and image analysis to the quantification of fragmentation in ceramics after impact loading

NASA Astrophysics Data System (ADS)

Forquin, Pascal; Ando, Edward

2017-01-01

Silicon carbide ceramics are widely used in personal body armour and protective solutions. However, during impact, an intense fragmentation develops in the ceramic tile due to high-strain-rate tensile loadings. In this work, microtomography equipment was used to analyse the fragmentation patterns of two silicon carbide grades subjected to edge-on impact (EOI) tests. The EOI experiments were conducted in two configurations. The so-called open configuration relies on the use of an ultra-high-speed camera to visualize the fragmentation process with an interframe time set to 1 µs. The so-called sarcophagus configuration consists in confining the target in a metallic casing to avoid any dispersion of fragments. The target is infiltrated after impact so the final damage pattern is entirely scanned using X-ray tomography and a microfocus source. Thereafter, a three-dimensional (3D) segmentation algorithm was tested and applied in order to separate fragments in 3D allowing a particle size distribution to be obtained. Significant differences between the two specimens of different SiC grades were noted. To explain such experimental results, numerical simulations were conducted considering the Denoual-Forquin-Hild anisotropic damage model. According to the calculations, the difference of crack pattern in EOI tests is related to the population of defects within the two ceramics. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

Time-averaged aerodynamic loads on the vane sets of the 40- by 80-foot and 80- by 120-foot wind tunnel complex

NASA Technical Reports Server (NTRS)

Aoyagi, Kiyoshi; Olson, Lawrence E.; Peterson, Randall L.; Yamauchi, Gloria K.; Ross, James C.; Norman, Thomas R.

1987-01-01

Time-averaged aerodynamic loads are estimated for each of the vane sets in the National Full-Scale Aerodynamic Complex (NFAC). The methods used to compute global and local loads are presented. Experimental inputs used to calculate these loads are based primarily on data obtained from tests conducted in the NFAC 1/10-Scale Vane-Set Test Facility and from tests conducted in the NFAC 1/50-Scale Facility. For those vane sets located directly downstream of either the 40- by 80-ft test section or the 80- by 120-ft test section, aerodynamic loads caused by the impingement of model-generated wake vortices and model-generated jet and propeller wakes are also estimated.

Is Augmented LISS Plating Biomechanically Advantageous Over Conventional LISS Plating In Unstable Osteoporotic Distal Femoral Fractures?

PubMed

Todorov, Dimitar; Zderic, Ivan; Richards, R Geoff; Lenz, Mark; Knobe, Matthias; Enchev, Dian; Baltov, Asen; Gueorguiev, Boyko; Stoffel, Karl

2018-05-10

Treatment of complex osteoporotic distal femur fractures with the Less Invasive Stabilization System (LISS) has been associated with high complication rates. The aim of this study was to investigate the biomechanical competence of two different techniques of augmented versus conventional LISS plating. Unstable distal femoral fracture AO/OTA 33-A3 was created via osteotomies in artificial femora simulating osteoporotic bone. Three study groups, consisting of 10 specimens each, were created for instrumentation with either LISS plate, LISS plate with additional polylactide intramedullary graft, or LISS plate plus medial locking plate (double plating). All specimens were non-destructively tested under axial (20-150N) and torsional (0-4Nm) quasi-static loading. Each construct was tested with two different working length (WL) configurations (long and short) of the LISS plate. Relative movements between the most medial superior and inferior osteotomy aspects were investigated via three-dimensional motion tracking analysis. Double plating revealed significantly smaller longitudinal and shear displacement than the other two techniques (P≤0.001). In addition, LISS plus graft fixation was with significantly less longitudinal displacement in comparison to conventional LISS plating (P < 0.001). Long WL resulted in significantly higher longitudinal and shear displacement compared to short WL for LISS and LISS plus graft (P≤0.032), but not for double plating (P > 0.999). In conclusion, intramedullary grafting resulted in significantly increased fracture stability under axial loading in comparison to conventional LISS plating. Although it was not efficient enough to provide comparable stability to double plating, intramedullary grafting may be considered as a useful biological alternative to the latter in a surgeon's armamentarium. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Integration of optical measurement methods with flight parameter measurement systems

NASA Astrophysics Data System (ADS)

Kopecki, Grzegorz; Rzucidlo, Pawel

2016-05-01

During the AIM (advanced in-flight measurement techniques) and AIM2 projects, innovative modern techniques were developed. The purpose of the AIM project was to develop optical measurement techniques dedicated for flight tests. Such methods give information about aircraft elements deformation, thermal loads or pressure distribution, etc. In AIM2 the development of optical methods for flight testing was continued. In particular, this project aimed at the development of methods that could be easily applied in flight tests in an industrial setting. Another equally important task was to guarantee the synchronization of the classical measuring system with cameras. The PW-6U glider used in flight tests was provided by the Rzeszów University of Technology. The glider had all the equipment necessary for testing the IPCT (image pattern correlation technique) and IRT (infrared thermometry) methods. Additionally, equipment adequate for the measurement of typical flight parameters, registration and analysis has been developed. This article describes the designed system, as well as presenting the system’s application during flight tests. Additionally, the results obtained in flight tests show certain limitations of the IRT method as applied.

In vitro evaluation of translating and rotating plates using a robot testing system under follower load.

PubMed

Yan, Y; Bell, K M; Hartman, R A; Hu, J; Wang, W; Kang, J D; Lee, J Y

2017-01-01

Various modifications to standard "rigid" anterior cervical plate designs (constrained plate) have been developed that allow for some degree of axial translation and/or rotation of the plate (semi-constrained plate)-theoretically promoting proper load sharing with the graft and improved fusion rates. However, previous studies about rigid and dynamic plates have not examined the influence of simulated muscle loading. The objective of this study was to compare rigid, translating, and rotating plates for single-level corpectomy procedures using a robot testing system with follower load. In-vitro biomechanical test. N = 15 fresh-frozen human (C3-7) cervical specimens were biomechanically tested. The follower load was applied to the specimens at the neutral position from 0 to 100 N. Specimens were randomized into a rigid plate group, a translating plate group and a rotating plate group and then tested in flexion, extension, lateral bending and axial rotation to a pure moment target of 2.0 Nm under 100N of follower load. Range of motion, load sharing, and adjacent level effects were analyzed using a repeated measures analysis of variance (ANOVA). No significant differences were observed between the translating plate and the rigid plate on load sharing at neutral position and C4-6 ROM, but the translating plate was able to maintain load through the graft at a desired level during flexion. The rotating plate shared less load than rigid and translating plates in the neutral position, but cannot maintain the graft load during flexion. This study demonstrated that, in the presence of simulated muscle loading (follower load), the translating plate demonstrated superior performance for load sharing compared to the rigid and rotating plates.

Load Asymmetry Observed During Orion Main Parachute Inflation

NASA Technical Reports Server (NTRS)

Morris, Aaron L.; Taylor, Thomas; Olson, Leah

2011-01-01

The Crew Exploration Vehicle Parachute Assembly System (CPAS) has flight tested the first two generations of the Orion parachute program. Three of the second generation tests instrumented the dispersion bridles of the Main parachute with a Tension Measuring System. The goal of this load measurement was to better understand load asymmetry during the inflation process of a cluster of Main parachutes. The CPAS Main parachutes exhibit inflations that are much less symmetric than current parachute literature and design guides would indicate. This paper will examine loads data gathered on three cluster tests, quantify the degree of asymmetry observed, and contrast the results with published design guides. Additionally, the measured loads data will be correlated with videos of the parachute inflation to make inferences about the shape of the parachute and the relative load asymmetry. The goal of this inquiry and test program is to open a dialogue regarding asymmetrical parachute inflation load factors.

Analysis of Static Load Test of a Masonry Arch Bridge

NASA Astrophysics Data System (ADS)

Shi, Jing-xian; Fang, Tian-tian; Luo, Sheng

2018-03-01

In order to know whether the carrying capacity of the masonry arch bridge built in the 1980s on the shipping channel entering and coming out of the factory of a cement company can meet the current requirements of Level II Load of highway, through the equivalent load distribution of the test vehicle according to the current design specifications, this paper conducted the load test, evaluated the bearing capacity of the in-service stone arch bridge, and made theoretical analysis combined with Midas Civil. The results showed that under the most unfavorable load conditions the measured strain and deflection of the test sections were less than the calculated values, the bridge was in the elastic stage under the design load; the structural strength and stiffness of the bridge had a certain degree of prosperity, and under the in the current conditions of Level II load of highway, the bridge structure was in a safe state.

Effect of load eccentricity on the buckling of thin-walled laminated C-columns

NASA Astrophysics Data System (ADS)

Wysmulski, Pawel; Teter, Andrzej; Debski, Hubert

2018-01-01

The study investigates the behaviour of short, thin-walled laminated C-columns under eccentric compression. The tested columns are simple-supported. The effect of load inaccuracy on the critical and post-critical (local buckling) states is examined. A numerical analysis by the finite element method and experimental tests on a test stand are performed. The samples were produced from a carbon-epoxy prepreg by the autoclave technique. The experimental tests rest on the assumption that compressive loads are 1.5 higher than the theoretical critical force. Numerical modelling is performed using the commercial software package ABAQUS®. The critical load is determined by solving an eigen problem using the Subspace algorithm. The experimental critical loads are determined based on post-buckling paths. The numerical and experimental results show high agreement, thus demonstrating a significant effect of load inaccuracy on the critical load corresponding to the column's local buckling.

26 CFR 48.4061(b)-2 - Definition of parts or accessories.

Code of Federal Regulations, 2010 CFR

2010-04-01

... connection therewith if the article is in effect the load being transported and the primary function of the...) In general. The term “parts or accessories” includes (1) any article the primary use of which is to... article the primary use of which is in connection with such chassis, body, or tractor, whether or not...

Field monitoring of static, dynamic, and statnamic pile loading tests using fibre Bragg grating strain sensors

NASA Astrophysics Data System (ADS)

Li, Jin; Correia, Ricardo P.; Chehura, Edmon; Staines, Stephen; James, Stephen W.; Tatam, Ralph; Butcher, Antony P.; Fuentes, Raul

2009-10-01

Pile loading test plays an important role in the field of piling engineering. In order to gain further insight into the load transfer mechanism, strain gauges are often used to measure local strains along the piles. This paper reports a case whereby FBG strain sensors was employed in a field trial conducted on three different types of pile loading tests in a glacial till. The instrumentation systems were configured to suit the specific characteristic of each type of test. Typical test results are presented. The great potential of using FBG sensors for pile testing is shown.

Arc Jet Testing of the TIRS Cover Thermal Protection System for Mars Exploration Rover

NASA Technical Reports Server (NTRS)

Szalai, Christine E.; Chen, Y.-K.; Loomis, Mark; Hui, Frank; Scrivens, Larry

2002-01-01

This paper summarizes the arc jet test results of the Mars Exploration Rover (MER) Silicone Impregnated Reusable Ceramic Ablator (SIRCA) Transverse Impulse Rocket System (TIRS) Cover test series in the Panel Test Facility (PTF) at NASA Ames Research Center (ARC). NASA ARC performed aerothermal environment analyses, TPS sizing and thermal response analyses, and arc jet testing to evaluate the MER SIRCA TIRS Cover design and interface to the aeroshell structure. The primary objective of this arc jet test series was to evaluate specific design details of the SIRCA TIRS Cover interface to the MER aeroshell under simulated atmospheric entry heating conditions. Four test articles were tested in an arc jet environment with various sea] configurations. The test condition was designed to match the predicted peak flight heat load at the gap region between the SIRCA and the backshell TPS material, SLA-561S, and resulted in an over-test (with respect to heat flux and heat load) for the apex region of the SIRCA TIRS Cover. The resulting pressure differential was as much as twenty times that predicted for the flight case, depending on the location, and there was no post-test visual evidence of over-heating or damage to the seal, bracket, or backshell structure. The exposed titanium bolts were in good condition at post-test and showed only a small amount of oxidation at the leading edge locations. Repeatable thermocouple data were obtained and SIRCA thermal response analyses were compared to applicable thermocouple data. For the apex region of the SIRCA TIRS Cover, a one-dimensional thermal response prediction proved overly conservative, as there were strong multi-dimensional conduction effects evident from the thermocouple data. The one-dimensional thermal response prediction compared well with the thermocouple data for the leading edge "lip" region at the bolt location. In general, the test results yield confidence in the baseline seal design to prevent hot gas ingestion at the bracket and composite aeroshell structure interface.

Embedded data collector (EDC) phase II load and resistance factor design (LRFD).

DOT National Transportation Integrated Search

2015-09-01

A total of 16 static load test results was collected in Florida and Louisiana. New static load tests on five test piles : in Florida (four of which were voided) were monitored with Embedded Data Collector (EDC) instrumentation and : contributed to th...

Effect of Students' Perceptions of Course Load on Test Anxiety

PubMed Central

Sansgiry, Sujit S.; Sail, Kavita

2006-01-01

Objectives The objective of this study was to examine the association between student perceptions of course load, their ability to manage time, and test anxiety. Methods A survey was self-administered to all students (professional years 1 through 4) enrolled in the PharmD curriculum at the University of Houston (2001) with items measuring test anxiety, perceived course load, and ability to manage time. Results One hundred ninety-eight students participated in the survey (response rate P1 = 48%, P2 = 52%, P3 = 52%, P4 = 72%). There was a significant difference in students' perception of course load, ability to manage time, and test anxiety scores across the 4 years. Test anxiety was positively correlated with students' perceptions of course load and negatively related to their ability to manage time with course work. Conclusions Students' perception of course load and their ability to manage time with their course work is associated with test anxiety. Future studies should evaluate the role of stress/time management programs to reduce stress and anxiety. PMID:17149404

Effect of students' perceptions of course load on test anxiety.

PubMed

Sansgiry, Sujit S; Sail, Kavita

2006-04-15

The objective of this study was to examine the association between student perceptions of course load, their ability to manage time, and test anxiety. A survey was self-administered to all students (professional years 1 through 4) enrolled in the PharmD curriculum at the University of Houston (2001) with items measuring test anxiety, perceived course load, and ability to manage time. One hundred ninety-eight students participated in the survey (response rate P1 = 48%, P2 = 52%, P3 = 52%, P4 = 72%). There was a significant difference in students' perception of course load, ability to manage time, and test anxiety scores across the 4 years. Test anxiety was positively correlated with students' perceptions of course load and negatively related to their ability to manage time with course work. Students' perception of course load and their ability to manage time with their course work is associated with test anxiety. Future studies should evaluate the role of stress/time management programs to reduce stress and anxiety.

Acoustic emission testing of composite vessels under sustained loading

NASA Technical Reports Server (NTRS)

Lark, R. F.; Moorhead, P. E.

1978-01-01

Acoustic emission (AE) tests have been conducted on small-diameter Kevlar 49/epoxy pressure vessels subjected to long-term sustained load-to-failure tests. Single-cycle burst tests were used as a basis for determining the test pressure in the sustained-loading tests. AE data from two vessel locations were compared. The data suggest that AE from vessel wall-mounted transducers is quite different for identical vessels subjected to the same pressure loading. AE from boss-mounted transducers yielded relatively consistent values. These values were not a function of time for vessel failure. The development of an AE test procedure for predicting the residual service life or integrity of composite vessels is discussed.

Shield evaluation and performance testing at the USMB`s Strategic Structures Testing Laboratory

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

Barczak, T.M.; Gearhart, D.F.

1996-12-31

Historically, shield performance testing is conducted by the support manufacturers at European facilities. The U.S. Bureau of Mines (USBM) has conducted extensive research in shield Mechanics and is now opening its Strategic Structures Testing (SST) Laboratory to the mining industry for shield performance testing. The SST Laboratory provides unique shield testing capabilities using the Mine Roof Simulator (MRS) load frame. The MRS provides realistic and cost-effective shield evaluation by combining both vertical and horizontal loading into a single load cycle; whereas, several load cycles would be required to obtain this loading in a static frame. In addition to these advantages,more » the USBM acts as an independent research organization to provide an unbiased assessment of shield performance. This paper describes the USBM`s shield testing program that is designed specifically to simulate in-service mining conditions using the unique the capabilities of the SST Laboratory.« less

Study on Mechanical Properties of Barite Concrete under Impact Load

NASA Astrophysics Data System (ADS)

Chen, Z. F.; Cheng, K.; Wu, D.; Gan, Y. C.; Tao, Q. W.

2018-03-01

In order to research the mechanical properties of Barite concrete under impact load, a group of concrete compression tests was carried out under the impact load by using the drop test machine. A high-speed camera was used to record the failure process of the specimen during the impact process. The test results show that:with the increase of drop height, the loading rate, the peak load, the strain under peak load, the strain rate and the dynamic increase factor (DIF) all increase gradually. The ultimate tensile strain is close to each other, and the time of impact force decreases significantly, showing significant strain rate effect.

Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster deceleration subsystem drop test vehicle. Volume 4: Pylon load data

NASA Technical Reports Server (NTRS)

Quade, D. A.

1978-01-01

The pylon loading at the drop test vehicle and wing interface attack points is presented. The loads shown are determined using a stiffness method, which assumes the side stiffness of the forward hook guide and the fore and aft stiffness of each drag pin to be equal. The net effect of this assumption is that the forward hook guide reacts approximately 96% of the drop test vehicle yawing moment. For a comparison of these loads to previous X-15 analysis design loadings, see Volume 1 of this document.

JT9D engine diagnostics. Task 2: Feasibility study of measuring in-service flight loads. [747 aircraft performance

NASA Technical Reports Server (NTRS)

Kafka, P. G.; Skibo, M. A.; White, J. L.

1977-01-01

The feasibility of measuring JT9D propulsion system flight inertia loads on a 747 airplane is studied. Flight loads background is discussed including the current status of 747/JT9D loads knowledge. An instrumentation and test plan is formulated for an airline-owned in-service airplane and the Boeing-owned RA001 test airplane. Technical and cost comparisons are made between these two options. An overall technical feasibility evaluation is made and a cost summary presented. Conclusions and recommendations are presented in regard to using existing inertia loads data versus conducting a flight test to measure inertia loads.

Effect of loading speed on the stress-induced magnetic behavior of ferromagnetic steel

NASA Astrophysics Data System (ADS)

Bao, Sheng; Gu, Yibin; Fu, Meili; Zhang, Da; Hu, Shengnan

2017-02-01

The primary goal of this research is to investigate the effect of loading speed on the stress-induced magnetic behavior of a ferromagnetic steel. Uniaxial tension tests on Q235 steel were carried out with various stress levels under different loading speeds. The variation of the magnetic signals surrounding the tested specimen was detected by a fluxgate magnetometer. The results indicated that the magnetic signal variations depended not only on the tensile load level but on the loading speed during the test. The magnetic field amplitude seemed to decrease gradually with the increase in loading speed at the same tensile load level. Furthermore, the evolution of the magnetic reversals is also related to the loading speed. Accordingly, the loading speed should be considered as one of the influencing variables in the Jies-Atherton model theory of the magnetomechanical effect.

10 CFR Appendix B to Subpart B of... - Uniform Test Method for Measuring Nominal Full Load Efficiency of Electric Motors

Code of Federal Regulations, 2011 CFR

2011-01-01

... Indirect Measurement of the Stray-Load Loss and Direct Measurement of the Stator Winding (I2R), Rotor...) or (b).), which are listed in order of preference. (ii) Page 17, subclause 6.4.1.3., No-load test... no-load until the input has stabilized. (iii) Page 40, subclause 8.6.3, Termination of test, the...