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Sample records for fatigue test program

  1. Fatigue Sensor Evaluation Program Laboratory Test Report.

    DTIC Science & Technology

    1975-10-01

    Evaluation Program", Work Statement, Cessna Report 31HE-6918-213, Addendum H, Revision J, 2 June 1972. 1.2 BACKGROUND The A-37 Aircraft Structural...34 ’: « •IIIS ......... li : « rtrtintr : •* M» c f M i H ::::::;:• ;:« ...j . .... ..:. •f’ ::.::::: ^::|:::: n» VH ft;; ** ViH ! * 1 - •• •-•• ; i...Program", Work Statement, Cessna Report 318E-6918-213, Addendum H, Revision J, 2 June 1972. 2. Micro-Measurements Product Bulletin PB-103-2, dated 1973

  2. Results of an interlaboratory fatigue test program conducted on alloy 800H at room and elevated temperatures

    NASA Technical Reports Server (NTRS)

    Ellis, J. R.

    1985-01-01

    The experimental approach adopted for low cycle fatigue tests of alloy 800H involved the use of electrohydraulic test systems, hour glass geometry specimens, diametral extensometers, and axial strain computers. Attempts to identify possible problem areas were complicated by the lack of reliable data for the heat of Alloy 800H under investigation. The method adopted was to generate definitive test data in an Interlaboratory Fatigue Test Program. The laboratories participating in the program were Argonne National Laboratory, Battelle Columbus, Mar-Test, and NASA Lewis. Fatigue tests were conducted on both solid and turbular specimens at temperatures of 20, 593, and 760 C and strain ranges of 2.0, 1.0, and 0.5 percent. The subject test method can, under certain circumstances, produce fatigue data which are serious in error. This approach subsequently was abandoned at General Atomic Company in favor of parallel gage length specimens and axial extensiometers.

  3. Fatigue Test Design: Scenarios for Biaxial Fatigue Testing of a 60-Meter Wind Turbine Blade

    SciTech Connect

    Post, Nathan

    2016-07-01

    Current practice in commercial certification of wind turbine blades is to perform separate flap and lead-lag fatigue tests. The National Renewable Energy Laboratory has been researching and evaluating biaxial fatigue testing techniques and demonstrating various options, typically on smaller-scale test articles at the National Wind Technology Center. This report evaluates some of these biaxial fatigue options in the context of application to a multimegawatt blade certification test program at the Wind Technology Testing Center in Charlestown, Massachusetts.

  4. Reversal bending fatigue testing

    DOEpatents

    Wang, Jy-An John; Wang, Hong; Tan, Ting

    2014-10-21

    Embodiments for apparatuses for testing reversal bending fatigue in an elongated beam are disclosed. Embodiments are configured to be coupled to first and second end portions of the beam and to apply a bending moment to the beam and create a pure bending condition in an intermediate portion of the beam. Embodiments are further configured to cyclically alternate the direction of the bending moment applied to the beam such that the intermediate portion of the beam cyclically bends in opposite directions in a pure bending condition.

  5. Accelerated Fatigue Test Rationale,

    DTIC Science & Technology

    1980-03-01

    stress cycles. The high cycle fatigue (i.e. elastic stress-strain) typically extends beyond 104 cycles. The Coffin - Manson low cycle fatigue expression...g "Engineering strain is usually more convenient to use than "true" strain. The Coffin - Manson can be modified 12J to give -1/B .- Cu (2 Nf) (21...Mowbray Ci03 has shown that this relationship also reduces to the Coffin - Manson low cycle fatigue expression. An important aspect of the Dowling and

  6. High Speed Research Program Sonic Fatigue

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A. (Technical Monitor); Beier, Theodor H.; Heaton, Paul

    2005-01-01

    The objective of this sonic fatigue summary is to provide major findings and technical results of studies, initiated in 1994, to assess sonic fatigue behavior of structure that is being considered for the High Speed Civil Transport (HSCT). High Speed Research (HSR) program objectives in the area of sonic fatigue were to predict inlet, exhaust and boundary layer acoustic loads; measure high cycle fatigue data for materials developed during the HSR program; develop advanced sonic fatigue calculation methods to reduce required conservatism in airframe designs; develop damping techniques for sonic fatigue reduction where weight effective; develop wing and fuselage sonic fatigue design requirements; and perform sonic fatigue analyses on HSCT structural concepts to provide guidance to design teams. All goals were partially achieved, but none were completed due to the premature conclusion of the HSR program. A summary of major program findings and recommendations for continued effort are included in the report.

  7. Evaluating Fatigue in Operational Settings: The NASA Ames Fatigue Countermeasures Program

    NASA Technical Reports Server (NTRS)

    Rosekind, Mark R.; Gregory, Kevin; Miller, Donna; Webbon, Lissa; Oyung, Ray

    1996-01-01

    In response to a 1980 Congressional request, NASA Ames initiated a program to examine fatigue in flight operations. The Program objectives are to examine fatigue, sleep loss, and circadian disruption in flight operations, determine the effects of these factors on flight crew performance, and the development of fatigue countermeasures. The NASA Ames Fatigue Countermeasures Program conducts controlled laboratory experiments, full-mission flight simulations, and field studies. A range of subjective, behavioral, performance, physiological, and environmental measures are used depending on study objectives. The Program has developed substantial expertise in gathering data during actual flight operations and in other work settings. This has required the development of ambulatory and other measures that can be carried throughout the world and used at 41,000 feet in aircraft cockpits. The NASA Ames Fatigue Countermeasures Program has examined fatigue in shorthaul, longhaul, overnight cargo, and helicopter operations. A recent study of planned cockpit rest periods demonstrated the effectiveness of a brief inflight nap to improve pilot performance and alertness. This study involved inflight reaction time/vigilance performance testing and EEG/EOG measures of physiological alertness. The NASA Ames Fatigue Countermeasures Program has applied scientific findings to the development of education and training materials on fatigue countermeasures, input to federal regulatory activities on pilot flight, duty, and rest requirements, and support of National Transportation Safety Board accident investigations. Current activities are examining fatigue in nonaugmented longhaul flights, regional/commuter flight operations, corporate/business aviation, and psychophysiological variables related to performance.

  8. Materials Reliability Program: Environmental Fatigue Testing of Type 304L Stainless Steel U-Bends in Simulated PWR Primary Water (MRP-137)

    SciTech Connect

    R.Kilian

    2004-12-01

    Laboratory data generated in the past decade indicate a significant reduction in component fatigue life when reactor water environmental effects are experimentally simulated. However, these laboratory data have not been supported by nuclear power plant component operating experience. In recent comprehensive review of laboratory, component and structural test data performed through the EPRI Materials Reliability Program, flow rate was identified as a critical variable that was generally not considered in laboratory studies but applicable in plant operating environments. Available data for carbon/low-alloy steel piping components suggest that high flow is beneficial regarding the effects of a reactor water environment. Similar information is lacking for stainless steel piping materials. This report documents progress made to date in an extensive testing program underway to evaluate the effects of flow rate on the corrosion fatigue of 304L stainless steel under simulated PWR primary water environmental conditions.

  9. Sonic fatigue testing of an advanced composite aileron

    NASA Technical Reports Server (NTRS)

    Soovere, J.

    1982-01-01

    The sonic fatigue test program to verify the design of the composite inboard aileron for the L-1011 airplane is described. The composite aileron is fabricated from graphite/epoxy minisandwich covers which are attached to graphite/epoxy front spar and ribs, and to an aluminum rear spar with fasteners. The program covers the development of random fatigue data by means of coupon testing and modal studies on a representative section of the composite aileron, culminating in the accelerated sonic fatigue proof test. The composite aileron sustained nonlinear panel vibration during the proof test without failure. Viscous damping coefficients as low as 0.4% were measured on the panels. The effects of moisture conditioning and elevated temperature on the random fatigue life of both undamaged and impact damaged coupons were investigated. The combination of impact damage, moisture, and a 180 F temperature could reduce the random fatigue life by 50%.

  10. Probabilistic Fatigue Damage Program (FATIG)

    NASA Technical Reports Server (NTRS)

    Michalopoulos, Constantine

    2012-01-01

    FATIG computes fatigue damage/fatigue life using the stress rms (root mean square) value, the total number of cycles, and S-N curve parameters. The damage is computed by the following methods: (a) traditional method using Miner s rule with stress cycles determined from a Rayleigh distribution up to 3*sigma; and (b) classical fatigue damage formula involving the Gamma function, which is derived from the integral version of Miner's rule. The integration is carried out over all stress amplitudes. This software solves the problem of probabilistic fatigue damage using the integral form of the Palmgren-Miner rule. The software computes fatigue life using an approach involving all stress amplitudes, up to N*sigma, as specified by the user. It can be used in the design of structural components subjected to random dynamic loading, or by any stress analyst with minimal training for fatigue life estimates of structural components.

  11. Creep-Fatigue Interaction Testing

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.

    2001-01-01

    Fatigue fives in metals are nominally time independent below 0.5 T(sub Melt). At higher temperatures, fatigue lives are altered due to time-dependent, thermally activated creep. Conversely, creep rates are altered by super. imposed fatigue loading. Creep and fatigue generally interact synergistically to reduce material lifetime. Their interaction, therefore, is of importance to structural durability of high-temperature structures such as nuclear reactors, reusable rocket engines, gas turbine engines, terrestrial steam turbines, pressure vessel and piping components, casting dies, molds for plastics, and pollution control devices. Safety and lifecycle costs force designers to quantify these interactions. Analytical and experimental approaches to creep-fatigue began in the era following World War II. In this article experimental and life prediction approaches are reviewed for assessing creep-fatigue interactions of metallic materials. Mechanistic models are also discussed briefly.

  12. Statistical treatment of fatigue test data

    SciTech Connect

    Raske, D.T.

    1980-01-01

    This report discussed several aspects of fatigue data analysis in order to provide a basis for the development of statistically sound design curves. Included is a discussion on the choice of the dependent variable, the assumptions associated with least squares regression models, the variability of fatigue data, the treatment of data from suspended tests and outlying observations, and various strain-life relations.

  13. Fatigue, Creep-Fatigue, and Thermomechanical Fatigue Life Testing of Alloys

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Lerch, Bradley A.; McGaw, Michael A.

    2000-01-01

    The fatigue crack initiation resistance of an alloy is determined by conducting a series of tests over a range of values of stress amplitude or strain range. The observed number of cycles to failure is plotted against the stress amplitude or strain range to obtain a fatigue curve. The fatigue properties quoted for an alloy are typically the constants used in the equation(s) that describe the fatigue curve. Fatigue lives of interest may be as low as 10(exp 2) or higher than 10(exp 9) cycles. Because of the enormous scatter associated with fatigue, dozens of tests may be needed to confidently establish a fatigue curve, and the cost may run into several thousands of dollars. To further establish the effects on fatigue life of the test temperature, environment, alloy condition, mean stress effects, creep-fatigue effects, thermomechanical cycling, etc. requires an extraordinarily large and usually very costly test matrix. The total effort required to establish the fatigue resistance of an alloy should not be taken lightly. Fatigue crack initiation tests are conducted on relatively small and presumed to be initially crack-free, samples of an alloy that are intended to be representative of the alloy's metallurgical and physical condition. Generally, samples are smooth and have uniformly polished surfaces within the test section. Some may have intentionally machined notches of well-controlled geometry, but the surface at the root of the notch is usually not polished. The purpose of polishing is to attain a reproducible surface finish. This is to eliminate surface finish as an uncontrolled variable. Representative test specimen geometries will be discussed later. Test specimens are cyclically loaded until macroscopically observable cracks initiate and eventually grow to failure. Normally, the fatigue failure life of a specimen is defined as the number of cycles to separation of the specimen into two pieces. Alternative definitions are becoming more common, particularly for

  14. Program for Weibull Analysis of Fatigue Data

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    2005-01-01

    A Fortran computer program has been written for performing statistical analyses of fatigue-test data that are assumed to be adequately represented by a two-parameter Weibull distribution. This program calculates the following: (1) Maximum-likelihood estimates of the Weibull distribution; (2) Data for contour plots of relative likelihood for two parameters; (3) Data for contour plots of joint confidence regions; (4) Data for the profile likelihood of the Weibull-distribution parameters; (5) Data for the profile likelihood of any percentile of the distribution; and (6) Likelihood-based confidence intervals for parameters and/or percentiles of the distribution. The program can account for tests that are suspended without failure (the statistical term for such suspension of tests is "censoring"). The analytical approach followed in this program for the software is valid for type-I censoring, which is the removal of unfailed units at pre-specified times. Confidence regions and intervals are calculated by use of the likelihood-ratio method.

  15. An Axial-Torsional, Thermomechanical Fatigue Testing Technique

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Bonacuse, Peter J.

    1995-01-01

    A technique for conducting strain-controlled, thermomechanical, axial-torsional fatigue tests on thin-walled tubular specimens was developed. Three waveforms of loading, namely, the axial strain waveform, the engineering shear strain waveform, and the temperature waveform were required in these tests. The phasing relationships between the mechanical strain waveforms and the temperature and axial strain waveforms were used to define a set of four axial-torsional, thermomechanical fatigue (AT-TMF) tests. Real-time test control (3 channels) and data acquisition (a minimum of 7 channels) were performed with a software program written in C language and executed on a personal computer. The AT-TMF testing technique was used to investigate the axial-torsional thermomechanical fatigue behavior of a cobalt-base superalloy, Haynes 188. The maximum and minimum temperatures selected for the AT-TMF tests were 760 and 316 C, respectively. Details of the testing system, calibration of the dynamic temperature profile of the thin-walled tubular specimen, thermal strain compensation technique, and test control and data acquisition schemes, are reported. The isothermal, axial, torsional, and in- and out-of-phase axial-torsional fatigue behaviors of Haynes 188 at 316 and 760 C were characterized in previous investigations. The cyclic deformation and fatigue behaviors of Haynes 188 in AT-TMF tests are compared to the previously reported isothermal axial-torsional behavior of this superalloy at the maximum and minimum temperatures.

  16. Thermomechanical Multiaxial Fatigue Testing Capability Developed

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Structural components in aeronautical gas turbine engines typically experience multiaxial states of stress under nonisothermal conditions. To estimate the durability of the various components in the engine, one must characterize the cyclic deformation and fatigue behavior of the materials used under thermal and complex mechanical loading conditions. To this end, a testing protocol and associated test control software were developed at the NASA Lewis Research Center for thermomechanical axial-torsional fatigue tests. These tests are to be performed on thin-walled, tubular specimens fabricated from the cobalt-based superalloy Haynes 188. The software is written in C and runs on an MS-DOS based microcomputer.

  17. Fatigue Testing of Abrasive Water Jet Cut Titanium

    SciTech Connect

    Hovanski, Yuri; Dahl, Michael E.; Williford, Ralph E.

    2009-06-08

    Battelle Memorial Institute as part of its U.S. Department of Energy (USDOE) Contract No. DE-AC05-76RL01830 to operate the Pacific Northwest National Laboratory (PNNL) provides technology assistance to qualifying small businesses in association with a Technology Assistance Program (TAP). Qualifying companies are eligible to receive a set quantity of labor associated with specific technical assistance. Having applied for a TAP agreement to assist with fatigue characterization of Abrasive Water Jet (AWJ) cut titanium specimens, the OMAX Corporation was awarded TAP agreement 09-02. This program was specified to cover dynamic testing and analysis of fatigue specimens cut from titanium alloy Ti-6%Al-4%V via AWJ technologies. In association with the TAP agreement, a best effort agreement was made to characterize fatigue specimens based on test conditions supplied by OMAX.

  18. Hybrid bearing technology for advanced turbomachinery: Rolling contact fatigue testing

    SciTech Connect

    Dill, J.F.

    1996-01-01

    The purpose of this paper is to describe the basic structure and results to date of a major ARPA funded effort to provide a tribological performance database on ceramic bearing materials and their interaction with standard bearing steels. Program efforts include studies of material physical properties, machining characteristics, and tribological performance. The majority of the testing completed to date focuses on rolling contact fatigue testing of the ceramic materials, including efforts to arrive at optimum approaches to evaluating ceramic/steel hybrid combinations in rolling contact fatigue.

  19. Final report on low-cycle fatigue and creep-fatigue testing of salt-filled alloy 800 specimens

    SciTech Connect

    Kaae, J L

    1982-05-01

    Uniaxial low-cycle fatigue and creep-fatigue tests have been carried out on hollow alloy 800 specimens that were either filled with air or with a molten mixture of sodium nitrate, potassium nitrate and an oxidizer. Low-cycle fatigue tests were carried out at 1200/sup 0/F and 650/sup 0/F by cycling the strain continuously between equal mangitude of tensile and compressive values at a rate of 4 x 10/sup -3/sec/sup -1/ until failure. The creep-fatigue tests were carried out at 1200/sup 0/F. The loading cycle differed from that of low-cycle fatigue testing only in the imposition of a hold at the peak compressive strain in each cycle. Cracks always initiated on the inner surface of the hollow specimen, and therefore, corrosive effects on crack propagation and initiation were controlled by the environment within the specimen cavity. In common with tests carried out earlier on steam-filled alloy 800 specimens, at 1200/sup 0/F in the presence of molten salt the heat of alloy 800 with the lower carbon content had a higher fatigue strength than the heat with the higher carbon content even though different heats were used in the two testing programs. The fatigue strength of the two heats of material in the presence of molten salt at 650/sup 0/F were about the same. Tests with air-filled specimens indicated that the presence of the molten salt degraded the fatigue life at 1200/sup 0/F but did not affect the creep fatigue life, while the presence of steam enhanced both the fatigue life and the creep-fatigue life.

  20. Fatigue strength of tubular structural elements at bending vibrations. Communication 2: TSE fatigue strength at programmed load variation

    NASA Astrophysics Data System (ADS)

    Gerasimchuk, O. N.; Gorodetskij, S. S.; Gryaznov, B. A.; Nalimov, Yu. S.

    1994-04-01

    Programs of a block loading with a prescribed and random alternation of stress amplitudes, simulating service load spectra, are presented. The results of fatigue testing of straight and bent tubular structural elements are given. A conclusion is drawn that low fatigue strength of VNS25 steel bent TSEs is due to an unfavorable technological inheritance of the tube bending and deplanation of the section during the test.

  1. Fatigue tests on big structure assemblies of concorde aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, V. P.; Perrais, J. P.

    1972-01-01

    Fatigue tests on structural assemblies of the Concorde supersonic transport aircraft are reported. Two main sections of the aircraft were subjected to pressure, mechanical load, and thermal static tests. The types of fatigue tests conducted and the results obtained are discussed. It was concluded that on a supersonic aircraft whose structural weight is a significant part of the weight analysis, many fatigue and static strength development tests should be made and fatigue and thermal tests of the structures are absolutely necessary.

  2. Fatigue testing a plurality of test specimens and method

    NASA Technical Reports Server (NTRS)

    Hodo, James D. (Inventor); Moore, Dennis R. (Inventor); Morris, Thomas F. (Inventor); Tiller, Newton G. (Inventor)

    1987-01-01

    Described is a fatigue testing apparatus for simultaneously subjecting a plurality of material test specimens to cyclical tension loading to determine the fatigue strength of the material. The fatigue testing apparatus includes a pulling head having cylinders defined therein which carry reciprocating pistons. The reciprocation of the pistons is determined by cyclical supplies of pressurized fluid to the cylinders. Piston rods extend from the pistons through the pulling head and are attachable to one end of the test specimens, the other end of the test specimens being attachable to a fixed base, causing test specimens attached between the piston rods and the base to be subjected to cyclical tension loading. Because all the cylinders share a common pressurized fluid supply, the breaking of a test specimen does not substantially affect the pressure of the fluid supplied to the other cylinders nor the tension applied to the other test specimens.

  3. Heat pipe fatigue test specimen: Metallurgical evaluation

    NASA Technical Reports Server (NTRS)

    Walak, Steven E.; Cronin, Michael J.; Grobstein, Toni

    1992-01-01

    An innovative creep/fatigue test was run to simulate the temperature, mechanical load, and sodium corrosion conditions expected in a heat pipe designed to supply thermal energy to a Stirling cycle power converter. A sodium-charged Inconel 718 heat pipe with a Nickel 200 screen wick was operated for 1090 hr at temperatures between 950 K (1250 F) and 1050 K (1430 F) while being subjected to creep and fatigue loads in a servo-hydraulic testing machine. After testing, the heat pipe was sectioned and examined using optical microscopy, scanning electron microscopy, and electron microprobe analysis with wavelength dispersive x-ray spectroscopy. The analysis concentrated on evaluating topographic, microstructural, and chemical changes in the sodium exposed surfaces of the heat pipe wall and wick. Surface changes in the evaporator, condenser, and adiabatic sections of the heat pipe were examined in an effort to correlate the changes with the expected sodium environment in the heat pipe. This report describes the setup, operating conditions, and analytical results of the sodium heat pipe fatigue test.

  4. Perceived stress and fatigue among students in a doctor of chiropractic training program

    PubMed Central

    Kizhakkeveettil, Anupama; Vosko, Andrew M.; Brash, Marissa; PH, Dr; Philips, Michael A.

    2017-01-01

    Objective High levels of stress and fatigue are associated with decreased academic success, well-being, and quality of life. The objective of this research was to quantify levels of perceived stress and fatigue among chiropractic students to identify sources of and student coping mechanisms for perceived stress and fatigue and to identify the relationship between students' perceived stress and fatigue. Methods A survey comprised of the Perceived Stress Scale, the Undergraduate Sources of Stress Survey, and the Piper Fatigue Scale was administered to chiropractic students in their 2nd, 5th, and 8th trimesters of doctoral study. Data were analyzed by descriptive statistics, 1-way analysis of variance, and linear correlation tests. Results Students reported having moderate to high levels of stress and fatigue, with higher levels of stress and fatigue seen in women than in men. A nonsignificant difference among stress scores and a significant difference among fatigue scores were observed based on program term. Levels of stress predicted levels of fatigue, and stress was strongly correlated with psychological health, relationships with family members, mood, and need for learning accommodations. Fatigue was strongly correlated with psychological health, academic demands, and conflicts between studies and other activities. Conclusion There are differences in the reporting of perceived stress and fatigue levels in this chiropractic student population based on gender. The correlation between fatigue and stress also suggests that measures that may alleviate one may likely affect the other. PMID:27552030

  5. Fatigue-Crack-Growth Computer Program

    NASA Technical Reports Server (NTRS)

    Forman, Royce G.; Shivakumar, V.; Newman, James C., Jr.

    1991-01-01

    Fatigue Crack Growth (NASA/FLAGRO) computer program developed as aid in predicting growth of preexisting flaws and cracks in structural components of space systems. Is enhanced version of FLAGRO4 and incorporates state-of-the-art improvements in both fracture mechanics and computer technology. Provides fracture-mechanics analyst with computerized method of evaluating "safe-crack-growth-life" capabilities of structural components. Also used to evaluate tolerance to damage of structure of given design. Designed modular to facilitate revisions and operation on minicomputers. Written in FORTRAN 77.

  6. A proposed USAF fatigue evaluation program based upon recent systems experience

    NASA Technical Reports Server (NTRS)

    Haviland, G. P.; Purkey, G. F.

    1972-01-01

    The United States Air Force has published a document entitled Aircraft Structural Integrity Program. One phase of the program is concerned with the fatigue life certification of all types of military aircraft. The document describes the criteria, analyses, and tests that are necessary in order to satisfy the USAF fatigue life requirement. Some recent and valid criticism has been directed toward the document, particularly the fatigue-life requirements contained in it. Some changes are proposed based on surveys conducted in the United States and abroad as well as some recent systems' experience. The surveys covered both military and civilian organizations. The fatigue certification case histories of selected military and commercial aircraft are presented. The design development element tests, preproduction design verification tests, and full-scale fatigue tests of each are described. A brief status report on the revisions to the MIL-A-008860 series specifications is included.

  7. High-Temperature, Low-Cycle Fatigue of Copper-Base Alloys for Rocket Nozzles. Part 1: Data Summary for Materials Tested in Prior Programs

    NASA Technical Reports Server (NTRS)

    Conway, J. B.; Stentz, R. H.; Berling, J. T.

    1975-01-01

    A more detailed analysis of the results obtained in 188 previously reported low-cycle fatigue tests of various candidate materials for regeneratively-cooled, reusable rocket nozzle liners was reported. Plots of load range versus cycles were reported for each test along with a stress-strain hysteresis loop near half-life. In addition, a summary table was provided to compare N5 (cycles to a five percent load range drop) and Nf (cycles to complete specimen separation) values for each test.

  8. Characterization of Solder Joint Reliability Using Cyclic Mechanical Fatigue Testing

    NASA Astrophysics Data System (ADS)

    Kim, Choong-Un; Bang, Woong-Ho; Xu, Huili; Lee, Tae-Kyu

    2013-10-01

    This article summarizes the mechanics of two mechanical fatigue methods, cyclic bending fatigue and shear fatigue, in inducing failure in solder joints in package assemblies, and it presents the characteristics of fatigue failures resulting from these methods using example cases of Sn-Pb eutectic and Sn-rich Pb-free solder alloys. Numerical simulation suggests that both testing configurations induce fatigue failure by the crack-opening mode. In the case of bending fatigue, the strain induced by the bending displacement is found to be sensitive to chip geometry, and it induces fatigue cracks mainly at the solder matrix adjacent to the printed circuit board interface. In case of shear fatigue, the failure location is firmly fixed at the solder neck, created by solder mask, where an abrupt change in the solder geometry occurs. Both methods conclude that the Coffin-Manson model is the most appropriate model for the isothermal mechanical fatigue of solder alloys. An analysis of fatigue characteristics using the frame of the Coffin-Manson model produces several insightful results, such as the reason why Pb-free alloys show higher fatigue resistance than Sn-Pb alloys even if they are generally more brittle. Our analysis suggests that it is related to higher work hardening. All these results indicate that mechanical fatigue can be an extremely useful method for fast screening of defective package structures and also in gaining a better understanding of fatigue failure mechanism and prediction of reliability in solder joints.

  9. Rolling element fatigue testing of gear materials

    NASA Technical Reports Server (NTRS)

    Nahm, A. H.

    1978-01-01

    Rolling element fatigue lives of eleven alloys were evaluated. The eleven alloys studied were three nitriding alloys (Super Nitralloy, Nitralloy 135, and Nitralloy N), four case carburizing alloys (AISI 9310, CBS 600, CBS 1000M and Vasco X-2), and four throughhardening alloys (Vasco Matrix II,AISI W-1, AISI S-2 and AISI O-2). Several different heat treatments and/or melting processes were studied on the three carburizing alloy steels. Metallurgical analyses were made before and after the RC rig tests. Test data were statistically analyzed using the Weibull distribution function. B-10 lives were compared versus VIM-VAR AISI M-50 and carburized VAR AISI 9310, as reference alloys.

  10. Eddy Current Method for Fatigue Testing

    NASA Technical Reports Server (NTRS)

    Simpson, John W. (Inventor); Fulton, James P. (Inventor); Wincheski, Russell A. (Inventor); Todhunter, Ronald G. (Inventor); Namkung, Min (Inventor); Nath, Shridhar C. (Inventor)

    1997-01-01

    Flux-focusing electromagnetic sensor using a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. A ferrous shield isolates a high-turn pick-up coil from an excitation coil. Use of the magnetic shield produces a null voltage output across the receiving coil in presence of an unflawed sample. Redistribution of the current flow in the sample caused by the presence of flaws. eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. Maximum sensor output is obtained when positioned symmetrically above the crack. By obtaining position of maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. Accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output resulting in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip enabling the search region to be clearly defined. Under low frequency operation, material thinning due to corrosion causes incomplete shielding of the pick-up coil. Low frequency output voltage of the probe is therefore a direct indicator of thickness of the test sample. Fatigue testing a conductive material is accomplished by applying load to the material, applying current to the sensor, scanning the material with the sensor, monitoring the sensor output signal, adjusting material load based on the sensor output signal of the sensor, and adjusting position of the sensor based on its output signal.

  11. Multi-Site Fatigue Testing and Characterization of Fuselage Panels from Aging Aircraft Structure

    DTIC Science & Technology

    2013-06-07

    Multi-site fatigue damage is a common problem in the riveted lap joint structure of aging aircraft. Modeling and characterization of such damage is...an especially daunting task. In this effort we present the results from fatigue tests which were performed on fuselage lap joints extracted from...in the lap joint . Some spot welded lap joint panels were also tested during the larger program; however, only the results from mechanically fastened

  12. The NASA Ames Fatigue Countermeasures Program: The Next Generation

    NASA Technical Reports Server (NTRS)

    Rosekind, Mark R.; Neri, David F.; Miller, Donna L.; Gregory, Kevin B.; Webbon, Lissa L.; Oyung, Ray L.

    1997-01-01

    Twenty-four hour, global aviation operations pose unique challenges to humans. Physiological requirements related to sleep, the internal circadian clock, and human fatigue are critical factors that are known to affect safety, performance, and productivity. Understanding the human operators' physiological capabilities, and limitations, will be important to address these issues as global demand for aviation activities continues to increase. In 1980, in response to a Congressional request, the National Aeronautics and Space Administration (NASA) Ames Research Center initiated a Fatigue/Jet Lag Program to examine the role of fatigue in flight operations. Originally established by Dr. John K. Lauber and Dr. Charles E. Billings, the Program was designed to address three objectives: (1) determine the extent of fatigue, sleep loss, and circadian disruption in flight operations; (2) determine how fatigue affected flight crew performance; and (3) develop strategies to maximize performance and alertness during flight operations.

  13. The influence of modifications of a fatigue loading history program on fatigue lifetime

    NASA Technical Reports Server (NTRS)

    Branger, J.

    1972-01-01

    Rectangular specimens of 7075 and 2014 aluminum alloys with two holes (stress concentration factor of 3.24) have been tested under axial fatigue loading on a six-rod test bed with modifications of the loading program, the surface particulars, and the frequency. The length of the precrack stage was investigated by use of a new crack detector. In most cases the two alloys behaved similarly, with similar life to crack start under the same loading. Some overloads lengthened the life. Truncation by omission of the lowest peak loads should be limited to about 20 percent of the ultimate load. Simplifying counting methods gave misleading results. Very thin surface layers of anodizing, protection by vinyl, dry nitrogen atmosphere, as well as stepwise reaming or grinding the surface of the holes, lengthened the life; thick anodized layers shortened the life. Compressing the hole surface by rolling had no influence. Frequencies at about 210 to 240 cpm produced shorter lives than those at 40 cpm. At 5.4 cpm the life was considerably longer. A model to better understand the precrack-stage fatigue mechanism is discussed.

  14. 1000–ton testing machine for cyclic fatigue tests of materials at liquid nitrogen temperatures

    SciTech Connect

    Khitruk, A. A.; Klimchenko, Yu. A.; Kovalchuk, O. A.; Marushin, E. L.; Mednikov, A. A.; Nasluzov, S. N.; Privalova, E. K.; Rodin, I. Yu.; Stepanov, D. B.; Sukhanova, M. V.

    2014-01-29

    One of the main tasks of superconductive magnets R and D is to determine the mechanical and fatigue properties of structural materials and the critical design elements in the cryogenic temperature range. This paper describes a new facility built based on the industrial 1000-ton (10 MN) testing machine Schenk PC10.0S. Special equipment was developed to provide the mechanical and cyclic tensile fatigue tests of large-scale samples at the liquid nitrogen temperature and in a given load range. The main feature of the developed testing machine is the cryostat, in which the device converting a standard compression force of the testing machine to the tensile force affected at the test object is placed. The control system provides the remote control of the test and obtaining, processing and presentation of test data. As an example of the testing machine operation the test program and test results of the cyclic tensile fatigue tests of fullscale helium inlet sample of the PF1 coil ITER are presented.

  15. Rolling element fatigue testing of gear materials

    NASA Technical Reports Server (NTRS)

    Nahm, A. H.

    1978-01-01

    Rolling element fatigue lives of nine alloys were evaluated in Rolling Contact (RC) rigs. Test conditions included a Hertzian stress at 4,826 MPa (700 ksi), a rolling speed of 6.23 m/sec (245 in/sec.). Tests were run with a Type I oil (MIL-L-7808G) at room temperature. B-10 lives (10% failure rate) of alloys were compared versus reference alloys, VIM-VAR AISI M-50 and VAR AISI 9310. Six case carburizing alloys (AISI 9310, CBS600, CBS1000M, EX00014, Vasco X-2 and EX00053) and three through-hardening alloys (AISI M-50, VascoMax 350 and Vasco Matrix 2 evaluated, showed RCF performance inferior or equivalent to that of AISI 9310 and AISI M-50. It was also found that the effects of vacuum melting processes, different tempering temperatures, freezing cycle during heat treating, shot peening, gold plating and chrome plating employed in the present investigation did not significantly affect RCF life.

  16. Fatigue testing of reinforced-concrete steel bars

    NASA Astrophysics Data System (ADS)

    Maropoulos, S.; Fasnakis, D.; Voulgaraki, Ch; Papanikolaou, S.; Maropoulos, A.; Antonatos, A.

    2016-11-01

    A number of low-cycle fatigue tests were conducted on reinforced-concrete steel bars of various diameters to study their behaviour under axial loading according to EN 10080 and EN 1421-3. Scanning electron microscopy was used to study the specimen fracture surfaces. The problems faced during testing are presented and a specimen preparation method is described that will aid researchers on fatigue testing to obtain accurate test results and save on material and time.

  17. Fatigue Crack Growth Threshold Testing of Metallic Rotorcraft Materials

    NASA Technical Reports Server (NTRS)

    Newman, John A.; James, Mark A.; Johnson, William M.; Le, Dy D.

    2008-01-01

    Results are presented for a program to determine the near-threshold fatigue crack growth behavior appropriate for metallic rotorcraft alloys. Four alloys, all commonly used in the manufacture of rotorcraft, were selected for study: Aluminum alloy 7050, 4340 steel, AZ91E Magnesium, and Titanium alloy Ti-6Al-4V (beta-STOA). The Federal Aviation Administration (FAA) sponsored this research to advance efforts to incorporate damage tolerance design and analysis as requirements for rotorcraft certification. Rotorcraft components are subjected to high cycle fatigue and are typically subjected to higher stresses and more stress cycles per flight hour than fixed-wing aircraft components. Fatigue lives of rotorcraft components are generally spent initiating small fatigue cracks that propagate slowly under near-threshold cracktip loading conditions. For these components, the fatigue life is very sensitive to the near-threshold characteristics of the material.

  18. Effect of Preloading on Fatigue Strength in Dynamic Fatigue Testing of Ceramic Materials at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Salem, Jonathan A.

    1995-01-01

    Previously derived solutions of fatigue strength as a function of preloading were verified by applying preloads to elevated temperature dynamic fatigue tests of 96 wt% alumina at 1000 C and NC 132 silicon nitride at 1100 C. The technique was found very useful in identification and control of the governing failure mechanism when multiple failure mechanisms, such as slow crack growth, creep and oxidation occurred simultaneously at elevated temperatures.

  19. Fatigue

    MedlinePlus

    ... to help you find out what's causing your fatigue and recommend ways to relieve it. Fatigue itself is not a disease. Medical problems, treatments, and personal habits can add to fatigue. These include Taking certain medicines, such as antidepressants, ...

  20. Rotating Beam Fatigue Testing and Hybrid Ceramic Bearings.

    DTIC Science & Technology

    1994-07-01

    1988, pp. 294-300. 18. Liu, Shih -Yu and Chen , I. W., "Fatigue of Yitria-stablized Zirconia, I. Fatigue Damage, Fracture Origin and Lifetime... Bill Ellingson of the Argonne National Laboratory. 2. Several new and survived rotating beam specimens were sent to the Argonne National Laboratory...Advanced Research Project Agency (ARPA) and Wright Laboratory (AFSC) with the support of Dr. Bill Coblenz, ARPA Ceramic Program Manager, with Mr. Karl

  1. Mechanical degradation of fuel cell membranes under fatigue fracture tests

    NASA Astrophysics Data System (ADS)

    Khorasany, Ramin M. H.; Sadeghi Alavijeh, Alireza; Kjeang, Erik; Wang, G. G.; Rajapakse, R. K. N. D.

    2015-01-01

    The effects of cyclic stresses on the fatigue and mechanical stability of perfluorosulfonic acid (PFSA) membranes are experimentally investigated under standard fuel cell conditions. The experiments are conducted ex-situ by subjecting membrane specimens to cyclic uniaxial tension at controlled temperature and relative humidity. The fatigue lifetime is measured in terms of the number of cycles until ultimate fracture. The results indicate that the membrane fatigue lifetime is a strong function of the applied stress, temperature, and relative humidity. The fatigue life increases exponentially with reduced stresses in all cases. The effect of temperature is found to be more significant than that of humidity, with reduced fatigue life at high temperatures. The maximum membrane strain at fracture is determined to decrease exponentially with increasing membrane lifetime. At a given fatigue life, a membrane exposed to fuel cell conditions is shown to accommodate more plastic strain before fracture than one exposed to room conditions. Overall, the proposed ex-situ membrane fatigue experiment can be utilized to benchmark the fatigue lifetime of new materials in a fraction of the time and cost associated with conventional in-situ accelerated stress testing methods.

  2. Recovery of Hip and Back Muscle Fatigue Following a Back Extension Endurance Test

    PubMed Central

    WANG-PRICE, SHARON; ALMADAN, MOHAMMAD; STODDARD, CARISSA; MOORE, DUSTIN

    2017-01-01

    Literature has not shown the minimum time required to recover from muscle fatigue after a prolonged trunk isometric contraction. The purpose of this study was to determine if the lumbar multifidus (LM) and gluteus maximus (GM) muscles would recover from fatigue after three different rest periods following performance of a back extension endurance test. Endurance time and electromyographic (EMG) activity of bilateral LM and GM muscles were collected from 12 healthy adults during a modified Biering-Sørensen test. On three separate visits, each participant performed two modified Biering-Sørensen tests, one before and one after a rest period (3, 6 or 9 min). For each endurance test, endurance time was measured and both mean and median EMG frequency fatigue rates were calculated. The results showed a significantly reduced endurance time and normalized mean frequency fatigue rates on the second modified Biering-Sørensen endurance test regardless of the rest periods (3, 6, and 9 min). This suggests that adequate rest should be considered for fatigue recovery when designing a back and hip endurance exercise program, and that future studies should investigate a rest time longer than 9 minutes for fatigue recovery following a modified Biering-Sørensen endurance test. PMID:28344736

  3. 77 FR 55105 - Aging Airplane Program: Widespread Fatigue Damage; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Parts 121 and 129 RIN 2120-AI05 Aging Airplane Program: Widespread... entitled ``Aging Airplane Program: Widespread Fatigue Damage'' (77 FR 30877), which corrected a final...

  4. Low-cycle fatigue testing methods

    NASA Technical Reports Server (NTRS)

    Lieurade, H. P.

    1978-01-01

    The good design of highly stressed mechanical components requires accurate knowledge of the service behavior of materials. The main methods for solving the problems of designers are: determination of the mechanical properties of the material after cyclic stabilization; plotting of resistance to plastic deformation curves; effect of temperature on the life on low cycle fatigue; and simulation of notched parts behavior.

  5. Compression and compression fatigue testing of composite laminates

    NASA Technical Reports Server (NTRS)

    Porter, T. R.

    1982-01-01

    The effects of moisture and temperature on the fatigue and fracture response of composite laminates under compression loads were investigated. The structural laminates studied were an intermediate stiffness graphite-epoxy composite (a typical angle ply laimna liminate had a typical fan blade laminate). Full and half penetration slits and impact delaminations were the defects examined. Results are presented which show the effects of moisture on the fracture and fatigue strength at room temperature, 394 K (250 F), and 422 K (300 F). Static tests results show the effects of defect size and type on the compression-fracture strength under moisture and thermal environments. The cyclic tests results compare the fatigue lives and residual compression strength under compression only and under tension-compression fatigue loading.

  6. Elevated temperature fatigue testing of metals

    NASA Technical Reports Server (NTRS)

    Hirschberg, M. H.

    1981-01-01

    The major technology areas needed to perform a life prediction of an aircraft turbine engine hot section component are discussed and the steps required for life prediction are outlined. These include the determination of the operating environment, the calculation of the thermal and mechanical loading of the component, the cyclic stress-strain and creep behavior of the material required for structural analysis, and the structural analysis to determine the local stress-strain-temperature-time response of the material at the critical location in the components. From a knowledge of the fatigue, creep, and failure resistance of the material, a prediction of the life of the component is made. Material characterization and evaluation conducted for the purpose of calculating fatigue crack initiation lives of components operating at elevated temperatures are emphasized.

  7. Structural fatigue test results for large wind turbine blade sections

    NASA Technical Reports Server (NTRS)

    Faddoul, J. R.; Sullivan, T. L.

    1982-01-01

    In order to provide quantitative information on the operating life capabilities of wind turbine rotor blade concepts for root-end load transfer, a series of cantilever beam fatigue tests was conducted. Fatigue tests were conducted on a laminated wood blade with bonded steel studs, a low cost steel spar (utility pole) with a welded flange, a utility pole with additional root-end thickness provided by a swaged collar, fiberglass spars with both bonded and nonbonded fittings, and, finally, an aluminum blade with a bolted steel fitting (Lockheed Mod-0 blade). Photographs, data, and conclusions for each of these tests are presented. In addition, the aluminum blade test results are compared to field failure information; these results provide evidence that the cantilever beam type of fatigue test is a satisfactory method for obtaining qualitative data on blade life expectancy and for identifying structurally underdesigned areas (hot spots).

  8. Spectrum fatigue testing of T-shaped tension clips

    NASA Astrophysics Data System (ADS)

    Palmberg, Bjoern; Wallstenius, Bengt

    1992-12-01

    An investigation of strain distributions during static loading and crack propagation and fatigue lives under spectrum loading of T-shaped tension clips was carried out. Three slightly different, with respect to geometry, T shaped tension clips made of aluminum alloy 7010-T73651 were studied. The type 1 and 4 test specimens were different only with respect to the web thickness of the clamping end. The type 1 and 2 test specimens were different with repect to milled flat circular countersink around the holes in the type 2 specimens and with respect to the radius between the web and foot. The spectrum fatigue loading consisted of a load sequence representative for the wing root, lower side, of a fighter aircraft. Tests were made at two different load levels for each specimen type. The strain measurements show that the countersink in the type 2 specimens increases the stresses in the fatigue critical region. This is also manifested in the spectrum fatigue life results, where type 2 specimens show the shortest fatigue lives. The strain measurements show that the torque used for the bolts in joining two test specimens or one test specimen and a dummy has a rather large impact on the strain in the fatigue region. The strains decrease with increasing torque. The spectrum fatigue loading resulted in approximately an equal number of flights to obtain a 10.0 mm crack for specimens of type 1 and 4. This suggests that the type 1 configuration is superior since the web thickness is smaller for this type as compared to the type 4 specimens. In other words, the type 4 specimens have an unnecessary oversize of the clamping end web thickness.

  9. Fatigue strength testing of LTCC and alumina ceramics bonds

    NASA Astrophysics Data System (ADS)

    Dąbrowski, A.; Matkowski, P.; Golonka, L.

    2012-12-01

    In this paper the results of fatigue strength tests of ceramic joints are presented. These tests have been performed on the samples subjected to thermal and vibration fatigue as well as on the reference samples without any additional loads. The main goal of the investigation was to determine the strength of hybrid ceramics joints using tensile testing machine. The experiment enabled evaluation of fatigue effects in the mentioned joints. Geometry of test samples has been designed according to FEM simulations, performed in ANSYS FEM environment. Thermal stress as well as the stress induced by vibrations have been analyzed in the designed model. In the experiments two types of ceramics have been used — LTCC green tape DP951 (DuPont) and alumina ceramic tape. The samples have been prepared by joining two sintered ceramic beams made of different types of material. The bonds have been realized utilizing low temperature glass or a layer of LTCC green tape.

  10. 75 FR 69745 - Aging Airplane Program: Widespread Fatigue Damage

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ...This final rule amends FAA regulations pertaining to certification and operation of transport category airplanes to prevent widespread fatigue damage in those airplanes. For certain existing airplanes, the rule requires design approval holders to evaluate their airplanes to establish a limit of validity of the engineering data that supports the structural maintenance program (LOV). For future......

  11. Fatigue

    MedlinePlus

    ... fatigue may be worsened with physical activity or mental stress. It is diagnosed based on the presence of a specific group of symptoms and after all other possible causes of fatigue are ruled out.

  12. Fatigue Testing of TBC on Structural Steel by Cyclic Bending

    NASA Astrophysics Data System (ADS)

    Musalek, Radek; Kovarik, Ondrej; Medricky, Jan; Curry, Nicholas; Bjorklund, Stefan; Nylen, Per

    2015-01-01

    For applications with variable loading, fatigue performance of coated parts is of utmost importance. In this study, fatigue performance of conventional structural steel coated with thermal barrier coating (TBC) was evaluated in cyclic bending mode by "SF-Test" device. Testing was carried out at each stage of the TBC preparation process, i.e., for as-received and grit-blasted substrates, as well as for samples with Ni-based bond-coat and complete TBC: bond-coat with YSZ-based top-coat. Comparison of results obtained for different loading amplitudes supplemented by fractographic analysis enabled identification of dominating failure mechanisms and demonstrated applicability of the high-frequency resonant bending test for evaluation of fatigue resistance alteration at each stage of the TBC deposition process.

  13. Biomechanical fatigue analysis of an advanced new carbon fiber/flax/epoxy plate for bone fracture repair using conventional fatigue tests and thermography.

    PubMed

    Bagheri, Zahra S; El Sawi, Ihab; Bougherara, Habiba; Zdero, Radovan

    2014-07-01

    The current study is part of an ongoing research program to develop an advanced new carbon fiber/flax/epoxy (CF/flax/epoxy) hybrid composite with a “sandwich structure” as a substitute for metallic materials for orthopedic long bone fracture plate applications. The purpose of this study was to assess the fatigue properties of this composite, since cyclic loading is one of the main types of loads carried by a femur fracture plate during normal daily activities. Conventional fatigue testing, thermographic analysis, and scanning electron microscopy (SEM) were used to analyze the damage progress that occurred during fatigue loading. Fatigue strength obtained using thermography analysis (51% of ultimate tensile strength) was confirmed using the conventional fatigue test (50–55% of ultimate tensile strength). The dynamic modulus (E⁎) was found to stay almost constant at 47 GPa versus the number of cycles, which can be related to the contribution of both flax/epoxy and CF/epoxy laminae to the stiffness of the composite. SEM images showed solid bonding at the CF/epoxy and flax/epoxy laminae, with a crack density of only 0.48% for the plate loaded for 2 million cycles. The current composite plate showed much higher fatigue strength than the main loads experienced by a typical patient during cyclic activities; thus, it may be a potential candidate for bone fracture plate applications. Moreover, the fatigue strength from thermographic analysis was the same as that obtained by the conventional fatigue tests, thus demonstrating its potential use as an alternate tool to rapidly evaluate fatigue strength of composite biomaterials.

  14. Biomechanical fatigue analysis of an advanced new carbon fiber/flax/epoxy plate for bone fracture repair using conventional fatigue tests and thermography.

    PubMed

    Bagheri, Zahra S; El Sawi, Ihab; Bougherara, Habiba; Zdero, Radovan

    2014-07-01

    The current study is part of an ongoing research program to develop an advanced new carbon fiber/flax/epoxy (CF/flax/epoxy) hybrid composite with a "sandwich structure" as a substitute for metallic materials for orthopedic long bone fracture plate applications. The purpose of this study was to assess the fatigue properties of this composite, since cyclic loading is one of the main types of loads carried by a femur fracture plate during normal daily activities. Conventional fatigue testing, thermographic analysis, and scanning electron microscopy (SEM) were used to analyze the damage progress that occurred during fatigue loading. Fatigue strength obtained using thermography analysis (51% of ultimate tensile strength) was confirmed using the conventional fatigue test (50-55% of ultimate tensile strength). The dynamic modulus (E(⁎)) was found to stay almost constant at 47GPa versus the number of cycles, which can be related to the contribution of both flax/epoxy and CF/epoxy laminae to the stiffness of the composite. SEM images showed solid bonding at the CF/epoxy and flax/epoxy laminae, with a crack density of only 0.48% for the plate loaded for 2 million cycles. The current composite plate showed much higher fatigue strength than the main loads experienced by a typical patient during cyclic activities; thus, it may be a potential candidate for bone fracture plate applications. Moreover, the fatigue strength from thermographic analysis was the same as that obtained by the conventional fatigue tests, thus demonstrating its potential use as an alternate tool to rapidly evaluate fatigue strength of composite biomaterials.

  15. X-43A Rudder Spindle Fatigue Life Estimate and Testing

    NASA Technical Reports Server (NTRS)

    Glaessgen, Edward H.; Dawicke, David S.; Johnston, William M.; James, Mark A.; Simonsen, Micah; Mason, Brian H.

    2005-01-01

    Fatigue life analyses were performed using a standard strain-life approach and a linear cumulative damage parameter to assess the effect of a single accidental overload on the fatigue life of the Haynes 230 nickel-base superalloy X-43A rudder spindle. Because of a limited amount of information available about the Haynes 230 material, a series of tests were conducted to replicate the overload and in-service conditions for the spindle and corroborate the analysis. Both the analytical and experimental results suggest that the spindle will survive the anticipated flight loads.

  16. Fatigue testing of plasma-sprayed thermal barrier coatings, volume 2

    NASA Technical Reports Server (NTRS)

    Cruse, T. A.; Nagy, A.; Popelar, C. F.

    1990-01-01

    A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.

  17. Comparing Rotary Bend Wire Fatigue Test Methods at Different Test Speeds

    NASA Astrophysics Data System (ADS)

    Weaver, Jason D.; Gutierrez, Erick J.

    2015-12-01

    Given its relatively simple setup and ability to produce results quickly, rotary bend fatigue testing is becoming commonplace in the medical device industry and is the subject of a new standard test method ASTM E2948-14. Although some research has been conducted to determine if results differ for different rotary bend fatigue test setups or test speeds, these parameters have not been extensively studied together. In this work, we investigate the effects of these two parameters on the fatigue life of three commonly used medical device alloys (ASTM F2063 nitinol, ASTM F138 stainless steel, and ASTM F1058 cobalt chromium). Results with three different rotary bend fatigue test setups revealed no difference in fatigue life among those setups. Increasing test speed, however, between 100 and 35,000 RPM led to an increased fatigue life for all three alloys studied (average number of cycles to fracture increased between 2.0 and 5.1 times between slowest and fastest test speed). Supplemental uniaxial tension tests of stainless steel wire at varying strain rates showed a strain rate dependence in the mechanical response which could in part explain the increased fatigue life at faster test speeds. How exactly strain rate dependence might affect the fatigue properties of different alloys at different alternating strain values requires further study. Given the difference in loading rates between benchtop fatigue tests and in vivo deformations, the potential for strain rate dependence should be considered when designing durability tests for medical devices and in extrapolating results of those tests to in vivo performance.

  18. Rolling-Element Fatigue Testing and Data Analysis - A Tutorial

    NASA Technical Reports Server (NTRS)

    Vlcek, Brian L.; Zaretsky, Erwin V.

    2011-01-01

    In order to rank bearing materials, lubricants and other design variables using rolling-element bench type fatigue testing of bearing components and full-scale rolling-element bearing tests, the investigator needs to be cognizant of the variables that affect rolling-element fatigue life and be able to maintain and control them within an acceptable experimental tolerance. Once these variables are controlled, the number of tests and the test conditions must be specified to assure reasonable statistical certainty of the final results. There is a reasonable correlation between the results from elemental test rigs with those results obtained with full-scale bearings. Using the statistical methods of W. Weibull and L. Johnson, the minimum number of tests required can be determined. This paper brings together and discusses the technical aspects of rolling-element fatigue testing and data analysis as well as making recommendations to assure quality and reliable testing of rolling-element specimens and full-scale rolling-element bearings.

  19. Effects of Total SAT® Test Time on Performance and Fatigue. Research Notes. RN-37

    ERIC Educational Resources Information Center

    Ackerman, Phillip L.; Kanfer, Ruth; Wolman, Stacey D.

    2005-01-01

    The current study was designed to examine performance effects and fatigue effects associated with different total SAT testing times. In addition, the researchers examined personality, motivation, and other determinants of individual differences in examinee fatigue before, during, and after testing.

  20. Structure analysis, fatigue testing, and lifetime prediction of composite steels

    NASA Astrophysics Data System (ADS)

    Sokolkin, Yu. V.; Chekalkin, A. A.; Babushkin, A. V.

    1998-05-01

    Composite steels prepared by technology of powder metallurgy are widely used as low cost parts with good resistance to wear, fracture, and corrosion. The development of powder composite steels is directly related to strength under vibration, fatigue stabilizing, and accurate lifetime prediction for actual composite topology. The fatigue behavior of powder steels was studied by experimental and numerical methods of composite mechanics and materials sciences. The chemical composition of composite steel is a pure iron powder as the base material and a handful of carbon, chromium, nickel, or phosphorus powders. The powder multi-component mixture is compacted by cold isostatic pressing to a rectangular form. The compactants are sintered in protective atmosphere. The microscale examination of the composite structure included an METAM-RV-21 metallographic optic microscope with a high-resolution ScanNexIIc scanner and an image processing package on the PC platform. The phase composition of powder steels has complex disordered topology with irregular ferrite/austenite grains, iron carbide inclusions, and pores. The microstructure images are treated according to the theory of stochastic processes as ergodic probability functions; statistical moments and a structural covariance function of the composite steels are given. The microscale stress-strain state of the composite steel is analyzed by finite element methods. The stiffness matrix of the composite steel is also presented together with stiffness matrices of ferrite/austenite grains, iron carbide inclusions, and pores as zero matrices. Endurance limits of the microstructural components are described by the Basquin or Coffin-Manson laws, respectively, as high and low cycle fatigue; cumulative microdamage in loading with a variable amplitude is taken from the Palmgren-Miner rule. Planar specimens were tested by console bending. Symmetric fatigue cycling was performed at a stable frequency of 20 Hz with endurance limits up

  1. Elevated temperature static and fatigue testing techniques

    NASA Astrophysics Data System (ADS)

    Harmon, D. M.; Coffey, F. J.; Antolovich, S. D.; Brown, R. C.

    Aircraft of the future, such as an aerospace vehicle or an advanced fighter, will have expanded operating envelopes and therefore, will be subject to extreme environmental conditions. They will experience high temperatures combined with high external loads. Due to the complexity of full scale testing with combined thermal and mechanical loads, subcomponent and coupon testing play an extremely important role in the verification of structural integrity. This paper describes testing facilities designed for elevated temperature testing of coupon specimens. These facilities are capable of simultaneously applying spectrum loads and a detailed thermal profile. A method is also outlined for developing realistic thermal and mechanical load profiles for advanced aircraft.

  2. Navy High-Strength Steel Corrosion-Fatigue Modeling Program

    DTIC Science & Technology

    2006-10-01

    30 4.1.2- 4 AF1410 Room Temperature Poisson’s Ratio Test on Specimen STL414- 6 , Second Loading Sequence...47 4.2.1- 4 Profile of Boeing Fatigue Specimen 100- 6 Scanned from the...68172 12 34859 1 55739 12 38158 2 73444 14 34999 2 82328 14 37463 2 96716 14 45864 4 43390 16 35046 4 44416 16 33487 4 48774 16 28622 6 35724

  3. Evaluation of composite flattened tubular specimen. [fatigue tests

    NASA Technical Reports Server (NTRS)

    Liber, T.; Daniel, I. M.

    1978-01-01

    Flattened tubular specimens of graphite/epoxy, S-glass/epoxy, Kevlar-49/epoxy, and graphite/S-glass/epoxy hybrid materials were evaluated under static and cyclic uniaxial tensile loading and compared directly with flat coupon data of the same materials generated under corresponding loading conditions. Additional development for the refinement of the flattened specimen configuration and fabrication was required. Statically tested graphite/epoxy, S-glass/epoxy, and Kevlar 49/epoxy flattened tube specimens exhibit somewhat higher average strengths than their corresponding flat coupons. Flattened tube specimens of the graphite/S-glass/epoxy hybrid and the graphite/epoxy flattened tube specimens failed in parasitic modes with consequential lower strength than the corresponding flat coupons. Fatigue tested flattened tube specimens failed in parasitic modes resulting in lower fatigue strengths than the corresponding flat coupons.

  4. Fatigue testing of thermoformed bidirectional LDF™-composites

    NASA Astrophysics Data System (ADS)

    Schuster, J.; Friedrich, K.

    1994-01-01

    Specimens made of Long Discontinuous Fiber (LDF™) composite material were elongated to different states of deformation by thermoforming. Tension-tension-fatigue tests were performed using waisted bidirectional specimens cut out of the thermoformed parts. These resulted in similar shapes of the Wöhler-curves fairly independently of the deformation state of the LDF™-material. In addition, the static strength values were not very much influenced by the elongation of the specimens. The specimens were nondestructively inspected by ultrasonics and thermography.

  5. Reversible Bending Fatigue Testing on Zry-4 Surrogate Rods

    SciTech Connect

    Wang, Jy-An John; Wang, Hong; Bevard, Bruce Balkcom; Howard, Rob L

    2014-01-01

    Testing high-burnup spent nuclear fuel (SNF) presents many challenges in areas such as specimen preparation, specimen installation, mechanical loading, load control, measurements, data acquisition, and specimen disposal because these tasks are complicated by the radioactivity of the test specimens. Research and comparison studies conducted at Oak Ridge National Laboratory (ORNL) resulted in a new concept in 2010 for a U-frame testing setup on which to perform hot-cell reversible bending fatigue testing. Subsequently, the three-dimensional finite element analysis and the engineering design of components were completed. In 2013 the ORNL team finalized the upgrade of the U-frame testing setup and the integration of the U-frame setup into a Bose dual linear motor test bench to develop a cyclic integrated reversible-bending fatigue tester (CIRFT). A final check was conducted on the CIRFT test system in August 2013, and the CIRFT was installed in the hot cell in September 2013 to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The fatigue responses of Zircaloy-4 (Zry-4) cladding and the role of pellet pellet and pellet clad interactions are critical to SNF vibration integrity, but such data are not available due to the unavailability of an effective testing system. While the deployment of the developed CIRFT test system in a hot cell will provide the opportunity to generate the data, the use of a surrogate rod has proven quite effective in identifying the underlying deformation mechanism of an SNF composite rod under an equivalent loading condition. This paper presents the experimental results of using surrogate rods under CIRFT reversible cyclic loading. Specifically, monotonic and cyclic bending tests were conducted on surrogate rods made of a Zry-4 tube and alumina pellet inserts, both with and without an epoxy bond.

  6. Development and Feasibility of an Evidence-Based Patient Education Program for Managing Fatigue in Multiple Sclerosis

    PubMed Central

    Feddersen, Lena Katharina; Lau, Stephanie; Köpke, Sascha; Moss-Morris, Rona; Heesen, Christoph; Pöttgen, Jana

    2016-01-01

    Background: Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease of the central nervous system. Fatigue is a common and disabling symptom, often causing decreased quality of life, social withdrawal, and unemployment. We developed and studied the feasibility of a cognitive-behavioral group intervention to manage fatigue in MS. We aimed to integrate the concepts of cognitive-behavioral therapy and evidence-based patient information. Methods: We conducted patient interviews and a focus group to assess patients' interest in and need for fatigue self-management training and developed the program accordingly. The program consists of six 90-minute modules, which were structured with the use of moderation cards, helping to guarantee treatment fidelity. The program was tested on three pilot groups (N = 16) in a rehabilitation center. Fatigue, depression, and coping self-efficacy were assessed at baseline and after the intervention. Acceptance and general satisfaction with the program were also evaluated. Results: Patient interviews elicited different characteristics of fatigue, suggesting that patients had different requirements. The program was very acceptable to patients. Pre-post assessments of the pilot study showed significantly improved scores on the Coping Self-Efficacy Scale (P = .013) but not on the Fatigue Scale for Motor and Cognitive Functions and the 30-item Inventory of Depressive Symptomatology. Conclusions: These preliminary results suggest that this program is a feasible cognitive-behavioral group training program that may improve coping self-efficacy and has the potential to subsequently reduce fatigue. The next step is evaluation of the program in a randomized controlled trial. PMID:27252600

  7. An optical motion measuring system for laterally oscillated fatigue tests

    NASA Technical Reports Server (NTRS)

    Tripp, John S.; Tcheng, Ping; Murri, Gretchen B.; Sharpe, Scott

    1993-01-01

    This paper describes an optical system developed for materials testing laboratories at NASA Langley Research Center (LaRC) for high resolution monitoring of the transverse displacement and angular rotation of a test specimen installed in an axial-tension bending machine (ATB) during fatigue tests. It consists of a small laser, optics, a motorized mirror, three photodiodes, electronic detection and counting circuits, a data acquisition system, and a personal computer. A 3-inch by 5-inch rectangular plate attached to the upper grip of the test machine serves as a target base for the optical system. The personal computer automates the fatigue test procedure, controls data acquisition, performs data reduction, and provides user displays. The data acquisition system also monitors signals from up to 16 strain gages mounted on the test specimen. The motion measuring system is designed to continuously monitor and correlate the amplitude of the oscillatory motion with the strain gage signals in order to detect the onset of failure of the composite test specimen. A prototype system has been developed and tested which exceeds the design specifications of +/- 0.01 inch displacement accuracy, and +/- 0.25 deg angular accuracy at a sampling rate of 100 samples per second.

  8. Development and Fatigue Testing of Ceramic Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Choi, Sung R.; Miller, Robert A.

    2004-01-01

    Ceramic thermal barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. Durability of the coating systems remains a critical issue with the ever-increasing temperature requirements. Thermal conductivity increase and coating degradation due to sintering and phase changes are known to be detrimental to coating performance. There is a need to characterize the coating thermal fatigue behavior and temperature limit, in order to potentially take full advantage of the current coating capability. In this study, thermal conductivity and cyclic fatigue behaviors of plasma-sprayed ZrO2-8wt%Y2O3 thermal barrier coatings were evaluated under high temperature, large thermal gradient and thermal cycling conditions. The coating degradation and failure processes were assessed by real-time monitoring of the coating thermal conductivity under the test conditions. The ceramic coating crack initiation and propagation driving forces and failure modes under the cyclic thermal loads will be discussed in light of the high temperature mechanical fatigue and fracture testing results.

  9. Automatic Test Program Generation.

    DTIC Science & Technology

    1978-03-01

    presents a test description language, NOPAL , in which a user may describe diagnostic tests, and a software system which automatically generates test...programs for an automatic test equipment based on the descriptions of tests. The software system accepts as input the tests specified in NOPAL , performs

  10. Fatigue-crack monitoring in-flight using acoustic emission - hardware, technique, and testing

    SciTech Connect

    Hutton, P.H.; Skorpik, J.R.; Lemon, D.K.

    1981-07-01

    The three programs described represent a logical evolutionary process toward effective flaw surveillance in aircraft using AE. The Macchi tests showed that an AE system can withstand extended in-flight service and collect meaningful information relative to fatigue crack growth at a single specific location. The MIrage aircraft work seeks to extend the methods demonstrated on the Macchi into a more complex circumstance. We are now attempting to detect and locate crack growth at any of twenty fastener locations in a relatively complex geometry. The DARPA pattern recognition program seeks to develop signal identification capability that would pave the way for general monitoring of aircraft structures using AE to detect fatigue crack growth. It appears that AE technology may be capable of enhancing aircraft safety assurance while reducing inspection requirements with the associated costs.

  11. Closed-Loop Control for Sonic Fatigue Testing Systems

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A.; Bossaert, Guido

    2001-01-01

    This article documents recent improvements to the acoustic control system of the Thermal Acoustic Fatigue Apparatus (TAFA), a progressive wave tube test facility at the NASA Langley Research Center, Hampton, VA. A brief summary of past acoustic performance is first given to serve as a basis of comparison with the new performance data using a multiple-input, closed-loop, narrow-band controller. Performance data in the form of test section acoustic power spectral densities and coherence are presented for a variety of input spectra including uniform, band-limited random and an expendable launch vehicle payload bay environment.

  12. Heating and cooling system. [for fatigue test specimens

    NASA Technical Reports Server (NTRS)

    Imig, L. A.; Gardner, M. R. (Inventor)

    1982-01-01

    A heating and cooling apparatus capable of cyclic heating and cooling of a test specimen undergoing fatigue testing is discussed. Cryogenic fluid is passed through a block clamped to the speciment to cool the block and the specimen. Heating cartridges penetrate the block to heat the block and the specimen to very hot temperaures. Control apparatus is provided to alternatively activate the cooling and heating modes to effect cyclic heating and cooling between very hot and very cold temperatures. The block is constructed of minimal mass to facilitate the rapid temperature changes.

  13. Hot fire fatigue testing results for the compliant combustion chamber

    NASA Technical Reports Server (NTRS)

    Pavli, Albert J.; Kazaroff, John M.; Jankovsky, Robert S.

    1992-01-01

    A hydrogen-oxygen subscale rocket combustion chamber was designed incorporating an advanced design concept to reduce strain and increase life. The design permits unrestrained thermal expansion of a circumferential direction and, thereby, provides structural compliance during the thermal cycling of hot-fire testing. The chamber was built and test fired at a chamber pressure of 4137 kN/sq m (600 psia) and a hydrogen-oxygen mixture ratio of 6.0. Compared with a conventional milled-channel configuration, the new structurally compliant chamber had a 134 or 287 percent increase in fatigue life, depending on the life predicted for the conventional configuration.

  14. Attention in Parkinson's disease with fatigue: evidence from the attention network test.

    PubMed

    Pauletti, Caterina; Mannarelli, Daniela; Locuratolo, Nicoletta; Pollini, Luca; Currà, Antonio; Marinelli, Lucio; Rinalduzzi, Steno; Fattapposta, Francesco

    2017-03-01

    Fatigue is a non-specific symptom that is common in chronic diseases and represents one of the most disabling symptoms in Parkinson's disease. PD patients often experience cognitive deficits related above all to executive functions. The relationship between cognitive changes and fatigue in PD patients has not been explored in depth. The Attention Network Test (ANT) is a rapid, widely used test to measure the efficiency of three attentional networks, i.e., alerting, orienting, and executive, by evaluating reaction times (RTs) in response to visual stimuli. To assess the association between fatigue and the efficiency of the attentional networks, according to the Posnerian view, ANT was administered to 15 parkinsonian patients with fatigue (PFS-16 > 2.95), 17 parkinsonian patients without fatigue, and 37 age- and sex-matched healthy controls. Anxiety, depression, quality of sleep, and quality of life were also assessed. Parkinsonian patients displayed significantly longer RTs and lower executive network efficiency than controls. Patients with fatigue displayed significantly lower executive network efficiency than patients without fatigue. Moreover, patients with fatigue exhibited a lower accuracy than either patients without fatigue or controls. Finally, patients without fatigue displayed a more efficient alerting network than either patients with fatigue or controls. Although the pathogenesis of fatigue is multifactorial, our results indicate that fatigue may be closely related to an alteration of the striato-thalamo-cortical loop connecting the neostriatum to the prefrontal cortex, which is also responsible for the executive dysfunction that is typical of Parkinson's disease.

  15. Cognitive fatigue influences students’ performance on standardized tests

    PubMed Central

    Sievertsen, Hans Henrik; Gino, Francesca; Piovesan, Marco

    2016-01-01

    Using test data for all children attending Danish public schools between school years 2009/10 and 2012/13, we examine how the time of the test affects performance. Test time is determined by the weekly class schedule and computer availability at the school. We find that, for every hour later in the day, test performance decreases by 0.9% of an SD (95% CI, 0.7–1.0%). However, a 20- to 30-minute break improves average test performance by 1.7% of an SD (95% CI, 1.2–2.2%). These findings have two important policy implications: First, cognitive fatigue should be taken into consideration when deciding on the length of the school day and the frequency and duration of breaks throughout the day. Second, school accountability systems should control for the influence of external factors on test scores. PMID:26884183

  16. NASALIFE - Component Fatigue and Creep Life Prediction Program

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Murthy, Pappu L. N.; Mital, Subodh K.

    2014-01-01

    NASALIFE is a life prediction program for propulsion system components made of ceramic matrix composites (CMC) under cyclic thermo-mechanical loading and creep rupture conditions. Although the primary focus was for CMC components, the underlying methodologies are equally applicable to other material systems as well. The program references empirical data for low cycle fatigue (LCF), creep rupture, and static material properties as part of the life prediction process. Multiaxial stresses are accommodated by Von Mises based methods and a Walker model is used to address mean stress effects. Varying loads are reduced by the Rainflow counting method or a peak counting type method. Lastly, damage due to cyclic loading and creep is combined with Minor's Rule to determine damage due to cyclic loading, damage due to creep, and the total damage per mission and the number of potential missions the component can provide before failure.

  17. Design of a Compact Fatigue Tester for Testing Irradiated Materials

    SciTech Connect

    Hartsell, Brian; Campbell, Michael; Fitton, Michael; Hurh, Patrick; Ishida, Taku; Nakadaira, Takeshi

    2015-06-01

    A compact fatigue testing machine that can be easily inserted into a hot cell for characterization of irradiated materials is beneficial to help determine relative fatigue performance differences between new and irradiated material. Hot cell use has been carefully considered by limiting the size and weight of the machine, simplifying sample loading and test setup for operation via master-slave manipulator, and utilizing an efficient design to minimize maintenance. Funded from a US-Japan collaborative effort, the machine has been specifically designed to help characterize titanium material specimens. These specimens are flat cantilevered beams for initial studies, possibly utilizing samples irradiated at other sources of beam. The option to test spherically shaped samples cut from the T2K vacuum window is also available. The machine is able to test a sample to $10^7$ cycles in under a week, with options to count cycles and sense material failure. The design of this machine will be presented along with current status.

  18. Detection of fatigue cracks by nondestructive testing methods

    NASA Technical Reports Server (NTRS)

    Anderson, R. T.; Delacy, T. J.; Stewart, R. C.

    1973-01-01

    The effectiveness was assessed of various NDT methods to detect small tight cracks by randomly introducing fatigue cracks into aluminum sheets. The study included optimizing NDT methods calibrating NDT equipment with fatigue cracked standards, and evaluating a number of cracked specimens by the optimized NDT methods. The evaluations were conducted by highly trained personnel, provided with detailed procedures, in order to minimize the effects of human variability. These personnel performed the NDT on the test specimens without knowledge of the flaw locations and reported on the flaws detected. The performance of these tests was measured by comparing the flaws detected against the flaws present. The principal NDT methods utilized were radiographic, ultrasonic, penetrant, and eddy current. Holographic interferometry, acoustic emission monitoring, and replication methods were also applied on a reduced number of specimens. Generally, the best performance was shown by eddy current, ultrasonic, penetrant and holographic tests. Etching provided no measurable improvement, while proof loading improved flaw detectability. Data are shown that quantify the performances of the NDT methods applied.

  19. Conducting High Cycle Fatigue Strength Step Tests on Gamma TiAl

    NASA Technical Reports Server (NTRS)

    Lerch, Brad; Draper, Sue; Pereira, J. Mike

    2002-01-01

    High cycle fatigue strength testing of gamma TiAl by the step test method is investigated. A design of experiments was implemented to determine if the coaxing effect occurred during testing. Since coaxing was not observed, step testing was deemed a suitable method to define the fatigue strength at 106 cycles.

  20. Mechanical Fatigue Testing of High Burnup Fuel for Transportation Applications

    SciTech Connect

    Wang, Jy-An John; Wang, Hong

    2015-05-01

    This report describes testing designed to determine the ability of high burnup (HBU) (>45 GWd/MTU) spent fuel to maintain its integrity under normal conditions of transportation. An innovative system, Cyclic Integrated Reversible-bending Fatigue Tester (CIRFT), has been developed at Oak Ridge National Laboratory (ORNL) to test and evaluate the mechanical behavior of spent nuclear fuel (SNF) under conditions relevant to storage and transportation. The CIRFT system is composed of a U-frame equipped with load cells for imposing the pure bending loads on the SNF rod test specimen and measuring the in-situ curvature of the fuel rod during bending using a set up with three linear variable differential transformers (LVDTs).

  1. Rolling contact fatigue testing of peek based composites

    NASA Astrophysics Data System (ADS)

    Avanzini, A.; Donzella, G.; Gallina, D.; Pandini, S.; Petrogalli, C.

    2010-06-01

    Rolling contact fatigue phenomenon was investigated on unfilled PEEK and on three different PEEK composites: 10% carbon micro-fiber, graphite and PTFE filled matrix, 30% carbon micro-fiber filled matrix, 30% glass micro-fiber filled matrix. For this aim, roller-shaped specimens were machined from extruded bars of these materials and subjected to rolling contact tests at different contact pressure levels by means of a four roller machine. Contact pressure-life diagrams and wear rates were so obtained and compared, highlighting a relationship with monotonic and hardness materials properties. Microscopic observations of contact surfaces and transversal section of the specimens also allowed observing the damage mechanisms occurred in the materials tested and the effects of the filler. In particular way, deep radial cracks appeared on unfilled PEEK, while spalling and delamination phenomena where found on composites. Diffuse microcracks were found at the filler-matrix interface of the composites specimens, confirming that the fatigue life of these materials is essentially determined by the crack propagation phase, also under rolling contact loading.

  2. Practical tests for monitoring performance, fatigue and recovery in triathletes.

    PubMed

    Coutts, Aaron J; Slattery, Katie M; Wallace, Lee K

    2007-12-01

    Few studies have described simple tests which can be used to provide an early warning of overreaching. The purpose of this study was to examine selected practical tests for monitoring changes in performance, fatigue and recovery of endurance athletes. Sixteen male triathletes were randomly assigned into matched groups. The normal training (NT) and intensified training (IT) groups completed 4 weeks of training followed by a 2-week taper. Physiological measures were taken pre- and post-overload and post-taper periods during an incremental treadmill test to exhaustion. Performance was assessed weekly using a 3-km run time trial (3 kmTT). Five-bound jump for distance (5BT) and submaximal running heart rate (HR(submax)) test were measured twice weekly and the Daily Analyses of Life Demands for Athletes (DALDA) were recorded. During the overload training period, the IT group completed approximately 290% more training load than the NT group (p<0.001). After the overload training period, 3kmTT in the IT group was reduced compared to both pre-training (3.7%, p<0.05) and the NT group (6.8%, p<0.05). 5BT was decreased by 7.9% in the IT group following the overload period (p<0.05). The IT group also demonstrated increases in stress reaction symptoms from the DALDA. Following the taper, the IT group improved 3 kmTT. In contrast, the performance, physiological and psychological markers of NT group remained relatively unchanged throughout the 6-week training period. There were weak significant correlations between weekly changes in 3 kmTT and 5BT (r=-0.37, p<0.01). The DALDA and 5BT may be practical tests for assessing changes in performance, fatigue and recovery of endurance athletes.

  3. Power wheelchair range testing and energy consumption during fatigue testing.

    PubMed

    Cooper, R A; VanSickle, D P; Albright, S J; Stewart, K J; Flannery, M; Robertson, R N

    1995-10-01

    The range of a power wheelchair depends on many factors including: battery type, battery state, wheelchair/rider weight, terrain, the efficiency of the drive train, and driving behavior. The purpose of this study was to evaluate the feasibility of three methods of estimating power wheelchair range. Another significant purpose was to compare the current draw on pavement to current draw on an International Standards Organization (ISO) Double Drum tester at one m/sec. Tests were performed on seven different power wheelchairs unloaded, and loaded with an ISO 100 kg test dummy. Each chair was configured according to the manufacturer's specifications, and tires were properly inflated. Experienced test technicians were used for the tennis court tests, and treadmill tests. An ISO 100 kg test dummy was used for the ISO Double Drum test. Energy consumption was measured over a distance of 1500 m for each of the three test conditions. The rolling surface was level in all cases. Repeated measure analysis of variance (ANOVA) revealed a significant difference (p = 0.0001) between the predicted range at maximum speed for the three tests. Post hoc analysis demonstrated a significant difference (p < 0.01) in estimated range at maximum speed between the Double Drum test and the treadmill test, as well as between the Double Drum test and the tennis court test. Our results indicate no significant difference (p > 0.05) between the predicted range at maximal speed between the treadmill and tennis court tests. A simple relationship does not exist between the results of range testing with the Double Drum tester and the tennis court. An alternative would be to permit the use of a treadmill for range testing as simple relationships between all pertinent treadmill and tennis court range data were found. For the Double Drum tester used, the current demand is higher than under normal usage. This presents a problem as current is related to load torque in a power wheelchair. Hence, the Double

  4. Microstructural changes induced near crack tip during corrosion fatigue tests in austenitic-ferritic steel.

    PubMed

    Gołebiowski, B; Swiatnicki, W A; Gaspérini, M

    2010-03-01

    Microstructural changes occurring during fatigue tests of austenitic-ferritic duplex stainless steel (DSS) in air and in hydrogen-generating environment have been investigated. Hydrogen charging of steel samples during fatigue crack growth (FCG) tests was performed by cathodic polarization of specimens in 0.1M H(2)SO(4) aqueous solution. Microstructural investigations of specimens after FCG tests were carried out using transmission electron microscopy to reveal the density and arrangement of dislocations formed near crack tip. To determine the way of crack propagation in the microstructure, electron backscatter diffraction investigations were performed on fatigue-tested samples in both kinds of environment. To reveal hydrogen-induced phase transformations the atomic force microscopy was used. The above investigations allowed us to define the character of fatigue crack propagation and microstructural changes near the crack tip. It was found that crack propagation after fatigue tests in air is accompanied with plastic deformation; a high density of dislocations is observed at large distance from the crack. After fatigue tests performed during hydrogen charging the deformed zone containing high density of dislocations is narrow compared to that after fatigue tests in air. It means that hydrogenation leads to brittle character of fatigue crack propagation. In air, fatigue cracks propagate mostly transgranularly, whereas in hydrogen-generating environment the cracks have mixed transgranular/interfacial character.

  5. The fracture morphology of nickel-base superalloys tested in fatigue and creep-fatigue at 650 C

    NASA Technical Reports Server (NTRS)

    Gayda, J.; Miner, R. V.

    1981-01-01

    The fracture surfaces of compact tension specimens from seven nickel-base superalloys fatigue tested at 650 C were studied by scanning electron microscopy and optical metallography to determine the nature and morphology of the crack surface in the region of stable growth. Crack propagation testing was performed as part of an earlier study at 650 C in air using a 0.33 Hz fatigue cycle and a creep-fatigue cycle incorporating a 900 second dwell at maximum load. In fatigue, alloys with a grain size greater than 20 micrometers, HIP Astroloy, Waspaloy, and MERL 76, exhibited transgranular fracture. MERL 76 also displayed numerous fracture sites which were associated with boundaries of prior powder particles. The two high strength, fine grain alloys, IN 100 and NASA IIB-7, exhibited intergranular fracture. Rene 95 and HIP plus forged Astroloy displayed a mixed failure mode that was transgranular in the coarse grains and intergranular in the fine grains. Under creep-fatigue conditions, fracture was found to be predominantly intergranular in all seven alloys.

  6. Design and fabrication of a bending rotation fatigue test rig for in situ electrochemical analysis during fatigue testing of NiTi shape memory alloy wires.

    PubMed

    Neelakantan, Lakshman; Zglinski, Jenni Kristin; Frotscher, Matthias; Eggeler, Gunther

    2013-03-01

    The current investigation proposes a novel method for simultaneous assessment of the electrochemical and structural fatigue properties of nickel-titanium shape memory alloy (NiTi SMA) wires. The design and layout of an in situ electrochemical cell in a custom-made bending rotation fatigue (BRF) test rig is presented. This newly designed test rig allows performing a wide spectrum of experiments for studying the influence of fatigue on corrosion and vice versa. This can be achieved by performing ex situ and∕or in situ measurements. The versatility of the combined electrochemical∕mechanical test rig is demonstrated by studying the electrochemical behavior of NiTi SMA wires in 0.9% NaCl electrolyte under load. The ex situ measurements allow addressing various issues, for example, the influence of pre-fatigue on the localized corrosion resistance, or the influence of hydrogen on fatigue life. Ex situ experiments showed that a pre-fatigued wire is more susceptible to localized corrosion. The synergetic effect can be concluded from the polarization studies and specifically from an in situ study of the open circuit potential (OCP) transients, which sensitively react to the elementary repassivation events related to the local failure of the oxide layer. It can also be used as an indicator for identifying the onset of the fatigue failure.

  7. Design and fabrication of a bending rotation fatigue test rig for in situ electrochemical analysis during fatigue testing of NiTi shape memory alloy wires

    SciTech Connect

    Neelakantan, Lakshman; Zglinski, Jenni Kristin; Eggeler, Gunther; Frotscher, Matthias

    2013-03-15

    The current investigation proposes a novel method for simultaneous assessment of the electrochemical and structural fatigue properties of nickel-titanium shape memory alloy (NiTi SMA) wires. The design and layout of an in situ electrochemical cell in a custom-made bending rotation fatigue (BRF) test rig is presented. This newly designed test rig allows performing a wide spectrum of experiments for studying the influence of fatigue on corrosion and vice versa. This can be achieved by performing ex situ and/or in situ measurements. The versatility of the combined electrochemical/mechanical test rig is demonstrated by studying the electrochemical behavior of NiTi SMA wires in 0.9% NaCl electrolyte under load. The ex situ measurements allow addressing various issues, for example, the influence of pre-fatigue on the localized corrosion resistance, or the influence of hydrogen on fatigue life. Ex situ experiments showed that a pre-fatigued wire is more susceptible to localized corrosion. The synergetic effect can be concluded from the polarization studies and specifically from an in situ study of the open circuit potential (OCP) transients, which sensitively react to the elementary repassivation events related to the local failure of the oxide layer. It can also be used as an indicator for identifying the onset of the fatigue failure.

  8. Bending fatigue tests on SiC-Al tapes under alternating stress at room temperature

    NASA Technical Reports Server (NTRS)

    Herzog, J. A.

    1981-01-01

    The development of a testing method for fatigue tests on SiC-Al tapes containing a small amount of SiC filaments under alternating stress is reported. The fatigue strength curves resulting for this composite are discussed. They permit an estimate of its behavior under continuous stress and in combination with various other matrices, especially metal matrices.

  9. Space Shuttle Crawler Transporter Vibration Analysis in Support of Rollout Fatigue Load Spectra Verification Program

    NASA Technical Reports Server (NTRS)

    Margasahayam, Ravi N.; Meyer, Karl A.; Nerolich, Shaun M.; Burton, Roy C.; Gosselin, Armand M.

    2004-01-01

    The Crawler Transporter (CT), designed and built for the Apollo Program in the 1960's and surpassing its initial operational life, has become an integral part of the Space Shuttle Program (SSP). The CT transports the Space Shuttle Vehicle (SSV) stack, atop the Mobile Launch Platform (MLP), from the Vehicle Assembly Building (VAB) to the launch pad. This support structure provides hydraulic jacking, leveling and load equalization for the 12 million pound stack on its 3.5-5.0 mile rollout to the launch pad. Major elements of the SSV, consisting of the orbiter, solid rocket boosters (SRB) and external tank (ET) have required fatigue analyses as part of the mission life certification. Compared to rollout vibration, the SSV sees relatively high vibration loads during launch, ascent, descent and landing phases of the mission. Although preliminary measured SRB vibration levels during rollout were of low amplitude and frequency, the duration of the rollout phase is typically high, from 5-6 hours. As part of an expanded mission life assessment, additional certification effort was initiated to define fatigue load spectra for rollout. This study addresses the CT vibration analyses in support of the rollout fatigue study. Structural models developed for modal and vibration analyses were used to identify unique CT, CT/MLP and CT/MLP/SRB vibration characteristics for comparison to instrumented rollout tests. Whereas the main structural and vibration characteristics of the SSV are well defined, minimum analytical and vibration test data on the Crawler Transporter were available. Unique vibration characteristics of the CT are attributable to the drive mechanism, hydraulic jacking system, structural framing and the CT-to-MLP support pad restraints. Initial tests performed on the CT/MLP/SRB configuration showed reasonable correlation with predicted mode shapes and frequencies.

  10. Muscular Activity and Fatigue in Lower-Limb and Trunk Muscles during Different Sit-To-Stand Tests

    PubMed Central

    Roldán-Jiménez, Cristina; Bennett, Paul; Cuesta-Vargas, Antonio I.

    2015-01-01

    Sit-to-stand (STS) tests measure the ability to get up from a chair, reproducing an important component of daily living activity. As this functional task is essential for human independence, STS performance has been studied in the past decades using several methods, including electromyography. The aim of this study was to measure muscular activity and fatigue during different repetitions and speeds of STS tasks using surface electromyography in lower-limb and trunk muscles. This cross-sectional study recruited 30 healthy young adults. Average muscle activation, percentage of maximum voluntary contraction, muscle involvement in motion and fatigue were measured using surface electrodes placed on the medial gastrocnemius (MG), biceps femoris (BF), vastus medialis of the quadriceps (QM), the abdominal rectus (AR), erector spinae (ES), rectus femoris (RF), soleus (SO) and the tibialis anterior (TA). Five-repetition STS, 10-repetition STS and 30-second STS variants were performed. MG, BF, QM, ES and RF muscles showed differences in muscle activation, while QM, AR and ES muscles showed significant differences in MVC percentage. Also, significant differences in fatigue were found in QM muscle between different STS tests. There was no statistically significant fatigue in the BF, MG and SO muscles of the leg although there appeared to be a trend of increasing fatigue. These results could be useful in describing the functional movements of the STS test used in rehabilitation programs, notwithstanding that they were measured in healthy young subjects. PMID:26506612

  11. NASA/FLAGRO - FATIGUE CRACK GROWTH COMPUTER PROGRAM

    NASA Technical Reports Server (NTRS)

    Forman, R. G.

    1994-01-01

    Structural flaws and cracks may grow under fatigue inducing loads and, upon reaching a critical size, cause structural failure to occur. The growth of these flaws and cracks may occur at load levels well below the ultimate load bearing capability of the structure. The Fatigue Crack Growth Computer Program, NASA/FLAGRO, was developed as an aid in predicting the growth of pre-existing flaws and cracks in structural components of space systems. The earlier version of the program, FLAGRO4, was the primary analysis tool used by Rockwell International and the Shuttle subcontractors for fracture control analysis on the Space Shuttle. NASA/FLAGRO is an enhanced version of the program and incorporates state-of-the-art improvements in both fracture mechanics and computer technology. NASA/FLAGRO provides the fracture mechanics analyst with a computerized method of evaluating the "safe crack growth life" capabilities of structural components. NASA/FLAGRO could also be used to evaluate the damage tolerance aspects of a given structural design. The propagation of an existing crack is governed by the stress field in the vicinity of the crack tip. The stress intensity factor is defined in terms of the relationship between the stress field magnitude and the crack size. The propagation of the crack becomes catastrophic when the local stress intensity factor reaches the fracture toughness of the material. NASA/FLAGRO predicts crack growth using a two-dimensional model which predicts growth independently in two directions based on the calculation of stress intensity factors. The analyst can choose to use either a crack growth rate equation or a nonlinear interpolation routine based on tabular data. The growth rate equation is a modified Forman equation which can be converted to a Paris or Walker equation by substituting different values into the exponent. This equation provides accuracy and versatility and can be fit to data using standard least squares methods. Stress

  12. Manipulator comparative testing program

    SciTech Connect

    Draper, J.V.; Handel, S.J.; Sundstrom, E.; Herndon, J.N.; Fujita, Y.; Maeda, M.

    1986-01-01

    The Manipulator Comparative Testing Program examined differences among manipulator systems from the United States and Japan. The manipulator systems included the Meidensha BILARM 83A, the Model M-2 of Central Research Laboratories Division of Sargent Industries (CRL), and the GCA Corporation PaR Systems Model 6000. The site of testing was the Remote Operations Maintenance Demonstration (ROMD) facility, operated by the Fuel Recycle Division in the Consolidated Fuel Reprocessing Program at the Oak Ridge National Laboratory (ORNL). In all stages of testing, operators using the CRL Model M-2 manipulator had consistently lower times to completion and error rates than they did using other machines. Performance was second best with the Meidensha BILARM 83A in master-slave mode. Performance with the BILARM in switchbox mode and the PaR 6000 manipulator was approximately equivalent in terms of criteria recorded in testing. These data show no impact of force reflection on task performance.

  13. Protuberance heating test program

    NASA Technical Reports Server (NTRS)

    Sieker, W. D.

    1966-01-01

    Results are presented of the protuberance heating test program. Four general protuberance shapes on a flat plate were tested. Presentation and evaluation of the data both on the protuberance and in the wake regions are made. The test program is an extension of the general protuberance heat transfer test. The additional series of tests was conducted to define the extent of wake heating and to assess the effects of Reynolds number variation on heating both on and around the protuberances. The protuberance models were mounted near the forward end of a six-foot instrumented test plate with stringers that simulated interstage and skirt structure of the Saturn S-4B stage. The tests were performed at Mach numbers of 2.49, 3.51, and 4.44. Reynolds numbers per foot of 3 million and 1.5 million were used for the two lower Mach numbers and 3 million for a Mach number of 4.44. The test Mach numbers simulated the Saturn S-4B flight conditions during the most severe aerodynamic heating period. The test Reynolds numbers were somewhat higher than the flight values, but lower values could not be used because of tunnel and instrumentation limitations. Oil flow runs were made on two representative models at various combinations of Mach number and Reynolds number to help define the extent of wake heating.

  14. EEG correlates of fatigue during administration of a neuropsychological test battery

    PubMed Central

    Barwick, Fiona; Arnett, Peter; Slobounov, Semyon

    2011-01-01

    Objective Mental fatigue, a poorly understood symptom of sports-related concussion, ideally requires assessment across multiple modalities. Our study aimed to examine mental fatigue effects among ten neurologically normal, athletically active students undergoing typical concussion testing. It is our intention to ultimately address the question whether fatigue effects due to mild traumatic brain injury (mTBI) may become confounded with fatigue effects due to testing effort. Methods Fourteen athletically active and neurologically normal volunteers were initially recruited from Penn State University. Self-reported fatigue, neuropsychological performance, and electroencephalographic (EEG) activity were measured throughout the whole testing duration. EEG measures in frequency domain (e.g., relative power of theta, alpha & beta bands) were examined over the course of neuropsychological (NP) test administration. Results Predicted fatigue effects over the course of testing included: (a) increased self-reported fatigue; (b) increased errors on the Stroop Interference Test; (c) significantly increased relative power of theta activity during the Stroop Interference Test in frontal-central and parietal regions; and (d) migration of alpha activation from the occipital to anterior (left parietal and pre-central) regions during the Stroop Interference task administered at the beginning compared with the end of testing. Conclusions Results supported predictions related to subjective fatigue and cognitive performance and offered partial support for predictions related to EEG activation patterns over the course of administering the NP testing. Significance Neurologically intact and athletically active college students demonstrate effects related to fatigue after undergoing a typical sports concussion assessment battery, including an increase in subjectively experienced fatigue, a decrease in cognitive task performance accuracy and associated modulations in EEG activity. This finding

  15. Transverse Tension Fatigue Life Characterization Through Flexure Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin; Chawan, Arun D.; Krueger, Ronald; Paris, Isabelle

    2001-01-01

    The transverse tension fatigue life of S2/8552 glass-epoxy and IM7/8552 carbon-epoxy was characterized using flexure tests of 90-degree laminates loaded in 3-point and 4-point bending. The influence of specimen polishing and specimen configuration on transverse tension fatigue life was examined using the glass-epoxy laminates. Results showed that 90-degree bend specimens with polished machined edges and polished tension-side surfaces, where bending failures where observed, had lower fatigue lives than unpolished specimens when cyclically loaded at equal stress levels. The influence of specimen thickness and the utility of a Weibull scaling law was examined using the carbon-epoxy laminates. The influence of test frequency on fatigue results was also documented for the 4-point bending configuration. A Weibull scaling law was used to predict the 4-point bending fatigue lives from the 3-point bending curve fit and vice-versa. Scaling was performed based on maximum cyclic stress level as well as fatigue life. The scaling laws based on stress level shifted the curve fit S-N characterizations in the desired direction, however, the magnitude of the shift was not adequate to accurately predict the fatigue lives. Furthermore, the scaling law based on fatigue life shifted the curve fit S-N characterizations in the opposite direction from measured values. Therefore, these scaling laws were not adequate for obtaining accurate predictions of the transverse tension fatigue lives.

  16. Metal Matrix Composites: Fatigue and Fracture Testing. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning techniques and results of testing metal matrix composites for fatigue and fracture. Methods include non-destructive testing techniques, and static and cyclic techniques for assessing compression, tensile, bending, and impact characteristics.

  17. The detection of fatigue cracks by nondestructive testing methods

    NASA Technical Reports Server (NTRS)

    Rummel, W. D.; Todd, P. H., Jr.; Frecska, S. A.; Rathke, R. A.

    1974-01-01

    X-radiographic penetrant, ultrasonic, eddy current, holographic, and acoustic emission techniques were optimized and applied to the evaluation of 2219-T87 aluminum alloy test specimens. One hundred eighteen specimens containing a total of 328 fatigue cracks were evaluated. The cracks ranged in length from 0.500 inch (1.27 cm) to 0.007 inch (0.018 cm) and in depth from 0.178 inch (0.451 cm) and 0.001 inch (0.003 cm). Specimen thicknesses were nominally 0.060 inch (0.152 cm) and 0.210 inch (0.532 cm) and surface finishes were nominally 32 and 125 rms and 64 and 200 rms respectively. Specimens were evaluated in the as-milled surface condition, in the chemically milled surface condition and, after proof loading, in a randomized inspection sequence. Results of the nondestructive test (NDT) evaluations were compared with actual crack size obtained by measurement of the fractured specimens. Inspection data was then analyzed to provide a statistical basis for determinating the threshold crack detection sensitivity (the largest crack size that would be missed) for each of the inspection techniques at a 95% probability and 95% confidence level.

  18. A high temperature fatigue and structures testing facility

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.; Mcgaw, Michael A.

    1987-01-01

    As man strives for higher levels of sophistication in air and space transportation, awareness of the need for accurate life and material behavior predictions for advanced propulsion system components is heightened. Such sophistication will require complex operating conditions and advanced materials to meet goals in performance, thrust-to-weight ratio, and fuel efficiency. To accomplish these goals will require that components be designed using a high percentage of the material's ultimate capabilities. This serves only to complicate matters dealing with life and material behavior predictions. An essential component of material behavior model development is the underlying experimentation which must occur to identify phenomena. To support experimentation, the NASA Lewis Research Center's High Temperature Fatigue and Structures Laboratory has been expanded significantly. Several new materials testing systems have been added, as well as an extensive computer system. The intent of this paper is to present an overview of the laboratory, and to discuss specific aspects of the test systems. A limited discussion of computer capabilities will also be presented.

  19. Evaluation of a Fatigue Countermeasures Training Program for Flight Attendants

    DTIC Science & Technology

    2011-11-01

    Fatigue was measured using a brief 4 self-assessment questionnaire called the Fatigue Assess- ment Scale (Michielsen, De Vries, & Van Heck ...Medicine and Infectious Disease , 3, 85-96 . Cigularov, K ., Chen, P ., Thurber, B .W ., & Stallones, L . (2008) . Investigation of the effectiveness of...of training eval- uation . Journal of Applied Psychology, 78, 311-328 . Michielsen, H .J ., De Vries, J ., & Van Heck J .L . (2003) . Psychometric

  20. Fatigue life on a full scale test rig: Forged versus cast wind turbine rotor shafts

    NASA Astrophysics Data System (ADS)

    Herrmann, J.; Rauert, T.; Dalhoff, P.; Sander, M.

    2016-09-01

    To reduce uncertainties associated with the fatigue life of the highly safety relevant rotor shaft and also to review today's design practice, the fatigue behaviour will be tested on a full scale test rig. Until now tests on full scale wind turbine parts are not common. Therefore, a general lack of experience on how to perform accelerated life time tests for those components exists. To clarify how to transfer real conditions to the test environment, the arrangements and deviations for the upcoming experimental test are discussed in detail. In order to complete investigations of weight saving potentials, next to getting a better comprehension of the fatigue behaviour by executing a full scale test, a further outcome are suggestions for the usage of cast and forged materials regarding the fatigue and the remaining life of the rotor shaft. It is shown, that it is worthwhile to think about a material exchange for the forged rotor shaft.

  1. Integrated Test Program Manual.

    DTIC Science & Technology

    1983-10-01

    of test requirements. program problems and conflicts. .:.0 Develop methods for assigning priorities 0 Secure engineering analyses of failures to...system modifications are evaluated, and esti- 3) To provide crews with analyses of their mates of the weapon system’s performance ship’s performance...the subsystem branches at Accuracy data are used to establish sufficient S. SSPO with analyses of the performance of impact and burst-height error

  2. Preliminary results from fatigue tests with reference to operational statistics

    NASA Technical Reports Server (NTRS)

    Gassner, E

    1950-01-01

    Simple elements were subjected to repeated loads of variable ampliture, chosen in such a way that they may be regarded as approximations to the operational loads (gust and maneuver) experienced by an airplane. The effect of varying some parameters was investigated briefly. Some discussion is given of the question whether a design according to current (1938 German) requirements for static strength is adequate from the fatigue point of view, and existing requirements on fatigue strength are compared,

  3. Proof test and fatigue crack growth modeling on 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Poe, C. C., Jr.; Dawicke, D. S.

    1990-01-01

    Pressure proof testing of aircraft fuselage structures has been suggested as a means of screening critical crack sizes and of extending their useful life. The objective of this paper is to study the proof-test concept and to model the crack-growth process on a ductile material. Simulated proof and operational fatigue life tests have been conducted on cracked panels made of 2024-T3 aluminum alloy sheet material. A fatigue crack-closure model was modified to simulate the proof test and operational fatigue cycling. Using crack-growth rate and resistance-curve data, the model was able to predict crack growth during and after the proof load. These tests and analyses indicate that the proof test increases fatigue life; but the beneficial life, after a 1.33 or 1.5 proof, was less than a few hundred cycles.

  4. Screening Test Results of Fatigue Properties of type 316LN Stainless Steel in Mercury

    SciTech Connect

    Pawel, S.J.

    1999-05-20

    Fully reversed, load-controlled uniaxial push-pull fatigue tests at room temperature have been performed in air and in mercury on specimens of type 316LN stainless steel. The results indicate a significant influence of mercury on fatigue properties. Compared to specimens tested in air, specimens tested in mercury had reproducibly shorter fatigue lives (by a factor of 2-3), and fracture faces exhibiting intergranular cracking. Preliminary indications are that crack initiation in each environment is similar, but mercury significantly accelerates crack propagation.

  5. Single-leg hop testing following fatiguing exercise: reliability and biomechanical analysis.

    PubMed

    Augustsson, J; Thomeé, R; Lindén, C; Folkesson, M; Tranberg, R; Karlsson, J

    2006-04-01

    A fatiguing exercise protocol was combined with single-leg hop testing to improve the possibilities of evaluating the effects of training or rehabilitation interventions. In the first test-retest experiment, 11 healthy male subjects performed two trials of single-leg hops under three different test conditions: non-fatigued and following fatiguing exercise, which consisted of unilateral weight machine knee extensions at 80% and 50%, respectively, of 1 repetition maximum (1 RM) strength. Intraclass correlation coefficients ranged from 0.75 to 0.98 for different hop test conditions, indicating that all tests were reliable. For the second experiment, eight healthy male subjects performed the fatiguing exercise protocol to investigate how fatigue influences lower-extremity joint kinematics and kinetics during single-leg hops. Hip, knee and ankle joint angles, moments and powers, as well as ground-reaction forces were recorded with a six-camera, motion-capture system and a force platform. Recovery of hop performance following the fatiguing exercise was also measured. During the take-off for the single-leg hops, hip and knee flexion angles, generated powers for the knee and ankle joints, and ground-reaction forces decreased for the fatigued hop conditions compared with the non-fatigued condition (P<0.05). Compared with landing during the non-fatigued condition, hip moments and ground-reaction forces were lower for the fatigued hop conditions (P<0.05). The negative joint power was two to three times greater for the knee than for the hip and five to 10 times greater for the knee than for the ankle during landing for all test conditions (P<0.05). Most measured variables had recovered three minutes post-exercise. It is concluded that the fatiguing exercise protocol combined with single-leg hop testing was a reliable method for investigating functional performance under fatigued test conditions. Further, subjects utilized an adapted hop strategy, which employed less hip and

  6. Test Population Selection from Weibull-Based, Monte Carlo Simulations of Fatigue Life

    NASA Technical Reports Server (NTRS)

    Vlcek, Brian L.; Zaretsky, Erwin V.; Hendricks, Robert C.

    2012-01-01

    Fatigue life is probabilistic and not deterministic. Experimentally establishing the fatigue life of materials, components, and systems is both time consuming and costly. As a result, conclusions regarding fatigue life are often inferred from a statistically insufficient number of physical tests. A proposed methodology for comparing life results as a function of variability due to Weibull parameters, variability between successive trials, and variability due to size of the experimental population is presented. Using Monte Carlo simulation of randomly selected lives from a large Weibull distribution, the variation in the L10 fatigue life of aluminum alloy AL6061 rotating rod fatigue tests was determined as a function of population size. These results were compared to the L10 fatigue lives of small (10 each) populations from AL2024, AL7075 and AL6061. For aluminum alloy AL6061, a simple algebraic relationship was established for the upper and lower L10 fatigue life limits as a function of the number of specimens failed. For most engineering applications where less than 30 percent variability can be tolerated in the maximum and minimum values, at least 30 to 35 test samples are necessary. The variability of test results based on small sample sizes can be greater than actual differences, if any, that exists between materials and can result in erroneous conclusions. The fatigue life of AL2024 is statistically longer than AL6061 and AL7075. However, there is no statistical difference between the fatigue lives of AL6061 and AL7075 even though AL7075 had a fatigue life 30 percent greater than AL6061.

  7. Test Population Selection from Weibull-Based, Monte Carlo Simulations of Fatigue Life

    NASA Technical Reports Server (NTRS)

    Vlcek, Brian L.; Zaretsky, Erwin V.; Hendricks, Robert C.

    2008-01-01

    Fatigue life is probabilistic and not deterministic. Experimentally establishing the fatigue life of materials, components, and systems is both time consuming and costly. As a result, conclusions regarding fatigue life are often inferred from a statistically insufficient number of physical tests. A proposed methodology for comparing life results as a function of variability due to Weibull parameters, variability between successive trials, and variability due to size of the experimental population is presented. Using Monte Carlo simulation of randomly selected lives from a large Weibull distribution, the variation in the L10 fatigue life of aluminum alloy AL6061 rotating rod fatigue tests was determined as a function of population size. These results were compared to the L10 fatigue lives of small (10 each) populations from AL2024, AL7075 and AL6061. For aluminum alloy AL6061, a simple algebraic relationship was established for the upper and lower L10 fatigue life limits as a function of the number of specimens failed. For most engineering applications where less than 30 percent variability can be tolerated in the maximum and minimum values, at least 30 to 35 test samples are necessary. The variability of test results based on small sample sizes can be greater than actual differences, if any, that exists between materials and can result in erroneous conclusions. The fatigue life of AL2024 is statistically longer than AL6061 and AL7075. However, there is no statistical difference between the fatigue lives of AL6061 and AL7075 even though AL7075 had a fatigue life 30 percent greater than AL6061.

  8. Cyclic Fatigue Testing for Application for paraglacial rock slope stability modelling

    NASA Astrophysics Data System (ADS)

    Grämiger, Lorenz; Perras, Matthew A.; Moore, Jeffrey R.; Loew, Simon

    2015-04-01

    In glacial environments, rock mass damage is influenced by stress redistribution caused by glaciation and deglaciation cycles. The intact rock strength, discontinuities, stress regime and environmental factors all contribute to the mechanical behavior of the rock slope. Critically-stressed rock walls are exposed to changing boundary conditions. The effect of stress changes during deglaciation of a major glacial period is not well constrained, neither the influence of smaller stress magnitudes of repeat glacier cycles during an interglacial. In an effort to constrain numerical rock slope model input values, a laboratory testing program has been conducted to address the role of fatigue on the intact rock strength. Baseline unconfined compression and Brazilian tensile testing has been conducted on gneissic rocks from the Aletsch valley in Switzerland. The baseline testing results are used to determine load levels for cyclic fatigue compression and tension testing. In the cyclic tests the intact rock samples are taken to the load levels determined from the baseline tests and cyclic loading and unloading is conducted around the nominal load level. The stress fluctuation chosen is between 2-10 MPa, which is equivalent to a glacial loading and unloading of 200-1000m of ice. Such ice thickness change are typical for the Grosser Aletsch glacier during the Lateglacial and Holocene. During cyclic loading and unloading the amount of damage is estimated by recording the number of acoustic emission events with time. Once the acoustic emission events per cycle decrease well below initial cycling levels the load level is increased and cyclic loading is continued at the new load level. This was done for both cyclic compression and cyclic Brazilian tensile tests. The aim of the cyclic tests is to understand what degree of pre-existing damage is required such that 2-10 MPa stress fluctuations could cause crack propagation and failure of laboratory samples in long-term cyclic fatigue

  9. Testing rig for low cycle fatigue tests in combined bending and torsion

    NASA Astrophysics Data System (ADS)

    Caligiana, Gianni; Curioni, Sergio

    1992-07-01

    In order to simulate, on samples, the fatigue behavior of notched or grooved shafts used in industrial plants, a biaxal testing equipment, to transform the alternate motion of a conventional testing machine into combined torsion and bending cyclic loadings, was devised and realized. Several different amplitude ratios between torsion and bending can be obtained beyond pure torsion and pure bending. Design choices, modeling, numerical simulations and experimental verifications performed for the testing apparatus are reported. Influence of misalignment and manufacturing imperfections on the behavior of the equipment are considered.

  10. Transient Pressure Test Article test program

    NASA Technical Reports Server (NTRS)

    Vibbart, Charles M.

    1988-01-01

    The Transient Pressure Test Article test program being conducted at NASA-Marshall is described. The main goal of the TPTA test program is to provide data to verify the sealing capability of the redesigned SRM field joints, the nozzle-to-case joint, and the igniter joint. The TPTA test program can be used to demonstrate the assembly/disassembly and reusability of the redesigned joints along with the adequacy of assembly/disassembly tooling, procedures, and inspections.

  11. 10 CFR 26.211 - Fatigue assessments.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Fatigue assessments. 26.211 Section 26.211 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.211 Fatigue assessments. (a) Licensees... addition to any other test or determination of fitness that may be required under §§ 26.31(c) and 26.77,...

  12. 10 CFR 26.211 - Fatigue assessments.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Fatigue assessments. 26.211 Section 26.211 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.211 Fatigue assessments. (a) Licensees... addition to any other test or determination of fitness that may be required under §§ 26.31(c) and 26.77,...

  13. 10 CFR 26.211 - Fatigue assessments.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Fatigue assessments. 26.211 Section 26.211 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.211 Fatigue assessments. (a) Licensees... addition to any other test or determination of fitness that may be required under §§ 26.31(c) and 26.77,...

  14. 10 CFR 26.211 - Fatigue assessments.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Fatigue assessments. 26.211 Section 26.211 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.211 Fatigue assessments. (a) Licensees... addition to any other test or determination of fitness that may be required under §§ 26.31(c) and 26.77,...

  15. 10 CFR 26.211 - Fatigue assessments.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Fatigue assessments. 26.211 Section 26.211 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.211 Fatigue assessments. (a) Licensees... addition to any other test or determination of fitness that may be required under §§ 26.31(c) and 26.77,...

  16. Manipulator comparative testing program

    SciTech Connect

    Draper, J.V.; Handel, S.J.; Sundstrom, E.; Herndon, J.N.; Fujita, Y.; Maida, M.

    1986-01-01

    The Manipulator Comparative Testing Program compared performance of selected manipulator systems under typical remote handling conditions. The site of testing was the Remote Operations and Maintenance Demonstration Facility operated by the Consolidated Fuel Reprocessing Program of the Oak Ridge National Laboratory. Three experiment examined differences among manipulator systems from the US and Japan. The manipulator systems included the Meidensha BILARM 83A, Central Research Laboratories' (CRL's) Model M-2, and GCA PaR systems Model 6000. Six manipulator and control mode combinations were evaluated: (a) the BILARM in master-slave mode without force reflection; (b) the BILARM in master-slave mode with force reflection; (c) the Model M-2 in master-slave mode without force reflection; (d) the Model M-2 in master-slave mode with force reflection; (e) the BILARM with switchbox controls; and (f) the PaR 6000 with switchbox controls. The experiments also examined differences between master-slave systems with and without force reflections, and differences between master-slave systems and switchbox-controlled systems.

  17. Isometric knee extensor fatigue following a Wingate test: peripheral and central mechanisms.

    PubMed

    Fernandez-del-Olmo, M; Rodriguez, F A; Marquez, G; Iglesias, X; Marina, M; Benitez, A; Vallejo, L; Acero, R M

    2013-02-01

    Central and peripheral fatigue have been explored during and after running or cycling exercises. However, the fatigue mechanisms associated with a short maximal cycling exercise (30 s Wingate test) have not been investigated. In this study, 10 volunteer subjects performed several isometric voluntary contractions using the leg muscle extensors before and after two bouts of cycling at 25% of maximal power output and two bouts of Wingate tests. Transcranial magnetic stimulation (TMS) and electrical motor nerve stimulation (NM) were applied at rest and during the voluntary contractions. Maximal voluntary contraction (MVC), voluntary activation (VA), twitch amplitude evoked by electrical nerve stimulation, M wave and motor potential evoked by TMS (MEP) were recorded. MVC, VA and twitch amplitude evoked at rest by NM decreased significantly after the first and second Wingate tests, indicating central and peripheral fatigue. MVC and VA, but not the twitch amplitude evoked by NM, recovered before the second Wingate test. These results suggest that the Wingate test results in a decrease in MVC associated with peripheral and central fatigue. While the peripheral fatigue is associated with an intramuscular impairment, the central fatigue seems to be the main reason for the Wingate test-induced impairment of MVC.

  18. A computer-controlled automated test system for fatigue and fracture testing

    SciTech Connect

    Nanstad, R.K.; Alexander, D.J.; Swain, R.L.; Hutton, J.T.; Thomas, D.L.

    1989-01-01

    A computer-controlled system consisting of a servohydraulic test machine, an in-house designed test controller, and a desktop computer has been developed for performing automated fracture toughness and fatigue crack growth testing both in the laboratory and in hot cells for remote testing of irradiated specimens. Both unloading compliance and dc-potential drop can be used to monitor crack growth. The test controller includes a dc-current supply programmer, a function generator for driving the servohydraulic test machine to required test outputs, five measurement channels (each consisting of low-pass filter, track/hold amplifier, and 16-bit analog-to-digital converter), and digital logic for various control and data multiplexing functions. The test controller connects to the computer via a 16-bit wide photo-isolated bidirectional bus. The computer, a Hewlett-Packard series 200/300, inputs specimen and test parameters from the operator, configures the test controller, stores test data from the test controller in memory, does preliminary analysis during the test, and records sensor calibrations, specimen and test parameters, and test data on flexible diskette for later recall and analysis with measured initial and final crack length information. During the test, the operator can change test parameters as necessary. 24 refs., 6 figs.

  19. Ferrographic analysis of wear debris generated in accelerated rolling element fatigue tests

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Parker, R. J.

    1977-01-01

    Ferrographic analysis was used to determine the types and quantities of wear particles generated during accelerated rolling contact fatigue tests. The NASA five-ball rolling contact fatigue tester was used. Ball specimens were made of AMS 5749, a corrosion-resistant high-temperature bearing steel. The lubricant was a super-refined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.52 billion Pa and a shaft speed of 10,000 rpm. Four types of wear particles were observed: normal rubbing wear particles, fatigue spall particles, spheres, and friction polymer.

  20. Elevated temperature biaxial fatigue

    NASA Technical Reports Server (NTRS)

    Jordan, E. H.

    1984-01-01

    A three year experimental program for studying elevated temperature biaxial fatigue of a nickel based alloy Hastelloy-X has been completed. A new high temperature fatigue test facility with unique capabilities has been developed. Effort was directed toward understanding multiaxial fatigue and correlating the experimental data to the existing theories of fatigue failure. The difficult task of predicting fatigue lives for non-proportional loading was used as an ultimate test for various life prediction methods being considered. The primary means of reaching improved undertanding were through several critical non-proportional loading experiments. It was discovered that the cracking mode switched from primarily cracking on the maximum shear planes at room temperature to cracking on the maximum normal strain planes at 649 C.

  1. A computer program for cyclic plasticity and structural fatigue analysis

    NASA Technical Reports Server (NTRS)

    Kalev, I.

    1980-01-01

    A computerized tool for the analysis of time independent cyclic plasticity structural response, life to crack initiation prediction, and crack growth rate prediction for metallic materials is described. Three analytical items are combined: the finite element method with its associated numerical techniques for idealization of the structural component, cyclic plasticity models for idealization of the material behavior, and damage accumulation criteria for the fatigue failure.

  2. Thermal fatigue test for turbine housing by a pulse YAG laser

    NASA Astrophysics Data System (ADS)

    Kutsuna, Muneharu; Fujita, Shinji; Sugita, Yuji; Yamada, Katsushige

    2000-02-01

    A steam turbine housing (casing) for power plant is subject to thermal fatigue in the long service. Evaluation of the life time is required for the replacement of turbine housing. In the present work, the possibility of thermal fatigue test by laser to accelerate the thermal damage of the materials (heat resisting Cr-Mo steel) and estimate the life time of casing in short time has been investigated using a pulse YAG laser. The test specimen are taken from the turbine housing which have been used for 100,000 hours in service. The pulse YAG laser of 100 pps was irradiated on the specimen with different beam spot sizes for one sec. and interrupted for 9 sec. as a thermal fatigue cycle. Max. cycle in this laser thermal fatigue tests was 5400 cycles. The peak temperature of theram cycle was about 220 degrees Celsius after 5400 cycles in this laser thermal fatigue test. The fatigue crack was observed at the root of circular groove after 5400 cycles.

  3. Characterization of wear debris generated in accelerated rolling-element fatigue tests

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Parker, R. J.

    1978-01-01

    A ferrographic analysis was used to determine the types and quantities of wear debris generated during accelerated rolling contact fatigue tests. The five-ball rolling contact fatigue tester was used. Ball specimens were made of a corrosion resistant, high-temperature bearing steel. The lubricant was a superrefined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.52 10 to the 9th power Pa and a shaft speed of 10,000 rpm. Four types of wear debris were observed: (1) normal rubbing wear particles, (2) fatigue microspall particles, (3) spheres, and (4) friction polymer deposits. The characterization of wear debris as a function of time was of limited use in predicting fatigue failures in these accelerated tests.

  4. Pompano subsea development -- Testing program

    SciTech Connect

    Nelson, R.; Berger, R.; Tyer, C.

    1996-12-31

    System reliability is essential for the economic success of any subsea oil and gas development. Testing programs can be developed to prove system reliability while still adhering to cost and schedule constraints. This paper describes a three-tiered equipment testing program that was employed for the Pompano Phase 2 subsea system. Program objectives, test descriptions, procedure development and test execution are discussed in detail. Lessons learned throughout the tests are also presented.

  5. Fatigue testing and damage development in continuous fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1988-01-01

    A general overview of the fatigue behavior of metal matrix composites (MMC) is presented. The first objective is to present experimental procedures and techniques for conducting a meaningful fatigue test to detect and quantify fatigue damage in MMC. These techniques include interpretation of stress-strain responses, acid etching of the matrix, edge replicas of the specimen under load, radiography, and micrographs of the failure surfaces. In addition, the paper will show how stiffness loss in continuous fiber reinforced metal matrix composites can be a useful parameter for detecting fatigue damage initiation and accumulation. Second, numerous examples of how fatigue damage can initiate and grow in various MMC are given. Depending on the relative fatigue behavior of the fiber and matrix, and the interface properties, the failure modes of MMC can be grouped into four categories: (1) matrix dominated, (2) fiber dominated, (3) self-similar damage growth, and (4) fiber/matrix interfacial failures. These four types of damage will be discussed and illustrated by examples with the emphasis on the fatigue of unnotched laminates.

  6. DOE/MSU composite material fatigue database: Test methods, materials, and analysis

    SciTech Connect

    Mandell, J.F.; Samborsky, D.D.

    1997-12-01

    This report presents a detailed analysis of the results from fatigue studies of wind turbine blade composite materials carried out at Montana State University (MSU) over the last seven years. It is intended to be used in conjunction with the DOE/MSU composite Materials Fatigue Database. The fatigue testing of composite materials requires the adaptation of standard test methods to the particular composite structure of concern. The stranded fabric E-glass reinforcement used by many blade manufacturers has required the development of several test modifications to obtain valid test data for materials with particular reinforcement details, over the required range of tensile and compressive loadings. Additionally, a novel testing approach to high frequency (100 Hz) testing for high cycle fatigue using minicoupons has been developed and validated. The database for standard coupon tests now includes over 4,100 data points for over 110 materials systems. The report analyzes the database for trends and transitions in static and fatigue behavior with various materials parameters. Parameters explored are reinforcement fabric architecture, fiber content, content of fibers oriented in the load direction, matrix material, and loading parameters (tension, compression, and reversed loading). Significant transitions from good fatigue resistance to poor fatigue resistance are evident in the range of materials currently used in many blades. A preliminary evaluation of knockdowns for selected structural details is also presented. The high frequency database provides a significant set of data for various loading conditions in the longitudinal and transverse directions of unidirectional composites out to 10{sup 8} cycles. The results are expressed in stress and strain based Goodman Diagrams suitable for design. A discussion is provided to guide the user of the database in its application to blade design.

  7. Guide for School Testing Programs.

    ERIC Educational Resources Information Center

    Ward, Annie W., Ed.; And Others

    Basically, test directors have four systemwide and building level responsibilities: (1) planning, administration and evaluation of standardized testing programs; (2) application of measurement and evaluation to school problems; (3) classroom testing and evaluation; and (4) external testing programs. In a series of brief memos, measurement and…

  8. Goals set after completing a teleconference-delivered program for managing multiple sclerosis fatigue.

    PubMed

    Asano, Miho; Preissner, Katharine; Duffy, Rose; Meixell, Maggie; Finlayson, Marcia

    2015-01-01

    Setting goals can be a valuable skill to self-manage multiple sclerosis (MS) fatigue. A better understanding of the goals set by people with MS after completing a fatigue management program can assist health care professionals with tailoring interventions for clients. This study aimed to describe the focus of goals set by people with MS after a teleconference-delivered fatigue management program and to evaluate the extent to which participants were able to achieve their goals over time. In total, 485 goals were set by 81 participants. Over a follow-up period, 64 participants rated 284 goals regarding progress made toward goal achievement. Approximately 50% of the rated goals were considered achieved. The most common type of goal achieved was that of instrumental activities of daily living. Short-term goals were more likely to be achieved. This study highlights the need for and importance of promoting and teaching goal-setting skills to people with MS.

  9. Goals Set After Completing a Teleconference-Delivered Program for Managing Multiple Sclerosis Fatigue

    PubMed Central

    Asano, Miho; Preissner, Katharine; Duffy, Rose; Meixell, Maggie

    2015-01-01

    Setting goals can be a valuable skill to self-manage multiple sclerosis (MS) fatigue. A better understanding of the goals set by people with MS after completing a fatigue management program can assist health care professionals with tailoring interventions for clients. This study aimed to describe the focus of goals set by people with MS after a teleconference-delivered fatigue management program and to evaluate the extent to which participants were able to achieve their goals over time. In total, 485 goals were set by 81 participants. Over a follow-up period, 64 participants rated 284 goals regarding progress made toward goal achievement. Approximately 50% of the rated goals were considered achieved. The most common type of goal achieved was that of instrumental activities of daily living. Short-term goals were more likely to be achieved. This study highlights the need for and importance of promoting and teaching goal-setting skills to people with MS. PMID:25871602

  10. Finding the ideal strategy: Full-scale fatigue testing of wind turbine rotor shafts

    NASA Astrophysics Data System (ADS)

    Rauert, T.; Herrmann, J.; Dalhoff, P.; Sander, M.

    2016-09-01

    For the purpose of a light weight design of rotor shafts, fatigue testing is necessary. Since full-scale fatigue tests of these large components are time consuming, costly and have not been done before, much effort has to be put into the implementation of a suitable test strategy. The paper presents the boundary conditions that have to be considered to determine the finite life regime of the component S/N-curve. A statistical simulation shows how much the derived S/N-curve is influenced by the specific test procedure.

  11. Analysis and optimization of an innovative fatigue tests profile for three axle semi-trailers

    NASA Astrophysics Data System (ADS)

    Malon, H.; Tello, L.; Martin, C.

    2011-10-01

    Nowadays, a fundamental aspect in the design of any type of vehicle, in particular of semi-trailers, is the development and testing of prototypes that confirm the correct performance of the vehicles before their launch into the market. At present, fatigue tests exist for different structural components from large machines to small components in vehicles, but up to now, there is no knowledge about fatigue tests of complete vehicles of large dimensions, with the exception of the fatigue tests of semi-trailers that are carried out by the company LECITRAILER S.A., under the supervision of the Transportation Engineering Area of the University of Zaragoza, in particular the research group VEHIVIAL. The aim of this paper is to decribe the process developed for the analysis and optimization of an initial profile of fatigue testing for semitrailer. The result of this optimization process is an innovative profile of fatigue testing for three axle semi-trailers developed by the University of Zaragoza in collaboration with the company LECITRAILER S.A., which is applied to the process of optimization of all the prototypes made by the company.

  12. Feasibility of an exercise intervention for fatigued breast cancer patients at a community-based cardiac rehabilitation program

    PubMed Central

    De Jesus, Stefanie; Fitzgeorge, Lyndsay; Unsworth, Karen; Massel, David; Suskin, Neville; Prapavessis, Harry; Sanatani, Michael

    2017-01-01

    Purpose Exercise is beneficial to quality of life after cancer treatment, yet few cancer survivors meet exercise guidelines. Our study sought to determine the feasibility of an oncology rehabilitation exercise program embedded within a cardiac rehabilitation program. Methods Patients who rated their fatigue >4/10 after completion of adjuvant chemotherapy for breast cancer were screened for eligibility and the outcomes were assessed (Piper Fatigue Scale, Functional Assessment of Cancer Therapy-Breast [FACT-B], Edmonton Symptom Assessment System, body composition, stress test, and physical activity measurement [accelerometer]). Participants received individualized exercise prescription. Following the 16-week program, repeat assessment plus patient acceptance and satisfaction survey was completed. The primary end point was the composite of accrual rate >25%, program adherence >80%, and mean compliance with accelerometer use >80%. Results Twenty of 24 screened patients consented to the study and completed the baseline assessment. Adherence was 30.3%. Mean accelerometer use was 3.88/7 days (78%). Fatigue at baseline was rated at 4.82/10, and at 3.59 (p = 0.09) after the intervention. Overall well-being (FACT-B) score changed from 92.7 to 98.3 (p = 0.05). There were no significant changes in body composition (except for bone mineral content), aerobic exercise capacity, or activity patterns. Conclusion Although the primary outcome was not met, our study indicates that an oncology exercise rehabilitation program can be incorporated into an existing cardiac rehabilitation program. Based on feedback received, we propose that in order to achieve exercise goals, frequent, encouraging, and tailored feedback and group sessions to foster a sense of community may additionally be needed to strengthen adherence to a prescribed exercise program. PMID:28228661

  13. Vacuum thermal-mechanical fatigue testing of two iron base high temperature alloys

    NASA Technical Reports Server (NTRS)

    Sheffler, K. D.

    1974-01-01

    Ultrahigh vacuum elevated temperature low cycle fatigue and thermal fatigue tests of 304 stainless steel and A-286 alloy have shown significant effects of frequency and combined temperature-strain cycling on fatigue life. At constant temperature, the cyclic life of both alloys was lower at lower frequencies. Combined temperature-strain cycling reduced fatigue life with respect to isothermal life at the maximum temperature of the thermal cycle. Life reductions with in-phase thermal cycling (tension at high temperature, compression at low temperature) were attributed to grain boundary cavitation caused by unreversed tensile grain boundary sliding. The proposed mechanism for out-of-phase cavity generation involved accumulation of unreversed compressive grain boundary displacements which could not be geometrically accomodated by intragranular deformation in the low-ductility A-286 alloy.

  14. A test procedure for determining the influence of stress ratio on fatigue crack growth

    NASA Technical Reports Server (NTRS)

    Fitzgerald, J. H.; Wei, R. P.

    1974-01-01

    A test procedure is outlined by which the rate of fatigue crack growth over a range of stress ratios and stress intensities can be determined expeditiously using a small number of specimens. This procedure was developed to avoid or circumvent the effects of load interactions on fatigue crack growth, and was used to develop data on a mill annealed Ti-6Al-4V alloy plate. Experimental data suggest that the rates of fatigue crack growth among the various stress ratios may be correlated in terms of an effective stress intensity range at given values of K max. This procedure is not to be used, however, for determining the corrosion fatigue crack growth characteristics of alloys when nonsteady-state effects are significant.

  15. Implementation of a Biaxial Resonant Fatigue Test Method on a Large Wind Turbine Blade

    SciTech Connect

    Snowberg, D.; Dana, S.; Hughes, S.; Berling, P.

    2014-09-01

    A biaxial resonant test method was utilized to simultaneously fatigue test a wind turbine blade in the flap and edge (lead-lag) direction. Biaxial resonant blade fatigue testing is an accelerated life test method utilizing oscillating masses on the blade; each mass is independently oscillated at the respective flap and edge blade resonant frequency. The flap and edge resonant frequency were not controlled, nor were they constant for this demonstrated test method. This biaxial resonant test method presented surmountable challenges in test setup simulation, control and data processing. Biaxial resonant testing has the potential to complete test projects faster than single-axis testing. The load modulation during a biaxial resonant test may necessitate periodic load application above targets or higher applied test cycles.

  16. Predicting Fatigue and Psychophysiological Test Performance from Speech for Safety-Critical Environments

    PubMed Central

    Baykaner, Khan Richard; Huckvale, Mark; Whiteley, Iya; Andreeva, Svetlana; Ryumin, Oleg

    2015-01-01

    Automatic systems for estimating operator fatigue have application in safety-critical environments. A system which could estimate level of fatigue from speech would have application in domains where operators engage in regular verbal communication as part of their duties. Previous studies on the prediction of fatigue from speech have been limited because of their reliance on subjective ratings and because they lack comparison to other methods for assessing fatigue. In this paper, we present an analysis of voice recordings and psychophysiological test scores collected from seven aerospace personnel during a training task in which they remained awake for 60 h. We show that voice features and test scores are affected by both the total time spent awake and the time position within each subject’s circadian cycle. However, we show that time spent awake and time-of-day information are poor predictors of the test results, while voice features can give good predictions of the psychophysiological test scores and sleep latency. Mean absolute errors of prediction are possible within about 17.5% for sleep latency and 5–12% for test scores. We discuss the implications for the use of voice as a means to monitor the effects of fatigue on cognitive performance in practical applications. PMID:26380259

  17. Stiffness reductions during tensile fatigue testing of graphite/epoxy angle-ply laminates

    NASA Technical Reports Server (NTRS)

    Odom, E. M.; Adams, D. F.

    1982-01-01

    Tensile fatigue data was generated under carefully controlled test conditions. A computerized data acquisition system was used to permit the measurement of dynamic modulus without interrupting the fatigue cycling. Two different 8-ply laminate configurations, viz, + or - 45 (2s) and + or - 67.5 (2s), of a T300/5208 graphite/epoxy composite were tested. The + or - 45 (2s) laminate did exhibit some modulus decay, although there was no well-defined correlation with applied stress level or number of cycles. The + or - 67.5 (2s) laminate did not exhibit any measurable modulus decay. Secondary effects observed included a small but distinct difference between modulus as measured statically and dynamically, a slight recovery of the modulus decay after a test interruption, and a significant viscoelastic (creep) response of the + or - 45 (2s) laminate during fatigue testing.

  18. Strapdown gyro test program

    NASA Technical Reports Server (NTRS)

    Irvine, R. B.; Vanalstine, R.

    1977-01-01

    The power spectral noise characteristic performance of the Teledyne two-degree-of-freedom dry tuned gimbal gyroscope was determined. Tests were conducted using a current configuration SDG-5 gyro in conjunction with test equipment with minor modification. Long term bias stability tests were conducted as well as some first difference performance tests. The gyro, test equipment, and the tests performed are described. Results are presented.

  19. Taming the Standardized Testing Program.

    ERIC Educational Resources Information Center

    Nettleton, Aileen L.

    The city-wide standardized testing program of Madison Public Schools was reviewed by a committee of a cross-section of school system educators as part of a total effort to design a testing program more sensitive to the needs of the system. As a result, standardized testing was reduced to reading (grades 1, 2, 3, 4, 5, and 8) and mathematics (grade…

  20. Postural Balance Following Aerobic Fatigue Tests: A Longitudinal Study Among Young Athletes.

    PubMed

    Steinberg, Nili; Eliakim, Alon; Zaav, Aviva; Pantanowitz, Michal; Halumi, Monder; Eisenstein, Tamir; Meckel, Yoav; Nemet, Dan

    2016-01-01

    General fatigue can cause aggravation of postural balance, with increased risk for injuries. The present longitudinal study aimed to evaluate the postural balance of young athletes following field aerobic tests throughout 1 year of training. Thirty children from a sports center in Nazareth, participating in a 3 times/week training program (specific to basketball, soccer, or athletic training), were assessed. Postural balance parameters were taken before, immediately after, and 10 min after a 20 m shuttle-run aerobic test, at 3 time points during 1 training year (Start/Y, Mid/Y, and End/Y). Fitness improved at the Mid/Y and End/Y compared to Start/Y. Postural balance significantly deteriorated immediately after the aerobic test and improved significantly in the 10-min testing in all 3 time points, with significant deterioration in the End/Y compared with the Start/Y. In conclusions, postural balance deteriorates immediately after aerobic exercises, and at the end of the year. To better practice drills related to postural balance and possibly to prevent injuries, it is best for young athletes to properly rest immediately following aerobic exercises and to practice postural balance mainly at the beginning and at the middle of the training year.

  1. Current activities in standardization of high-temperature, low-cycle-fatigue testing techniques in the United States

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Ellis, J. Rodney; Swindeman, Robert W.

    1990-01-01

    The American Society for Testing and Materials (ASTM) standard E606-80 is the most often used recommended testing practice for low-cycle-fatigue (LCF) testing in the United States. The standard was first adopted in 1977 for LCF testing at room temperature and was modified in 1980 to include high-temperature testing practices. Current activity within ASTM is aimed at extending the E606-80 recommended practices to LCF under thermomechanical conditions, LCF in high-pressure hydrogen, and LCF in metal-matrix composite materials. Interlaboratory testing programs conducted to generate a technical base for modifying E606-80 for the aforementioned LCF test types are discussed.

  2. Surface Fatigue Tests Of M50NiL Gears And Bars

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Bamberger, Eric N.

    1994-01-01

    Report presents results of tests of steels for use in gears and bearings of advanced aircraft. Spur-gear endurance tests and rolling-element surface fatigue tests performed on gear and bar specimens of M50NiL steel processed by vacuum induction melting and vacuum arc remelting (VIM-VAR). Compares results of tests with similar tests of specimens of VIM-VAR AISI 9310 steel and of AISI 9310 steel subjected to VAR only.

  3. Mobilestar field test program

    NASA Technical Reports Server (NTRS)

    Rubow, Wayne

    1988-01-01

    Various field tests were performed in order to gain practical experience and a broader understanding of mobile communications. The first phase consisted of CW propagation tests to develop firsthand experience of propagation phenomena. From this information, estimates of the feasibility and accuracy of power control were possible. The next phase tested the idea of power control. Equipment representative of that expected to be used in an actual mobile satellite communication system was assembled and tested under a variety of environments.

  4. Innovative vibration technique applied to polyurethane foam as a viable substitute for conventional fatigue testing

    NASA Astrophysics Data System (ADS)

    Peralta, Alexander; Just-Agosto, Frederick; Shafiq, Basir; Serrano, David

    2012-12-01

    Lifetime prediction using three-point bending (TPB) can at times be prohibitively time consuming and costly, whereas vibration testing at higher frequency may potentially save time and revenue. A vibration technique that obtains lifetimes that reasonably match those determined under flexural TPB fatigue is developed. The technique designs the specimen with a procedure based on shape optimization and finite element analysis. When the specimen is vibrated in resonance, a stress pattern that mimics the stress pattern observed under conventional TPB fatigue testing is obtained. The proposed approach was verified with polyurethane foam specimens, resulting in an average error of 4.5% when compared with TPB.

  5. The algorithm of crack and crack tip coordinates detection in optical images during fatigue test

    NASA Astrophysics Data System (ADS)

    Panin, S. V.; Chemezov, V. O.; Lyubutin, P. S.; Titkov, V. V.

    2017-02-01

    An algorithm of crack detection during fatigue testing of materials, designed to automate the process of cyclic loading and tracking the crack tip, is proposed and tested. The ultimate goal of the study is aimed at controlling the displacements of the optical system with regard to the specimen under fatigue loading to ensure observation of the ‘area of interest’. It is shown that the image region that contains the crack may be detected and positioned with an average error of 1.93%. In terms of determining the crack tip position, the algorithm provides the accuracy of its localization with the average error value of 56 pixels.

  6. Test chip assembler and test program generator

    NASA Technical Reports Server (NTRS)

    Pina, C. A.

    1985-01-01

    One of the major problems in working at the geometry level for the generation of either test structure or functional circuit designs is the amount of labor involved in the design phase. To reduce the amount of labor involved in both the design and test of the structures used, JPL has developed a design and test program consisting of a Test Chip Assembler (TCA) and a Test Program Generator (TPG), which creates the geometrical description of the structures and generates the necessary test information using a high-level language. This system reduces the design time for a test chip by a factor of 30. To analyze the data obtained from wafer probing, a statistical package called STMJPL was developed. Some of the capabilities of the JPL software (STMJPL) are described.

  7. Rolling-element fatigue life of silicon nitride balls: Preliminary test results

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.

    1972-01-01

    Hot pressed silicon nitride was evaluated as a rolling element bearing material. The five-ball fatigue tester was used to test 12.7 mm (0.500 in.) diameter balls at a maximum Hertz stress of 800,000 psi at a race temperature of 130 F. The fatigue spalls in the silicon nitride resembled those in typical bearing steels. The ten-percent fatigue life of the silicon nitride balls was approximately one-eighth to one-fifth that of typical bearing steels (52100 and M-50). The load capacity of the silicon nitride was approximately one-third that of typical bearing steels. The load capacity of the silicon nitride was significantly higher than previously tested ceramic materials for rolling element bearings.

  8. Elevated temperature biaxial fatigue

    NASA Technical Reports Server (NTRS)

    Jordan, E. H.

    1985-01-01

    A 3 year experimental program for studying elevated temperature biaxial fatigue of a nickel based alloy Hastelloy-X has been completed. A new high temperature fatigue test facility with unique capabilities has been developed. Effort was directed toward understanding multiaxial fatigue and correlating the experimental data to the existing theories of fatigue failure. The difficult task of predicting fatigue lives for nonproportional loading was used as an ultimate test for various life prediction methods being considered. The primary means of reaching improved understanding were through several critical nonproportional loading experiments. The direction of cracking observed on failed specimens was also recorded and used to guide the development of the theory. Cyclic deformation responses were permanently recorded digitally during each test. It was discovered that the cracking mode switched from primarily cracking on the maximum shear planes at room temperature to cracking on the maximum normal strain planes at 649 C. In contrast to some other metals, loading path in nonproportional loading had little effect on fatigue lives. Strain rate had a small effect on fatigue lives at 649 C. Of the various correlating parameters the modified plastic work and octahedral shear stress were the most successful.

  9. Laser Cut Nitinol Tubing Fatigue Coupon: Design, Testing, and Endurance Limit

    NASA Astrophysics Data System (ADS)

    Forcucci, Stephen J.

    2014-07-01

    Nitinol medical device implants made from a laser cut tubing process (i.e., stents, valve structures, etc.) frequently require a fatigue durability assessment, which necessitates determining the material fatigue properties. Towards the goal of determining the strain-based endurance limit of medical grade superelastic Nitinol tubing, a coupon was designed and evaluated via FEA using Abaqus software, produced via laser cutting, shape setting, and electro-polishing processes, and then fatigue tested to 10 million cycles. FEA was used to determine the strain versus alternating displacement amplitude for the coupon. Error due to dimensional tolerances was determined. The coupons were then fatigue tested in a 37 °C temperature deionized water bath at alternating strain levels ranging from 0.75 to 4.0% at zero mean strain. Sample replication was greater than 90%, and the median alternating strain fatigue limit was determined via two methods. Confidence and reliability with maximum likelihood statistics are used to present a strain-based endurance limit for the material. The results seem to differ from previous published values.

  10. FLAPS (Fatigue Life Analysis Programs): Computer Programs to Predict Cyclic Life Using the Total Strain Version of Strainrange Partitioning and Other Life Prediction Methods. Users' Manual and Example Problems, Version 1.0

    NASA Technical Reports Server (NTRS)

    Arya, Vinod K.; Halford, Gary R. (Technical Monitor)

    2003-01-01

    This manual presents computer programs FLAPS for characterizing and predicting fatigue and creep-fatigue resistance of metallic materials in the high-temperature, long-life regime for isothermal and nonisothermal fatigue. The programs use the Total Strain version of Strainrange Partitioning (TS-SRP), and several other life prediction methods described in this manual. The user should be thoroughly familiar with the TS-SRP and these life prediction methods before attempting to use any of these programs. Improper understanding can lead to incorrect use of the method and erroneous life predictions. An extensive database has also been developed in a parallel effort. The database is probably the largest source of high-temperature, creep-fatigue test data available in the public domain and can be used with other life-prediction methods as well. This users' manual, software, and database are all in the public domain and can be obtained by contacting the author. The Compact Disk (CD) accompanying this manual contains an executable file for the FLAPS program, two datasets required for the example problems in the manual, and the creep-fatigue data in a format compatible with these programs.

  11. Fatigue strength testing employed for evaluation and acceptance of jet-engine instrumentation probes

    NASA Astrophysics Data System (ADS)

    Armentrout, E. C.

    1980-03-01

    This report outlines the fatigue type testing performed on instrumentation rakes and probes intended for use in the air flow passages of jet-engines during full-scale engine tests at Lewis Research Center. Included is a discussion of each type of test performed, the results that may be derived and means of inspection. A design and testing sequence outlines the procedures and considerations involved in the generation of suitable instrument probes.

  12. Evaluation of Creep-Fatigue Damage Based on Simplified Model Test Approach

    SciTech Connect

    Wang, Yanli; Li, Tianlei; Sham, Sam; Jetter, Robert I

    2013-01-01

    Current methods used in the ASME Code, Subsection NH for the evaluation of creep-fatigue damage are based on the separation of elevated temperature cyclic damage into two parts, creep damage and fatigue damage. This presents difficulties in both evaluation of test data and determination of cyclic damage in design. To avoid these difficulties, an alternative approach was identified, called the Simplified Model Test or SMT approach based on the use of creep-fatigue hold time test data from test specimens with elastic follow-up conservatively designed to bound the response of general structural components of interest. A key feature of the methodology is the use of the results of elastic analysis directly in design evaluation similar to current methods in the ASME Code, Subsection NB. Although originally developed for current material included in Subsection NH, recent interest in the application of Alloy 617 for components operating at very high temperatures has caused renewed interest in the SMT approach because it provides an alternative to the proposed restriction on the use of current Subsection NH simplified methods at very high temperatures. A comprehensive review and assessment of five representative simplified methods for creep-fatigue damage evaluation is presented in Asayama [1]. In this review the SMT methodology was identified as the best long term approach but the need for test data precluded its near term implementation. Asayama and Jetter [2] is a summary of the more comprehensive report by Asayama [1] with a summary of the SMT approach presented by Jetter [3].

  13. Fatigue Crack Growth Rate Test Results for Al-Li 2195 Parent Metal, Variable Polarity Plasma Arc Welds and Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Wagner, John A.; Domack, Marcia S.

    2000-01-01

    The fatigue crack growth rate of aluminum-lithium (Al-Li) alloy 2195 plate and weldments was determined at 200-F, ambient temperature and -320-F. The effects of stress ratio (R), welding process, orientation and thickness were studied. Results are compared with plate data from the Space Shuttle Super Lightweight Tank (SLWT) allowables program. Data from the current series of tests, both plate and weldment, falls within the range of data generated during the SLWT allowables program.

  14. DOE HEPA filter test program

    SciTech Connect

    1998-05-01

    This standard establishes essential elements of a Department of Energy (DOE) program for testing HEPA filters to be installed in DOE nuclear facilities or used in DOE-contracted activities. A key element is the testing of HEPA filters for performance at a DOE Filter Test Facility (FTF) prior to installation. Other key elements are (1) providing for a DOE HEPA filter procurement program, and (2) verifying that HEPA filters to be installed in nuclear facilities appear on a Qualified Products List (QPL).

  15. The Effect of Group Mindfulness-based Stress Reduction and Consciousness Yoga Program on Quality of Life and Fatigue Severity in Patients with MS

    PubMed Central

    Nejati, Somayeh; Rajezi Esfahani, Sepideh; Rahmani, Soheila; Afrookhteh, Gita; Hoveida, Shahrzad

    2016-01-01

    Introduction: The chronic nature of Multiple Sclerosis (MS), have can leave devastating effects on quality of life and fatigue. The present research aimed to study the effect of group Mindfulness-based Stress Reduction (MBSR) and conscious yoga program on the quality of life and fatigue severity among patients with MS. Methods: This study was quasi-experimental with intervention and control groups. The statistical population included all members to MS Society of Tehran Province, 24 of whom diagnosed with MS were selected as the sample based on the inclusion criteria. The subjects were randomly assigned into the test group (12 patients) and the control group (12 patients). MS Quality of Life-54 (MSQOL-54) and Fatigue Severity Scale (FSS) were used for data collection. Subjects in the test group underwent a MBSR and conscious yoga program in 8 two-hour sessions. The data were analyzed using the SPSS ver.13 software. Results: The study findings showed that there was a significant difference between subjects in the experimental and control groups in terms of mean score of some subscales of quality of life including physical health, role limitations due to physical and emotional problems, energy, emotional well-being, health distress, health perception, and satisfaction with sexual function, overall quality of life, and fatigue severity. Conclusion: The results show that the program is effective in reduction of fatigue severity and improving some subscales of quality of life in MS patients. Hence, this supportive method can be used as an effective way for improving quality of life and relieving fatigue in MS patients. PMID:28032077

  16. The Effect of Group Mindfulness-based Stress Reduction and Consciousness Yoga Program on Quality of Life and Fatigue Severity in Patients with MS.

    PubMed

    Nejati, Somayeh; Rajezi Esfahani, Sepideh; Rahmani, Soheila; Afrookhteh, Gita; Hoveida, Shahrzad

    2016-12-01

    Introduction: The chronic nature of Multiple Sclerosis (MS), have can leave devastating effects on quality of life and fatigue. The present research aimed to study the effect of group Mindfulness-based Stress Reduction (MBSR) and conscious yoga program on the quality of life and fatigue severity among patients with MS. Methods: This study was quasi-experimental with intervention and control groups. The statistical population included all members to MS Society of Tehran Province, 24 of whom diagnosed with MS were selected as the sample based on the inclusion criteria. The subjects were randomly assigned into the test group (12 patients) and the control group (12 patients). MS Quality of Life-54 (MSQOL-54) and Fatigue Severity Scale (FSS) were used for data collection. Subjects in the test group underwent a MBSR and conscious yoga program in 8 two-hour sessions. The data were analyzed using the SPSS ver.13 software. Results: The study findings showed that there was a significant difference between subjects in the experimental and control groups in terms of mean score of some subscales of quality of life including physical health, role limitations due to physical and emotional problems, energy, emotional well-being, health distress, health perception, and satisfaction with sexual function, overall quality of life, and fatigue severity. Conclusion: The results show that the program is effective in reduction of fatigue severity and improving some subscales of quality of life in MS patients. Hence, this supportive method can be used as an effective way for improving quality of life and relieving fatigue in MS patients.

  17. Ferrographic analysis of wear debris generated in accelerated rolling element fatigue tests

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Parker, R. J.

    1977-01-01

    The types and quantities of wear particles generated during accelerated ball rolling contact fatigue tests were determined. Ball specimens were made of AMS 5749, a corrosion resistant, high-temperature bearing steel. The lubricant was a super-refined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.215 times 10 to the 9th power Pa and a shaft speed of 10,000 rpm. Four types of wear particles were observed; normal rubbing wear particles, fatigue spall particles, spheres, and friction polymer.

  18. A Modified Constant-Stress Coupon for Enhanced Natural Crack Start during Fatigue Testing

    DTIC Science & Technology

    2016-05-01

    Metallic Technologies Group within DST Group (Shekhter et al. 2015; Loader, Shekhter and Turk 2015; Loader et al. 2016; Niclis and Harrison 2016...Example. October 2006. Niclis J, T Harrison . Fatigue Implications of surface treated AA7050-T7451 tested under VA loading. DST Group Technical Report

  19. Fatigue testing of low-cost fiberglass composite wind turbine blade materials

    NASA Technical Reports Server (NTRS)

    Hofer, K. E.; Bennett, L. C.

    1981-01-01

    The static and fatigue behavior of transverse filament tape (TFT) fiberglass/epoxy and TFT/polyester composites was established by the testing of specimens cut from panels fabricated by a filament winding process used for the construction of large experimental wind turbine blades.

  20. Evaluation of advanced lubricants for aircraft applications using gear surface fatigue tests

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Shimski, John

    1991-01-01

    Surface pitting fatigue life tests were conducted with five lubricants, using spur gears made from a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 steel. The gears were case carbonized and hardened to a Rockwell c-60 and finish ground. The gear pitch diameter was 8.89 cm. The lot of gears was divided into five groups, each of which was tested with a different lubricant. The test lubricants can be classified as synthetic polyol-esters with various viscosities and additive packages. Test conditions included bulk gear temperature of 350 K, a maximum Hertz stress of 1.71 GPa (248 ksi) at the pitch line, and a speed of 10,000 RPM. The lubricant with a viscosity that provided a specific film thickness greater than one and with an additive package produced far greater gear surface fatigue lives than lubricants with a viscosity that provided specific film thickness less than one. A low viscosity lubricant with an additive package produced gear surface fatigue lives equivalent to a similar base stock lubricant with 30 percent higher viscosity, but without an additive package. Lubricants with the same viscosity and similar additive packages gave equivalent gear surface fatigue lives.

  1. Design of PF-1 Coil Helium Inlet and Dummy Joint Samples for Fatigue Tests at 77K

    NASA Astrophysics Data System (ADS)

    Nasluzov, S. N.; Sukhanova, M. V.; Rodin, I. Yu.; Marushin, E. L.; Mednikov, A. A.; Stepanov, D. B.; Lantsetov, A. A.; Khitruk, A. A.

    A helium inlet and dummy joint between conductors are one of the most important elements of the winding pack of the ITER PF -1 coil double pancakes. A helium inlet is used for letting liquid helium into the PF-1 coil conductor. A full-scale helium inlet sample for fatigue tests and the respective tooling were designed and manufactured. Fatigue tests of the full-scale helium inlet sample were conducted in accordance with ITER requirements testing parameters in order to check the fatigue strength of the structure. Before the fatigue tests thermo-cycling of the helium inlet in the temperature range of 77 to 293 K was conducted. Before and after the fatigue tests the leak tightness of the full-scale helium inlet sample was validated by the vacuum chamber method. A low ohm electrical joint is used to connect two NbTi «CICC» conductors of PF-1 coil into a single electrical loop. To qualify the design and technology of manufacturing of the electrical joint, a full-scale dummy joint sample was developed for fatigue tests at 77 K. The main design feature of the full-scale dummy joint sample for fatigue tests is a symmetrical model of two dummy joint samples with simultaneous loading to compensate the bending moment. Fatigue tests of the full-scale helium inlet sample at 77 K have been successfully conducted in 2013. Fatigue tests of the full-scale dummy joint sample will be conducted in 2014. This paper represents the results of calculating the stress-strain state of the symmetrical model of the full-scale dummy joint sample for fatigue tests with the prescribed loading and strain, the work on designing the symmetrical model of the dummy joint sample for fatigue tests and the test facility for conducting fatigue tests at 77 K. Also the results of the leak tightness tests and thermo-cycling of the full-scale helium inlet and the results of it fatigue tests at 77 K, are presented.

  2. Conducting thermomechanical fatigue test in air at light water reactor relevant temperature intervals

    NASA Astrophysics Data System (ADS)

    Ramesh, Mageshwaran; Leber, Hans J.; Diener, Markus; Spolenak, Ralph

    2011-08-01

    In Light Water Reactors (LWR), many structural components are made of austenitic stainless steels (SS). These components are subject to extreme conditions, such as large temperature gradients and pressure loads during service. Hence, the fatigue and fracture behavior of austenitic SS under these conditions has evoked consistent interest over the years. Most studies dealing with this problem in the past, investigated the isothermal fatigue (IF) condition, which is not the case in the service, and less attention has been paid to thermomechanical fatigue (TMF). Moreover, the existing codes of practice and standards for TMF testing are mainly derived from the high temperature TMF tests ( T mean > 400 °C). This work presents the development of a facility to perform TMF tests under LWR relevant temperature interval in air. The realized testing parameters and tolerances are compared with the recommendations of existing codes of practice and standards from high temperature tests. The effectiveness of the testing facility was verified with series of TMF and IF tests performed on specimens made out of a commercial austenitic SS TP347 pipe material. The results revealed that the existing tolerances in standards are quite strict for the application of lower temperature ranges TMF tests. It was found that the synchronous, in-phase (IP) TMF tested specimens possess a higher lifetime than those subjected to the asynchronous, out-of-phase (OP) TMF and IF at T max in the investigated strain range for austenitic SS. Nevertheless, the fatigue lifetime of all the test conditions was similar in the engineering scale.

  3. The detection of tightly closed flaws by nondestructive testing (NDT) methods. [fatigue crack formation in aluminum alloy test specimens

    NASA Technical Reports Server (NTRS)

    Rummel, W. D.; Rathke, R. A.; Todd, P. H., Jr.; Mullen, S. J.

    1975-01-01

    Liquid penetrant, ultrasonic, eddy current and X-radiographic techniques were optimized and applied to the evaluation of 2219-T87 aluminum alloy test specimens in integrally stiffened panel, and weld panel configurations. Fatigue cracks in integrally stiffened panels, lack-of-fusion in weld panels, and fatigue cracks in weld panels were the flaw types used for evaluation. A 2319 aluminum alloy weld filler rod was used for all welding to produce the test specimens. Forty seven integrally stiffened panels containing a total of 146 fatigue cracks, ninety three lack-of-penetration (LOP) specimens containing a total of 239 LOP flaws, and one-hundred seventeen welded specimens containing a total of 293 fatigue cracks were evaluated. Nondestructive test detection reliability enhancement was evaluated during separate inspection sequences in the specimens in the 'as-machined or as-welded', post etched and post proof loaded conditions. Results of the nondestructive test evaluations were compared to the actual flaw size obtained by measurement of the fracture specimens after completing all inspection sequences. Inspection data were then analyzed to provide a statistical basis for determining the flaw detection reliability.

  4. The History of Structural Fatigue Testing at Fishermans Bend Australia

    DTIC Science & Technology

    2005-10-01

    Test GAF Government Aircraft Factories IFOSTP International Follow - On Structural Test Project LEX Leading Edge...project known as the International Follow - On DSTO-TR-1773 34 Structural Test Project ( IFOSTP ). IFOSTP consisted of three separate FSFTs supported by...J. Roussel, L. Molent, A.D. Graham and N. Schmidt, The Canadian and Australian F/A-18 International Follow - On Structural

  5. Nevada Test Site closure program

    SciTech Connect

    Shenk, D.P.

    1994-08-01

    This report is a summary of the history, design and development, procurement, fabrication, installation and operation of the closures used as containment devices on underground nuclear tests at the Nevada Test Site. It also addresses the closure program mothball and start-up procedures. The Closure Program Document Index and equipment inventories, included as appendices, serve as location directories for future document reference and equipment use.

  6. Vibration fatigue analysis and multi-axial effect in testing of aerospace structures

    NASA Astrophysics Data System (ADS)

    Aykan, Murat; Çelik, Mehmet

    2009-04-01

    The work reported in this paper compared the fatigue damage accumulated under uni-axial loading (a procedure promoted by the vibration testing standards) to that induced by multi-axial loading. The comparison was performed for a helicopter structural element (the flare dispenser bracket of the self-defensive system's Chaff), which is exposed to the particular combination of wide-band random with sinusoidal vibrations, which is characteristic to the helicopter dynamic environment. The evaluation of the fatigue damage induced by these loads requires the calculation or measurement of the structure's dynamic response in terms of stresses or strains, and the application of the appropriate methodology to this response. In this work, dynamic response was calculated in the frequency domain based on the relations between the power spectral density matrixes of the excitations to that of the responses for a linear system. The transfer matrix that relates the excitation to the responses was evaluated numerically. The power spectral densities of the responses evaluated at different locations on the structure were used in the determination of the responses' statistics (the counting of the loading cycles), which, combined with an appropriate physics of failure model (fatigue model), enabled the evaluation of the accumulated fatigue damage. The uni-axial-induced fatigue was evaluated from vibration tests of the kind promoted by military standards (it is assumed that axis-by-axis loading is cumulatively equal to multi-axial loading), and compared to that evaluated by analysis for the multi-axial loading. Also a numerical comparison of the effects of the two kinds of loading was performed. The results showed that the error of uni-axial testing varied for a wide range of parameters. The work led to the conclusion that simultaneous multi-axis vibration testing can improve significantly the laboratory's vibration simulation realism.

  7. Fatigue life and performance testing of hybrid ceramic ball bearings

    SciTech Connect

    Chiu, Y.P.; Prason, P.K.; Dezzani, M.

    1996-03-01

    Hybrid ceramic ball bearings are finding increased applications in machine tool spindles and aerospace vehicles. Results of three types of testing hybrid ceramic ball bearing are presented and discussed. The first is the classical endurance testing of highly loaded hybrid bearings with good lubrication. The second is the endurance test of hybrid nitrided bearings after running in a contaminated lubricant which caused dented raceways. The third is the high-speed performance testing of spindle bearings lubricated with grease or an oil-air mixture. Recent material development, bearing temperature at high-speed and reliability considerations are discussed. 14 refs., 9 fig., 4 tab.

  8. Transient Pressure Test Article Test Program

    NASA Technical Reports Server (NTRS)

    Vibbart, Charles M.

    1989-01-01

    The Transient Pressure Test Article (TPTA) test program is being conducted at a new test facility located in the East Test Area at the National Aeronautics and Space Administration's (NASA's) Marshall Space Flight Center (MSFC) in Huntsville, Alabama. This facility, along with the special test equipment (STE) required for facility support, was constructed specifically to test and verify the sealing capability of the Redesigned Solid Rocket Motor (RSRM) field, igniter, and nozzle joints. The test article consists of full scale RSRM hardware loaded with inert propellant and assembled in a short stack configuration. The TPTA is pressurized by igniting a propellant cartridge capable of inducing a pressure rise rate which stimulates the ignition transient that occurs during launch. Dynamic loads are applied during the pressure cycle to simulate external tank attach (ETA) strut loads present on the ETA ring. Sealing ability of the redesigned joints is evaluated under joint movement conditions produced by these combined loads since joint sealing ability depends on seal resilience velocity being greater than gap opening velocity. Also, maximum flight dynamic loads are applied to the test article which is either pressurized to 600 psia using gaseous nitrogen (GN2) or applied to the test article as the pressure decays inside the test article on the down cycle after the ignition transient cycle. This new test facility is examined with respect to its capabilities. In addition, both the topic of test effectiveness versus space vehicle flight performance and new aerospace test techniques, as well as a comparison between the old SRM design and the RSRM are presented.

  9. AUSSAT battery life test program

    NASA Technical Reports Server (NTRS)

    Gorian, P. W.; Pickett, D. F., Jr.; Bogner, R. S.; Chao, T. I.; Jordan, J. P.; Clark, K. B.

    1985-01-01

    AUSSAT Pty. Ltd., the Australian National Satellite organization, has contracted with the Hughes Aircraft Company (HAC) for the construction of 3 satellites based on the now familiar HS-376 product line. As part of the AUSSAT contract, HAC is conducting an extensive NiCd battery life test program. The life test program, objectives and test results to date are described. Particular emphasis is given to the evaluation of the FS2117 separator as a future replacement for the Pellon 2505 separator of which only a very limited quantity remains.

  10. Analysis of wear-debris from full-scale bearing fatigue tests using the ferrograph

    NASA Technical Reports Server (NTRS)

    Jones, W. R.; Loewenthal, S. H.

    1980-01-01

    The ferrograph was used to determine the types and quantities of wear particles generated during full-scale bearing fatigue tests. Deep-groove ball bearings made from AISI 52100 steel were used. A MIL-L-23699 tetraester lubricant was used in a recirculating lubrication system containing a 49 mm absolute filter. Test conditions included a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm, and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the ferrograph was more sensitive (up to 23 hr) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis. Four particle types were observed: normal rubbing wear particles, spheres, nonferrous particles, and severe wear (spall) fragments.

  11. Analysis of wear debris from full-scale bearing fatigue tests using the Ferrograph

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Loewenthal, S. H.

    1980-01-01

    The Ferrograph was used to determine the types of quantities of wear particles generated during full-scale bearing fatigue tests. Deep-groove ball bearings made from AISI 52100 steel were used. A MIL-L-23699 tetraester lubricant was used in a recirculating lubrication system containing a 49-micron absolute filter. Test conditions included a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the Ferrograph was more sensitive (up to 23 h) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis (SOAP). Four particle types were observed: normal rubbing wear particles, spheres, nonferrous particles, and severe wear (spall) fragments.

  12. Ferrographic analysis of wear debris from full-scale bearing fatigue tests

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Loewenthal, S. H.

    1979-01-01

    The Ferrograph was used to determine the types and quantities of wear particles generated during full scale bearing fatigue tests. Deep-groove ball bearings made from steel were used. A tetraester lubricant was used in a recirculating lubricant system containing a 49 micrometers absolute filter. Test conditions include a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm, and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the Ferrograph was more sensitive (up to 23 hr) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis. Four particle types were observed: normal rubbing weather particles, spheres, nonferrous particles, and severe wear (spall) fragments.

  13. Agonist and antagonist muscle activation during maximal and submaximal isokinetic fatigue tests of the knee extensors.

    PubMed

    Hassani, A; Patikas, D; Bassa, E; Hatzikotoulas, K; Kellis, E; Kotzamanidis, C

    2006-12-01

    The purpose of this study was to examine the differences in electromyographic activity of agonist and antagonist knee musculature between a maximal and a submaximal isokinetic fatigue protocol. Fourteen healthy males (age: 24.3+/-2.5 years) performed 25 maximal (MIFP) and 60 submaximal (SIFP) isokinetic concentric efforts of the knee extensors at 60 degrees s(-1), across a 90 degrees range of motion. The two protocols were performed a week apart. The EMG activity of vastus medialis (VM), vastus lateralis (VL) and biceps femoris (BF) were recorded using surface electrodes. The peak torque (PT) and average EMG (aEMG) were expressed as percentages of pre-fatigue maximal value. One-way analysis of variance indicated a significant (p<0.05) decline of PT during the maximal (45.7%) and submaximal (46.8%) protocols. During the maximal test, the VM and VL aEMG initially increased and then decreased. In contrast, VM and VL aEMG continuously increased during submaximal testing (p<0.05). The antagonist (BF) aEMG remained constant during maximal test but it increased significantly and then declined during the submaximal testing. The above results indicate that agonist and antagonist activity depends on the intensity of the selected isokinetic fatigue test.

  14. Self-reported post-exertional fatigue in Gulf War veterans: roles of autonomic testing.

    PubMed

    Li, Mian; Xu, Changqing; Yao, Wenguo; Mahan, Clare M; Kang, Han K; Sandbrink, Friedhelm; Zhai, Ping; Karasik, Pamela A

    2014-01-07

    To determine if objective evidence of autonomic dysfunction exists from a group of Gulf War veterans with self-reported post-exertional fatigue, we evaluated 16 Gulf War ill veterans and 12 Gulf War controls. Participants of the ill group had self- reported, unexplained chronic post-exertional fatigue and the illness symptoms had persisted for years until the current clinical study. The controls had no self-reported post-exertional fatigue either at the time of initial survey nor at the time of the current study. We intended to identify clinical autonomic disorders using autonomic and neurophysiologic testing in the clinical context. We compared the autonomic measures between the 2 groups on cardiovascular function at both baseline and head-up tilt, and sudomotor function. We identified 1 participant with orthostatic hypotension, 1 posture orthostatic tachycardia syndrome, 2 distal small fiber neuropathy, and 1 length dependent distal neuropathy affecting both large and small fiber in the ill group; whereas none of above definable diagnoses was noted in the controls. The ill group had a significantly higher baseline heart rate compared to controls. Compound autonomic scoring scale showed a significant higher score (95% CI of mean: 1.72-2.67) among ill group compared to controls (0.58-1.59). We conclude that objective autonomic testing is necessary for the evaluation of self-reported, unexplained post-exertional fatigue among some Gulf War veterans with multi-symptom illnesses. Our observation that ill veterans with self-reported post-exertional fatigue had objective autonomic measures that were worse than controls warrants validation in a larger clinical series.

  15. Cracking and Spalling Behavior of HVOF Thermally Sprayed WC-Co-Cr Coating in Bend and Axial Fatigue Tests

    NASA Astrophysics Data System (ADS)

    Gui, M.; Eybel, R.; Asselin, B.; Monerie-Moulin, F.

    2015-03-01

    In this work, WC-10Co-4Cr coating was sprayed by high-velocity oxygen fuel (HVOF) process on Almen strip and axial fatigue coupon. Three-point bend test was used to bend Almen strip coating specimens with tensile and compressive stress applied to the coating. Axial fatigue coating specimens were tested at a load stress of 1250 MPa and a stress ratio of R = -1. Process condition of Thermal spraying was found to have an effect on spalling performance of the coating in the fatigue test. The mechanism of cracking and spalling process in the coating was studied in bend and fatigue conditions. Based on deformation difference between the coating and the substrate, the factors, especially coating thickness, to impact the coating spalling behavior in axial fatigue test are discussed. HVOF-sprayed WC-10Co-4Cr coating matches the deformation of base substrate by cracking when tensile stress is applied in bend and fatigue tests because the coating has very limit deformation capability. In axial fatigue test of WC-10Co-4Cr coating specimen, the substrate works in a stress-to-strain manner; however the coating works in a strain-to-stress manner and is stressed due to the substrate deformation.

  16. F-14 Wing Outer Panel Fatigue Test Spectrum.

    DTIC Science & Technology

    1987-04-01

    Department of the Navy Washington. D.C. 20361- 3300 88 ..* W-. . . . . P - 5. F F:::,:::. 5* NOTICES - REPORT NUMBERING SYSTEM - The numbering of technical...APPROVED BY:______________ DATE; % W. F. MORONEY a CAPT. MSC, U.S. NAVY ., .1 SECURITY CLASSiFICATION OF THIS PAGE ,qJ, 1q93 A𔃻Lg REPORT DOCUMENTATION...NAVAL AIR SYSTEMS COMMAND IN/A S9. ADDRESS (City. Stat. and IV Code) 10. SO’URCE OF FUNDING NUMBERS DEPARTMENT OF THE NAVY PROGRAM PROJEC TASK WORK UNIT

  17. Postdialysis fatigue.

    PubMed

    Sklar, A H; Riesenberg, L A; Silber, A K; Ahmed, W; Ali, A

    1996-11-01

    To clarify the demographic and clinicolaboratory features of postdialysis fatigue (PDF), we enrolled 85 patients on maintenance hemodialysis in a cross-sectional study using validated questionnaires and chart review. Forty-three patients complained of fatigue after dialysis. On formal testing using the Kidney Disease Questionnaire, the PDF group had statistically greater severity of fatigue and somatic complaints than the group of patients without subjective fatigue (P = 0.03 and 0.04, respectively). On a scale measuring intensity of fatigue (1 = least to 5 = worst), the PDF group average was 3.4 +/- 1.2. PDF subjects reported that 80% +/- 25% of dialysis treatments were followed by fatigue symptoms. In 28 (65%) of patients, the symptoms started with the first dialysis treatment. They reported needing an average of 4.8 hours of rest or sleep to overcome the fatigue symptoms (range, 0 to 24 hours). There were no significant differences between patients with and without PDF in the following parameters: age; sex; type of renal disease; presence of diabetes mellitus, heart disease (congestive, ischemic), or chronic obstructive lung disease; blood pressure response to dialysis; type or adequacy of dialysis regimen; hematocrit; electrolytes; blood urea nitrogen; creatinine; cholesterol; albumin; parathyroid hormone; ejection fraction; and use of antihistamines, benzodiazepines, and narcotics. In the fatigue group, there was significantly greater use of antihypertensive medications known to have fatigue as a side effect (P = 0.007). Depression was more common in the fatigue group by Beck Depression score (11.6 +/- 8.0 v 7.8 +/- 6.3; P = 0.02). We conclude that (1) postdialysis fatigue is a common, often incapacitating symptom in patients on chronic extracorporeal dialysis; (2) no routinely measured parameter of clinical or dialytic function appears to predict postdialysis fatigue; and (3) depression is highly associated with postdialysis fatigue, but the cause

  18. DOD Space Test Program (STP)

    NASA Technical Reports Server (NTRS)

    Smith, Llwyn

    1995-01-01

    This paper describes the Space Test Program (STP) which provides access to space for the DOD-wide space research and development (R&D) community. STP matches a ranked list of sanctioned experiments with available budgets and searches for the most cost effective mechanisms to get the experiments into space. The program has successfully flown over 350 experiments, using dedicated freeflyer spacecraft, secondary space on the Space Shuttle, and various host satellites.

  19. Lamb wave ultrasonic evaluation of welded AA2024 specimens at tensile static and fatigue testing

    NASA Astrophysics Data System (ADS)

    Burkov, M. V.; Byakov, A. V.; Shah, R. T.; Lyubutin, P. S.; Panin, S. V.

    2015-10-01

    The paper deals with the investigation of Lamb waves ultrasonic testing technique applied for evaluation of different stress-strain and damaged state of aluminum specimens at static and fatigue loading in order to develop a Structural Health Monitoring (SHM) approach. The experimental results of tensile testing of AA2024T3 specimens with welded joints are presented. Piezoelectric transducers used as actuators and sensors were adhesively bonded to the specimen's surface using two component epoxy. The set of static and cyclic tensile tests with two frequencies of acoustic testing (50 kHz and 335 kHz) were performed. The recorded signals were processed to calculate the maximum envelope in order to evaluate the changes of the stress-strain state of the specimen and its microstructure during static tension. The registered data are analyzed and discussed in terms of signal attenuation due to the formation of fatigue defects during cyclic loading. Understanding the relations between acoustic signal features and fatigue damages will provide us the ability to determine the damage state of the structure and its residual lifetime in order to design a robust SHM system.

  20. A computerized test system for thermal-mechanical fatigue crack growth

    NASA Technical Reports Server (NTRS)

    Marchand, N.; Pelloux, R. M.

    1986-01-01

    A computerized testing system to measure fatigue crack growth under thermal-mechanical fatigue conditions is described. Built around a servohydraulic machine, the system is capable of a push-pull test under stress-controlled or strain-controlled conditions in the temperature range of 25 to 1050 C. Temperature and mechanical strain are independently controlled by the closed-loop system to simulate the complex inservice strain-temperature relationship. A d-c electrical potential method is used to measure crack growth rates. The correction procedure of the potential signal to take into account powerline and RF-induced noises and thermal changes is described. It is shown that the potential drop technique can be used for physical mechanism studies and for modelling crack tip processes.

  1. Evaluation of Dynamic Mechanical Loading as an Accelerated Test Method for Ribbon Fatigue

    SciTech Connect

    Bosco, Nick; Silverman, Timothy J.; Wohlgemuth, John; Kurtz, Sarah; Inoue, Masanao; Sakurai, Keiichiro; Shioda, Tsuyoshi; Zenkoh, Hirofumi; Hirota, Kusato; Miyashita, Masanori; Tadanori, Tanahashi; Suzuki, Soh; Chen, Yifeng; Verlinden, Pierre J.

    2014-12-31

    Dynamic Mechanical Loading (DML) of photovoltaic modules is explored as a route to quickly fatigue copper interconnect ribbons. Results indicate that most of the interconnect ribbons may be strained through module mechanical loading to a level that will result in failure in a few hundred to thousands of cycles. Considering the speed at which DML may be applied, this translates into a few hours of testing. To evaluate the equivalence of DML to thermal cycling, parallel tests were conducted with thermal cycling. Preliminary analysis suggests that one +/-1 kPa DML cycle is roughly equivalent to one standard accelerated thermal cycle and approximately 175 of these cycles are equivalent to a 25-year exposure in Golden Colorado for the mechanism of module ribbon fatigue.

  2. Evaluation of Dynamic Mechanical Loading as an Accelerated Test Method for Ribbon Fatigue: Preprint

    SciTech Connect

    Bosco, N.; Silverman, T. J.; Wohlgemuth, J.; Kurtz, S.; Inoue, M.; Sakurai, K.; Shinoda, T.; Zenkoh, H.; Hirota, K.; Miyashita, M.; Tadanori, T.; Suzuki, S.

    2015-04-07

    Dynamic Mechanical Loading (DML) of photovoltaic modules is explored as a route to quickly fatigue copper interconnect ribbons. Results indicate that most of the interconnect ribbons may be strained through module mechanical loading to a level that will result in failure in a few hundred to thousands of cycles. Considering the speed at which DML may be applied, this translates into a few hours o testing. To evaluate the equivalence of DML to thermal cycling, parallel tests were conducted with thermal cycling. Preliminary analysis suggests that one +/-1 kPa DML cycle is roughly equivalent to one standard accelerated thermal cycle and approximately 175 of these cycles are equivalent to a 25-year exposure in Golden Colorado for the mechanism of module ribbon fatigue.

  3. An engineering method for estimating notch-size effect in fatigue tests on steel

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul; Hardrath, Herbert F

    1952-01-01

    Neuber's proposed method of calculating a practical factor of stress concentration for parts containing notches of arbitrary size depends on the knowledge of a "new material constant" which can be established only indirectly. In this paper, the new constant has been evaluated for a large variety of steels from fatigue tests reported in the literature, attention being confined to stresses near the endurance limit. Reasonably satisfactory results were obtained with the assumption that the constant depends only on the tensile strength of the steel. Even in cases where the notches were cracks of which only the depth was known, reasonably satisfactory agreement was found between calculated and experimental factors. It is also shown that the material constant can be used in an empirical formula to estimate the size effect on unnotched specimens tested in bending fatigue.

  4. The use of fatigue tests in the manufacture of automotive steel wheels.

    NASA Astrophysics Data System (ADS)

    Drozyner, P.; Rychlik, A.

    2016-08-01

    Production for the automotive industry must be particularly sensitive to the aspect of safety and reliability of manufactured components. One of such element is the rim, where durability is a feature which significantly affects the safety of transport. Customer complaints regarding this element are particularly painful for the manufacturer because it is almost always associated with the event of accident or near-accident. Authors propose original comprehensive method of quality control at selected stages of rims production: supply of materials, production and pre-shipment inspections. Tests by the proposed method are carried out on the originally designed inertial fatigue machine The machine allows bending fatigue tests in the frequency range of 0 to 50 Hz at controlled increments of vibration amplitude. The method has been positively verified in one of rims factory in Poland. Implementation resulted in an almost complete elimination of complaints resulting from manufacturing and material errors.

  5. NEP Space Test Program Objective

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The objective of the Nuclear Electric Propulsion (NEP) space test program is to launch an NEP satellite powered by the Russion Topaz 2 reactor by Dec. 1995. The primary goals of the NEP space test program are as follows: (1) demonstrate the feasibility of launching a space nuclear power system; (2) demonstrate and orbit adjust capability using NEP; (3) evaluate the in-orbit performance of the Topaz 2 reactor and selected electric thrusters; and (4) measure, analyze, and model the NEP self-induced environment. The discussion is presented in vugraph form.

  6. Using interstimulus interval to maximise sensitivity of the Psychomotor Vigilance Test to fatigue.

    PubMed

    Matthews, Raymond W; Ferguson, Sally A; Sargent, Charli; Zhou, Xuan; Kosmadopoulos, Anastasi; Roach, Gregory D

    2017-02-01

    There is some evidence that short interstimulus intervals (ISIs) on the Psychomotor Vigilance Test (PVT) are associated with longer and more varied reaction times (RTs). Preparation processes may impede RT following short ISIs, resulting in additional unexplained variance. The aims of this study were to investigate whether there is an effect of ISI on RT and errors within the PVT, and whether such an effect changes with three elements of fatigue: time of day, prior wake and time on task. Twelve male participants completed 49 PVTs across 7× 28h periods of forced desynchrony. For analysis, RTs, reciprocal reaction times (1/RT), false starts and lapse responses within each 10min session were assigned to a 1-s ISI group, a 2-min time of task group, a 2.5-h PW level and a 60° phase of the circadian rhythm of core body temperature (as a measure of time of day). Responses following short ISIs (2-5s) were significantly slower and more varied than responses following longer ISIs (5-10s). The likelihood of a lapse was also higher for short ISIs, while the probability of a false start increased as a function of ISI. These effects were independent of the influences of time of day, prior wake and time on task. Hence, mixed model ANOVAs comprising only long ISIs (5-10s) contained stronger effect sizes for fatigue than a model of all ISIs (2-10s). Including an ISI variable in a model improved the model fit and explained more variance associated with fatigue. Short ISIs resulted in long RTs both in the presence and absence of fatigue, possibly due to preparation processes or ISI conditioning. Hence, omitting short ISI trials from RT means or including an ISI variable in analysis can reduce unwanted variance in PVT data, improving the sensitivity of the PVT to fatigue.

  7. Modeling and Prediction of Corrosion-Fatigue Failures in AF1410 Steel Test Specimens

    DTIC Science & Technology

    2009-01-12

    the curve was modeled using the Coffin- Manson equation (references 9 and 10); with the equation coefficients derived from a log-log regression of the...fatigue test data were modeled using a bilinear log-log fit of the Coffin- Manson relation described previously. The elastic portion of the Coffin... Manson curve was assumed fixed. The slope (B) and intercept (A) errors of the plastic strain regression curve are Student-t distributed when transformed

  8. Strainrange partitioning life predictions of the long time metal properties council creep-fatigue tests

    NASA Technical Reports Server (NTRS)

    Saltsman, J. F.; Halford, G. R.

    1979-01-01

    The method of strainrange partitioning is used to predict the cyclic lives of the Metal Properties Council's long time creep-fatigue interspersion tests of several steel alloys. Comparisons are made with predictions based upon the time- and cycle-fraction approach. The method of strainrange partitioning is shown to give consistently more accurate predictions of cyclic life than is given by the time- and cycle-fraction approach.

  9. Validation of a software program for measuring fatigue-related changes in keystroke durations.

    PubMed

    Kim, Jeong Ho; Johnson, Peter W

    2011-01-01

    Intensive computer use has been associated with musculoskeletal disorders (MSDs). Although the underlying mechanisms are still not fully understood, muscle fatigue is thought to be a contributing factor. Previous studies have shown that keystroke durations are related to muscle twitch durations and may be used as a surrogate measure of muscle fatigue. Software tools have been developed to measure keystroke durations; however, the accuracy of these programs may be influenced by the computer and/or the operating system (OS). Keystrokes were collected from six subjects and analyzed to determine whether there were any differences in keystroke durations measured by an OS-dependant software program and keystrokes collected directly from the keyboard using a USB analyzer (gold standard). The results demonstrated that the OS-dependant software program underestimated keystroke durations by 3.8 ms (103.5 vs. 107.3 ms; p < 0.0001) but keystroke durations at the individual level were highly correlated between the two systems (R(2) = 0.997). Despite the small differences, the high correlation between systems indicated that the software program could be used to collect keystroke durations.

  10. Prediction of frequency for simulation of asphalt mix fatigue tests using MARS and ANN.

    PubMed

    Ghanizadeh, Ali Reza; Fakhri, Mansour

    2014-01-01

    Fatigue life of asphalt mixes in laboratory tests is commonly determined by applying a sinusoidal or haversine waveform with specific frequency. The pavement structure and loading conditions affect the shape and the frequency of tensile response pulses at the bottom of asphalt layer. This paper introduces two methods for predicting the loading frequency in laboratory asphalt fatigue tests for better simulation of field conditions. Five thousand (5000) four-layered pavement sections were analyzed and stress and strain response pulses in both longitudinal and transverse directions was determined. After fitting the haversine function to the response pulses by the concept of equal-energy pulse, the effective length of the response pulses were determined. Two methods including Multivariate Adaptive Regression Splines (MARS) and Artificial Neural Network (ANN) methods were then employed to predict the effective length (i.e., frequency) of tensile stress and strain pulses in longitudinal and transverse directions based on haversine waveform. It is indicated that, under controlled stress and strain modes, both methods (MARS and ANN) are capable of predicting the frequency of loading in HMA fatigue tests with very good accuracy. The accuracy of ANN method is, however, more than MARS method. It is furthermore shown that the results of the present study can be generalized to sinusoidal waveform by a simple equation.

  11. Fatigue of Self-Healing Nanofiber-based Composites: Static Test and Subcritical Crack Propagation.

    PubMed

    Lee, Min Wook; Sett, Soumyadip; Yoon, Sam S; Yarin, Alexander L

    2016-07-20

    Here, we studied the self-healing of composite materials filled with epoxy-containing nanofibers. An initial incision in the middle of a composite sample stretched in a static fatigue test can result in either crack propagation or healing. In this study, crack evolution was observed in real time. A binary epoxy, which acted as a self-healing agent, was encapsulated in two separate types of interwoven nano/microfibers formed by dual-solution blowing, with the core containing either epoxy or hardener and the shell being formed from poly(vinylidene fluoride)/ poly(ethylene oxide) mixture. The core-shell fibers were encased in a poly(dimethylsiloxane) matrix. When the fibers were damaged by a growing crack in this fiber-reinforced composite material because of static stretching in the fatigue test, they broke and released the healing agent into the crack area. The epoxy used in this study was cured and solidified for approximately an hour at room temperature, which then conglutinated and healed the damaged location. The observations were made for at least several hours and in some cases up to several days. It was revealed that the presence of the healing agent (the epoxy) in the fibers successfully prevented the propagation of cracks in stretched samples subjected to the fatigue test. A theoretical analysis of subcritical cracks was performed, and it revealed a jumplike growth of subcritical cracks, which was in qualitative agreement with the experimental results.

  12. Applications of infrared thermography for nondestructive testing of fatigue cracks in steel bridges

    NASA Astrophysics Data System (ADS)

    Sakagami, Takahide; Izumi, Yui; Kobayashi, Yoshihiro; Mizokami, Yoshiaki; Kawabata, Sunao

    2014-05-01

    In recent years, fatigue crack propagations in aged steel bridge which may lead to catastrophic structural failures have become a serious problem. For large-scale steel structures such as orthotropic steel decks in highway bridges, nondestructive inspection of deteriorations and fatigue damages are indispensable for securing their safety and for estimating their remaining strength. As conventional NDT techniques for steel bridges, visual testing, magnetic particle testing and ultrasonic testing have been commonly employed. However, these techniques are time- and labor- consuming techniques, because special equipment is required for inspection, such as scaffolding or a truck mount aerial work platform. In this paper, a new thermography NDT technique, which is based on temperature gap appeared on the surface of structural members due to thermal insulation effect of the crack, is developed for detection of fatigue cracks. The practicability of the developed technique is demonstrated by the field experiments for highway steel bridges in service. Detectable crack size and factors such as measurement time, season or spatial resolution which influence crack detectability are investigated.

  13. CHARACTERIZATION OF A MOBILE OSCILLATORY FATIGUE OPERATOR FOR WIND TURBINE BLADE TESTING

    SciTech Connect

    Donohoo, P.E.; Cotrell, J.

    2008-01-01

    Laboratory testing of wind turbine blades is required to meet wind turbine design standards, reduce machine cost, and reduce the technical and fi nancial risks of deploying mass-produced wind turbine models. Fatigue testing at the National Wind Technology Center (NWTC) is currently conducted using Universal Resonance Excitation (UREX) technology. In a UREX test, the blade is mounted to a rigid stand and hydraulic exciters mounted to the blade are used to excite the blade to its resonant frequency. A drawback to UREX technology is that mounting hydraulic systems to the blade is diffi cult and requires a relatively long set-up period. An alternative testing technology called the Mobile Oscillatory Fatigue Operator (MOFO) has been analyzed. The MOFO uses an oscillating blade test-stand rather than a rigid stand, avoiding the need to place hydraulic systems on the blade. The MOFO will be demonstrated by converting an existing test-stand at the NWTC to an oscillating stand that can test blades up to 25 m in length. To obtain the loads necessary to design the MOFO, the system motion is modeled using rigid body and lumped mass dynamics models. Preliminary modeling indicates the existing stand can be converted to a MOFO relatively easily. However, the blade dynamic models suggest that blade bending moment distributions are signifi cantly different for UREX and MOFO testing; more sophisticated models are required to assess the implication of this difference on the accuracy of the test.

  14. Advanced Failure Determination Measurement Techniques Used in Thermal Fatigue Life Testing of Electronic Packaging

    NASA Technical Reports Server (NTRS)

    Wallace, A. P.; Cornford, S. L.; Gross, M. A.

    1996-01-01

    Thermal fatigue life testing of various electronic packaging technologies is being performed by the Reliability Technology Group at the Jet Propulsion Laboratory. These testing efforts are in progress to improve uderstanding of the reliability issues associated with low volume packaging technologies for space applications and to develop qualification and acceptance approaches for these technologies. The work described here outlines the electrical failure detection techniques used during testing by documenting the circuits and components used to make these measurements, the sensitivity of the measurements, and the applicability of each specific measurement.

  15. Optical guidance vidicon test program

    NASA Technical Reports Server (NTRS)

    Eiseman, A. R.; Stanton, R. H.; Voge, C. C.

    1976-01-01

    A laboratory and field test program was conducted to quantify the optical navigation parameters of the Mariner vidicons. A scene simulator and a camera were designed and built for vidicon tests under a wide variety of conditions. Laboratory tests characterized error sources important to the optical navigation process and field tests verified star sensitivity and characterized comet optical guidance parameters. The equipment, tests and data reduction techniques used are described. Key test results are listed. A substantial increase in the understanding of the use of selenium vidicons as detectors for spacecraft optical guidance was achieved, indicating a reduction in residual offset errors by a factor of two to four to the single pixel level.

  16. Mission Adaptive Wing test program

    NASA Technical Reports Server (NTRS)

    Birk, Frank T.; Smith, Rogers E.

    1986-01-01

    With the completion of the F-111 test-bed Mission Adaptive Wing (MAW) test program's manual flight control system, emphasis has been shifted to flight testing of MAW automatic control modes. These encompass (1) cruise camber control, (2) maneuver camber control, (3) maneuver load control, and (4) maneuver enhancement and load alleviation control. The aircraft is currently cleared to a 2.5-g maneuvering limit due to generally higher variable-incidence wing pivot loads than had been anticipated, especially at the higher wing-camber settings. Buffet is noted to be somewhat higher than expected at the higher camber settings.

  17. Fatigue and fracture overview

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.

    1986-01-01

    The accomplishments achieved under the isotropic creep-fatigue crack initiation life prediction program are summarized. A sizeable creep-fatigue crack initiation data base was generated on the nickel-base superalloy, B-1900. Companion constitutive modeling programs have also generated extensive data bases on the same heat of material. The crack initiation results have formed the basis of a new approach to creep-fatigue life prediction. The term Cyclic Damage Accumulation (CDA) was coined for the method, which was evaluated under isothermal, uniaxial conditions. Stringent laboratory verification experiments were used to test the accuracy of the method. Considering the quite limited material property data needed to evaluate the constants in the approach, the prediction accuracy is acceptable. At the expense of the larger data base required, Lewis developed total strain- strainrange partitioning method (TS-SRP) is capable of a higher degree of accuracy.

  18. Influence of axle-wheel interface on ultrasonic testing of fatigue cracks in wheelset.

    PubMed

    Makino, Kazunari; Biwa, Shiro

    2013-01-01

    For the ultrasonic testing at the wheel seat of railway axles, quantitative investigation of the reflection and transmission phenomena at the axle-wheel interface is important. This paper describes the influence of the axle-wheel interface on the ultrasonic testing of a fatigue crack in a wheelset by applying the spring interface model. The normal and tangential stiffnesses were identified experimentally for an as-manufactured wheelset at the normal incidence, and the reflection coefficient for the shear-wave oblique incidence was calculated. A parametric study was performed to clarify the influence of these interfacial stiffnesses on the incident-angle dependence of the reflection coefficient. The calculated reflection coefficient at the incident angle of 45° qualitatively explained the relative echo-height decrease due to the presence of a wheel observed experimentally for a wheelset in fatigue loading by rotating bending. The quantitative difference between the experimental and calculated results was considered to be due to the reduction of the effective interference of shrink fit by the wear at the axle-wheel interface during the fatigue loading as well as by the applied bending moment. For the estimated relative echo-height decrease to agree with the experimental results, the interfacial stiffnesses were found to be smaller than the values identified for the as-manufactured wheelset by a factor of 0.5-0.7.

  19. An electromyographic-based test for estimating neuromuscular fatigue during incremental treadmill running.

    PubMed

    Camic, Clayton L; Kovacs, Attila J; Enquist, Evan A; VanDusseldorp, Trisha A; Hill, Ethan C; Calantoni, Austin M; Yemm, Allison J

    2014-12-01

    The purposes of the present study were two fold: (1) to determine if the model used for estimating the physical working capacity at the fatigue threshold (PWCFT) from electromyographic (EMG) amplitude data during incremental cycle ergometry could be applied to treadmill running to derive a new neuromuscular fatigue threshold for running, and (2) to compare the running velocities associated with the PWCFT, ventilatory threshold (VT), and respiratory compensation point (RCP). Fifteen college-aged subjects (21.5 ± 1.3 y, 68.7 ± 10.5 kg, 175.9 ± 6.7 cm) performed an incremental treadmill test to exhaustion with bipolar surface EMG signals recorded from the vastus lateralis. There were significant (p < 0.05) mean differences in running velocities between the VT (11.3 ± 1.3 km h(-1)) and PWCFT (14.0 ± 2.3 km h(-1)), VT and RCP (14.0 ± 1.8 km h(-1)), but not the PWCFT and RCP. The findings of the present study indicated that the PWCFT model could be applied to a single continuous, incremental treadmill test to estimate the maximal running velocity that can be maintained prior to the onset of neuromuscular fatigue. In addition, these findings suggested that the PWCFT, like the RCP, may be used to differentiate the heavy from severe domains of exercise intensity.

  20. Report on FY15 Alloy 617 SMT Creep-Fatigue Test Results

    SciTech Connect

    Wang, Yanli; Jetter, Robert I.; Baird, Seth T.; Pu, Chao; Sham, Sam

    2015-06-22

    For the temperature range of 990-950C, Alloy 617 is a candidate IHX structural material for high temperature gas reactors (HTGRs) because of its high temperature creep properties. Also, its superior strength over a broad temperature range also offers advantages for certain component applications. In order for the designers to be able to use Alloy 617 for these high temperature components, Alloy 617 has to be approved for use in Section III (the nuclear section) of the ASME (American Society of Mechanical Engineers) Boiler and Pressure Vessel Code. A plan has been developed to propose a Code Case for use of Alloy 617 at elevated temperature in Section III of the ASME Code by September 2015. There has not been a new high temperature material approved for use in Section III for almost 20 years. The Alloy 617 Code Case effort would lead the way to establish a path for Code qualification of new high temperature materials of interest to other advanced SMRs. Creep-fatigue at elevated temperatures is the most damaging structural failure mode. In the past 40 years significant efforts have been devoted to the elevated temperature Code rule development in Section III, Subsection NH* of the ASME Boiler and Pressure Vessel Code, to ascertain conservative structural designs to prevent creep-fatigue failure. The current Subsection NH creep-fatigue procedure was established by the steps of (1) analytically obtaining a detailed stress-strain history, (2) comparing the stress and strain components to cyclic test results deconstructed into stress and strain quantities, and (3) recombining the results to obtain a damage function in the form of the so-called creep-fatigue damage-diagram. The deconstruction and recombination present difficulties in evaluation of test data and determination of cyclic damage in design. The uncertainties in these steps lead to the use of overly conservative design factors in the current creep-fatigue procedure. In addition, and of major significance to the

  1. The influence of load misalignment during uniaxial low-cycle fatigue testing. I - Modeling. II - Applications

    NASA Astrophysics Data System (ADS)

    Kandil, F. A.; Dyson, B. F.

    1993-05-01

    A quantitative model for predicting the extent of lifetime scatter in low-cycle fatigue due to the bending effect caused by load misalignment is proposed. The model is based on the bending mechanism and the type of extensometer used to control strain and the fatigue characteristics of the material. A consequence of a lateral offset in the center-lines of the load-train with respect to either a machine's frame or ram is found to be the most damaging bending mechanism. Two types of scatter under consideration include repeatability scatter due to testing practice within a single laboratory and reproducibility scatter among laboratories. The model is applied to four alloys, including AISI 316L, Nimonic 101, 9 Cr-1 Mo, and IN 718. Results show that in all four materials a major fraction of the data scatter could be attributed to bending. At the lowest strain range the predicted bending component represents the highest proportion of the experimental interlaboratory scatter.

  2. Thermal-mechanical fatigue test apparatus for metal matrix composites and joint attachments

    NASA Technical Reports Server (NTRS)

    Westfall, Leonard J.; Petrasek, Donald W.

    1988-01-01

    Two thermal-mechanical fatigue (TMF) test facilities were designed and developed, one to test tungsten fiber reinforced metal matrix composite specimens at temperature up to 1430C (2600F) and another to test composite/metal attachment bond joints at temperatures up to 760F (1400F). The TMF facility designed for testing tungsten fiber reinforced metal matrix composites permits test specimen temperature excursions from room temperature to 1430C (2600F) with controlled heating and loading rates. A strain-measuring device measures the strain in the test section of the specimen during each heating and cooling cycle with superimposed loads. Data is collected and recorded by a computer. The second facility is designed to test composite/metal attachment bond joints and to permit heating to a maximum temperature of 760C (1400F) within 10 min and cooling to 150C (300F) within 3 min. A computer controls specimen temperature and load cycling.

  3. Thermal-mechanical fatigue test apparatus for metal matrix composites and joint attachments

    NASA Technical Reports Server (NTRS)

    Westfall, L. J.; Petrasek, D. W.

    1985-01-01

    Two thermal-mechanical fatigue (TMF) test facilities were designed and developed, one to test tungsten fiber reinforced metal matrix composite specimens at temperature up to 1430C (2600F) and another to test composite/metal attachment bond joints at temperatures up to 760C (1400 F). The TMF facility designed for testing tungsten fiber reinforced metal matrix composites permits test specimen temperature excursions from room temperature to 1430C (2600F) with controlled heating and loading rates. A strain-measuring device measures the strain in the test section of the specimen during each heating and cooling cycle with superimposed loads. Data is collected and recorded by a computer. The second facility is designed to test composite/metal attachment bond joints and to permit heating to a maximum temperature of 760C (1400F) within 10 min and cooling to 150C (300F) within 3 min. A computer controls specimen temperature and load cycling.

  4. Creep-fatigue interaction in aircraft gas turbine components by simulation and testing at scaled temperatures

    NASA Astrophysics Data System (ADS)

    Sabour, Mohammad Hossein

    components in general, and specifically using thermal scaling for the first time for prototype and model with two different materials. (2) Developing 1-D creep ANSYS macro to study creep effects to get meaningful results for industrial applications of gas turbine blade. (3) Analyzing the curve veering and flattening phenomena in rotating blade at thermal environment, using Lagrange-Bhat method. (4) Simple constitutive models in creep-fatigue interaction are proposed that can predict the lifetime in complicated situations of creep-fatigue, using the pure creep and pure fatigue test data.

  5. Tensile and Fatigue Testing and Material Hardening Model Development for 508 LAS Base Metal and 316 SS Similar Metal Weld under In-air and PWR Primary Loop Water Conditions

    SciTech Connect

    Mohanty, Subhasish; Soppet, William; Majumdar, Saurin; Natesan, Ken

    2015-09-01

    This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable in September 2015 under the work package for environmentally assisted fatigue under DOE’s Light Water Reactor Sustainability program. In an April 2015 report we presented a baseline mechanistic finite element model of a two-loop pressurized water reactor (PWR) for systemlevel heat transfer analysis and subsequent thermal-mechanical stress analysis and fatigue life estimation under reactor thermal-mechanical cycles. In the present report, we provide tensile and fatigue test data for 508 low-alloy steel (LAS) base metal, 508 LAS heat-affected zone metal in 508 LAS–316 stainless steel (SS) dissimilar metal welds, and 316 SS-316 SS similar metal welds. The test was conducted under different conditions such as in air at room temperature, in air at 300 oC, and under PWR primary loop water conditions. Data are provided on materials properties related to time-independent tensile tests and time-dependent cyclic tests, such as elastic modulus, elastic and offset strain yield limit stress, and linear and nonlinear kinematic hardening model parameters. The overall objective of this report is to provide guidance to estimate tensile/fatigue hardening parameters from test data. Also, the material models and parameters reported here can directly be used in commercially available finite element codes for fatigue and ratcheting evaluation of reactor components under in-air and PWR water conditions.

  6. Generation of driving profile on a multi-axial vibration table for vibration fatigue testing

    NASA Astrophysics Data System (ADS)

    Kim, Chan-Jung; Kang, Yeon June; Lee, Bong-Hyun

    2012-01-01

    A multi-axial simulation table (MAST) is widely used for vibration fatigue testing; it reliably reproduces the operational multi-axial motion of a specimen. The main concern in this multi-axial testing is to determine the driving profile because this profile guarantees the service life cycle of a specimen. This paper presents a method for generating a driving profile using a combination of measured acceleration responses under special events. To explain this method clearly, vehicle components are selected as target components, and the corresponding driving profile of each component is derived using the proposed method.

  7. A tension-torsional fatigue testing apparatus for micro-scale components

    NASA Astrophysics Data System (ADS)

    Fu, Sichao; Wang, Lei; Chen, Gang; Yu, Dunji; Chen, Xu

    2016-01-01

    Mechanical characterization of micro-scale components under complex loading conditions is a great challenge. To meet such a challenge, a microtension-torsional fatigue testing apparatus is developed in this study that specializes in the evaluation of multiaxial fatigue behavior of thin stent wires. The actuation and measurement in two controlled directions are incorporated in the tensile and torsional load frames, respectively, and a thrust air bearing is applied for the coupling of the two frames. The axial deformation of specimens measured by a grating sensor built in the linear motor and by a non-contact displacement detect system is compared and corrected. The accuracy of the torque measurement is proved by torsion tests on thin wires of 316L stainless steel in nominal diameters of 100 μm. Multistep torsion test, multiaxial ratcheting test, and a fully strain controlled multiaxial cyclic test are performed on 100 μm and 200 μm-diameter 316L wires using this apparatus. The capability of the equipment in tension-torsional cyclic tests for micro-scale specimens is demonstrated by the experimental results.

  8. Periodontal Stain Test Diagnosis Program

    DTIC Science & Technology

    1989-01-01

    inflammatory loss of attachment and bone in adolescents ; lesions are often associated with incisors and first molars; no evidence of systemic disease . RISK...FACTORS: When determining susceptibility to periodontal disease , patients in the previous classifications should be considered high risk patients if...AD-A247 28411i 11111l l l1113111! Eilli UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL PERIODONTAL STAIN TEST DIAGNOSIS PROGRAM D T IC Prof. E.J. Burkes

  9. PUMA test program for SBWR

    SciTech Connect

    Ishii, M.; Revankar, S.T.; Dowlati, R.

    1996-03-01

    The objective of the PUMA integral test program is to obtain confirmatory test data for the SBWR Developed by the General Electric-Nuclear Energy Company. The program was initiated in July 1993 under the sponsorship of the NRC. The SBWR has a simplified coolant circulation system and a passive emergency cooling system. The engineered safety systems and safety-grade systems in the SBWR are: (1) the Automatic Depressurization System (ADS), (2) the Gravity-Driven Cooling System (GDCS), (3) the Passive Containment Cooling System (PCCS), (4) the Isolation Condenser Systems (ICS), and (5) the Pressure Suppression Pool (SP). The GDCS and PCCS are new designs unique to the SBWR and do not exist in operating BWRs. The ICS is similar to those in some operating BWRs. The PCCS is designed for low-pressure operation for the containment cooling, but the ICS is capable of high pressure operation as well to cool the reactor pressure vessel. The PUMA design was completed based on an extensive scaling analysis. The PUMA facility having 1/4 height and 1/400 volume scales is constructed. Various facility characterization tests and instrumentation and data acquisition system checks are performed presently. The facility acceptance test will be performed in November and integral tests will be initiated.

  10. A New High-Speed, High-Cycle, Gear-Tooth Bending Fatigue Test Capability

    NASA Technical Reports Server (NTRS)

    Stringer, David B.; Dykas, Brian D.; LaBerge, Kelsen E.; Zakrajsek, Andrew J.; Handschuh, Robert F.

    2011-01-01

    A new high-speed test capability for determining the high cycle bending-fatigue characteristics of gear teeth has been developed. Experiments were performed in the test facility using a standard spur gear test specimens designed for use in NASA Glenn s drive system test facilities. These tests varied in load condition and cycle-rate. The cycle-rate varied from 50 to 1000 Hz. The loads varied from high-stress, low-cycle loads to near infinite life conditions. Over 100 tests were conducted using AISI 9310 steel spur gear specimen. These results were then compared to previous data in the literature for correlation. Additionally, a cycle-rate sensitivity analysis was conducted by grouping the results according to cycle-rate and comparing the data sets. Methods used to study and verify load-path and facility dynamics are also discussed.

  11. Reversible Bending Fatigue Test System for Investigating Vibration Integrity of Spent Nuclear Fuel during Transportation

    SciTech Connect

    Wang, Jy-An John; Wang, Hong; Bevard, Bruce Balkcom; Howard, Rob L; Flanagan, Michelle

    2013-01-01

    Transportation packages for spent nuclear fuel (SNF) must meet safety requirements under normal and accident conditions as specified by federal regulations. During transportation, SNF experiences unique conditions and challenges to cladding integrity due to the vibrational and impact loading during road or rail shipment. Oak Ridge National Laboratory (ORNL) has been developing testing capabilities that can be used to improve the understanding of the impacts on SNF integrity due to vibration loading, especially for high burn-up SNF in normal transportation operation conditions. This information can be used to meet the nuclear industry and U.S. Nuclear Regulatory Commission needs in the area of safety and security of spent nuclear fuel storage and transport operations. The ORNL developed test system can perform reversible-bending fatigue testing to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The testing apparatus is also designed to meet the challenges of hot-cell operation, including remote installation and detachment of the SNF test specimen, in-situ test specimen deformation measurement, and implementation of a driving system suitable for use in a hot cell. The system contains a U-frame set-up equipped with uniquely designed grip rigs, to protect SNF rod and to ensure valid test results, and use of 3 specially designed LVDTs to obtain the in-situ curvature measurement. A variety of surrogate test rods have been used to develop and calibrate the test system as well as in performing a series of systematic cyclic fatigue tests. The surrogate rods include stainless steel (SS) cladding, SS cladding with cast epoxy, and SS cladding with alumina pellets inserts simulating fuel pellets. Testing to date has shown that the interface bonding between the SS cladding and the alumina pellets has a significant impact on the bending response of the test rods as well as their fatigue strength. The failure behaviors observed from

  12. Reversal bending fatigue test system for investigating vibration integrity of spent nuclear fuel during transportation

    SciTech Connect

    Wang, Jy -An; Wang, Hong; Bevard, Bruce Balkcom; Howard, Rob L.; Flanagan, Michelle E.

    2014-09-01

    Transportation packages for spent nuclear fuel (SNF) must meet safety requirements under normal and accident conditions as specified by federal regulations. During transportation, SNF experiences unique conditions and challenges to cladding integrity due to the vibrational and impact loading during road or rail shipment. Oak Ridge National Laboratory (ORNL) has been developing testing capabilities that can be used to improve the understanding of the impacts on SNF integrity due to vibration loading, especially for high burn-up SNF in normal transportation operation conditions. This information can be used to meet the nuclear industry and U.S.Nuclear Regulatory Commission needs in the area of safety and security of SNF storage and transportation operations. The ORNL developed test system can perform reversal bending fatigue testing to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The testing apparatus is also designed to meet the challenges of hot cell operation, including remote installation and detachment of the SNF test specimen, in situ test specimen deformation measurement, and implementation of a driving system suitable for use in a hot cell. The system contains a U frame set-up equipped with uniquely designed grip rigs to protect the SNF rod sample and to ensure valid test results, and uses three specially designed linear variable differential transformers to obtain the in situ curvature measurement. A variety of surrogate test rods have been used to develop and calibrate the test system as well as in performing a series of systematic cyclic fatigue tests. The surrogate rods include stainless steel (SS) cladding, SS cladding with cast epoxy and SS cladding with alumina pellet inserts simulating fuel pellets. Testing to date has shown that the interface bonding between the SS cladding and the alumina pellets has a significant impact on the bending response of the test rods as well as their fatigue strength. The

  13. Reversal bending fatigue test system for investigating vibration integrity of spent nuclear fuel during transportation

    DOE PAGES

    Wang, Jy -An; Wang, Hong; Bevard, Bruce Balkcom; ...

    2014-09-01

    Transportation packages for spent nuclear fuel (SNF) must meet safety requirements under normal and accident conditions as specified by federal regulations. During transportation, SNF experiences unique conditions and challenges to cladding integrity due to the vibrational and impact loading during road or rail shipment. Oak Ridge National Laboratory (ORNL) has been developing testing capabilities that can be used to improve the understanding of the impacts on SNF integrity due to vibration loading, especially for high burn-up SNF in normal transportation operation conditions. This information can be used to meet the nuclear industry and U.S.Nuclear Regulatory Commission needs in the areamore » of safety and security of SNF storage and transportation operations. The ORNL developed test system can perform reversal bending fatigue testing to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The testing apparatus is also designed to meet the challenges of hot cell operation, including remote installation and detachment of the SNF test specimen, in situ test specimen deformation measurement, and implementation of a driving system suitable for use in a hot cell. The system contains a U frame set-up equipped with uniquely designed grip rigs to protect the SNF rod sample and to ensure valid test results, and uses three specially designed linear variable differential transformers to obtain the in situ curvature measurement. A variety of surrogate test rods have been used to develop and calibrate the test system as well as in performing a series of systematic cyclic fatigue tests. The surrogate rods include stainless steel (SS) cladding, SS cladding with cast epoxy and SS cladding with alumina pellet inserts simulating fuel pellets. Testing to date has shown that the interface bonding between the SS cladding and the alumina pellets has a significant impact on the bending response of the test rods as well as their fatigue strength

  14. Rolling contact fatigue of surface modified 440C using a 'Ge-Polymet' type disc rod test rig

    NASA Technical Reports Server (NTRS)

    Thom, Robert L.

    1989-01-01

    Through hardened 440 C martensitic stainless steel test specimens were surface modified and tested for changes in rolling contact fatigue using a disc on rod test rig. The surface modifications consisted of nitrogen, boron, titanium, chromium, tantalum, carbon, or molybdenum ion implantation at various ion fluences and energies. Tests were also performed on specimens reactively sputtered with titanium nitride.

  15. Effect of testing frequency on the corrosion fatigue of a squeeze-cast aluminum alloy

    SciTech Connect

    Shiozawa, Kazuaki; Sun, Shuming; Eadie, R.L.

    2000-04-01

    The corrosion fatigue crack propagation behavior of a squeeze-cast Al-Si-Mg-Cu aluminum alloy (AC8A-T6), which had been precracked in air, was investigated at testing frequencies of 0.1, 1, 5, and 10 Hz under a stress ration (R) of 0.1. Compact-toughness specimens were precracked about t mm in air prior to the corrosion fatigue test in a 3 pct saline solution. At some near-threshold conditions, these cracks propagated faster than would be predicted by the mechanical driving force. This anomalous corrosion fatigue crack growth was affected by the initial stress-intensity-factor range ({Delta}K{sub i}), the precracking conditions, and the testing frequency. The initial crack propagation rate was as much as one order of magnitude higher than the rate for the same conditions in air. This rapid rate was associated with preferential propagation along the interphase interface in the eutectic structure. It is believed that a chemical reaction at the crack tip and/or hydrogen-assisted cracking produced the phenomenon. Eventual retardation and complete arrest of crack growth after this initial rapid growth occurred within a short period at low {Delta}K values, when the testing frequency was low (0.1 and 1 Hz). This retardation was accompanied by corrosion product-induced crack closure and could be better explained by the contributory stress-intensity-factor range ({Delta}K{sub cont}) than by the effective stress-intensity-factor range ({Delta}k{sub eff}).

  16. Dual laser gyro test program

    NASA Astrophysics Data System (ADS)

    Jones, Malcolm E.; Moore, Kim Eric

    This paper addresses the results of a comparative test evaluation of two similar-sized but otherwise dissimilar ring laser gyroscopes (RLG's). Both units were tested side by side, with the input axes (IA's) parallel, on the same test table. This report describes the rationale and design factors considered important to the test objectives. Emphasis was placed upon the evaluation of the scale factor (SF) linearity, drift rate stability (short term and long term), and derived rate. Conclusions drawn were (1) that dual operation had an observable but insignificant effect on the test results, (2) that the benefits of dual operation outweighed the additional design and analysis efforts required at the outset of the program, and (3) that the performance characteristics of the two test articles were significantly different. The differences between the two test articles (1) led to suggestions which could direct one vendor toward obtaining improved performance and (2) resulted in the creation of a conceptually new method (DELTA TIME-COUNT histogram) for quickly assessing the quality of laser gyros (or any digital sensor device for that matter).

  17. Thermal fatigue tests of a radiative heat shield panel for a hypersonic transport

    NASA Technical Reports Server (NTRS)

    Webb, Granville L.; Clark, Ronald K.; Sharpe, Ellsworth L.

    1985-01-01

    A pair of corrugation stiffened, beaded skin Rene 41 heat shield panels were exposed to 20,000 thermal cycles between room temperature and 1450 F to evaluate the thermal fatigue response of Rene 41 metallic heat shields for hypersonic cruise aircraft applications. At the conclusion of the tests, the panels retained substantial structural integrity; however, there were cracks and excessive wear in the vicinity of fastener holes and there was an 80-percent loss in ductility of the skin. Shrinkage of the panel which caused the cracks and wear must be considered in design of panels for Thermal Protection Systems (TPS) applications.

  18. Thermal fatigue tests of a radiative heat shield panel for a hypersonic transport

    SciTech Connect

    Webb, G.L.; Clark, R.K.; Sharpe, E.L.

    1985-09-01

    A pair of corrugation stiffened, beaded skin Rene 41 heat shield panels were exposed to 20,000 thermal cycles between room temperature and 1450 F to evaluate the thermal fatigue response of Rene 41 metallic heat shields for hypersonic cruise aircraft applications. At the conclusion of the tests, the panels retained substantial structural integrity; however, there were cracks and excessive wear in the vicinity of fastener holes and there was an 80-percent loss in ductility of the skin. Shrinkage of the panel which caused the cracks and wear must be considered in design of panels for Thermal Protection Systems (TPS) applications.

  19. 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.

  20. A multi-frequency fatigue testing method for wind turbine rotor blades

    NASA Astrophysics Data System (ADS)

    Eder, M. A.; Belloni, F.; Tesauro, A.; Hanis, T.

    2017-02-01

    Rotor blades are among the most delicate components of modern wind turbines. Reliability is a crucial aspect, since blades shall ideally remain free of failure under ultra-high cycle loading conditions throughout their designated lifetime of 20-25 years. Full-scale blade tests are the most accurate means to experimentally simulate damage evolution under operating conditions, and are therefore used to demonstrate that a blade type fulfils the reliability requirements to an acceptable degree of confidence. The state-of-the-art testing method for rotor blades in industry is based on resonance excitation where typically a rotating mass excites the blade close to its first natural frequency. During operation the blade response due to external forcing is governed by a weighted combination of its eigenmodes. Current test methodologies which only utilise the lowest eigenfrequency induce a fictitious damage where additional tuning masses are required to recover the desired damage distribution. Even with the commonly adopted amplitude upscaling technique fatigue tests remain a time-consuming and costly endeavour. The application of tuning masses increases the complexity of the problem by lowering the natural frequency of the blade and therefore increasing the testing time. The novel method presented in this paper aims at shortening the duration of the state-of-the-art fatigue testing method by simultaneously exciting the blade with a combination of two or more eigenfrequencies. Taking advantage of the different shapes of the excited eigenmodes, the actual spatial damage distribution can be more realistically simulated in the tests by tuning the excitation force amplitudes rather than adding tuning masses. This implies that in portions of the blade the lowest mode is governing the damage whereas in others higher modes contribute more significantly due to their higher cycle count. A numerical feasibility study based on a publicly available large utility rotor blade is used to

  1. A Comparison of Zero Mean Strain Rotating Beam Fatigue Test Methods for Nitinol Wire

    NASA Astrophysics Data System (ADS)

    Norwich, Dennis W.

    2014-07-01

    Zero mean strain rotating beam fatigue testing has become the standard for comparing the fatigue properties of Nitinol wire. Most commercially available equipment consists of either a two-chuck or a chuck and bushing system, where the wire length and center-to-center axis distance determine the maximum strain on the wire. For the two-chuck system, the samples are constrained at either end of the wire, and both chucks are driven at the same speed. For the chuck and bushing system, the sample is constrained at one end in a chuck and rides freely in a bushing at the other end. These equivalent systems will both be herein referred to as Chuck-to-Chuck systems. An alternate system uses a machined test block with a specific radius to guide the wire at a known strain during testing. In either system, the test parts can be immersed in a temperature-controlled fluid bath to eliminate any heating effect created in the specimen due to dissipative processes during cyclic loading (cyclic stress induced the formation of martensite) Wagner et al. ( Mater. Sci. Eng. A, 378, p 105-109, 1). This study will compare the results of the same starting material tested with each system to determine if the test system differences affect the final results. The advantages and disadvantages of each system will be highlighted and compared. The factors compared will include ease of setup, operator skill level required, consistency of strain measurement, equipment test limits, and data recovery and analysis. Also, the effect of test speed on the test results for each system will be investigated.

  2. Residual strength and crack propagation tests on C-130 airplane center wings with service-imposed fatigue damage

    NASA Technical Reports Server (NTRS)

    Snider, H. L.; Reeder, F. L.; Dirkin, W. J.

    1972-01-01

    Fourteen C-130 airplane center wings, each containing service-imposed fatigue damage resulting from 4000 to 13,000 accumulated flight hours, were tested to determine their fatigue crack propagation and static residual strength characteristics. Eight wings were subjected to a two-step constant amplitude fatigue test prior to static testing. Cracks up to 30 inches long were generated in these tests. Residual static strengths of these wings ranged from 56 to 87 percent of limit load. The remaining six wings containing cracks up to 4 inches long were statically tested as received from field service. Residual static strengths of these wings ranged from 98 to 117 percent of limit load. Damage-tolerant structural design features such as fastener holes, stringers, doublers around door cutouts, and spanwise panel splices proved to be effective in retarding crack propagation.

  3. Spallation source materials test program

    SciTech Connect

    Maloy, S.A.; Sommer, W.F.

    1997-12-01

    A spallation source materials program has been developed to irradiate and test candidate materials (Inconel 718, 316L and 304L stainless steel, modified 9Cr-1Mo(T91), Al6061-T6, Al5052-O) for use in the Accelerator Production of Tritium (APT) target and blanket in prototypic proton and neutron fluxes at prototypic temperatures. The study uses the 800 MeV, 1mA proton accelerator at the Los Alamos Neutron Science Center (LANSCE) which produces a Gaussian beam with 2 sigma = 3 cm. The experimental set-up contains prototypic modules of the tungsten neutron source and the lead/aluminum blanket with mechanical testing specimens of candidate APT materials placed in specific locations in the irradiation area. These specimens have been irradiated for greater than 3,600 hours with a maximum proton fluence of 4--5 {times} 10{sup 21} p/cm{sup 2} in the center of the proton beam. Specimens will yield some of the first data on the effect of proton irradiation to high dose on the materials` properties from tensile tests, 3 pt. bend tests, fracture toughness tests, pressurized tubes, U-bend stress corrosion cracking specimens, corrosion measurements and microstructural characterization of transmission electron microscopy specimens.

  4. Advanced expander test bed program

    NASA Technical Reports Server (NTRS)

    Masters, A. I.; Mitchell, J. C.

    1991-01-01

    The Advanced Expander Test Bed (AETB) is a key element in NASA's Chemical Transfer Propulsion Program for development and demonstration of expander cycle oxygen/hydrogen engine technology component technology for the next space engine. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced missions focused components and new health monitoring techniques. The split-expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust.

  5. 14 CFR 117.9 - Fatigue education and awareness training program.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Fatigue education and awareness training... FLIGHT AND DUTY LIMITATIONS AND REST REQUIREMENTS: FLIGHTCREW MEMBERS (EFF. 1-4-14) § 117.9 Fatigue... any employee providing direct management oversight of those areas. (b) The fatigue education...

  6. 14 CFR 117.9 - Fatigue education and awareness training program.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Fatigue education and awareness training... FLIGHT AND DUTY LIMITATIONS AND REST REQUIREMENTS: FLIGHTCREW MEMBERS § 117.9 Fatigue education and... providing direct management oversight of those areas. (b) The fatigue education and awareness...

  7. Testing program overview: What does a good program look like

    SciTech Connect

    Hegedus, A.S. )

    1992-01-01

    A good testing program is vital to the safe, reliable, and efficient operation of a nuclear facility. A testing program consists of more than scheduling, performing, and reviewing results. It includes seven interrelated critical elements, all of which are necessary to provide complete control over a station's testing program. The personnel at Peach Bottom atomic power station wanted to evaluate their testing program. The result was a report that described the framework for a complete testing program. Once the framework was developed, an implementation team was formed to develop the specific plan and schedule for modifying the existing program to conform to the framework.

  8. Design and evaluation of a 3 million DN series-hybrid thrust bearing. [stability tests and fatigue tests

    NASA Technical Reports Server (NTRS)

    Scibbe, H. W.; Winn, L. W.; Eusepi, M.

    1976-01-01

    The bearing, consisting of a 150-mm ball bearing and a centrifugally actuated, conical, fluid-film bearing, was fatigue tested. Test conditions were representative of a mainshaft ball bearing in a gas turbine engine operating at maximum thrust load to simulate aircraft takeoff conditions. Tests were conducted up to 16000 rpm and at this speed an axial load of 15568 newtons (3500 lb) was safely supported by the hybrid bearing system. Through the series-hybrid bearing principle, the effective ball bearing speed was reduced to approximately one-half of the shaft speed. It was concluded that a speed reduction of this magnitude results in a ten-fold increase in the ball bearing fatigue life. A successful evaluation of fluid-film bearing lubricant supply failure was performed repeatedly at an operating speed of 10,000 rpm. A complete and smooth changeover to full-scale ball bearing operation was effected when the oil supply to the fluid-film bearing was cut off. Reactivation of the fluid-film oil supply system resulted in a flawless return to the original mode of hybrid operation.

  9. Progeria Research Foundation Diagnostic Testing Program

    MedlinePlus

    ... Interview with John Tacket Find the Other 150 Medical Research NEW! Lonafarnib Pre-clinical Drug Supply Program What's ... Scientific Publications Grand Rounds Workshop 2010 Videos Home » Medical Research » Diagnostic Testing The PRF Diagnostic Testing Program The ...

  10. Advanced expander test bed program

    NASA Technical Reports Server (NTRS)

    Riccardi, D. P.; Mitchell, J. C.

    1993-01-01

    The Advanced Expander Test Bed (AETB) is a key element in NASA's Space Chemical Engine Technology Program for development and demonstration of expander cycle oxygen/hydrogen engine and advanced component technologies applicable to space engines as well as launch vehicle upper stage engines. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced mission focused components and new health monitoring techniques in an engine system environment. The split expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust. Contract work began 27 Apr. 1990. During 1992, a major milestone was achieved with the review of the final design of the oxidizer turbopump in Sep. 1992.

  11. Computer program to assess impact of fatigue and fracture criteria on weight and cost of transport aircraft

    NASA Technical Reports Server (NTRS)

    Tanner, C. J.; Kruse, G. S.; Oman, B. H.

    1975-01-01

    A preliminary design analysis tool for rapidly performing trade-off studies involving fatigue, fracture, static strength, weight, and cost is presented. Analysis subprograms were developed for fatigue life, crack growth life, and residual strength; and linked to a structural synthesis module which in turn was integrated into a computer program. The part definition module of a cost and weight analysis program was expanded to be compatible with the upgraded structural synthesis capability. The resultant vehicle design and evaluation program is named VDEP-2. It is an accurate and useful tool for estimating purposes at the preliminary design stage of airframe development. A sample case along with an explanation of program applications and input preparation is presented.

  12. 47 CFR 73.1620 - Program tests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Program tests. 73.1620 Section 73.1620... Rules Applicable to All Broadcast Stations § 73.1620 Program tests. (a) Upon completion of construction..., program tests may be conducted in accordance with the following: (1) The permittee of a nondirectional...

  13. 47 CFR 73.713 - Program tests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Program tests. 73.713 Section 73.713... International Broadcast Stations § 73.713 Program tests. (a) Upon completion of construction of an international..., the permittee may request authority to conduct program tests. Such request shall be filed with the...

  14. 47 CFR 73.713 - Program tests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Program tests. 73.713 Section 73.713... International Broadcast Stations § 73.713 Program tests. (a) Upon completion of construction of an international..., the permittee may request authority to conduct program tests. Such request shall be filed with the...

  15. 47 CFR 73.1620 - Program tests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Program tests. 73.1620 Section 73.1620... Rules Applicable to All Broadcast Stations § 73.1620 Program tests. (a) Upon completion of construction..., program tests may be conducted in accordance with the following: (1) The permittee of a nondirectional...

  16. Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests

    PubMed Central

    Feng, Aihen; Chen, Daolun; Li, Cheng; Gu, Xijia

    2010-01-01

    We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor. PMID:22163621

  17. Overview of the fatigue/fracture/life working group program at the Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Mcgaw, Michael A.

    1989-01-01

    Constitutive and life prediction models are developed and verified for materials typically used in hot gas path components of reusable space propulsion systems over the range of relevant operating environments. The efforts were centered on the development of crack initiation life prediction methods, while the efforts of a counterpart group were centered on the development of cyclic crack propagation life prediction methods. The complexion of the active tasks are presented. A significant new task started this year will incorporate the various material constitutive and life prediction models developed in this program into a comprehensive creep-fatigue damage analysis and life assessment computer code. The program will function as a postprocessor to general structural analysis programs (such as finite element or boundary element codes) using the output of such analyses (stress, strain, and temperature fields as functions of time) as the input to the damage analysis and life assessment code. The code will be designed to execute on engineering/scientific workstations and will feature a windowing, mouse-driven user interface. Current plans call for the code to be finished and made available for use in mid 1991.

  18. Mast material test program (MAMATEP)

    NASA Technical Reports Server (NTRS)

    Ciancone, Michael L.; Rutledge, Sharon K.

    1988-01-01

    The Mast Material Test Program (MAMATEP) at NASA Lewis is discussed. Objectives include verifying the need for, and evaluating the performance of, various protection techniques for the Solar Array Assembly mast of the Space Station Photovoltaic Power Module. Mast material samples were evaluated in terms of mass and bending modulus, measured before and after environmental exposure. Test environments included atomic oxygen exposure (RF plasma asher), thermal cycling, and mechanical flexing. Protective coatings included CV-1144 silicon, a Ni/Au/InSn eutectic, and an open weave, Al braid. Results indicate that unprotected samples degrade in an atomic oxygen environment at a steady rate. Open weave, Al braid offers little protection for the fiberglass-epoxy sample in an asher environment. Ni/Au/InSn eutectic offers excellent protection in an asher environment prior to thermal cycling and mechanical flexing. Long duration asher results from unprotected samples indicate that, even though the fiberglass-epoxy degrades, a protection technique may not be necessary to ensure structural integrity. However, a protection technique may be desirable to limit or contain the amount of debris generated by the degradation of the fiberglass-epoxy.

  19. Laser High-Cycle Thermal Fatigue of Pulse Detonation Engine Combustor Materials Tested

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Fox, Dennis S.; Miller, Robert A.

    2001-01-01

    Pulse detonation engines (PDE's) have received increasing attention for future aerospace propulsion applications. Because the PDE is designed for a high-frequency, intermittent detonation combustion process, extremely high gas temperatures and pressures can be realized under the nearly constant-volume combustion environment. The PDE's can potentially achieve higher thermodynamic cycle efficiency and thrust density in comparison to traditional constant-pressure combustion gas turbine engines (ref. 1). However, the development of these engines requires robust design of the engine components that must endure harsh detonation environments. In particular, the detonation combustor chamber, which is designed to sustain and confine the detonation combustion process, will experience high pressure and temperature pulses with very short durations (refs. 2 and 3). Therefore, it is of great importance to evaluate PDE combustor materials and components under simulated engine temperatures and stress conditions in the laboratory. In this study, a high-cycle thermal fatigue test rig was established at the NASA Glenn Research Center using a 1.5-kW CO2 laser. The high-power laser, operating in the pulsed mode, can be controlled at various pulse energy levels and waveform distributions. The enhanced laser pulses can be used to mimic the time-dependent temperature and pressure waves encountered in a pulsed detonation engine. Under the enhanced laser pulse condition, a maximum 7.5-kW peak power with a duration of approximately 0.1 to 0.2 msec (a spike) can be achieved, followed by a plateau region that has about one-fifth of the maximum power level with several milliseconds duration. The laser thermal fatigue rig has also been developed to adopt flat and rotating tubular specimen configurations for the simulated engine tests. More sophisticated laser optic systems can be used to simulate the spatial distributions of the temperature and shock waves in the engine. Pulse laser high

  20. Low cycle thermal fatigue testing of beryllium grades for ITER plasma facing components

    SciTech Connect

    Watson, R.D.; Youchison, D.L.; Dombrowski, D.E.; Guiniatouline, R.N.; Kupriynov, I.B.

    1996-02-01

    A novel technique has been used to test the relative low cycle thermal fatigue resistance of different grades of US and Russian beryllium, which is proposed as plasma facing armor for fusion reactor first wall, limiter, and divertor components. The 30 kW electron beam test system at Sandia National Laboratories was used to sweep the beam spot along one direction at 1 Hz. This produces a localized temperature ``spike`` of 750{degree}C for each pass of the beam. Large thermal stresses in excess of the yield strength are generated due to very high spot heat flux, 250 MW/m{sup 2}. Cyclic plastic strains on the order of 0.6% produced visible cracking on the heated surface in less than 3000 cycles. An in-vacuo fiber optic borescope was used to visually inspect the beryllium surfaces for crack initiation. Grades of US beryllium tested included: S-65C, S- 65H, S-200F, S-200F-H, SR-200, I-400, extruded high purity, HIP`d spherical powder, porous beryllium (94% and 98% dense), Be/30% BeO, Be/60% BeO, and TiBe{sub 12}. Russian grades included: TGP-56, TShGT, DShG-200, and TShG-56. Both the number of cycles to crack initiation, and the depth of crack propagation, were measured. The most fatigue resistant grades were S-65C, DShG-200, TShGT, and TShG-56. Rolled sheet Be (SR-200) showed excellent crack propagation resistance in the plane of rolling, despite early formation of delamination cracks. Only one sample showed no evidence of surface melting, Extruded (T). Metallographic and chemical analyses are provided. Good agreement was found between the measured depth of cracks and a 2-D elastic-plastic finite element stress analysis.

  1. Floating Breakwater Prototype Test Program: Seattle, Washington.

    DTIC Science & Technology

    1986-03-01

    however, several of the longitudinal pipes broke as a result of faulty welds , and the break- water had to be removed from the test site 6 months ahead...A poor weld between the two sections had finally failed because of a combination of corrosion and fatigue, allowing the .,,. two pipe sections to pull...breakwater should be redesigned. If a single 4-in.-diam by 40-in.-long keeper pipe were welded in place, the expensive 4-way cross coupler and 2-in. ID

  2. Axial and torsional fatigue behavior of a cobalt-base alloy

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1991-01-01

    In order to develop elevated temperature multiaxial fatigue life prediction models for the wrought cobalt-base alloy, Haynes 188, a multiaxial fatigue data base is required. To satisfy this need, an elevated temperature experimental program on Haynes 188 consisting of axial, torsional, inphase and out of phase axial-torsional fatigue experiments was designed. Elevated temperature axial and torsional fatigue experiments were conducted under strain control on thin wall tubular specimens of Haynes 188 in air. Test results are given.

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

    SciTech Connect

    Niezrecki, Christopher; Avitabile, Peter; Chen, Julie; Sherwood, James; Lundstrom, Troy; LeBlanc, Bruce; Hughes, Scott; Desmond, Michael; Beattie, Alan; Rumsey, Mark; Klute, Sandra M.; Pedrazzani, Renee; Werlink, Rudy; Newman, John

    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-optic 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.

  4. Random Vibration Tests for Prediction of Fatigue Life of Diffuser Structure for Gas Dynamic Laser

    NASA Astrophysics Data System (ADS)

    Maurer, O. F.; Banaszak, D. L.

    1980-01-01

    Static and dynamic strain measurements which were taken during test stand operations of the gas dynamic laser (GDL) for the AF Airborne Laser Laboratory indicated that higher than expected vibrational stress levels may possibly limit the fatigue life of the laser structure. Particularly the diffuser sidewall structure exhibited large amplitude random vibrations which were excited by the internal gas flow. The diffuser structure consists of two layers of brazed stainless steel, AISI-347, panels. Cooling ducts were milled into the outer face sheet. These in turn are backed by the inner face sheet. So called T-rail stiffeners silver-brazed to the outer face sheets add the required stiffness and divide the sidewall into smaller rectangular plate sections.

  5. 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

  6. The effect of a virtual reality exercise program on physical fitness, body composition, and fatigue in hemodialysis patients.

    PubMed

    Cho, Hyeyoung; Sohng, Kyeong-Yae

    2014-10-01

    [Purpose] The aim of the present study was to investigate the effects of a virtual reality exercise program (VREP) on physical fitness, body composition, and fatigue in hemodialysis (HD) patients with end-stage renal failure. [Subjects and Methods] A nonequivalent control group pretest-posttest design was used. Forty-six HD patients were divided into exercise (n=23) and control groups (n=23); while waiting for their dialyses, the exercise group followed a VREP, and the control group received only their usual care. The VREP was accomplished using Nintendo's Wii Fit Plus for 40 minutes, 3 times a week for 8 weeks during the period of May 27 to July 19, 2013. Physical fitness (muscle strength, balance, flexibility), body composition (skeletal muscle mass, body fat rate, arm and leg muscle mass), and fatigue were measured at baseline and after the intervention. [Results] After the VREP, physical fitness and body composition significantly increased, and the level of fatigue significantly decreased in the exercise group. [Conclusion] These results suggest that a VREP improves physical fitness, body composition, and fatigue in HD patients. Based on the findings, VREPs should be used as a health promotion programs for HD patients.

  7. The Effect of a Virtual Reality Exercise Program on Physical Fitness, Body Composition, and Fatigue in Hemodialysis Patients

    PubMed Central

    Cho, Hyeyoung; Sohng, Kyeong-Yae

    2014-01-01

    [Purpose] The aim of the present study was to investigate the effects of a virtual reality exercise program (VREP) on physical fitness, body composition, and fatigue in hemodialysis (HD) patients with end-stage renal failure. [Subjects and Methods] A nonequivalent control group pretest-posttest design was used. Forty-six HD patients were divided into exercise (n=23) and control groups (n=23); while waiting for their dialyses, the exercise group followed a VREP, and the control group received only their usual care. The VREP was accomplished using Nintendo’s Wii Fit Plus for 40 minutes, 3 times a week for 8 weeks during the period of May 27 to July 19, 2013. Physical fitness (muscle strength, balance, flexibility), body composition (skeletal muscle mass, body fat rate, arm and leg muscle mass), and fatigue were measured at baseline and after the intervention. [Results] After the VREP, physical fitness and body composition significantly increased, and the level of fatigue significantly decreased in the exercise group. [Conclusion] These results suggest that a VREP improves physical fitness, body composition, and fatigue in HD patients. Based on the findings, VREPs should be used as a health promotion programs for HD patients. PMID:25364137

  8. Effect of Test Frequency on Fatigue Crack Growth Rates of Ti-6Al-4V ELI Alloy at Cryogenic Temperature

    SciTech Connect

    Yuri, T.; Ono, Y.; Ogata, T.

    2006-03-31

    In order to clarify the effect of test frequency on the fatigue crack growth rates (da/dN) of Ti-6Al-4V ELI alloy have been investigated at cryogenic temperature. The fatigue crack growth tests were conducted using the test frequencies of 5 and 20 Hz, respectively. At 4 K, the effects of the test frequencies on the fatigue crack growth rates of Ti-6Al-4V ELI alloy were not clear or significant. The fatigue crack growth rates in the low propagation rate region at 4 K were smaller than those at 293 K. On the other hand, those in the high propagation rate region at 4 K were bigger than those at 293 K. The former is considered that the crack closure level was higher as compared to that at 293 K and the latter is due to the difference values of the fracture toughness at 4 and 293 K, respectively. The fracture surfaces of compact tension (CT) specimens in the high propagation rate regions at each test temperature revealed the striations, and furthermore accompanied with the flute fracture surface at 4 K. On the other hand, those of CT specimens in the low propagation rate region at 4 K were found facet-like fracture surfaces corresponding with almost the {alpha}-grain size.

  9. NASALife-Component Fatigue and Creep Life Prediction Program and Illustrative Examples

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Mital, Subodh K.; Gyekenyesi, John Z.

    2005-01-01

    NASALife is a life prediction program for propulsion system components made of ceramic matrix composites (CMC) under cyclic thermo-mechanical loading and creep rupture conditions. Although, the primary focus was for CMC components the underlying methodologies are equally applicable to other material systems as well. The program references data for low cycle fatigue (LCF), creep rupture, and static material properties as part of the life prediction process. Multiaxial stresses are accommodated by Von Mises based methods and a Walker model is used to address mean stress effects. Varying loads are reduced by the Rainflow counting method. Lastly, damage due to cyclic loading (Miner s rule) and creep are combined to determine the total damage per mission and the number of missions the component can survive before failure are calculated. Illustration of code usage is provided through example problem of a CMC turbine stator vane made of melt-infiltrated, silicon carbide fiber-reinforced, silicon carbide matrix composite (MI SiC/SiC)

  10. Decreased oxygen extraction during cardiopulmonary exercise test in patients with chronic fatigue syndrome

    PubMed Central

    2014-01-01

    Background The insufficient metabolic adaptation to exercise in Chronic Fatigue Syndrome (CFS) is still being debated and poorly understood. Methods We analysed the cardiopulmonary exercise tests of CFS patients, idiopathic chronic fatigue (CFI) patients and healthy visitors. Continuous non-invasive measurement of the cardiac output by Nexfin® (BMEYE B.V. Amsterdam, the Netherlands) was added to the cardiopulmonary exercise tests. The peak oxygen extraction by muscle cells and the increase of cardiac output relative to the increase of oxygen uptake (ΔQ’/ΔV’O2) were measured, calculated from the cardiac output and the oxygen uptake during incremental exercise. Results The peak oxygen extraction by muscle cells was 10.83 ± 2.80 ml/100ml in 178 CFS women, 11.62 ± 2.90 ml/100 ml in 172 CFI, and 13.45 ± 2.72 ml/100 ml in 11 healthy women (ANOVA: P=0.001), 13.66 ± 3.31 ml/100 ml in 25 CFS men, 14.63 ± 4.38 ml/100 ml in 51 CFI, and 19.52 ± 6.53 ml/100 ml in 7 healthy men (ANOVA: P=0.008). The ΔQ’/ΔV’O2 was > 6 L/L (normal ΔQ’/ΔV’O2 ≈ 5 L/L) in 70% of the patients and in 22% of the healthy group. Conclusion Low oxygen uptake by muscle cells causes exercise intolerance in a majority of CFS patients, indicating insufficient metabolic adaptation to incremental exercise. The high increase of the cardiac output relative to the increase of oxygen uptake argues against deconditioning as a cause for physical impairment in these patients. PMID:24456560

  11. Design of Linear Control System for Wind Turbine Blade Fatigue Testing

    NASA Astrophysics Data System (ADS)

    Toft, Anders; Roe-Poulsen, Bjarke; Christiansen, Rasmus; Knudsen, Torben

    2016-09-01

    This paper proposes a linear method for wind turbine blade fatigue testing at Siemens Wind Power. The setup consists of a blade, an actuator (motor and load mass) that acts on the blade with a sinusoidal moment, and a distribution of strain gauges to measure the blade flexure. Based on the frequency of the sinusoidal input, the blade will start oscillating with a given gain, hence the objective of the fatigue test is to make the blade oscillate with a controlled amplitude. The system currently in use is based on frequency control, which involves some non-linearities that make the system difficult to control. To make a linear controller, a different approach has been chosen, namely making a controller which is not regulating on the input frequency, but on the input amplitude. A non-linear mechanical model for the blade and the motor has been constructed. This model has been simplified based on the desired output, namely the amplitude of the blade. Furthermore, the model has been linearised to make it suitable for linear analysis and control design methods. The controller is designed based on a simplified and linearised model, and its gain parameter determined using pole placement. The model variants have been simulated in the MATLAB toolbox Simulink, which shows that the controller design based on the simple model performs adequately with the non-linear model. Moreover, the developed controller solves the robustness issue found in the existent solution and also reduces the needed energy for actuation as it always operates at the blade eigenfrequency.

  12. Displacement measurement on specimens subjected to non-Gaussian random vibrations in fatigue life tests

    NASA Astrophysics Data System (ADS)

    Troncossi, M.; Di Sante, R.; Rivola, A.

    2014-05-01

    High-cycle fatigue life tests conducted using controlled random vibrations are commonly used to evaluate failure in components and structures. In most cases, a Gaussian distribution of both the input vibration and the stress response is assumed, while real-life loads may be non-Gaussian causing the response to be non-Gaussian as well. Generating non-Gaussian drive signals with high kurtosis and a given power spectral density, however, does not always guarantee that the stress response will actually be non-Gaussian, because this depends on the adherence of the tested system to the Central Limit Theorem. On the other side, suitable measurement methods need to be developed in order to estimate the stress amplitude response at critical failure locations, and therefore to evaluate and select input loads. In this paper, a simple test rig with a notched cantilevered specimen was developed to measure the response and examine the kurtosis values in the case of stationary Gaussian, stationary non-Gaussian, and non-stationary non-Gaussian excitation signals. The Laser Doppler Vibrometry (LDV) technique was used for the first time in this type of test, to estimate the specimen stress amplitude response in terms of differential displacement at the notch section ends. A method based on the use of accelerometers to correct for the occasional signal drops occurring during the experiment is described and the results are discussed with respect to the ability of the test procedure to evaluate the output signal.

  13. An advanced test technique to quantify thermomechanical fatigue damage accumulation in composite materials

    NASA Technical Reports Server (NTRS)

    Castelli, Michael G.

    1993-01-01

    A mechanical test technique was developed to assist in quantifying the accumulation of damage in composite materials during thermomechanical fatigue (TMF) cycling. This was accomplished by incorporating definitive elastic mechanical property measurements into an ongoing load-controlled TMF test without disturbing the test specimen or significantly altering the test conditions. The technique allows two fundamental composite properties consisting of the isothermal elastic static moduli and the macroscopic coefficient of thermal expansion (CTE) to be measured and collected as functions of the TMF cycles. The specific implementation was incorporated into the commonly employed idealized in-phase and out-of-phase TMF cycles. However, the techniques discussed could be easily implemented into any form of load-controlled TMF mission cycle. By quantifying the degradations of these properties, tremendous insights are gained concerning the progression of macroscopic composite damage and often times the progression of damage within a given constituent. This information should also be useful for the characterization and essential for the verification of analytical damage modeling methodologies. Several examples utilizing this test technique are given for three different fiber lay-ups of titanium metal matrix composites.

  14. Acoustic emission monitoring of a wind turbine blade during a fatigue test

    SciTech Connect

    Beattie, A.G.

    1997-01-01

    A fatigue test of a wind turbine blade was conducted at the National Renewable Energy Laboratory in the fall of 1994. Acoustic emission monitoring of the test was performed, starting with the second loading level. The acoustic emission data indicated that this load exceeded the strength of the blade. From the first cycle at the new load, an oil can type of deformation occurred in two areas of the upper skin of the blade. One of these was near the blade root and the other was about the middle of the tested portion of the blade. The emission monitoring indicated that no damage was taking place in the area near the root, but in the deforming area near the middle of the blade, damage occurred from the first cycles at the higher load. The test was stopped after approximately one day and the blade was declared destroyed, although no gross damage had occurred. Several weeks later the test was resumed, to be continued until gross damage occurred. The upper skin tore approximately one half hour after the cycling was restarted.

  15. A single electromyographic testing point is valid to monitor neuromuscular fatigue during continuous exercise.

    PubMed

    Galen, Sujay S; Malek, Moh H

    2014-10-01

    Two different protocols for estimating the electromyographic fatigue threshold (EMGFT) have been proposed in the literature. These protocols are distinguished by the number of visits required to determine the EMGFT. The purpose of this study, therefore, was to statistically compare the estimated EMGFT from the single-visit incremental test and the multiple-visit constant workload tests for single-leg knee-extensor exercise. Seven healthy college-aged men [mean ± SEM; age = 25.0 ± 0.7 years] performed the incremental test and on separate occasions also performed 4 constant workload tests to voluntary exhaustion. The EMG amplitude was recorded from the rectus femoris muscle during all the testing sessions. For the single-visit test, the EMG amplitude vs. time relationship for each power output was examined using linear regression. For the multiple-visit tests, the EMG amplitude vs. time relationship was calculated for each constant power output. Thereafter, the power outputs were plotted as a function of the slope coefficient for the EMG amplitude vs. time relationships, and linear regression was performed. The EMGFT was defined as the intersection of the regression line with the y-intercept of the power output vs. slope coefficient plot. The results indicated that the estimated EMGFT from the single-visit test was significantly (p = 0.012) lower than the estimate from the multiple-visit tests. Because this test is performed during a single visit and concludes within 20 minutes, it may also have application in clinical rehabilitation settings and not merely for an athletic population.

  16. Progress Letter Report on Bending Fatigue Test System Development for Spent Nuclear Fuel Vibration Integrity Study (Out-of-cell fatigue testing development - Task 2.4)

    SciTech Connect

    Wang, Jy-An John; Wang, Hong; Cox, Thomas S; Baldwin, Charles A; Bevard, Bruce Balkcom

    2013-08-01

    Vibration integrity of high burn-up spent nuclear fuel in transportation remains to be a critical component of US nuclear waste management system. The structural evaluation of package for spent fuel transportation eventually will need to see if the content or spent fuel is in a subcritical condition. However, a system for testing and characterizing such spent fuel is still lacking mainly due to the complication involved with dealing radioactive specimens in a hot cell environment. Apparently, the current state-of-the-art in spent fuel research and development is quite far away from the delivery of reliable mechanical property data for the assessment of spent fuels in the transport package evaluation. Under the sponsorship of US NRC, ORNL has taken the challenge in developing a robust testing system for spent fuel in hot cell. An extensive literature survey was carried out and unique requirements of such testing system were identified. The U-frame setup has come to the top among various designs examined for reverse bending fatigue test of spent fuel rod. The U-frame has many features that deserve mentioned here: Easy to install spent fuel rod in test; Less linkages than in conventional bending test setup such as three-point or four-point bending; Target the failure mode relevant to the fracture of spent fuel rod in transportation by focusing on pure bending; The continuous calibrations and modifications resulted in the third generation (3G) U-frame testing setup. Rigid arms are split along the LBB axis at rod sample ends. For each arm, this results in a large arm body and an end piece. Mating halves of bushings were modified into two V-shaped surfaces on which linear roller bearings (LRB) are embedded. The rod specimen is installed into the test fixture through opening and closing slide end-pieces. The 3G apparently has addressed major issues of setup identified in the previous stage and been proven to be eligible to be further pursued in this project. On the other

  17. Fatigue reliability based optimal design of planar compliant micropositioning stages

    NASA Astrophysics Data System (ADS)

    Wang, Qiliang; Zhang, Xianmin

    2015-10-01

    Conventional compliant micropositioning stages are usually developed based on static strength and deterministic methods, which may lead to either unsafe or excessive designs. This paper presents a fatigue reliability analysis and optimal design of a three-degree-of-freedom (3 DOF) flexure-based micropositioning stage. Kinematic, modal, static, and fatigue stress modelling of the stage were conducted using the finite element method. The maximum equivalent fatigue stress in the hinges was derived using sequential quadratic programming. The fatigue strength of the hinges was obtained by considering various influencing factors. On this basis, the fatigue reliability of the hinges was analysed using the stress-strength interference method. Fatigue-reliability-based optimal design of the stage was then conducted using the genetic algorithm and MATLAB. To make fatigue life testing easier, a 1 DOF stage was then optimized and manufactured. Experimental results demonstrate the validity of the approach.

  18. Effects of a 4-Week Multimodal Rehabilitation Program on Quality of Life, Cardiopulmonary Function, and Fatigue in Breast Cancer Patients

    PubMed Central

    Do, Junghwa; Cho, Youngki

    2015-01-01

    Purpose This study examines the effects of a rehabilitation program on quality of life (QoL), cardiopulmonary function, and fatigue in breast cancer patients. The program included aerobic exercises as well as stretching and strengthening exercises. Methods Breast cancer patients (n=62) who had completed chemotherapy were randomly assigned to an early exercise group (EEG; n=32) or a delayed exercise group (DEG; n=30). The EEG underwent 4 weeks of a multimodal rehabilitation program for 80 min/day, 5 times/wk for 4 weeks. The DEG completed the same program during the next 4 weeks. The European Organization for Research and Treatment of Cancer-Core Quality of Life Questionnaire (EORTC QLQ-C30), EORTC Breast Cancer-Specific Quality of Life Questionnaire (EORTC QLQ-BR23), predicted maximal volume of oxygen consumption (VO2max), and fatigue severity scale (FSS) were used for assessment at baseline, and at 2, 4, 6, and 8 weeks. Results After 8 weeks, statistically significant differences were apparent in global health, physical, role, and emotional functions, and cancer-related symptoms such as fatigue and pain, nausea, and dyspnea on the EORTC QLQ-C30; cancer-related symptoms involving the arm and breast on the EORTC QLQ-BR23; the predicted VO2max; muscular strength; and FSS (p<0.050), according to time, between the two groups. Conclusion The results of our study suggest that a supervised multimodal rehabilitation program may improve the physical symptoms, QoL, and fatigue in patients with breast cancer. PMID:25834616

  19. An unsupervised pattern recognition approach for AE data originating from fatigue tests on polymer-composite materials

    NASA Astrophysics Data System (ADS)

    Doan, D. D.; Ramasso, E.; Placet, V.; Zhang, S.; Boubakar, L.; Zerhouni, N.

    2015-12-01

    This work investigates acoustic emission generated during tension fatigue tests carried out on a carbon fiber reinforced polymer (CFRP) composite specimen. Since massive fatigue data processing, especially noise reduction, remains an important challenge in AE data analysis, a Mahalanobis distance-based noise modeling has been proposed in the present work to tackle this problem. A sequential feature selection based on Davies-Bouldin index has been implemented for fast dimensionality reduction. An unsupervised classifier offline-learned from quasi-static data is then used to classify the data to different AE sources with the possibility to dynamically accommodate with unseen ones. With an efficient proposed noise removal and automatic separation of AE events, this pattern discovery procedure provides an insight into fatigue damage development in composites in the presence of millions of AE events.

  20. Influence of sustained submaximal clenching fatigue test on electromyographic activity and maximum voluntary bite forces in healthy subjects and patients with temporomandibular disorders.

    PubMed

    Xu, L; Fan, S; Cai, B; Fang, Z; Jiang, X

    2017-05-01

    This study aimed to investigate whether the fatigue induced by sustained motor task in the jaw elevator muscles differed between healthy subjects and patients with temporomandibular disorder (TMD). Fifteen patients with TMD and thirteen age- and sex-matched healthy controls performed a fatigue test consisting of sustained clenching contractions at 30% maximal voluntary clenching intensity until test failure (the criterion for terminating the fatigue test was when the biting force decreased by 10% or more from the target force consecutively for >3 s). The pre- and post-maximal bite forces (MBFs) were measured. Surface electromyographic signals were recorded from the superficial masseter muscles and anterior temporal muscles bilaterally, and the median frequency at the beginning, middle and end of the fatigue test was calculated. The duration of the fatigue test was also quantified. Both pre- and post-MBFs were lower in patients with TMD than in controls (P < 0·01). No significant difference was found in the percentage change in MBF between groups. The duration of the fatigue test in TMD patients was significantly shorter than that of the controls (P < 0·05). Our results suggest that, compared to healthy subjects, patients with TMD become more easily fatigued, but the electromyographic activation process during the fatigue test is similar between healthy subjects and patients with TMD. However, the mechanisms involved in this process remain unclear, and further research is warranted.

  1. Bending fatigue tests on flattened strand wire rope at high working loads

    SciTech Connect

    Wang, R.C.; Shapiro, D.E.

    1995-09-01

    The US Bureau of Mines established a wire rope research laboratory to examine the factors that affect the safety and the useful life of wire rope. In the most recent work, two 32-mm 6x27H flattened strand ropes were degraded on a bending fatigue machine. The two tests were run at constant loads of 285 and 347 kN or safety factors of 2.5 and 2. Nondestructive and tensile strength tests were performed on samples of the ropes to determine the relationship between rope deterioration and rope breaking strength. Neither the area loss nor the number of broken wires measured from nondestructive tests could be used as clear indicators of the loss of strength. However, it was found from the tensile tests for both rope specimens that the strength loss was associated with the reduction of breaking strain. This suggests that measuring the strain of many short sections of a rope in the elastic region may locate the high stress sections and thus determine the condition of the rope.

  2. Elevated-temperature fracture toughness and fatigue testing of steels for geothermal applications. Annual progress report

    SciTech Connect

    Cutler, R.A.; Goodman, E.C.; Guest, R.V.; Hendrickson, R.R.; Leslie, W.C.

    1980-11-01

    Conventional drill bit steels exhibit increased wear and decreased toughness when run at elevated temperatures in geothermal wells. Bits are therefore run at lower speeds and lighter loads, resulting in lower penetration rates for geothermal wells than for conventional rock drilling. Carpenter EX-00053, Timken CBS 600, Timken CBS 1000M and Vasco X-2M, steels with improved hot hardness (improved wear resistance), were tested in conjunction with the steels used for cones (AISI 4820 and 9315) and lugs (AISI 8620 and 9315) in conventional roller cone rock bits. Shortrod fracture toughness measurements were made on each of these steels between room temperature and 400/sup 0/C. Fatigue crack resistance was determined at 300/sup 0/C for high-temperature steels and at room temperature for conventional steels. Scanning electron microscopy analyses of the fractured short-rod specimens were correlated with observed crack behavior from the test records. Test results are discussed, recommendations made for further testing and preliminary steel selections made for improved geothermal bits.

  3. An assessment of wind tunnel test data on flexible thermal protection materials and results of new fatigue tests of threads

    NASA Technical Reports Server (NTRS)

    Coe, Charles F.

    1985-01-01

    Advanced Flexible Reusable Surface Insulation (AFRSI) was developed as a replacement for the low-temperature (white) tiles on the Space Shuttle. The first use of the AFRSI for an Orbiter flight was on the OMS POD of Orbiter (OV-099) for STS-6. Post flight examination after STS-6 showed that damage had occurred to the AFRSI during flight. The failure anomaly between previous wind-tunnel tests and STS-6 prompted a series of additional wind tunnel tests to gain an insight as to the cause of the failure. An assessment of all the past STS-6 wind tunnel tests pointed out the sensitivity of the test results to scaling of dynamic loads due to the difference of boundary layer thickness, and the material properties as a result of exposure to heating. The thread component of the AFRSI was exposed to fatigue testing using an apparatus that applied pulsating aerodynamic loads on the threads similar to the loads caused by an oscillating shock. Comparison of the mean values of the number-of-cycles to failure showed that the history of the thread was the major factor in its performance. The thread and the wind tunnel data suggests a mechanism of failure for the AFRSI.

  4. Space Shuttle wind tunnel testing program

    NASA Technical Reports Server (NTRS)

    Whitnah, A. M.; Hillje, E. R.

    1984-01-01

    A major phase of the Space Shuttle Vehicle (SSV) Development Program was the acquisition of data through the space shuttle wind tunnel testing program. It became obvious that the large number of configuration/environment combinations would necessitate an extremely large wind tunnel testing program. To make the most efficient use of available test facilities and to assist the prime contractor for orbiter design and space shuttle vehicle integration, a unique management plan was devised for the design and development phase. The space shuttle program is reviewed together with the evolutional development of the shuttle configuration. The wind tunnel testing rationale and the associated test program management plan and its overall results is reviewed. Information is given for the various facilities and models used within this program. A unique posttest documentation procedure and a summary of the types of test per disciplines, per facility, and per model are presented with detailed listing of the posttest documentation.

  5. Life sciences experiments mission development test program

    NASA Technical Reports Server (NTRS)

    Bush, W. H., Jr.; White, R. C.

    1978-01-01

    The development, goals, and experimental programs of the three Spacelab Mission Developmental tests are described. The tests were structured as a total simulation of a dedicated mission commencing with experiment solicitation; continuing with experiment development, integration, and mission planning; and ending with the actual conduct of a seven-day 24-hour per day mission in mockup facilities. Topics such as test payload management; payload integration, training, and testing; test operations and program facilities are discussed.

  6. Partnership Council MGUE Test Program

    DTIC Science & Technology

    2015-04-29

    representative operational threat environments • Utilization of Live Sky M NAV signals - MGUE Test Operations • Racks: Static Tests • RQ-11 B Raven...Integration, Static /Dynamic Tests First Successful Flight Data Collection of Integrated M-Code Receiver 2015 04 29 _Partnership Council MGU E Test

  7. Evaluation of Fatigue Performance of Asphalt Based on Constant Strain DSR Test

    NASA Astrophysics Data System (ADS)

    Zhu, H. Z.; Yan, E. H.; Lu, Z. T.

    2017-02-01

    Asphalt performance has important effect on the fatigue resistance performance of asphalt mixture. This research based on the DSR time scanning mode, investigated the constant strain performance of 70 # matrix asphalt and SBS modified asphalt. Based on 50% G* 0 to simulate the fatigue performance of two kinds of the asphalt.

  8. Thermal fatigue testing of a diffusion-bonded beryllium divertor mock-up under ITER relevant conditions

    SciTech Connect

    Youchison, D.L.; Guiniiatouline, R.; Watson, R.D.

    1994-12-31

    Thermal response and thermal fatigue tests of four 5 mm thick beryllium tiles on a Russian divertor mock-up were completed on the Electron Beam Test System at Sandia National Laboratories. The beryllium tiles were diffusion bonded onto an OFHC copper saddleblock and a DSCu (MAGT) tube containing a porous coating. Thermal response tests were performed on the tiles to an absorbed heat flux of 5 MW/m{sup 2} and surface temperatures near 300{degrees}C using 1.4 MPa water at 5.0 m/s flow velocity and an inlet temperature of 8-15{degrees}C. One tile was exposed to incrementally increasing heat fluxes up to 9.5 MW/m{sup 2} and surface temperatures up to 690{degrees}C before debonding at 10 MW/m{sup 2}. A third tile debonded after 9200 thermal fatigue cycles at 5 MW/m{sup 2}, while another debonded after 6800 cycles. In all cases, fatigue failure occurred in the intermetallic layers between the beryllium and copper. No fatigue cracking of the bulk beryllium was observed. During thermal cycling, a gradual loss of porous coating produced increasing sample temperatures. These experiments indicate that diffusion-bonded beryllium tiles can survive several thousand thermal cycles under ITER relevant conditions without failure. However, the reliability of the diffusion bonded Joint remains a serious issue.

  9. Elevated Temperature Fracture Toughness and Fatigue Testing of Steels for Geothermal Applications

    SciTech Connect

    Cutler, R.A.; Goodman, E.C.; Hendrickson, R.R.

    1981-10-01

    Conventional drill bit steels exhibit increased wear and decreased toughness when run at elevated temperatures in geothermal wells. Bits are therefore run at lower speeds and lighter loads, resulting in lower penetration rates for geothermal drilling than for conventional rock drilling. Carpenter EX-00053, Timken CBS 600, Timken CBS 1000M and Vasco X-2M steels with improved hot hardness (improved wear resistance), were tested in conjunction with the steels used for cones (AISI 4829, 3915 and EX55) in conventional roller cones and lugs (AISI 8620, 9315 and EX55) in conventional roller cone rock bits. Short-rod fracture toughness measurements were made on each of these steels between room temperature and 400{degree}C. Fatigue crack resistance was determined at 300{degree}C for high-temperature steels and at room temperature for conventional steels. Scanning electron microscopy analyses of the fractured short-rod specimens were correlated with observed crack behavior from the test records. Materials testing results are discussed and steel selections made for improved geothermal bits. Carpenter EX-00053 and Timken CBS 1000M steels meet all design requirements for use in stabilizers, lugs and cones at temperatures to 400{degree}C. It is recommended that EX-00053 and CBS 1000M be manufactured for geothermal drilling at the Geysers site. [DJE 2005

  10. Space Shuttle Partial Stack Rollout Test Analytical Correlation In Support Of Fatigue Load Development

    NASA Technical Reports Server (NTRS)

    DelBasso, Steve; Dolenz, Jim; Wilson, Lee

    2005-01-01

    A rollout test with only the Solid Rocket Boosters was conducted in November 2003 to gather structural dynamic response data of the transportation environment from the Vehicle Assembly Building to the Launch Pad. The data was acquired to develop and validate analytical methods used to predict rollout Orbiter fatigue load spectra. Earlier predictions computed by a base drive approach with only 5 input drive degrees-of-freedom raised questions that commissioned the partial stack test. Not only was there a concern because of the input degree-of-freedom omission due to measurement limitations, but there was also a concern with the implementation of the "large mass" itself. Three methods were evaluated with the partial stack test data. The analytical correlations to measured strain derived SRB base loads and acceleration5 showed the earlier 5 degree-of-freedom base drive approach to yield the most conservative results for all quantities monitored except the SRB base moment about the axis in which the input drive was missing. This non-conservative shortcoming led to a recommendation to use either the 6 degree-of-freedom base drive or the 12 degree-of-freedom Craig-Bampton boundary drive methods whose results did not substantially differ.

  11. High temperature fatigue behavior of Haynes 188

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Saltsman, James F.; Kalluri, Sreeramesh

    1988-01-01

    The high temperature, creep-fatigue behavior of Haynes 188 was investigated as an element in a broader thermomechanical fatigue life prediction model development program at the NASA-Lewis. The models are still in the development stage, but the data that were generated possess intrinsic value on their own. Results generated to date is reported. Data were generated to characterize isothermal low cycle fatigue resistance at temperatures of 316, 704, and 927 C with cyclic failure lives ranging from 10 to more than 20,000. These results follow trends that would be predicted from a knowledge of tensile properties, i.e., as the tensile ductility varies with temperature, so varies the cyclic inelastic straining capacity. Likewise, as the tensile strength decreases, so does the high cyclic fatigue resistance. A few two-minute hold-time cycles at peak compressive strain were included in tests at 760 C. These results were obtained in support of a redesign effort for the Orbital Maneuverable System engine. No detrimental effects on cyclic life were noted despite the added exposure time for creep and oxidation. Finally, a series of simulated thermal fatigue tests, referred to as bithermal fatigue tests, were conducted using 316 C as the minimum and 760 C as the maximum temperature. Only out-of-phase bithermal tests were conducted to date. These test results are intended for use as input to a more general thermomechanical fatigue life prediction model based on the concepts of the total strain version of Strainrange Partitioning.

  12. Effectiveness of a tailored neck training program on neck strength, movement, and fatigue in under-19 male rugby players: a randomized controlled pilot study

    PubMed Central

    Barrett, Matthew D; McLoughlin, Terence F; Gallagher, Kieran R; Gatherer, Don; Parratt, Michael TR; Perera, Jonathan R; Briggs, Tim WR

    2015-01-01

    Purpose To investigate the effect of a tailored neck muscle conditioning program on neck muscle strength, neck muscle fatigue, and range of neck movement in 16–18-year-old male rugby players. Materials and methods Thirty-four male rugby players were divided into forward and back playing positions and randomized within these groups. Seventeen players were randomly assigned to each group. The test group was given a tailored 6-week exercise regime based on their baseline measurements to be performed three times a week in addition to their normal training and playing. The control group trained and played as normal. The outcome measures used were cervical spine range of movement, neck strength, and neck muscle fatigability. Results There were no clinically relevant statistically significant differences between the two groups. Trends identified between the two groups suggest that a tailored neck exercise program increases neck strength, particularly neck extension, and increases resistance to fatigue, as well as influencing right- and left-sided neck muscle balance. A reduction in range of movement was also demonstrated in the test group. There was a great deal of variability in range of movement and strength within this age group. No previously undiagnosed neck conditions were detected, and there were no adverse events reported. Conclusion This study has shown that neck strength, range of movement, and susceptibility of the neck muscles to fatigue can be influenced using a focused neck training regime. It forms an important basis for a larger, multicenter study to ensure the neck is given due attention in rugby training and receives the same focus of conditioning as other parts of the body. PMID:25999771

  13. The relationship between blood potassium, blood lactate, and electromyography signals related to fatigue in a progressive cycling exercise test.

    PubMed

    Tenan, Matthew S; McMurray, Robert G; Blackburn, B Troy; McGrath, Melanie; Leppert, Kyle

    2011-02-01

    Local muscle fatigue may be related to potassium efflux from the muscle cell and/or lactate accumulation within the muscle. Local fatigue causes a decrease in median frequency (MPF) of the electromyogram's power spectrum during isometric contractions but its relationship to changes in potassium and lactate during dynamic exercise is equivocal. Thus, this investigation evaluated relationships between changes in the MPF from the vastus lateralis and blood levels of lactate and potassium during an incremental cycling test and recovery. Trained cyclists (n=8) completed a discontinuous, graded cycle test to exhaustion under normal and glycogen-reduced conditions. The glycogen reduced condition promoted an environment of lower lactate production while permitting a consistent potassium response. Blood samples and maximal isometric EMG data were collected at the end of each stage and during recovery. Maximal lactate levels were ∼ 60% lower in the glycogen reduced condition; potassium was similar between trials. MPF did not change significantly at volitional fatigue. Further, MPF was not significantly related to lactate (p>0.27) or potassium (p>0.16) in either condition. Though both lactate and potassium have been implicated as factors relating to local muscle fatigue, neither is significantly related to changes in MPF during or after progressive exercise on a cycle ergometer.

  14. Test-Anxiety Program and Test Gains with Nursing Classes

    ERIC Educational Resources Information Center

    Evans, Ginger; Ramsey, Gary; Driscoll, Richard

    2010-01-01

    Nursing programs can be highly stressful, and nursing students have been found to be more test-anxious than other students. The present investigation examines a practical program to reduce test-anxiety impairment and improve academic performance for a significant number of highly anxious nursing students. Incoming nursing students were screened…

  15. Determining The Electromyographic Fatigue Threshold Following a Single Visit Exercise Test.

    PubMed

    Galen, Sujay S; Guffey, Darren R; Coburn, Jared W; Malek, Moh H

    2015-07-27

    Theoretically, the electromyographic (EMG) fatigue threshold is the exercise intensity an individual can maintain indefinitely without the need to recruit more motor units which is associated with an increase in the EMG amplitude. Although different protocols have been used to estimate the EMG fatigue threshold they require multiple visits which are impractical for a clinical setting. Here, we present a protocol for estimating the EMG fatigue threshold for cycle ergometry which requires a single visit. This protocol is simple, convenient, and completed within 15-20 min, therefore, has the potential to be translated into a tool that clinicians can use in exercise prescription.

  16. 2009 GED Testing Program Statistical Report

    ERIC Educational Resources Information Center

    GED Testing Service, 2010

    2010-01-01

    The "2009 GED[R] Testing Program Statistical Report" is the 52nd annual report in the program's 68-year history of providing a second opportunity for adults without a high school credential to earn their jurisdiction's GED credential. The report provides candidate demographic and GED Test performance statistics as well as historical…

  17. Test Preparation Programs: Counselors' Views and Involvement.

    ERIC Educational Resources Information Center

    Michael, Noreen; Edwards, Patricia A.

    1991-01-01

    Surveyed 90 elementary and secondary school counselors to examine strategies employed in test preparation programs, degree to which counselors follow structured curriculum in presenting test-taking activities to students, extent to which counselors target particular strategies, and how counselors evaluate program success. Found counselors more…

  18. Simplification of Fatigue Test Requirements for Damage Tolerance of Composite Interstage Launch Vehicle Hardware

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    The issue of fatigue loading of structures composed of composite materials is considered in a requirements document that is currently in place for manned launch vehicles. By taking into account the short life of these parts, coupled with design considerations, it is demonstrated that the necessary coupon level fatigue data collapse to a static case. Data from a literature review of past studies that examined compressive fatigue loading after impact and data generated from this experimental study are presented to support this finding. Damage growth, in the form of infrared thermography, was difficult to detect due to rapid degradation of compressive properties once damage growth initiated. Unrealistically high fatigue amplitudes were needed to fail 5 of 15 specimens before 10,000 cycles were reached. Since a typical vehicle structure, such as the Ares I interstage, only experiences a few cycles near limit load, it is concluded that static compression after impact (CAI) strength data will suffice for most launch vehicle structures.

  19. The Effects of Task Type on Time to Task Failure During Fatigue: A Modified Sørensen Test.

    PubMed

    Russ, David W; Ross, Andrew J; Clark, Brian C; Thomas, James S

    2017-03-28

    Understanding mechanisms of fatigue of the trunk extensors is important because fatigue is a major factor in predicting incidence of low back pain, but few studies have examined trunk extensor fatigue muscles using differing load types and measured the amplitude and frequency domain of the electromyographic signal to explain these differences. Sixteen healthy participants performed position- and force-matching fatigue tasks in a modified Sørensen test position. Time to task failure was significantly longer during the position-matching task compared to force-matching task (58.3 ± 6.6 min vs. 36.1 ± 5.4 min). This finding is the opposite of that commonly reported for the appendicular muscle, but the mean power frequency shifts and muscle activation patterns of the trunk and hip extensors did not explain this difference. The mean power frequency shifts and muscle activation patterns of the trunk and hip extensors did not explain this difference. The greater time to task failure during the position-matching task may reflect adaptation of the trunk extensor muscles to optimize maintaining specific joint angles more so than specific loads.

  20. Neuromuscular Fatigue During a Modified Biering-Sørensen Test in Subjects with and Without Low Back Pain

    PubMed Central

    Pitcher, Mark J.; Behm, David G.; MacKinnon, Scott N.

    2007-01-01

    Studies employing modified Biering-Sørenson tests have reported that low back endurance is related to the potential for developing low back pain. Understanding the manner in which spinal musculature fatigues in people with and without LBP is necessary to gain insight into the sensitivity of the modified Biering-Sørenson test to differentiate back health. Twenty male volunteers were divided into a LBP group of subjects with current subacute or a history of LBP that limited their activity (n = 10) and a control group (n = 10). The median frequency of the fast Fourier transform was calculated from bilateral surface electromyography (EMG) of the upper lumbar erector spinae (ULES), lower lumbar erector spinae (LLES) and biceps femoris while maintaining a prescribed modified Biering-Sørensen test position and exerting isometric forces equivalent to 100, 120, 140 and 160% of the estimated mass of the head-arms-trunk (HAT) segment. Time to failure was also investigated across the percentages of HAT. Fatigue time decreased with increasing load and differences between groups increased as load increased, however these differences were not significant. Significant differences in the EMG median frequency between groups occurred in the right biceps femoris (p ≤ 0.05) with significant pairwise differences occurring at 140% for the left biceps femoris and at 160% for the right biceps femoris. There were significant pairwise differences at 120% for average EMG of the right biceps femoris and at 140% for the right ULES, and right and left biceps femoris (p ≤ 0.05). The modified Biering-Sørensen test as usually performed at 100% HAT is not sufficient to demonstrate significant differences between controls and subjects with varying degrees of mild back disability based on the Oswestry classification. Key pointsThe results do not wholly support the modified Biering-Sørensen test utilizing resistance of 100% HAT to discern differences in fatigue in subjects with mild low back

  1. Fatigue Testing of the MK3 Mod0 2000 Lb Bail Lugs: Test Report

    DTIC Science & Technology

    1990-08-01

    REPORT REQUESTING AUTHORITY: No. 1 Central Ammunition Depot, RAAF ITEMS TESTED: Sixty one MK3 MODO 2000 lb bail lugs from four different lot numbers SUMMARY...identifying run-out, lugs from lot numbers I and 4 shall be used due to the availability of a larger quantity of these lugs in comparison to the others. 5...to lugs from four different lot numbers as follows: F1/*t = MK3 MODO (ET) 30003-1380540 ETW-1 277 F2/** = MK3 MODO 30003-1380540 SMN81J 001008 F3

  2. Propulsion Induced Effects Test Program

    NASA Technical Reports Server (NTRS)

    Cappuccio, Gelsomina; Won, Mark; Bencze, Dan

    1999-01-01

    The objective of this milestone is to assess the propulsion/airframe integration characteristics of the Technology Concept Airplane and design variations through computational analysis and experimental subsonic through supersonic wind tunnel testing. The Milestone will generate a comprehensive CFD and wind tunnel data base of the baseline, and design variations. Emphasis will be placed on establishing the propulsion induced effects on the flight performance of the Technology Concept Airplane with all appropriate wind tunnel corrections.

  3. Experimental and Finite Element Modeling of Near-Threshold Fatigue Crack Growth for the K-Decreasing Test Method

    NASA Technical Reports Server (NTRS)

    Smith, Stephen W.; Seshadri, Banavara R.; Newman, John A.

    2015-01-01

    The experimental methods to determine near-threshold fatigue crack growth rate data are prescribed in ASTM standard E647. To produce near-threshold data at a constant stress ratio (R), the applied stress-intensity factor (K) is decreased as the crack grows based on a specified K-gradient. Consequently, as the fatigue crack growth rate threshold is approached and the crack tip opening displacement decreases, remote crack wake contact may occur due to the plastically deformed crack wake surfaces and shield the growing crack tip resulting in a reduced crack tip driving force and non-representative crack growth rate data. If such data are used to life a component, the evaluation could yield highly non-conservative predictions. Although this anomalous behavior has been shown to be affected by K-gradient, starting K level, residual stresses, environmental assisted cracking, specimen geometry, and material type, the specifications within the standard to avoid this effect are limited to a maximum fatigue crack growth rate and a suggestion for the K-gradient value. This paper provides parallel experimental and computational simulations for the K-decreasing method for two materials (an aluminum alloy, AA 2024-T3 and a titanium alloy, Ti 6-2-2-2-2) to aid in establishing clear understanding of appropriate testing requirements. These simulations investigate the effect of K-gradient, the maximum value of stress-intensity factor applied, and material type. A material independent term is developed to guide in the selection of appropriate test conditions for most engineering alloys. With the use of such a term, near-threshold fatigue crack growth rate tests can be performed at accelerated rates, near-threshold data can be acquired in days instead of weeks without having to establish testing criteria through trial and error, and these data can be acquired for most engineering materials, even those that are produced in relatively small product forms.

  4. Experimental investigation of fatigue behavior of carbon fiber composites using fully-reversed four-point bending test

    NASA Astrophysics Data System (ADS)

    Amiri, Ali

    Carbon fiber reinforced polymers (CFRP) have become an increasingly notable material for use in structural engineering applications. Some of their advantages include high strength-to-weight ratio, high stiffness-to-weight ratio, and good moldability. Prediction of the fatigue life of composite laminates has been the subject of various studies due to the cyclic loading experienced in many applications. Both theoretical studies and experimental tests have been performed to estimate the endurance limit and fatigue life of composite plates. One of the main methods to predict fatigue life is the four-point bending test. In most previous works, the tests have been done in one direction (load ratio, R, > 0). In the current work, we have designed and manufactured a special fixture to perform a fully reversed bending test (R = -1). Static four-point bending tests were carried out on three (0°/90°)15 and (± 45°)15 samples to measure the mechanical properties of CFRP. Testing was displacement-controlled at the rate of 10 mm/min until failure. In (0°/90°)15 samples, all failed by cracking/buckling on the compressive side of the sample. While in (± 45°)15 all three tests, no visual fracture or failure of the samples was observed. 3.4 times higher stresses were reached during four-point static bending test of (0° /90°)15 samples compared to (± 45°)15. Same trend was seen in literature for similar tests. Four-point bending fatigue tests were carried out on (0° /90°)15 sample with stress ratio, R = -1 and frequency of 5 Hz. Applied maximum stresses were approximately 45%, 56%, 67%, 72% and 76% of the measured yield stress for (0° /90°)15 samples. There was visible cracking through the thickness of the samples. The expected downward trend in fatigue life with increasing maximum applied stress was observed in S-N curves of samples. There appears to be a threshold for ‘infinite’ life, defined as 1.7 million cycles in the current work, at a maximum stress of about

  5. Deformation monitoring with off-the-shelf digital cameras for civil engineering fatigue testing

    NASA Astrophysics Data System (ADS)

    Detchev, I.; Habib, A.; He, F.; El-Badry, M.

    2014-06-01

    Deformation monitoring of civil infrastructure systems is important in terms of both their safety and serviceability. The former refers to estimating the maximum loading capacity during the design stages of a building project, and the latter means performing regularly scheduled maintenance of an already existing structure. Traditionally, large structures have been monitored using surveying techniques, while fine-scale monitoring of structural components such as beams and trusses has been done with strain gauge instrumentation. In the past decade, digital photogrammetric systems coupled with image processing techniques have also been used for deformation monitoring. The major advantage of this remote sensing method for performing deformation monitoring is that there is no need to access the object of interest while testing is in progress. The paper is a result of an experiment where concrete beams with polymer support sheets are subjected to dynamic loading conditions by a hydraulic actuator in a structures laboratory. This type of loading is also known as fatigue testing, and is used to simulate the typical use of concrete beams over a long period of time. From a photogrammetric point of view, the challenge for this type of experiment is to avoid motion artifacts by maximizing the sensor frame rate, and at the same time to have a good enough image quality in order to achieve satisfactory reconstruction precision. This research effort will investigate the optimal camera settings (e.g., aperture, shutter speed, sensor sensitivity, and file size resolution) in order to have a balance between high sensor frame rate and good image quality. The results will be first evaluated in terms of their repeatability, and then also in terms of their accuracy. The accuracy of the results will be checked against another set of results coming from high quality laser transducers.

  6. In vitro bond strength and fatigue stress test evaluation of different adhesive cements used for fixed space maintainer cementation

    PubMed Central

    Cantekin, Kenan; Delikan, Ebru; Cetin, Secil

    2014-01-01

    Objective: The purposes of this research were to (1) compare the shear-peel bond strength (SPBS) of a band of a fixed space maintainer (SM) cemented with five different adhesive cements; and (2) compare the survival time of bands of SM with each cement type after simulating mechanical fatigue stress. Materials and Methods: Seventy-five teeth were used to assess retentive strength and another 50 teeth were used to assess the fatigue survival time. SPBS was determined with a universal testing machine. Fatigue testing was conducted in a ball mill device. Results: The mean survival time of bands cemented with R & D series Nova Glass-LC (6.2 h), Transbond Plus (6.7 h), and R & D series Nova Resin (6.8 h) was significantly longer than for bands cemented with Ketac-Cem (5.4 h) and GC Equia (5.2 h) (P < 0.05). Conclusion: Although traditional glass ionomer cement (GIC) cement presented higher retentive strength than resin-based cements (resin, resin modified GIC, and compomer cement), resin based cements, especially dual cure resin cement (nova resin cement) and compomer (Transbond Plus), can be expected to have lower failure rates for band cementation than GIC (Ketac-Cem) in the light of the results of the ball mill test. PMID:25202209

  7. Fatigue Crack Growth Behavior Evaluation of Grainex Mar-M 247 for NASA's High Temperature, High Speed Turbine Seal Test Rig

    NASA Technical Reports Server (NTRS)

    Delgado, Irebert R.; Steinetz, Bruce M.; Rimnac, Clare M.; Lewandowski, John J.

    2008-01-01

    The fatigue crack growth behavior of Grainex Mar-M 247 is evaluated for NASA s Turbine Seal Test Facility. The facility is used to test air-to-air seals primarily for use in advanced jet engine applications. Because of extreme seal test conditions of temperature, pressure, and surface speeds, surface cracks may develop over time in the disk bolt holes. An inspection interval is developed to preclude catastrophic disk failure by using experimental fatigue crack growth data. By combining current fatigue crack growth results with previous fatigue strain-life experimental work, an inspection interval is determined for the test disk. The fatigue crack growth life of the NASA disk bolt holes is found to be 367 cycles at a crack depth of 0.501 mm using a factor of 2 on life at maximum operating conditions. Combining this result with previous fatigue strain-life experimental work gives a total fatigue life of 1032 cycles at a crack depth of 0.501 mm. Eddy-current inspections are suggested starting at 665 cycles since eddy current detection thresholds are currently at 0.381 mm. Inspection intervals are recommended every 50 cycles when operated at maximum operating conditions.

  8. System-Wide Tests of Occupational Programs.

    ERIC Educational Resources Information Center

    Perlmutter, Deborah E.

    This report presents the background methodology, findings, and recommendations of three studies that comprised System-Wide Tests of Occupational Programs, a 4-year research program to assess the impact of vocational education using various followup techniques. Part 1 focuses on Project CATCH (Career Training Choice), a followup study of students…

  9. MIUS integration and subsystems test program

    NASA Technical Reports Server (NTRS)

    Beckham, W. S., Jr.; Shows, G. C.; Redding, T. E.; Wadle, R. C.; Keough, M. B.; Poradek, J. C.

    1976-01-01

    The MIUS Integration and Subsystems Test (MIST) facility at the Lyndon B. Johnson Space Center was completed and ready in May 1974 for conducting specific tests in direct support of the Modular Integrated Utility System (MIUS). A series of subsystems and integrated tests was conducted since that time, culminating in a series of 24-hour dynamic tests to further demonstrate the capabilities of the MIUS Program concepts to meet typical utility load profiles for a residential area. Results of the MIST Program are presented which achieved demonstrated plant thermal efficiencies ranging from 57 to 65 percent.

  10. Space station structures and dynamics test program

    NASA Technical Reports Server (NTRS)

    Moore, Carleton J.; Townsend, John S.; Ivey, Edward W.

    1987-01-01

    The design, construction, and operation of a low-Earth orbit space station poses unique challenges for development and implementation of new technology. The technology arises from the special requirement that the station be built and constructed to function in a weightless environment, where static loads are minimal and secondary to system dynamics and control problems. One specific challenge confronting NASA is the development of a dynamics test program for: (1) defining space station design requirements, and (2) identifying the characterizing phenomena affecting the station's design and development. A general definition of the space station dynamic test program, as proposed by MSFC, forms the subject of this report. The test proposal is a comprehensive structural dynamics program to be launched in support of the space station. The test program will help to define the key issues and/or problems inherent to large space structure analysis, design, and testing. Development of a parametric data base and verification of the math models and analytical analysis tools necessary for engineering support of the station's design, construction, and operation provide the impetus for the dynamics test program. The philosophy is to integrate dynamics into the design phase through extensive ground testing and analytical ground simulations of generic systems, prototype elements, and subassemblies. On-orbit testing of the station will also be used to define its capability.

  11. Fatigue test of a fiberglass based composite panel. Increasing the lifetime of freight wagon

    NASA Astrophysics Data System (ADS)

    Sobek, M.; Baier, A.; Grabowski, Ł.; Majzner, M.

    2016-08-01

    In the XXI century transportation of goods plays a key role in the economy. Due to a good logistics the economy is able to grow fluently. Although land transportation is carried out mainly through trucks for the last several years there has been noted an increase in the percentage share of rail transport in the freight transport. The main goods transported by railways are mineral fuels, mining and quarrying products. They constitute the greater part of 70% of total transported goods. Transportation of material of such high weight, high hardness and with different shapes involves increased and accelerated wear and tear of the cargo space of the wagon. This process is also magnified by substances used to prevent overheating or goods theft. Usually they are in the form of chemical compounds powder, eg. Calcium. A very large impact on the wear of the freight wagons hull is made because of mechanical damage. Their source comes mostly from loading cargo with impetus and using heavy machines during unloading. A large number of cycles of loading and unloading during the working period causes abrasion of body and as a result after several years a wagon car qualifies for a major maintenance. Possibility of application composite panels in the process of renovating the wagons body could reduce the weight of whole train and prolong the service life between mandatory technical inspection. The Paper "Fatigue test of a fiberglass based composite panel. Increasing the lifetime of freight wagon" presents the research process and the results of the endurance test of the composite panel samples fixed to a metal plate. As a fixing method a stainless steel rivet nut and a stainless steel button head socket screws were chosen. Cyclic and multiple load were applied to test samples using a pneumatic cylinder. Such a methodology simulated the forces resulting from loading and unloading of the wagon and movement of the cargo during transport. In the study a dedicated stand equipped with a

  12. Noncontact measurement of ultrasonic attenuation during rotating fatigue test of steel

    NASA Astrophysics Data System (ADS)

    Ogi, Hirotsugu; Hirao, Masahiko; Minoura, Kiyoshi

    1997-04-01

    Acoustic resonance technique has been applied to monitor the fatigue damage process of steel pipes exposed to rotating bending fatigue. The technique incorporates a superheterodyne spectrometer and an electromagnetic acoustic transducer (EMAT). The EMAT was newly developed for this purpose, and uses the magnetostrictive mechanism of ferromagnetic metals and excites and detects axial shear waves traveling around the sample pipe with axial polarization. Noncontact ultrasonic spectroscopy permits the accurate determination of the resonant frequency and the attenuation coefficient throughout the fatigue life. The attenuation coefficient shows a sharp peak around 80%-90% of the life. The evolution is interpreted as reflecting dislocation multiplication, depinning, and formation of cell structures, which is supported by transmission electron microscopy observations.

  13. Indentation hardness: A simple test that correlates with the dissipated-energy predictor for fatigue-life in bovine pericardium membranes for bioprosthetic heart valves.

    PubMed

    Tobaruela, Almudena; Rojo, Francisco Javier; García Paez, José María; Bourges, Jean Yves; Herrero, Eduardo Jorge; Millán, Isabel; Alvarez, Lourdes; Cordon, Ángeles; Guinea, Gustavo V

    2016-08-01

    The aim of this study was to evaluate the variation of hardness with fatigue in calf pericardium, a biomaterial commonly used in bioprosthetic heart valves, and its relationship with the energy dissipated during the first fatigue cycle that has been shown to be a predictor of fatigue-life (García Páez et al., 2006, 2007; Rojo et al., 2010). Fatigue tests were performed in vitro on 24 pericardium specimens cut in a root-to-apex direction. The specimens were subjected to a maximum stress of 1MPa in blocks of 10, 25, 50, 100, 250, 500, 1000 and 1500 cycles. By means of a modified Shore A hardness test procedure, the hardness of the specimen was measured before and after fatigue tests. Results showed a significant correlation of such hardness with fatigue performance and with the energy dissipated in the first cycle of fatigue, a predictor of pericardium durability. The study showed indentation hardness as a simple and reliable indicator of mechanical performance, one which could be easily implemented in improving tissue selection.

  14. Elasto-Plastic 3D Finite Element Contact Analysis of a Hole Containing a Circular Insert in a Fatigue Test Coupon

    DTIC Science & Technology

    2015-08-01

    primarily concerned with the results of a three-dimensional elasto– plastic finite element contact analysis of a typical aluminium fatigue test coupon...determine the nonlinear three-dimensional elasto–plastic contact stress distributions around a circular hole in an aluminium plate that is fitted...Australian Air Force (RAAF) airframes. An aluminium -alloy fatigue test coupon (see Figure 1) has been designed and applied in support of the validation of

  15. [Effects of a Four-Week Rehabilitation Program on Motor Performance, Quality of Life and Fatigue in Childhood Cancer Patients and Healthy Siblings].

    PubMed

    Däggelmann, J; Krauth, K A; Mailand, P; Nopper, S; Renniger, M; Bündgen, L; Rustler, V; Bloch, W; Baumann, F T

    2017-04-01

    Aim In Germany all childhood cancer patients and their families are offered the opportunity to participate in a four-week, family-oriented, inpatient rehabilitation program in order to facilitate (re-)integration into everyday life. The aim of this study is to evaluate the effect of this rehabilitation program on motor performance, quality of life (QoL) and fatigue. Methods Motor performance, QoL and fatigue were assessed in 22 childhood cancer patients and 20 healthy siblings at the beginning (t1) and the end (t2) of the four-week rehabilitation program, as well as 6 months later (t3). Results At t1 significant differences between groups were found in motor performance and physical well-being. Improvements in motor performance, QoL and fatigue were found in both groups. Conclusion Different preconditions must be considered. Childhood cancer patients as well as healthy siblings benefit from a family-oriented rehabilitation program.

  16. Accurate diagnosis of myalgic encephalomyelitis and chronic fatigue syndrome based upon objective test methods for characteristic symptoms

    PubMed Central

    Twisk, Frank NM

    2015-01-01

    Although myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) are considered to be synonymous, the definitional criteria for ME and CFS define two distinct, partially overlapping, clinical entities. ME, whether defined by the original criteria or by the recently proposed criteria, is not equivalent to CFS, let alone a severe variant of incapacitating chronic fatigue. Distinctive features of ME are: muscle weakness and easy muscle fatigability, cognitive impairment, circulatory deficits, a marked variability of the symptoms in presence and severity, but above all, post-exertional “malaise”: a (delayed) prolonged aggravation of symptoms after a minor exertion. In contrast, CFS is primarily defined by (unexplained) chronic fatigue, which should be accompanied by four out of a list of 8 symptoms, e.g., headaches. Due to the subjective nature of several symptoms of ME and CFS, researchers and clinicians have questioned the physiological origin of these symptoms and qualified ME and CFS as functional somatic syndromes. However, various characteristic symptoms, e.g., post-exertional “malaise” and muscle weakness, can be assessed objectively using well-accepted methods, e.g., cardiopulmonary exercise tests and cognitive tests. The objective measures acquired by these methods should be used to accurately diagnose patients, to evaluate the severity and impact of the illness objectively and to assess the positive and negative effects of proposed therapies impartially. PMID:26140274

  17. Accurate diagnosis of myalgic encephalomyelitis and chronic fatigue syndrome based upon objective test methods for characteristic symptoms.

    PubMed

    Twisk, Frank Nm

    2015-06-26

    Although myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) are considered to be synonymous, the definitional criteria for ME and CFS define two distinct, partially overlapping, clinical entities. ME, whether defined by the original criteria or by the recently proposed criteria, is not equivalent to CFS, let alone a severe variant of incapacitating chronic fatigue. Distinctive features of ME are: muscle weakness and easy muscle fatigability, cognitive impairment, circulatory deficits, a marked variability of the symptoms in presence and severity, but above all, post-exertional "malaise": a (delayed) prolonged aggravation of symptoms after a minor exertion. In contrast, CFS is primarily defined by (unexplained) chronic fatigue, which should be accompanied by four out of a list of 8 symptoms, e.g., headaches. Due to the subjective nature of several symptoms of ME and CFS, researchers and clinicians have questioned the physiological origin of these symptoms and qualified ME and CFS as functional somatic syndromes. However, various characteristic symptoms, e.g., post-exertional "malaise" and muscle weakness, can be assessed objectively using well-accepted methods, e.g., cardiopulmonary exercise tests and cognitive tests. The objective measures acquired by these methods should be used to accurately diagnose patients, to evaluate the severity and impact of the illness objectively and to assess the positive and negative effects of proposed therapies impartially.

  18. Cryogenic fatigue data developed for Inconel 718

    NASA Technical Reports Server (NTRS)

    Schmidt, E. H.

    1967-01-01

    Data were obtained on the cryogenic fatigue properties of Inconel 718 bar using axial loading and rotating beam fatigue tests. Results also disclosed the fatigue properties of Inconel 718 sheet materials.

  19. Test Method for the Fatigue Life of Layered TiB/Ti Functionally Graded Beams Subjected to Fully Reversed Bending

    NASA Astrophysics Data System (ADS)

    Byrd, Larry; Rickerd, Greg; Wyen, Travis; Cooley, Glenn; Quast, Jeff

    2008-02-01

    Sonic fatigue of aircraft is characterized by fully reversed bending of components subjected to acoustic excitation. This problem is compounded in high temperature environments because solutions for acoustics which tend to result in stiff structures make thermal problems worse. Conversely solutions to the thermal problem which allow expansion often fail in the presence of high acoustic levels. Errors in fatigue life prediction in the combined environment often range from a factor of 4 to 10. This results in either heavy, overly stiff structure or premature failure. This work will test the hypothesis that the fatigue life of a layered functionally graded material (FGM) will be dominated by the failure of the stiffest outer layer. This is based on the observation that for isotropic materials the life is approximately 90% crack initiation and only 10% crack growth before failure. Four sets of cantilever specimens will be tested using an electro-mechanical shaker for base excitation. The excitation will be narrow band random around the fundamental frequency. Two sets of specimens are of uniform composition consisting of 85%TiB/Ti and two are graded specimens consisting of layers that vary from commercially pure titanium to 85%TiB/Ti. Strain vs number of cycles to failure curves will be generated with both constant amplitude sine and narrow band random around the fundamental frequency excitation. The results will be examined to compare life of the uniform material to the functionally graded material. Also to be studied will be the use of Miner's rule to predict the fatigue life of the randomly excited specimens.

  20. Balloon launched decelerator test program: Post-test test report

    NASA Technical Reports Server (NTRS)

    Dickinson, D.; Schlemmer, J.; Hicks, F.; Michel, F.; Moog, R. D.

    1972-01-01

    Balloon Launched Decelerator Test (BLDT) flights were conducted during the summer of 1972 over the White Sands Missile Range. The purpose of these tests was to qualify the Viking disk-gap band parachute system behind a full-scale simulator of the Viking Entry Vehicle over the maximum range of entry conditions anticipated in the Viking '75 soft landing on Mars. Test concerns centered on the ability of a minimum weight parachute system to operate without structural damage in the turbulent wake of the blunt-body entry vehicle (140 deg, 11.5 diameter cone). This is the first known instance of parachute operation at supersonic speeds in the wake of such a large blunt body. The flight tests utilized the largest successful balloon-payload weight combination known to get to high altitude (120kft) where rocket engines were employed to boost the test vehicle to supersonic speeds and dynamic pressures simulating the range of conditions on Mars.

  1. AISI/DOE Technology Roadmap Program: Characterization of Fatigue and Crash Performance of New Generation High Strength Steels for Automotive Applications

    SciTech Connect

    Brenda Yan; Dennis Urban

    2003-04-21

    A 2-year project (2001-2002) to generate fatigue and high strain data for a new generation of high strength steels (HSS) has been completed in December 2002. The project tested eleven steel grades, including Dual Phase (DP) steels, Transformation-Induced Plasticity (TRIP) steels, Bake Hardenable (BH) steels, and conventional High Strength Low Alloy (HSLA) steels. All of these steels are of great interest in automotive industry due to the potential benefit in weight reduction, improved fuel economy, enhanced crash energy management and total system cost savings. Fatigue behavior includes strain controlled fatigue data notch sensitivity for high strength steels. High strain rate behavior includes stress-strain data for strain rates from 0.001/s to 1000/s, which are considered the important strain rate ranges for crash event. The steels were tested in two phases, seven were tested in Phase 1 and the remaining steels were tested in Phase. In a addition to the fatigue data and high st rain rate data generated for the steels studied in the project, analyses of the testing results revealed that Advanced High Strength Steels (AHSS) exhibit significantly higher fatigue strength and crash energy absorption capability than conventional HSS. TRIP steels exhibit exceptionally better fatigue strength than steels of similar tensile strength but different microstructure, for conditions both with or without notches present

  2. Kentucky's Vocational Beginning Teacher Testing Program Handbook.

    ERIC Educational Resources Information Center

    Kentucky State Dept. of Education, Frankfort. Office of Vocational Education.

    This handbook is designed to provide teacher applicants and vocational educators with general information about Kentucky's Beginning Vocational Teacher Testing Program. Information is provided on amended chapter 396 of Kentucky's Revised Statute, which stipulates that all new/beginning teachers successfully complete appropriate written tests and…

  3. Program for Area Concentration Achievement Testing.

    ERIC Educational Resources Information Center

    Golden, Anthony J.

    The Program for Area Concentration Achievement Testing (PACAT) produces the cooperative assessment instrument known as the Area Concentration Achievement Test (ACAT). The ACAT uses a model designed specifically to measure curricular strengths and weaknesses and to provide this information at the departmental level. PACAT has developed 57…

  4. Stennis personnel participate in test program

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Fernando Figueroa (left), an aerospace technologist at Stennis, and John Schmatzel (center), a professor on loan from Rowan University in Glassboro, N.J., joined Ray Wang, president of Mobitrum Corp., in Silver Springs, Md., to test a virtual sensor instrument in development. The test was performed as part of NASA's Facilitated Access to the Space Environment for Technology Development and Training program.

  5. CLIC RF High Power Production Testing Program

    SciTech Connect

    Syratchev, I.; Riddone, G.; Tantawi, S.G.; /SLAC

    2011-11-02

    The CLIC Power Extraction and Transfer Structure (PETS) is a passive microwave device in which bunches of the drive beam interact with the impedance of the periodically loaded waveguide and generate RF power for the main linac accelerating structure. The demands on the high power production ({approx} 150 MW) and the needs to transport the 100 A drive beam for about 1 km without losses, makes the PETS design rather unique and the operation very challenging. In the coming year, an intense PETS testing program will be implemented. The target is to demonstrate the full performance of the PETS operation. The testing program overview and test results available to date are presented.

  6. High Frequency Fatigue of Turbine Blade Material.

    DTIC Science & Technology

    1982-10-01

    TESTS 83 APPENDIX II - S-N DATA FOR INCONEL - 718 99...amplitude tests were run on sheet Inconel - 718 at 650*C. The data is presented as da/dM vs AK o plots and in tabular maj or form. These tests are included in...Kip 98 APPENDIX II S-N DATA FOR INCONEL - 718 During the early stages of this program, several fatigue life tests , (S-N tests ), were run on Inconel - 718

  7. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity

    PubMed Central

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-01-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s-1, and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p < 0.05, Hedge’s g = 4.27). Both measures were highly associated (r = 0.83), and the 95% limits of agreement (LoA) represented 24.5% of TWWAnT. TWFAT of knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p < 0.05, g = 9.52). By contrast, both measures were not associated (r = 0.09), and the 95% LoA represented 31.1% of TWWAnT. Combining TWFAT of knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p < 0.05, g = 5.26), a moderate association (r = 0.65) and 95% LoA representing 25.5% of TWWAnT. We concluded that TWFAT of knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key points Total work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test). The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a

  8. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity.

    PubMed

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-03-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s(-1), and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p < 0.05, Hedge's g = 4.27). Both measures were highly associated (r = 0.83), and the 95% limits of agreement (LoA) represented 24.5% of TWWAnT. TWFAT of knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p < 0.05, g = 9.52). By contrast, both measures were not associated (r = 0.09), and the 95% LoA represented 31.1% of TWWAnT. Combining TWFAT of knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p < 0.05, g = 5.26), a moderate association (r = 0.65) and 95% LoA representing 25.5% of TWWAnT. We concluded that TWFAT of knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key pointsTotal work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test).The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a high

  9. Propulsion Induced Effects (PIE) Test Program

    NASA Technical Reports Server (NTRS)

    Cappuccio, Gelsomina; Won, Mark J.

    1999-01-01

    The Propulsion Induced Effects (PIE) test program is being lead by NASA Ames for Configuration Aerodynamics (CA). Representatives from CA, Technology Integration (TI), Inlet, and the Nozzle ITD's are working with Ames in defining and executing this test program. The objective of the CA 4-14 milestone is to assess the propulsion/airframe integration characteristics of the Technology Concept Airplane (TCA) and design variations using computational and experimental methods. The experimental aspect includes static calibrations, transonic and supersonic wind tunnel testing. The test program will generate a comprehensive database that will include all appropriate wind tunnel corrections, with emphasis placed on establishing the propulsion induced effects on the flight performance of the TCA.

  10. Fatigue test results of the rotating steel blades of steam turbine K-25-0.6 GEO with ion-plasma coating

    NASA Astrophysics Data System (ADS)

    Kachalin, G. V.; Mednikov, A. F.; Tkhabisimov, A. B.; Arkad'ev, D. A.; Temkin, S. G.; Senina, N. A.

    2016-12-01

    Fatigue test results of the rotating steel blades of the fourth stage of the K-25-0.6 low pressure cylinder Geo steam turbine manufactured in the Kaluga Turbine Plant (hereinafter, KTP) with the ion-plasma coating were presented. Coating formation was carried out at the National Research University (MPEI) on the Gefest vacuum pilot plant by the magnetron sputtering method. Characteristics of the obtained coating were analyzed with the use of the scientific-research equipment of the National Research University (MPEI). Fatigue tests of the rotating blades and determination of the fatigue strength of the material with the ion-plasma coating were carried out on the electrodynamic vibration machines VEDS-400A in the KTP structural laboratory. The following characteristics were obtained after tests: Ti-TiN composition, 10-11 μm thickness, 1200 HV 0.05 microhardness. Fatigue tests showed that destruction, regardless of availability or nonavailability of the coating, took place by cross-section in the root zone both on the leading and trailing edges of the blade, i.e., in the most stressed zones. It was found out that the maximum stresses during tests were revealed in the root section along the trailing edge on the blade pressure side, and the less stresses were on the leading edge. Fatigue strength of the working blades after coating formation increased by 12% minimum. Results of the fatigue tests prove the previously obtained data concerning 10-12% increase of the fatigue strength of the blade steel with the ion-plasma coating and allow claiming that the process of their formation exerts the positive influence on the fatigue characteristics of the blade materials.

  11. Etude de la resistance en fatigue des materiaux bitumineux

    NASA Astrophysics Data System (ADS)

    Touhara, Radouen

    The goal of this research program is to evaluate and characterize the fatigue behaviour of two GB20 hot mix asphalt made with two different bitumen. One of them is made in laboratory with a straight-run PG58-28 bitumen, while the second mix was made in an asphalt plant with a PG64-28 bitumen. Two characterization tests, in homogeneous conditions, done in traction/compression on cylindrical specimens are used in this study. First, a complex modulus test performed in the linear viscoelasticity (LVE) domain is used to characterize the mixes and second, a fatigue test is done to evaluate the mixes performances. The fatigue tests were done in strain controlled at different amplitude. All fatigue tests were performed at 10Hz, but at different temperatures (10, 20 and 30°C) in order to evaluate the effect of the temperature on the fatigue behaviour of those mixes. In this document, the results are presented, and the analysis of the results as a function of the grade of bitumen, the tests’ temperature and the dispersion of the results is performed. Also, the DGCB method is applied to the fatigue results to calculate the rate of damage per cycle followed by a study of the different failure criteria (Nf) to predict the fatigue life of asphalt mixes. Keywords: bituminous materials, fatigue, complex modulus, Damage.

  12. Application of Self Nulling Eddy Current Probe Technique to the Detection of Fatigue Crack Initiation and Control of Test Procedures

    NASA Technical Reports Server (NTRS)

    Namkung, M.; Nath, S.; Wincheski, B.; Fulton, J. P.

    1994-01-01

    A major part of fracture mechanics is concerned with studying the initiation and propagation of fatigue cracks. This typically requires constant monitoring of crack growth during fatigue cycles and the knowledge of the precise location of the crack tip at any given time. One technique currently available for measuring fatigue crack length is the Potential Drop method. The method, however, may be inaccurate if the direction of crack growth deviates considerably from what was assumed initially or the curvature of the crack becomes significant. Another popular approach is to optically view the crack using a high magnification microscope, but this entails a person constantly monitoring it. The present proposed technique uses an automated scheme, in order to eliminate the need for a person to constantly monitor the experiment. Another technique under development elsewhere is to digitize an optical image of the test specimen surface and then apply a pattern recognition algorithm to locate the crack tip. A previous publication showed that the self nulling eddy current probe successfully tracked a simulated crack in an aluminum sample. This was the impetus to develop an online real time crack monitoring system. An automated system has been developed which includes a two axis scanner mounted on the tensile testing machine, the probe and its instrumentation and a personal computer (PC) to communicate and control all the parameters. The system software controls the testing parameters as well as monitoring the fatigue crack as it propagates. This paper will discuss the experimental setup in detail and demonstrate its capabilities. A three dimensional finite element model is utilized to model the magnetic field distribution due to the probe and how the probe voltage changes as it scans the crack. Experimental data of the probe for different samples under zero load, static load and high cycle fatigue load will be discussed. The final section summarizes the major accomplishments

  13. Modeling axial compression fatigue in fiber ropes

    SciTech Connect

    Hearle, J.W.S.; Hobbs, R.E.; Overington, M.S.; Banfield, S.J.

    1995-12-31

    The modeling of long-term fatigue performance of twisted ropes has been extended to cover axial compression fatigue. This mode of failure has been observed in use and testing of ropes. It is characterized by sharp cooperative kinking of yarns, which leads to flex fatigue breakage of fibers. A model of pipeline buckling was modified to allow for plasticity in bending. An axial and lateral restraints, which influence the buckling, were derived from the existing rope mechanics model. Axial compression was introduced into the total computational model, in order to predict the form of buckling and the consequent fiber failure. An alternative use of the program is simply to detect conditions in which axial compression occurs as an indication of the occurrence of fatigue.

  14. Crack propagation monitoring in a full-scale aircraft fatigue test based on guided wave-Gaussian mixture model

    NASA Astrophysics Data System (ADS)

    Qiu, Lei; Yuan, Shenfang; Bao, Qiao; Mei, Hanfei; Ren, Yuanqiang

    2016-05-01

    For aerospace application of structural health monitoring (SHM) technology, the problem of reliable damage monitoring under time-varying conditions must be addressed and the SHM technology has to be fully validated on real aircraft structures under realistic load conditions on ground before it can reach the status of flight test. In this paper, the guided wave (GW) based SHM method is applied to a full-scale aircraft fatigue test which is one of the most similar test status to the flight test. To deal with the time-varying problem, a GW-Gaussian mixture model (GW-GMM) is proposed. The probability characteristic of GW features, which is introduced by time-varying conditions is modeled by GW-GMM. The weak cumulative variation trend of the crack propagation, which is mixed in time-varying influence can be tracked by the GW-GMM migration during on-line damage monitoring process. A best match based Kullback-Leibler divergence is proposed to measure the GW-GMM migration degree to reveal the crack propagation. The method is validated in the full-scale aircraft fatigue test. The validation results indicate that the reliable crack propagation monitoring of the left landing gear spar and the right wing panel under realistic load conditions are achieved.

  15. Experimental stress analysis and fatigue tests of five 24-in. NPS ANSI Standard B16. 9 tees. [PWR; BWR

    SciTech Connect

    Moore, S.E.; Hayes, J.K.; Weed, R.A.

    1985-03-01

    Experimental stress analyses and low-cycle fatigue tests of five 24-in. nominal pipe size American National Standards Institute (ANSI) Standard B16.9 forged tees are documented in this report. The tees, designated as Oak Ridge National Laboratory tees T10, T11, T12, T13, and T16, were tested under subcontract at Combustion Engineering, Inc. in Chattanooga, Tennessee. Experimental stress analyses were conducted for 12 individual loadings on each tee. Each test model was instrumented with approx. 225, 1/8-in. three-gage, 45/sup 0/ strain rosettes on the inside and outside surfaces; and 6 linear variable differential transformers mounted on special nonflexible holding frames for measuring deflections and rotations of the pipe extensions. Following completion of the strain-gate tests, each tee was fatigue tested to failure with either a fully reversed displacement controlled in-plane bending moment on the branch or a cyclic internal pressure that ranged from a value slightly above zero to about 90% of the nominal yield pressure of the pipe extensions.

  16. Effects of general fatigue induced by incremental maximal exercise test on gait stability and variability of healthy young subjects.

    PubMed

    Vieira, Marcus Fraga; de Sá E Souza, Gustavo Souto; Lehnen, Georgia Cristina; Rodrigues, Fábio Barbosa; Andrade, Adriano O

    2016-10-01

    The purpose of this study was to determine whether general fatigue induced by incremental maximal exercise test (IMET) affects gait stability and variability in healthy subjects. Twenty-two young healthy male subjects walked in a treadmill at preferred walking speed for 4min prior (PreT) the test, which was followed by three series of 4min of walking with 4min of rest among them. Gait variability was assessed using walk ratio (WR), calculated as step length normalized by step frequency, root mean square (RMSratio) of trunk acceleration, standard deviation of medial-lateral trunk acceleration between strides (VARML), coefficient of variation of step frequency (SFCV), length (SLCV) and width (SWCV). Gait stability was assessed using margin of stability (MoS) and local dynamic stability (λs). VARML, SFCV, SLCV and SWCV increased after the test indicating an increase in gait variability. MoS decreased and λs increased after the test, indicating a decrease in gait stability. All variables showed a trend to return to PreT values, but the 20-min post-test interval appears not to be enough for a complete recovery. The results showed that general fatigue induced by IMET alters negatively the gait, and an interval of at least 20min should be considered for injury prevention in tasks with similar demands.

  17. Effects of Holding Time on Thermomechanical Fatigue Properties of Compacted Graphite Iron Through Tests with Notched Specimens

    NASA Astrophysics Data System (ADS)

    Ghodrat, Sepideh; Riemslag, Ton A. C.; Kestens, Leo A. I.; Petrov, Roumen H.; Janssen, Michael; Sietsma, Jilt

    2013-05-01

    In cylinder heads of compacted graphite iron (CGI), the heating and cooling cycles can lead to localized cracking due to thermomechanical fatigue (TMF). Traditionally, TMF behavior is studied by thermal cycling of smooth specimens. The resulting number of cycles to failure ( N f) constitutes a single parameter that can be used to predict actual service failures. Nevertheless, there are also some drawbacks of the conventional testing procedures, most noticeably the prolonged testing times and a considerable scatter in test results. To address these drawbacks, TMF tests were performed using notched specimens, resulting in shorter testing times with less scatter. In the case of cast iron, artificial notches do not necessarily change the TMF behavior since the inherent graphite particles behave as internal notches. Using a notch depth of 0.2 mm, the effect of prolonged holding times (HT) on TMF lifetime was studied and a clear effect was found. Extended holding times were also found to be accompanied by relaxation of compressive stresses, causing higher tensile stresses to develop in the subsequent low temperature stages of the TMF cycles. The lifetimes in notched CGI specimens can be predicted by the Paris' fatigue crack growth model. This model was used to differentiate between the individual effects of stress level and holding times on TMF lifetime. Microstructural changes were evaluated by analyzing quantitative data sets obtained by orientation contrast microscopy based on electron backscattered diffraction (EBSD).

  18. LOGMIS Programmed Texts, Tests and Answers.

    DTIC Science & Technology

    1979-04-01

    This publication contains the programmed text and related test and answer booklets produced to teach field users correct procedures for utilization of the Army’s Logistics Management Information System (LOGMIS). It was prepared by ARINC Research Corporation under Contract DAEA18-77-C-0184 for the Logistics Evaluation Branch, Plans and Programs Division of the Assistant Chief of Staff for Logistics, U.S. Army Communications Command. (Author)

  19. Lithium-Ion Verification Test Program

    NASA Technical Reports Server (NTRS)

    McKissock, Barbara; Manzo, Michelle; Miller, Thomas; Reid, Concha; Bennett, William; Gemeiner, Russel

    2006-01-01

    Need for technology verification for aerospace applications. Structure flexible program that will allow assessment of current technology capabilities. Provide information about various vendors. Provide for assessment of technology developments. Developed statistical DOE to interpret relationships in data and to address program test goals and resource limitations. Data will be used to develop a model to predict life of cells as a function of DOD, temperature, and EOCV.

  20. High Cycle Fatigue (HCF) Science and Technology Program, 2001 Annual Report

    DTIC Science & Technology

    2002-05-01

    Future Efforts 2.7.1 Advanced High Cycle Fatigue Mechanics 2.7.2 HCF Properties of Welds on Nickel-Based Alloys 18 2.1 Microstructure Effects of...the purpose of the investigation was also to study the crystal orientation influence on, and the microstructural features that affect, the cyclic...and Ti alloys. v A continuum level mechanics model (Adhesion Model), incorporating interfacial adhesion, material properties and contact loads, for

  1. CCDs at ESO: A Systematic Testing Program

    NASA Astrophysics Data System (ADS)

    Abbott, T. M. C.; Warmels, R. H.

    ESO currently offers a stable of 12 CCDs for use by visiting astronomers. It is incumbent upon ESO to ensure that these devices perform according to their advertised specifications (Abbott 1994). We describe a systematic, regular testing program for CCDs which is now being applied at La Silla. These tests are designed to expose failures which may not have catastrophic effects but which may compromise observations. The results of these tests are stored in an archive, accessible to visiting astronomers, and will be subject to trend analysis. The test are integrated in the CCD reduction package of the Munich Image Data Analysis System (ESO-MIDAS).

  2. Electric power system test and verification program

    NASA Technical Reports Server (NTRS)

    Rylicki, Daniel S.; Robinson, Frank, Jr.

    1994-01-01

    Space Station Freedom's (SSF's) electric power system (EPS) hardware and software verification is performed at all levels of integration, from components to assembly and system level tests. Careful planning is essential to ensure the EPS is tested properly on the ground prior to launch. The results of the test performed on breadboard model hardware and analyses completed to date have been evaluated and used to plan for design qualification and flight acceptance test phases. These results and plans indicate the verification program for SSF's 75-kW EPS would have been successful and completed in time to support the scheduled first element launch.

  3. Fiber optic strain monitoring of textile GFRP during RTM molding and fatigue tests by using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Kosaka, Tatsuro; Osaka, Katsuhiko; Nakakita, Satoru; Fukuda, Takehito

    2003-08-01

    This paper describes cure and health monitoring of glass fiber reinforced plastics (GFRP) textile composites both during a resin transfer molding (RTM) process and in loading tests. Carbon fiber reinforced plastics (CFRP) textile composites also were used for a comparative study. Fiber Bragg grating (FBG) fiber optic sensors were embedded in FRP to monitor internal strain. From the results of cure monitoring, it was found that the embedded FBG sensors were useful to know when cured resin constrained fibers. It also appeared that specimens were subjected to friction stress resulted from difference of coefficient of thermal expansion between FRP and a stainless steel mold in cooling process of RTM molding. After the molding, tensile and fatigue tests were conducted. The results of tensile tests showed that output of the embedded FBG sensors agreed well that of surface-bonded strain gauges despite deterioration of reflected spectra form the sensors. From the results of fatigue tests, the FBG sensors showed good status until 100,000 cycles when specimens had no damage. From these results, it can be concluded that embedded FBG sensors have good capability of monitoring internal strain in textile FRP both during RTM process and in service.

  4. Acoustic fatigue testing on different materials and skin-stringer elements

    NASA Astrophysics Data System (ADS)

    Koenig, Klaus

    1994-09-01

    Within a comparative study, 29 different coupons covering 8 different designs and 6 different materials were fatigued by an excitation of 30 g(exp 2)/Hz on a shaker. The selected designs and materials represent realistic alternatives of an aircraft surface structure. The investigation led to the following conclusion: (1) Besides classical aluminium, CFRP is the best material with regard to sonic fatigue. (2) Al/Li, ARALL and Al layer materials showed shorter life times than the classical Al. (3) The most striking improvement in design for the dimensions selected here was achieved with separate doublers between skin and stringer. (4) The modal damping found was most often smaller than the 1.7 percent of the critical as known from ESDU for Al. (5) Pure CFRP without rivets showed the smallest damping: 0.6 - 0.9 percent.

  5. Adaption of an In-Situ Microscale Tension Technique to Enable Fatigue Testing (PREPRINT)

    DTIC Science & Technology

    2012-08-01

    the crystallographic orientations of the matrix β phase also will influence the mechanical response, although to a lesser degree than the α phase...Thus, the variation in mechanical properties as a function of crystallographic orientation could be expected to account for the scatter in yield... mechanical properties , including fatigue performance, are strongly related to the crystallographic texture of these alloys.[5-7] With the combined use

  6. Testing of concurrent programs and partial specifications

    SciTech Connect

    Hamlet, D.

    1982-12-01

    The testing problems of concurrent systems include those of sequential programs, but there are two additional difficulties: the scheduling of tasks may alter the behavior, making tests misleading; testing may be conducted at an early stage of development, by users who are not software experts. Concurrent process systems can be modeled by a collection of finite-state transducers, in a way that displays their unique problems. The specification languages PAISLey and Gist approach the definition of concurrent systems differently, but both permit users to execute partially defined systems. The declarative language PROLOG, although not explicitly designed for concurrent programming, exhibits similar characteristics. Prototype execution has some unexpected implications for testing, and for final implementation.

  7. Wind turbine blade fatigue tests: lessons learned and application to SHM system development

    SciTech Connect

    Taylor, Stuart G.; Farinholt, Kevin M.; Jeong, Hyomi; Jang, JaeKyung; Park, Gyu Hae; Todd, Michael D.; Farrar, Charles R.; Ammerman, Curtt N.

    2012-06-28

    This paper presents experimental results of several structural health monitoring (SHM) methods applied to a 9-meter CX-100 wind turbine blade that underwent fatigue loading. The blade was instrumented with piezoelectric transducers, accelerometers, acoustic emission sensors, and foil strain gauges. It underwent harmonic excitation at its first natural frequency using a hydraulically actuated resonant excitation system. The blade was initially excited at 25% of its design load, and then with steadily increasing loads until it failed. Various data were collected between and during fatigue loading sessions. The data were measured over multiple frequency ranges using a variety of acquisition equipment, including off-the-shelf systems and specially designed hardware developed by the authors. Modal response, diffuse wave-field transfer functions, and ultrasonic guided wave methods were applied to assess the condition of the wind turbine blade. The piezoelectric sensors themselves were also monitored using a sensor diagnostics procedure. This paper summarizes experimental procedures and results, focusing particularly on fatigue crack detection, and concludes with considerations for implementing such damage identification systems, which will be used as a guideline for future SHM system development for operating wind turbine blades.

  8. No Critical Peripheral Fatigue Threshold during Intermittent Isometric Time to Task Failure Test with the Knee Extensors

    PubMed Central

    Froyd, Christian; Beltrami, Fernando G.; Millet, Guillaume Y.; Noakes, Timothy D.

    2016-01-01

    It has been proposed that group III and IV muscle afferents provide inhibitory feedback from locomotor muscles to the central nervous system, setting an absolute threshold for the development of peripheral fatigue during exercise. The aim of this study was to test the validity of this theory. Thus, we asked whether the level of developed peripheral fatigue would differ when two consecutive exercise trials were completed to task failure. Ten trained sport students performed two exercise trials to task failure on an isometric dynamometer, allowing peripheral fatigue to be assessed 2 s after maximal voluntary contraction (MVC) post task failure. The trials, separated by 8 min, consisted of repeated sets of 10 × 5-s isometric knee extension followed by 5-s rest between contractions. In each set, the first nine contractions were performed at a target force at 60% of the pre-exercise MVC, while the 10th contraction was a MVC. MVC and evoked force responses to supramaximal electrical femoral nerve stimulation on relaxed muscles were assessed during the trials and at task failure. Stimulations at task failure consisted of single stimulus (SS), paired stimuli at 10 Hz (PS10), paired stimuli at 100 Hz (PS100), and 50 stimuli at 100 Hz (tetanus). Time to task failure for the first trial (12.84 ± 5.60 min) was longer (P < 0.001) than for the second (5.74 ± 1.77 min). MVC force was significantly lower at task failure for both trials compared with the pre-exercise values (both P < 0.001), but there were no differences in MVC at task failure in the first and second trials (P = 1.00). However, evoked peak force for SS, PS100, and tetanus were all reduced more at task failure in the second compared to the first trial (P = 0.014 for SS, P < 0.001 for PS100 and tetanus). These results demonstrate that subjects do not terminate exercise at task failure because they have reached a critical threshold in peripheral fatigue. The present data therefore question the existence of a

  9. An indentation fatigue strength law

    NASA Astrophysics Data System (ADS)

    Xu, Baoxing; Yonezu, Akio; Chen, Xi

    2010-05-01

    Indentation fatigue, where a cyclic load is applied on the sample via an indenter, emerges as an alternative approach for measuring the fatigue properties of materials. We have carried out indentation fatigue tests on a poly(vinyl chloride) (PVC) bulk material, as well as on TiN and NiP films/coatings deposited on SUS304 steel substrates, and demonstrate that a simple power-law relationship can be established between the indentation load amplitude and number of cycles to failure. Such a law is very similar to the conventional fatigue strength law obtained from uniaxial tests. The agreement between the fatigue stress exponents obtained by uniaxial and indentation fatigue tests suggests the potential applicability of the indentation fatigue technique for extracting the fatigue properties of materials.

  10. Three Dimensional Constraint Effects on the Estimated (Delta)CTOD during the Numerical Simulation of Different Fatigue Threshold Testing Techniques

    NASA Technical Reports Server (NTRS)

    Seshadri, Banavara R.; Smith, Stephen W.

    2007-01-01

    Variation in constraint through the thickness of a specimen effects the cyclic crack-tip-opening displacement (DELTA CTOD). DELTA CTOD is a valuable measure of crack growth behavior, indicating closure development, constraint variations and load history effects. Fatigue loading with a continual load reduction was used to simulate the load history associated with fatigue crack growth threshold measurements. The constraint effect on the estimated DELTA CTOD is studied by carrying out three-dimensional elastic-plastic finite element simulations. The analysis involves numerical simulation of different standard fatigue threshold test schemes to determine how each test scheme affects DELTA CTOD. The American Society for Testing and Materials (ASTM) prescribes standard load reduction procedures for threshold testing using either the constant stress ratio (R) or constant maximum stress intensity (K(sub max)) methods. Different specimen types defined in the standard, namely the compact tension, C(T), and middle cracked tension, M(T), specimens were used in this simulation. The threshold simulations were conducted with different initial K(sub max) values to study its effect on estimated DELTA CTOD. During each simulation, the DELTA CTOD was estimated at every load increment during the load reduction procedure. Previous numerical simulation results indicate that the constant R load reduction method generates a plastic wake resulting in remote crack closure during unloading. Upon reloading, this remote contact location was observed to remain in contact well after the crack tip was fully open. The final region to open is located at the point at which the load reduction was initiated and at the free surface of the specimen. However, simulations carried out using the constant Kmax load reduction procedure did not indicate remote crack closure. Previous analysis results using various starting K(sub max) values and different load reduction rates have indicated DELTA CTOD is

  11. Hydraulic Diagnostics and Fault Isolation Test Program.

    DTIC Science & Technology

    1987-02-13

    and Fault Isolation Test Program was to demonstrate and evaluate the practicality of a fault detection and isolation system on an aircraft. The...system capable of fault detection and isolation in a hydraulic subsystem through the use of sensors and a microprocessor (Fig. 1). The microprocessor...DISCUSSION 2.1 DESCRIPTION OF HYDRAULIC SYSTEM SIMULATOR The fault detection and isolation test arrangement consisted of a high pressure, lightweight

  12. Cooperative field test program for wind systems

    SciTech Connect

    Bollmeier, W.S. II; Dodge, D.M.

    1992-03-01

    The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.

  13. United States Ski Team Fitness Testing Program.

    ERIC Educational Resources Information Center

    Gettman, Larry R.

    Presented is a fitness profile designed to identify the individual athlete's strengths and weaknesses. Specifically, the areas of fitness examined are a) muscular strength; b) cardiovascular respiratory function; c) body composition; and d) motor abilities, agility, and speed. The procedures in the testing program involve the following: a) the…

  14. Crime Laboratory Proficiency Testing Research Program.

    ERIC Educational Resources Information Center

    Peterson, Joseph L.; And Others

    A three-year research effort was conducted to design a crime laboratory proficiency testing program encompassing the United States. The objectives were to: (1) determine the feasibility of preparation and distribution of different classes of physical evidence; (2) assess the accuracy of criminalistics laboratories in the processing of selected…

  15. French Flight Test Program LEA Status

    DTIC Science & Technology

    2010-09-01

    PROMETHEE program ([9]); • A3CP ([10]); • PTAH-SOCAR (MBDA- Astrium ST); and • Cooperation with research laboratories (Ref11 to Ref13). Today...several PTAH-SOCAR C/SiC composite panels have been successfully tested by MBDA and Astrium ST in representative conditions and long accumulated

  16. Fourteen Years of Assessment: Regents' Testing Program.

    ERIC Educational Resources Information Center

    Bridges, Jean Bolen

    In 1972, the Board of Regents of the University System of Georgia instituted the Regents' Testing Program (RTP) to provide systemwide information on the status of student competence in reading and writing and to provide a uniform means of identifying those students who fail to attain minimum levels of competence in these areas. Since 1972, some…

  17. Fatigue damage observed non-destructively in fibre composite coupon test specimens by X-ray CT

    NASA Astrophysics Data System (ADS)

    Jespersen, K. M.; Mikkelsen, L. P.

    2016-07-01

    This study presents a method for monitoring the 3D fatigue damage progression on a micro-structural level in a glass fibre/polymer coupon test specimen by means of laboratory X-ray Computed Tomography (CT). A modified mount and holder made for the standard test samples to fit into the X-ray CT scanner along with a tension clamp solution is presented. Initially, the same location of the test specimen is inspected by ex-situ X-ray CT during the fatigue loading history, which shows the damage progression on a micro-structural level. The openings of individual uni-directional (UD) fibre fractures are seen to generally increase with the number of cycles, and new regions of UD fibre fractures also appear. There are some UD fibre fractures that are difficult to detect since their opening is small. Therefore, the effect of tension on the crack visibility is examined afterwards using a tension clamp solution. With applied tension some additional cracks become visible and the openings of fibre fractures increases, which shows the importance of applied tension during the scan.

  18. Evaluation of taper joints with combined fatigue and crevice corrosion testing: comparison to human explanted modular prostheses.

    PubMed

    Reclaru, L; Brooks, R A; Zuberbühler, M; Eschler, P-Y; Constantin, F; Tomoaia, G

    2014-01-01

    The requirement for revision surgery of total joint replacements is increasing and modular joint replacement implants have been developed to provide adjustable prosthetic revision systems with improved intra-operative flexibility. An electrochemical study of the corrosion resistance of the interface between the distal and proximal modules of a modular prosthesis was performed in combination with a cyclic fatigue test. The complexity resides in the existence of interfaces between the distal part, the proximal part, and the dynamometric screw. A new technique for evaluating the resistance to cyclic dynamic corrosion with crevice stimulation was used and the method is presented. In addition, two components of the proximal module of explanted Ti6Al4V and Ti6Al7Nb prostheses were investigated by optical and electron microscopy. Our results reveal that: The electrolyte penetrates into the interface between the distal and proximal modules during cyclic dynamic fatigue tests, the distal module undergoes cracking and corrosion was generated at the interface between the two models; The comparison of the explanted proximal parts with the similar prostheses evaluated following cyclic dynamic crevice corrosion testing showed that there were significant similarities indicating that this method is suitable for evaluating materials used in the fabrication of modular prostheses.

  19. A study of elevated temperature testing techniques for the fatigue behavior of PMCS: Application to T650-35/AMB21

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, Andrew L.; Gastelli, Michael G.; Ellis, John R.; Burke, Christopher S.

    1995-01-01

    An experimental study was conducted to investigate the mechanical behavior of a T650-35/AMB21 eight-harness satin weave polymer composite system. Emphasis was placed on the development and refinement of techniques used in elevated temperature uniaxial PMC testing. Issues such as specimen design, gripping, strain measurement, and temperature control and measurement were addressed. Quasi-static tensile and fatigue properties (R(sub sigma) = 0.1) were examined at room and elevated temperatures. Stiffness degradation and strain accumulation during fatigue cycling were recorded to monitor damage progression and provide insight for future analytical modeling efforts. Accomplishments included an untabbed dog-bone specimen design which consistently failed in the gage section, accurate temperature control and assessment, and continuous in-situ strain measurement capability during fatigue loading at elevated temperatures. Finally, strain accumulation and stiffness degradation during fatigue cycling appeared to be good indicators of damage progression.

  20. Space shuttle orbiter vehicle star tracker test program plan

    NASA Technical Reports Server (NTRS)

    Smith, R. A.

    1974-01-01

    The development model test program was written to provide guidance for essential star tracker test support to the Space Shuttle Orbiter Program. The program organization included test equipment preparation, prototype baseline/acceptance tests, prototype total performance tests, and prototype special tests. Test configurations, preparation phase, documentation, scheduling, and manpower requirements are discussed. The test program permits an early evaluation of the tracker's performance prior to completion and testing of the final flight models.

  1. 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.

  2. Micromechanics of Fatigue.

    DTIC Science & Technology

    1992-06-01

    recalled. Application of the derived tools to Apha-Two- Titanium Aluminide Aliov is made with a first series of strain controlled fatigue tests the locally...accumulation, and, multiaxial fatigue. In section 6, application is performed on the Alpha-Two- Titanium Alum:Aide Alloy.With a first serie of strain controlled ...tests needed for the identification of the model are described in the following figures. Test n’l is a classical tensile test strain controlled 1 = 0

  3. Periodic Overload and Transport Spectrum Fatigue Crack Growth Tests of Ti62222STA and Al2024T3 Sheet

    NASA Technical Reports Server (NTRS)

    Phillips, Edward P.

    1999-01-01

    Variable amplitude loading crack growth tests have been conducted to provide data that can be used to evaluate crack growth prediction codes. Tests with periodic overloads or overloads followed by underloads were conducted on titanium alloy Ti-6Al-2Sn-2Zr-2Mo-2Cr solution treated and aged (Ti62222STA) material at room temperature and at 350 F. Spectrum fatigue crack growth tests were conducted on two materials (Ti62222STA and aluminum alloy 2024-T3) using two transport lower-wing test spectra at two temperatures (room temperature and 350 F (Ti only)). Test lives (growth from an initial crack half-length of 0.15 in. to failure) were recorded in all tests and the crack length against cycles (or flights) data were recorded in many of the tests. The following observations were made regarding the test results: (1) in tests of the Ti62222STA material, the tests at 350 F had longer lives than those at room temperature, (2) in tests to the MiniTwist spectrum, the Al2024T3 material showed much greater crack growth retardations due to the highest stresses in the spectrum than did the Ti62222STA material, and (3) comparisons of material crack growth performances on an "equal weight" basis were spectrum dependent.

  4. Low-cycle thermal fatigue

    NASA Technical Reports Server (NTRS)

    Halford, G. R.

    1986-01-01

    A state-of-the-art review is presented of the field of thermal fatigue. Following a brief historical review, the concept is developed that thermal fatigue can be viewed as processes of unbalanced deformation and cracking. The unbalances refer to dissimilar mechanisms occurring in opposing halves of thermal fatigue loading and unloading cycles. Extensive data summaries are presented and results are interpreted in terms of the unbalanced processes involved. Both crack initiation and crack propagation results are summarized. Testing techniques are reviewed, and considerable discussion is given to a technique for thermal fatigue simulation, known as the bithermal fatigue test. Attention is given to the use of isothermal life prediction methods for the prediction of thermal fatigue lives. Shortcomings of isothermally-based life prediction methods are pointed out. Several examples of analyses and thermal fatigue life predictions of high technology structural components are presented. Finally, numerous dos and don'ts relative to design against thermal fatigue are presented.

  5. Ex-situ tensile fatigue-creep testing: A powerful tool to simulate in-situ mechanical degradation in fuel cells

    NASA Astrophysics Data System (ADS)

    Sadeghi Alavijeh, A.; Venkatesan, S. V.; Khorasany, R. M. H.; Kim, W. H. J.; Kjeang, E.

    2016-04-01

    An ex-situ tensile fatigue and creep based accelerated stress test (TFC-AST) is proposed to evaluate the mechanical stability of catalyst coated membranes (CCMs) used in fuel cells. The fatigue-creep action of the TFC test is analyzed by tensile and hygrothermal expansion measurements on partially degraded specimens supplemented by microstructural characterization using transmission electron microscopy, revealing significant decay in mechanical properties as well as morphological rearrangement due to the combined fatigue and creep loading. Through comparison with in-situ hygrothermally degraded CCMs, the TFC-AST protocol is demonstrated to be an economical alternative to the costly in-situ mechanical accelerated stress tests that can reduce the test duration by more than 99%.

  6. Static tests of the propulsion system. [Propfan Test Assessment program

    NASA Technical Reports Server (NTRS)

    Withers, C. C.; Bartel, H. W.; Turnberg, J. E.; Graber, E. J.

    1987-01-01

    Advanced, highly-loaded, high-speed propellers, called propfans, are promising to revolutionize the transport aircraft industry by offering a 15- to 30-percent fuel savings over the most advanced turbofans without sacrificing passenger comfort or violating community noise standards. NASA Lewis Research Center and industry have been working jointly to develop the needed propfan technology. The NASA-funded Propfan Test Assessment (PTA) Program represents a key element of this joint program. In PTA, Lockheed-Georgia, working in concert with Hamilton Standard, Rohr Industries, Gulfstream Aerospace, and Allison, is developing a propfan propulsion system which will be mounted on the left wing of a modified Gulfstream GII aircraft and flight tested to verify the in-flight characteristics of a 9-foot diameter, single-rotation propfan. The propfan, called SR-7L, was designed and fabricated by Hamilton Standard under a separate NASA contract. Prior to flight testing, the PTA propulsion system was static tested at the Rohr Brown Field facility. In this test, propulsion system operational capability was verified and data was obtained on propfan structural response, system acoustic characteristics, and system performance. This paper reports on the results of the static tests.

  7. Nevada Test Site Radiation Protection Program

    SciTech Connect

    Radiological Control Managers' Council, Nevada Test Site

    2007-08-09

    Title 10 Code of Federal Regulations (CFR) 835, 'Occupational Radiation Protection', establishes radiation protection standards, limits, and program requirements for protecting individuals from ionizing radiation resulting from the conduct of U.S. Department of Energy (DOE) activities. 10 CFR 835.101(a) mandates that DOE activities be conducted in compliance with a documented Radiation Protection Program (RPP) as approved by DOE. This document promulgates the RPP for the Nevada Test Site (NTS), related (onsite or offsite) DOE National Nuclear Security Administration Nevada Site Office (NNSA/NSO) operations, and environmental restoration offsite projects.

  8. Refinements and Tests of an Advanced Controller to Mitigate Fatigue Loads in the Controls Advanced Research Turbine: Preprint

    SciTech Connect

    Wright, A.; Fleming, P.

    2010-12-01

    Wind turbines are complex, nonlinear, dynamic systems forced by aerodynamic, gravitational, centrifugal, and gyroscopic loads. The aerodynamics of wind turbines are nonlinear, unsteady, and complex. Turbine rotors are subjected to a complicated 3-D turbulent wind inflow field, with imbedded coherent vortices that drive fatigue loads and reduce lifetime. Design of control algorithms for wind turbines must account for multiple control objectives. Future large multi-megawatt turbines must be designed with lighter weight structures, using active controls to mitigate fatigue loads, while maximizing energy capture. Active damping should be added to these dynamic structures to maintain stability for operation in a complex environment. At the National Renewable Energy Laboratory (NREL), we have designed, implemented, and tested advanced controls to maximize energy extraction and reduce structural dynamic loads. These control designs are based on linear models of the turbine that are generated by specialized modeling software. In this paper, we present field test results of an advanced control algorithm to mitigate blade, tower, and drivetrain loads in Region 3.

  9. Space Shuttle solid rocket motor testing for return to flight - Transient Pressure Test Article test program

    NASA Technical Reports Server (NTRS)

    Vibbart, Charles M.

    1988-01-01

    The Transient Pressure Test Article (TPTA) test program, which is being conducted at a new facility at NASA-Marshall, is described. The facility is designed to test and verify the sealing capability of the redesigned solid rocket motor's (RSRM) field, igniter, and nozzle joints. The test article consists of full-scale RSRM hardware loaded with inert propellant and assembled in a short stack configuration. The test facility is described as well as test implementation, test effectiveness, and test results.

  10. Test program, helium II orbital resupply coupling

    NASA Technical Reports Server (NTRS)

    Hyatt, William S.

    1991-01-01

    The full scope of this program was to have included development tests, design and production of custom test equipment and acceptance and qualification testing of prototype and protoflight coupling hardware. This program was performed by Ball Aerospace Systems Division, Boulder, Colorado until its premature termination in May 1991. Development tests were performed on cryogenic face seals and flow control devices at superfluid helium (He II) conditions. Special equipment was developed to allow quantified leak detection at large leak rates up to 8.4 x 10(exp -4) SCCS. Two major fixtures were developed and characterized: The Cryogenic Test Fixture (CTF) and the Thermal Mismatch Fixture (Glovebox). The CTF allows the coupling hardware to be filled with liquid nitrogen (LN2), liquid helium (LHe) or sub-cooled liquid helium when hardware flow control valves are either open or closed. Heat leak measurements, internal and external helium leakage measurements, cryogenic proof pressure tests and external load applications are performed in this fixture. Special reusable MLI closures were developed to provide repeatable installations in the CTF. The Thermal Mismatch Fixture allows all design configurations of coupling hardware to be engaged and disengaged while measuring applied forces and torques. Any two hardware components may be individually thermally preconditioned within the range of 117 deg K to 350 deg K prior to engage/disengage cycling. This verifies dimensional compatibility and operation when thermally mismatched. A clean, dry GN2 atmosphere is maintained in the fixture at all times. The first shipset of hardware was received, inspected and cycled at room temperature just prior to program termination.

  11. Test program, helium II orbital resupply coupling

    NASA Astrophysics Data System (ADS)

    Hyatt, William S.

    1991-12-01

    The full scope of this program was to have included development tests, design and production of custom test equipment and acceptance and qualification testing of prototype and protoflight coupling hardware. This program was performed by Ball Aerospace Systems Division, Boulder, Colorado until its premature termination in May 1991. Development tests were performed on cryogenic face seals and flow control devices at superfluid helium (He II) conditions. Special equipment was developed to allow quantified leak detection at large leak rates up to 8.4 x 10(exp -4) SCCS. Two major fixtures were developed and characterized: The Cryogenic Test Fixture (CTF) and the Thermal Mismatch Fixture (Glovebox). The CTF allows the coupling hardware to be filled with liquid nitrogen (LN2), liquid helium (LHe) or sub-cooled liquid helium when hardware flow control valves are either open or closed. Heat leak measurements, internal and external helium leakage measurements, cryogenic proof pressure tests and external load applications are performed in this fixture. Special reusable MLI closures were developed to provide repeatable installations in the CTF. The Thermal Mismatch Fixture allows all design configurations of coupling hardware to be engaged and disengaged while measuring applied forces and torques. Any two hardware components may be individually thermally preconditioned within the range of 117 deg K to 350 deg K prior to engage/disengage cycling. This verifies dimensional compatibility and operation when thermally mismatched. A clean, dry GN2 atmosphere is maintained in the fixture at all times. The first shipset of hardware was received, inspected and cycled at room temperature just prior to program termination.

  12. Balloon launched Viking decelerator test program

    NASA Technical Reports Server (NTRS)

    Moog, R. D.; Michel, F. C.

    1973-01-01

    Four BLDT flights were conducted during the summer of 1972. The purpose of these tests was to qualify the Viking parachute system behind the full-scale Viking entry vehicle over the maximum range of entry conditions anticipated in the Viking '75 soft landing on Mars. A summary of the test series is presented. Test conditions ranged from a Mach number of 2.0 to 0.5 and dynamic pressure from 11.7 to 4.4 psf. This range of conditions covers the uncertainty in entry conditions at Mars due to atmospheric and entry performance uncertainties. Emphasis is placed on parachute performance and simulated Mars entry vehicle motions as influenced by the parachute performance. Conclusions are presented regarding the ability of the parachute to perform within the operational parameters required for a successful soft Martian landing. A list of references which covers all reports in the qualification test program is included.

  13. 16 CFR 1209.33 - Reasonable testing program.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INTERIM SAFETY STANDARD FOR CELLULOSE INSULATION Certification § 1209.33 Reasonable testing program. (a... standard, a reasonable testing program shall be used to support certificates of compliance for cellulose insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is...

  14. 16 CFR 1209.33 - Reasonable testing program.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INTERIM SAFETY STANDARD FOR CELLULOSE INSULATION Certification § 1209.33 Reasonable testing program. (a... standard, a reasonable testing program shall be used to support certificates of compliance for cellulose insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is...

  15. 16 CFR 1209.33 - Reasonable testing program.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INTERIM SAFETY STANDARD FOR CELLULOSE INSULATION Certification § 1209.33 Reasonable testing program. (a... standard, a reasonable testing program shall be used to support certificates of compliance for cellulose insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is...

  16. 16 CFR 1209.33 - Reasonable testing program.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INTERIM SAFETY STANDARD FOR CELLULOSE INSULATION Certification § 1209.33 Reasonable testing program. (a... standard, a reasonable testing program shall be used to support certificates of compliance for cellulose insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is...

  17. 16 CFR 1209.33 - Reasonable testing program.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INTERIM SAFETY STANDARD FOR CELLULOSE INSULATION Certification § 1209.33 Reasonable testing program. (a... standard, a reasonable testing program shall be used to support certificates of compliance for cellulose insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is...

  18. Test and Evaluation of Program Slicing Tools

    DTIC Science & Technology

    2012-12-19

    and engineering databases. Berzins received BS, MS, EE, and PhD degrees from MIT and has been on the faculty at the University of Texas and the...slice. C. Existing Tools A thesis (Lim & Ben Kahia, 2011) was done at the Naval Postgraduate School (NPS) in which the students tried to find a...reduction of testing effort (Unpublished master’s thesis ). Naval Postgraduate School, Monterey, CA. Weiser, M. (1984). Program slicing. IEEE

  19. Lithium-Ion Verification Test Program

    NASA Technical Reports Server (NTRS)

    McKissock, Barbara; Manzo, Michelle; Miller, Thomas; Reid, Concha; Bennett, William; Gemeiner, Russel

    2004-01-01

    In order to assess the capabilities of current aerospace lithium-ion cells to perform long-term NASA missions, low-earth-orbits (LEO) testing to evaluate long-term cycle life was initiated. A flexible program was developed at NASA Glenn Research Center to enable assessment of technology developments as they occur as well as provide information about different cell vendors and cell designs. Following extensive characterization testing, cells are tested using LEO charge and discharge profiles under ten different combinations of test conditions that were statistically chosen to determine the effects of depth-of-discharge, temperature, and end-of-charge voltage on LEO cycle life. Four cells from each vendor are tested at each specific combination of conditions. Conditions included in the test matrix are depth-of-discharges of 20%, 30, 35%, and 40%; temperatures of 20, 30, and 40 C; and end-of-charge voltages of 3.85 V, 3.95 V, and 4.05 V. Cells are randomly assigned to packs and packs are randomly assigned to test conditions. The capacity of the cells to 3.0 V at the conditions of the test is being periodically measured. The results of this testing will be used to model cell performance and degradation as a function of test operating conditions. Cells are being evaluated in 4-cell series strings with charge voltage limits being applied to individual cells by charge control units designed and built at NASA Glenn Research Center. Testing is being performed at the Naval Surface Warfare Center/Crane Division in Crane, IN. Testing was initiated in September 2004 with 40 Ah cells from Saft and 30 Ah cells from Lithion. The test program is being expanded with the addition of cells from MSA and the addition of small cell modules is being considered. Preliminary results showing voltage, temperature, usable capacity per unit mass, and voltage dispersion as their changes over time for the cells at 20 C is presented.

  20. Long-Term Materials Test Program: materials exposure test plan

    SciTech Connect

    1981-12-01

    The Long Term Materials Test Program is designed to identify promising corrosion resistant materials for coal-fired gas turbine applications. Resistance of materials to long term accelerated corrosion will be determined through realistic PFB environmental exposure of candidate turbine materials for up to 14,000 hours. Selected materials also will be evaluated for their ability to withstand the combined erosive and corrosive aspects of the PFB effluent. A pressurized fluidized bed combustor facility has been constructed at the General Electric Coal Utilization Research Laboratory at Malta, New York. The 12-inch diameter combustor will burn high sulfur coal with moderate-to-high chlorine and alkali levels and utilize dolomite as the sulfur sorbent. Hot gas cleanup is achieved using three stages of cyclone separators. Downstream of the cylone separators, a low velocity test section (approx. 30 ft/s) capable of housing 180 pin specimens 1/4'' diameter has been installed to assess the corrosion resistance of the various materials at three different temperatures ranging from 1300 to 1600/sup 0/F. Following the low velocity test section is a high velocity test section consisting of four cascades of airfoil shaped specimens, six specimens per cascade. This high velocity test section is being used to evaluate the combined effects of erosion and corrosion on the degradation of gas turbine materials at gas velocities of 800 to 1400 ft/s. This report summarizes the materials selection and materials exposure test plan for the Long Term Materials Test.

  1. Static and fatigue testing of full-scale fuselage panels fabricated using a Therm-X(R) process

    NASA Technical Reports Server (NTRS)

    Dinicola, Albert J.; Kassapoglou, Christos; Chou, Jack C.

    1992-01-01

    Large, curved, integrally stiffened composite panels representative of an aircraft fuselage structure were fabricated using a Therm-X process, an alternative concept to conventional two-sided hard tooling and contour vacuum bagging. Panels subsequently were tested under pure shear loading in both static and fatigue regimes to assess the adequacy of the manufacturing process, the effectiveness of damage tolerant design features co-cured with the structure, and the accuracy of finite element and closed-form predictions of postbuckling capability and failure load. Test results indicated the process yielded panels of high quality and increased damage tolerance through suppression of common failure modes such as skin-stiffener separation and frame-stiffener corner failure. Finite element analyses generally produced good predictions of postbuckled shape, and a global-local modelling technique yielded failure load predictions that were within 7% of the experimental mean.

  2. Thermal Fatigue Testing of ZrO2-Y2O3 Thermal Barrier Coating Systems using a High Power CO2 Laser

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1997-01-01

    In the present study, the mechanisms of fatigue crack initiation and propagation, and of coating failure, under thermal loads that simulate diesel engine conditions, are investigated. The surface cracks initiate early and grow continuously under thermal Low Cycle Fatigue (LCF) and High Cycle Fatigue (HCF) stresses. It is found that, in the absence of interfacial oxidation, the failure associated with LCF is closely related to coating sintering and creep at high temperatures. Significant LCF and HCF interactions have been observed in the thermal fatigue tests. The fatigue crack growth rate in the ceramic coating strongly depends on the characteristic HCF cycle number, N*(sub NCF), which is defined as the number of HCF cycles per LCF cycle. The crack growth rate is increased from 0.36 microns/LCF cycle for a pure LCF test to 2.8 microns/LCF cycle for a combined LCF and HCF test at N*(sub NCF) about 20,000. A surface wedging model has been proposed to account for the HCF crack growth in the coating systems. This mechanism predicts that HCF damage effect increases with increasing surface temperature swing, the thermal expansion coefficient and the elastic modulus of the ceramic coating, as well as with the HCF interacting depth. A good agreement has been found between the analysis and experimental evidence.

  3. Fatigue Strength of Diamond Coating-Substrate Interface Quantified by a Dynamic Simulation of the Inclined Impact Test

    NASA Astrophysics Data System (ADS)

    Skordaris, G.

    2014-10-01

    Fatigue damage of the nanocrystalline diamond coating (NCD) bonding to the cemented carbide substrate develops when repetitive impact loads are applied onto the film. Thus, the highly compressive residual stresses of a NCD film are released leading to its lifting from the substrate (bulge formation). The present paper deals with the analytical description of the progressive failure of the NCD coating-substrate interface under repetitive impacts. In this context, an advanced 3D-finite element analysis model was developed for the dynamic simulation of the inclined impact test, using the LS-DYNA software. This model considers the high thermal compressive residual stresses developed in the NCD coating structure during cooling from chemical vapour deposition process temperature to ambient one. The fatigue failure of the NCD coating-substrate interface is associated with a critical shear failure stress (SFLS). The determined SFLS represents the maximum operational stress permitted in the NCD film-substrate interface in order to avoid the coating detachment initiation. According to the results obtained, the successive impacts lead to a progressive weakening of the initial film-substrate interface strength depending upon the pretreatments prior to the NCD coating deposition.

  4. Measurement of Deflection in Concrete Beams During Fatigue Loading Test Using the Microsoft Kinect 2.0

    NASA Astrophysics Data System (ADS)

    Lahamy, Herve; Lichti, Derek D.; Steward, Jeremy; El-Badry, Mamdouh; Moravvej, Mohammad

    2016-03-01

    This study focuses on 3 Hz fatigue load testing of a reinforced concrete beam in laboratory conditions. Three-dimensional (3D) image time series of the beam's top surface were captured with the Microsoft time-of-flight Kinect 2.0 sensor. To estimate the beam deflection, the imagery was first segmented to extract the top surface of the beam. The centre line was then modeled using third-order B-splines. The deflection of the beam as a function of time was estimated from the modeled centre line and, following past practice, also at several witness plates attached to the side of the beam. Subsequent correlation of the peak displacement with the applied loading cycles permitted estimation of fatigue in the beam. The accuracy of the deflections was evaluated by comparison with the measurements obtained using a Keyence LK-G407 laser displacement sensors. The results indicate that the deflections can be recovered with sub-millimetre accuracy using the centreline profile modelling method.

  5. Effects of an 8-Week Outdoor Brisk Walking Program on Fatigue in Hi-Tech Industry Employees: A Randomized Control Trial.

    PubMed

    Wu, Li-Ling; Wang, Kuo-Ming; Liao, Po-I; Kao, Yu-Hsiu; Huang, Yi-Ching

    2015-10-01

    Over 73% of hi-tech industry employees in Taiwan lack regular exercise. They are exposed to a highly variable and stressful work environment for extended periods of time, and may subsequently experience depression, detrimental to workers' physiological and mental health. In this cross-sectional survey, the authors explored the effect of an 8-week brisk walking program on the fatigue of employees in the hi-tech industry. The participants, from a hi-tech company in northern Taiwan, were randomly assigned to an experimental group (EG; 41 subjects, Mage = 33.34 ± 6.40) or control group (CG; 45 subjects, Mage = 29.40 ± 3.60). Following the 8-week brisk walking program, the EG showed significantly lower scores for subjective fatigue, working motivation, attention, and overall fatigue. The authors confirmed that the 8-week outdoor brisk walking program significantly improved the level of fatigue among employees of the hi-tech industry. The finding serves as an important reference for health authorities in Taiwan and provides awareness of workplace health promotion in the hi-tech industry.

  6. Columbia University flow instability experimental program: Volume 6. Single annulus tests, transient test program

    SciTech Connect

    Dougherty, T.; Maciuca, C.; McAssey, E.V. Jr.; Reddy, D.G.; Yang, B.W.

    1992-09-01

    The coolant in the Savannah River Site (SRS) production nuclear reactor assemblies is circulated as a subcooled liquid under normal operating conditions. This coolant is evenly distributed throughout multiple annular flow channels with a uniform pressure profile across each coolant flow channel. During the postulated Loss of Coolant Accident (LOCA), which is initiated by a hypothetical guillotine pipe break, the coolant flow through the reactor assemblies is significantly reduced. The flow reduction and accompanying power reduction (after shutdown is initiated) occur in the first 1 to 2 seconds of the LOCA. This portion of the LOCA is referred to as the Flow Instability phase. This report presents the experimental results for the transient portion of the single annulus test program. The test program was designed to investigate the onset of flow instability in an annular geometry similar to the MARK 22 reactor. The test program involved testing of both a ribless heater and a ribbed heater under steady state as well as transient conditions. The ribbed heater testing is currently underway and will be reported separately. The steady state portion of this test program with ribless heater was completed and reported in report No. CU-HTRF-T3A. The present report presents transient test results obtained from a ribless, uniform annulus test section. A total of thirty five transients were conducted with six cases in which flow excursion occurred. No unstable conditions resulted for tests in which the steady state Q{sub ratio} OFI limit was not exceeded.

  7. A novel anatomical short glass fiber reinforced post in an endodontically treated premolar mechanical resistance evaluation using acoustic emission under fatigue testing.

    PubMed

    Wang, Hsuan-Wen; Chang, Yen-Hsiang; Lin, Chun-Li

    2017-01-01

    This study evaluates the fracture resistance in an endodontically treated tooth using circular fiber-reinforced composite (FRC) and innovated anatomical short glass fiber reinforced (SGFR) posts under fatigue testing, monitored using the acoustic emission (AE) technique. An anatomical SGFR fiber post with an oval shape and slot/notch design was manufactured using an injection-molding machine. Crown/core maxillary second premolar restorations were executed using the anatomical SGFR and commercial cylindrical fiber posts under fatigue test to understand the mechanical resistances. The load versus AE signals in the fracture and fatigue tests were recorded to evaluate the restored tooth failure resistance. The static fracture resistance results showed that teeth restored using the anatomical SGFR post presented higher resistance than teeth restored using the commercial FRC post. The fatigue test endurance limitation (1.2×10(6) cycles) was 207.1N for the anatomical SGFR fiber post, higher than the 185.3N found with the commercial FRC post. The average accumulated number of AE signals and corresponding micro cracks for the anatomical SGFR fiber post (153.0 hits and 2.44 cracks) were significantly lower than those for the commercial FRC post (194.7 hits and 4.78 cracks) under 40% of the static maximum resistance fatigue test load (pass 1.2×10(6) cycles). This study concluded that the anatomical SGFR fiber post with surface slot/notch design made using precise injection molding presented superior static fracture resistance and fatigue endurance limitation than those for the commercial FRC post in an endodontically treated premolar.

  8. How My Program Passed the Turing Test

    NASA Astrophysics Data System (ADS)

    Humphrys, Mark

    In 1989, the author put an ELIZA-like chatbot on the Internet. The conversations this program had can be seen - depending on how one defines the rules (and how seriously one takes the idea of the test itself) - as a passing of the Turing Test. This is the first time this event has been properly written. This chatbot succeeded due to profanity, relentless aggression, prurient queries about the user, and implying that they were a liar when they responded. The element of surprise was also crucial. Most chatbots exist in an environment where people expectto find some bots among the humans. Not this one. What was also novel was the onlineelement. This was certainly one of the first AI programs online. It seems to have been the first (a) AI real-time chat program, which (b) had the element of surprise, and (c) was on the Internet. We conclude with some speculation that the future of all of AI is on the Internet, and a description of the "World- Wide-Mind" project that aims to bring this about.

  9. BPX insulation irradiation program test results

    SciTech Connect

    McManamy, T.J. ); Kanemoto, G. ); Snook, P.G. . Plasma Physics Lab.)

    1991-01-01

    The toroidal field coil insulation for the Burning Plasma Experiment (BPX) is expected to receive a radiation dose of nearly 10{sup 10} rad and to withstand significant mechanical stresses. An irradiation test program was performed at the Idaho National Engineering Laboratory (INEL) using the Advanced Technology Reactor (ATR) for irradiations to doses on the order of 3 {times} 10{sup 10} rad. The flexure and shear strength with compression of commercially procured sheet material were reported earlier. A second series of tests has been performed to slightly higher dose levels with vacuum impregnated materials, glass strand material, and Spaulrad-S sheet samples. Vacuum impregnation with a Shell 9405 resin and 9470 hardener was used to produce bonded copper squares and flexure samples of both pure resin and resin with S-glass. A new test fixture was developed to test the bonded samples in shear without applied compression. The Spaulrad-S flexure samples demonstrated a loss of strength with irradiation, similar to previous results. The pure resin lost nearly all flexibility, while the S-glass-reinforced samples retained between 30% and 40% of the initial flexure strength. The S-glass strands showed a 30% loss of strength at the higher dose level when tested in tension. The bonded copper squares had a low room-temperature shear strength of approximately 17 MPa before irradiation, which was unchanged in the irradiated samples. Shear testing of unirradiated bonded copper squares with ten different types of surface treatment revealed that the low shear strength resulted from the polyurethane primer used. In the later series of test, the epoxy-based primers and DZ-80 from Ciba-Geigy did much better, with shear strengths on the order of 40 MPa. These samples also demonstrated a resistance to cryogenic shock. One irradiated bonded sample was tested up 10 210 MPa in compression, the limit of the test fixture, without failure.

  10. Gear Fatigue Diagnostics and Prognostics

    DTIC Science & Technology

    2013-01-01

    one for single gear tooth fatigue, and one for gear-on-gear dynamometer-based tester ) we have been collecting crack initiation and crack propagation...fatigue tester ); and torque, angular speed, vibration, temperature, and crack-propagation (gear-on-gear dynamometer-based tester ). The main outcome...Description The test consists of two set of tests on a dynamometer and one set of test on the fatigue tester and some additional activities. Fig

  11. Apparatus and method for fatigue testing of a material specimen in a high-pressure fluid environment

    DOEpatents

    Wang, Jy-An; Feng, Zhili; Anovitz, Lawrence M; Liu, Kenneth C

    2013-06-04

    The invention provides fatigue testing of a material specimen while the specimen is disposed in a high pressure fluid environment. A specimen is placed between receivers in an end cap of a vessel and a piston that is moveable within the vessel. Pressurized fluid is provided to compression and tension chambers defined between the piston and the vessel. When the pressure in the compression chamber is greater than the pressure in the tension chamber, the specimen is subjected to a compression force. When the pressure in the tension chamber is greater than the pressure in the compression chamber, the specimen is subjected to a tension force. While the specimen is subjected to either force, it is also surrounded by the pressurized fluid in the tension chamber. In some examples, the specimen is surrounded by hydrogen.

  12. Fatigue biomarker index: an objective salivary measure of fatigue level.

    PubMed

    Michael, Darren J; Daugherty, Sheena; Santos, Adrienne; Ruby, Brent C; Kalns, John E

    2012-03-01

    Fatigue changed the composition of the small-molecular weight (sMW) proteome of saliva during a 10h session of moderate (70% of maximum ventilatory threshold) physical exertion. Saliva samples were collected from nine recreationally trained cyclists participating in a cross-over study designed to simulate prolonged manual labor, a military operation or wildfire-suppression work. During each hour of the study, participants performed an exercise program that included upper and lower body exercises separated by short periods of recovery. Over the course of the study, fatigue level increased as suggested by a significant increase in the participants' relative perceived exertion. The composition of the sMW proteome was investigated using reversed-phase liquid chromatography with mass-spectrometric detection. Isotopes of acetic anhydride were used for mass-specific labeling of samples and subsequent identification of ions with significant changes in intensity. Cluster analysis was used to identify a pair of peptides with concentrations that changed in opposite directions with fatigue level, i.e. concentration of one peptide increased while concentration of the other decreased. The sequences of the two peptides were determined by high-resolution mass spectrometry. The ratio of the ion intensities of these two peptides, referred to as the fatigue biomarker index, was calculated for subjects throughout the study. The FBI values from the start of the study likely arose from a different distribution than the FBI values measured at the end of the study (Mann-Whitney test, P<.05). While this study is restricted to a small population of recreationally trained cyclists performing exercise under controlled conditions, it holds promise for the development of an objective salivary measurement of fatigue that is applicable to a much broader population performing in uncontrolled environments.

  13. Fracture mechanics characterization of welds: Fatigue life analysis of notches at welds: J(sub Ic) fracture toughness tests for weld metal

    NASA Astrophysics Data System (ADS)

    Underwood, John H.

    1995-03-01

    In this report two methods of fracture analysis of welds will be emphasized, one addressing fatigue life testing and analysis of notches at welds, and the other addressing the final fracture of the welded component and the fracture toughness tests used to characterize final fracture. These fatigue and fracture methods will be described by referring to recent work from the technical literature and from the U.S. Army Armament Research, Development, and Engineering Center, primarily fracture case study and fracture test method development investigations. A brief general summary will be given of fatigue and fracture methods and concepts that have application to welded structures. Specific fatigue crack initiation tests and analysis methods will be presented, using example results from a welded stainless steel box beam of a cannon carriage. Recent improvements and simplifications in J.integral fracture toughness tests will be described, particularly those related to welds. Fracture toughness measurements for various stainless steel weld metals and heat treatments will also be described.

  14. Review of sonic fatigue technology

    NASA Technical Reports Server (NTRS)

    Clarkson, B. L.

    1994-01-01

    From the early-1960s until the mid-1980s, there was very little theoretical development for sonic fatigue prediction. Design nomographs based on simple theoretical models and results of specially designed tests were developed for most common aircraft structures. The use of advanced composites in the 1980s, however, generated an increased interest in development of more sophisticated theoretical models because of the possibilities for a much wider range of structural designs. The purpose of this report is to review sonic fatigue technology and, in particular, to assess recent developments. It also suggests a plan for a coordinated program of theoretical and experimental work to meet the anticipated needs of future aerospace vehicles.

  15. The Ethics of Test Preparation at Intensive English Language Programs.

    ERIC Educational Resources Information Center

    Palmer, Ian C.

    It is concluded from a review of the literature and consideration of the type and objectives of tests and programs in English as a second language that, just as limiting an instructional program to what is to be tested in standardized tests would be inappropriate, so would constructing such a program without regard for what was to be tested. It is…

  16. Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves

    SciTech Connect

    Somogyi, D.; Alvarez, P.D.; Kalsi, M.S.

    1996-12-01

    Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the {open_quote}Thrust Rating Increase{close_quote} test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner`s rule. Model predictions were validated against actual cyclic loading test results.

  17. Department of Defense Space Test Program

    NASA Astrophysics Data System (ADS)

    Sims, Eleni M.; Zdenek, Jeffery S.

    2000-11-01

    During the 1960's, as the importance of the space environment was recognized, it became apparent that space systems technologies needed to be developed at a rapid rate. The Department of Defense (DoD) realized that before developing and deploying space systems for operational use, the needed to be tested in space. At that time no organization of funds were readily available to provide timely spaceflight for military space systems. As a result, the DoD Space Test Program (STP) was created in 1966 by a memorandum from the Director of Defense Research and Engineering (DDR&E). The purpose of this program was to provide flight opportunities for all DoD research and development activities in an economic and efficient manner. For a payload to be flown by STP it must first be sponsored by a DoD organization. The payload is then briefed through a series of service review boards until it reaches the DoD level. The DoD Space Experiment Review Board (SERB) makes the final selections and gives STP a ranked list of payloads to attempt to fly. This process happens annually, and STP flies as many payloads as funding and opportunity allow.

  18. Attention network test: assessment of cognitive function in chronic fatigue syndrome.

    PubMed

    Togo, Fumiharu; Lange, Gudrun; Natelson, Benjamin H; Quigley, Karen S

    2015-03-01

    Information processing difficulties are common in patients with chronic fatigue syndrome (CFS). It has been shown that the time it takes to process a complex cognitive task, rather than error rate, may be the critical variable underlying CFS patients' cognitive complaints. The Attention Network Task (ANT) developed by Fan and colleagues may be of clinical utility to assess cognitive function in CFS, because it allows for simultaneous assessment of mental response speed, also called information processing speed, and error rate under three conditions challenging the attention system. Comparison of data from two groups of CFS patients (those with and without comorbid major depressive disorder; n = 19 and 22, respectively) to controls (n = 29) consistently showed that error rates did not differ among groups across conditions, but speed of information processing did. Processing time was prolonged in both CFS groups and most significantly affected in response to the most complex task conditions. For simpler tasks, processing time was only prolonged in CFS participants with depression. The data suggest that the ANT may be a task that could be used clinically to assess information processing deficits in individuals with CFS.

  19. Residual Stress Changes in Fatigue. Volume 2. A Simulation Model for Stress Measurements in Notched Test Specimens by X-Ray Diffraction

    DTIC Science & Technology

    1989-03-01

    Report No. NADC-88141-60 (Volume II) DTIC S F-!. r-CT E MAY 2 6 1~98D RESIDUAL STRESS CHANGES IN FATIGUE VOLUME II - A SIMULATION MODEL FOR STRESS ...Residual Stress Changes in Fatigue: Vol. II. A Simulation Model for Stress Measurements in Notched Test Specimens by X-Ray Diffraction 12 PERSONAL...Simulation; Residual Stress ; X-Ray Difraction ’/ -, . .. 20 11 1 19 ABSTRACT (Continue on reverse if necessary and identif by block number) The state of

  20. Influence of fatigue testing and cementation mode on the load-bearing capability of bovine incisors restored with crowns and FRC posts.

    PubMed

    Nothdurft, Frank P; Schmitt, Thomas; Rupf, Stefan; Pospiech, Peter R

    2011-01-01

    The aim of the study was to evaluate the influence of fatigue and cementation mode on the fracture behaviour of endodontically treated bovine incisors restored with fiber-reinforced-composite (FRC) posts and crowns. Forty-eight endodontically treated incisors were restored with FRC posts, composite build-ups, and cast crowns. In 16 teeth, each of the posts were cemented conventionally with KetacCem (3M Espe) or adhesively with Panavia F (Kuraray) or RelyXUniCem (3M Espe). One-half of the specimens in each group were subjected to thermal cycling with 10,000 cycles at 5-55°C and mechanical aging, loading the specimens in 1,200,000 cycles with 50 N. Fracture resistance was determined by loading the specimens until fracture at an angle of 45°. The loading test showed that cementation mode and fatigue testing had an influence on the load bearing capability. Before fatigue testing no statistically significant differences between the different cementation modes could be detected. After fatigue testing, conventionally cemented FRC posts lead to statistically significant higher fracture loads compared to adhesively luted posts. Most specimens fractured in a favourable way, independent from the type of cementation.

  1. Improved Performance Band Track Program: Test Report

    DTIC Science & Technology

    1985-04-01

    fatigue strength @ 10 cycles (ksi) smooth 15 est. 50 notched 5 est. 30 Structural Properties ultimate...Old R281 15 - 5PH 3 STD Old R281 4330 4 STD R281 15 - 5PH 5 STD R281 4330 6 STD R281 4330 7 STD R281 4330 8 STD R281 4330 9 STD R281 4330 10 STD R281 4330...11 TIGHT R281 4330 12 TIGHT R230 4330 S 13 STD Old R281 4330 14 STD Old R281 15 - 5PH 15 STD R281 15 - 5PH 16 STD R281 15 - 5PH 17 STD R230 15 - 5PH

  2. Surface fatigue life of carburized and hardened M50NiL and AISI 9310 spur gears and rolling-contact test bars

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Bamberger, Eric N.

    1989-01-01

    Spur gear endurance tests and rolling-element surface tests were conducted to investigate vacuum-induction-melted, vacuum-arc-melted (VIM-VAR) M50NiL steel for use as a gear steel in advanced aircraft applications, to determine its endurance characteristics, and to compare the results with those for standard VAR and VIM-VAR AISI 9310 gear material. Tests were conducted with spur gears and rolling-contact bars manufactured from VIM-VAR M50NiL and VAR and VIM-VAR AISI 9310. The gear pitch diameter was 8.9 cm (3.5 in.). Gear test conditions were an inlet oil temperature of 320 K (116 F), and outlet oil temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench rolling-element fatigue tests were conducted at ambient temperatures with a bar speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPA (700 ksi). The VIM-VAR M50NiL gears had a surface fatigue life that was 4.5 and 11.5 times that for VIM-VAR and VAR AISI 9310 gears, respectively. The surface fatigue life of the VIM-VAR M50NiL rolling-contact bars was 13.2 and 21.6 times that for the VIM-VAR and VAR AISI 9310, respectively. The VIM-VAR M50NiL material was shown to have good resistance to fracture through a fatigue spall and to have fatigue life far superior to that of both VIM-VAR and VAR AISI 9310 gears and rolling-contact bars.

  3. Atlas of fatigue curves

    SciTech Connect

    Boyer, H.E.

    1986-01-01

    This Atlas was developed to serve engineers who are looking for fatigue data on a particular metal or alloy. Having these curves compiled in a single book will also facilitate the computerization of the involved data. It is pointed out that plans are under way to make the data in this book available in ASCII files for analysis by computer programs. S-N curves which typify effects of major variables are considered along with low-carbon steels, medium-carbon steels, alloy steels, HSLA steels, high-strength alloy steels, heat-resisting steels, stainless steels, maraging steels, cast irons, and heat-resisting alloys. Attention is also given to aluminum alloys, copper alloys, magnesium alloys, molybdenum, tin alloys, titanium and titanium alloys, zirconium, steel castings, closed-die forgings, powder metallurgy parts, composites, effects of surface treatments, and test results for component parts.

  4. Microcomputer Network for Computerized Adaptive Testing (CAT): Program Listing.

    ERIC Educational Resources Information Center

    Quan, Baldwin; And Others

    This program listing is a supplement to the Microcomputer Network for Computerized Adaptive Testing (CAT). The driver textfile program allows access to major subprograms of the CAT project. The test administration textfile program gives examinees a prescribed set of subtests. The parameter management textfile program establishes a file containing…

  5. Capturing Uncertainty in Fatigue Life Data

    DTIC Science & Technology

    2014-09-18

    Several parameters can be investigated in fatigue testing . Factors such as loading, specimen geometry, material behavior, and thermal or chemical...of time they have spent with me discussing material sciences, fatigue testing , and their modeling efforts. Finally, a considerable amount of thanks...pricing structures for insurance policies. In fatigue , engineers can characterize metal alloys, quantify material responses to testing conditions, and

  6. Fatigue Test of Cytochrome C Self-Assembled on a 11-MUA Layer Based on Electrochemical Analysis for Bioelectronic Device.

    PubMed

    Lee, Taek; Chung, Yong-Ho; Chen, Qi; Min, Junhong; Choi, Jeong-Woo

    2015-08-01

    A cytochrome c/11-MUA heterolayer was fabricated to analyze its electrochemical characteristics in harsh conditions for a stable bioelectronic device. Since a cytochrome c/11-MUA heterolayer has been applied to construct the bioelectronics device such as non-volatile biomemory device, an understanding of electrochemical property of the heterolayer in harsh conditions such as variation of temperature and pH, and repetition of usage is necessary to manufacture a stable platform of bioelectronic device. Cytochrome c, a metalloprotein to have a heme group, was self-assembled on the Au surface via the chemical linker 11-mercaptoundecanoic acid (11-MUA). Immobilization of the heterolayer was confirmed by surface-enhanced Raman spectroscopy (SERS) and scanning tunneling microscopy (STM). The fatigue test was done by investigating the redox properties based on cyclic voltammetry (CV) of the heterolayer. The retention time test and pH dependence, thermal test of the fabricated heterolayer were conducted by CV, which showed that the fabricated film retained redox properties for more than 33 days, and from pH 5.0 to pH 9.0, from 15 °C to 55 °C. Taken together, our results show that a cytochrome c/11-MUA heterolayer is very stable, which could be used as a platform of bioelectronic device.

  7. Spacecraft Testing Programs: Adding Value to the Systems Engineering Process

    NASA Technical Reports Server (NTRS)

    Britton, Keith J.; Schaible, Dawn M.

    2011-01-01

    Testing has long been recognized as a critical component of spacecraft development activities - yet many major systems failures may have been prevented with more rigorous testing programs. The question is why is more testing not being conducted? Given unlimited resources, more testing would likely be included in a spacecraft development program. Striking the right balance between too much testing and not enough has been a long-term challenge for many industries. The objective of this paper is to discuss some of the barriers, enablers, and best practices for developing and sustaining a strong test program and testing team. This paper will also explore the testing decision factors used by managers; the varying attitudes toward testing; methods to develop strong test engineers; and the influence of behavior, culture and processes on testing programs. KEY WORDS: Risk, Integration and Test, Validation, Verification, Test Program Development

  8. Cyclic fatigue analysis of rocket thrust chambers. Volume 1: OFHC copper chamber low cycle fatigue

    NASA Technical Reports Server (NTRS)

    Miller, R. W.

    1974-01-01

    A three-dimensional finite element elasto-plastic strain analysis was performed for the throat section of a regeneratively cooled rocket combustion chamber. The analysis employed the RETSCP finite element computer program. The analysis included thermal and pressure loads, and the effects of temperature dependent material properties, to determine the strain range corresponding to the chamber operating cycle. The analysis was performed for chamber configuration and operating conditions corresponding to a hydrogen-oxygen combustion chamber which was fatigue tested to failure. The computed strain range at typical chamber operating conditions was used in conjunction with oxygen-free, high-conductivity (OHFC) copper isothermal fatigue test data to predict chamber low-cycle fatigue life.

  9. Human Machine Interface Programming and Testing

    NASA Technical Reports Server (NTRS)

    Foster, Thomas Garrison

    2013-01-01

    Human Machine Interface (HMI) Programming and Testing is about creating graphical displays to mimic mission critical ground control systems in order to provide NASA engineers with the ability to monitor the health management of these systems in real time. The Health Management System (HMS) is an online interactive human machine interface system that monitors all Kennedy Ground Control Subsystem (KGCS) hardware in the field. The Health Management System is essential to NASA engineers because it allows remote control and monitoring of the health management systems of all the Programmable Logic Controllers (PLC) and associated field devices. KGCS will have equipment installed at the launch pad, Vehicle Assembly Building, Mobile Launcher, as well as the Multi-Purpose Processing Facility. I am designing graphical displays to monitor and control new modules that will be integrated into the HMS. The design of the display screen will closely mimic the appearance and functionality of the actual modules. There are many different field devices used to monitor health management and each device has its own unique set of health management related data, therefore each display must also have its own unique way to display this data. Once the displays are created, the RSLogix5000 application is used to write software that maps all the required data read from the hardware to the graphical display. Once this data is mapped to its corresponding display item, the graphical display and hardware device will be connected through the same network in order to test all possible scenarios and types of data the graphical display was designed to receive. Test Procedures will be written to thoroughly test out the displays and ensure that they are working correctly before being deployed to the field. Additionally, the Kennedy Ground Controls Subsystem's user manual will be updated to explain to the NASA engineers how to use the new module displays.

  10. 78 FR 12259 - Unmanned Aircraft System Test Site Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-22

    ... Federal Aviation Administration 14 CFR Part 91 Unmanned Aircraft System Test Site Program AGENCY: Federal... Administration and the Department of Defense, develop a test site program for the integration of unmanned aircraft systems in to the National Airspace System. The overall purpose of this test site program is...

  11. 49 CFR 219.607 - Railroad random alcohol testing programs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Railroad random alcohol testing programs. 219.607... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CONTROL OF ALCOHOL AND DRUG USE Random Alcohol and Drug Testing Programs § 219.607 Railroad random alcohol testing programs. (a) Each railroad must submit for FRA...

  12. 49 CFR 219.607 - Railroad random alcohol testing programs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Railroad random alcohol testing programs. 219.607... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CONTROL OF ALCOHOL AND DRUG USE Random Alcohol and Drug Testing Programs § 219.607 Railroad random alcohol testing programs. (a) Each railroad must submit for FRA...

  13. 49 CFR 219.607 - Railroad random alcohol testing programs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Railroad random alcohol testing programs. 219.607... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CONTROL OF ALCOHOL AND DRUG USE Random Alcohol and Drug Testing Programs § 219.607 Railroad random alcohol testing programs. (a) Each railroad must submit for FRA...

  14. 77 FR 30877 - Aging Airplane Program: Widespread Fatigue Damage; Technical Amendment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ..., 121, and 129 [Docket No. FAA-2006-24281; Amendment Nos. 26-6, 121-360, 129-51] RIN 2120-AI05 Aging... On November 15, 2010, the FAA published a final rule entitled, ``Aging Airplane Program: Widespread... Airbus to comply with Sec. 26.21. As stated in the preamble of the rule entitled, ``Aging...

  15. Overview of the Space Launch System Transonic Buffet Environment Test Program

    NASA Technical Reports Server (NTRS)

    Piatak, David J.; Sekula, Martin K.; Rausch, Russ D.; Florance, James R.; Ivanco, Thomas G.

    2015-01-01

    Fluctuating aerodynamic loads are a significant concern for the structural design of a launch vehicle, particularly while traversing the transonic flight environment. At these trajectory conditions, unsteady aerodynamic pressures can excite the vehicle dynamic modes of vibration and result in high structural bending moments and vibratory environments. To ensure that vehicle structural components and subsystems possess adequate strength, stress, and fatigue margins in the presence of buffet and other environments, buffet forcing functions are required to conduct the coupled load analysis of the launch vehicle. The accepted method to obtain these buffet forcing functions is to perform wind-tunnel testing of a rigid model that is heavily instrumented with unsteady pressure transducers designed to measure the buffet environment within the desired frequency range. Two wind-tunnel tests of a 3 percent scale rigid buffet model have been conducted at the Langley Research Center Transonic Dynamics Tunnel (TDT) as part of the Space Launch System (SLS) buffet test program. The SLS buffet models have been instrumented with as many as 472 unsteady pressure transducers to resolve the buffet forcing functions of this multi-body configuration through integration of the individual pressure time histories. This paper will discuss test program development, instrumentation, data acquisition, test implementation, data analysis techniques, and several methods explored to mitigate high buffet environment encountered during the test program. Preliminary buffet environments will be presented and compared using normalized sectional buffet forcing function root-meansquared levels along the vehicle centerline.

  16. A systems approach to solder joint fatigue in spacecraft electronic packaging

    NASA Technical Reports Server (NTRS)

    Ross, R. G., Jr.

    1991-01-01

    Differential expansion induced fatigue resulting from temperature cycling is a leading cause of solder joint failures in spacecraft. Achieving high reliability flight hardware requires that each element of the fatigue issue be addressed carefully. This includes defining the complete thermal-cycle environment to be experienced by the hardware, developing electronic packaging concepts that are consistent with the defined environments, and validating the completed designs with a thorough qualification and acceptance test program. This paper describes a useful systems approach to solder fatigue based principally on the fundamental log-strain versus log-cycles-to-failure behavior of fatigue. This fundamental behavior has been useful to integrate diverse ground test and flight operational thermal-cycle environments into a unified electronics design approach. Each element of the approach reflects both the mechanism physics that control solder fatigue, as well as the practical realities of the hardware build, test, delivery, and application cycle.

  17. Columbia University Flow Instability Experimental Program, Volume 5: Single annulus tests, steady-state test program

    SciTech Connect

    Dougherty, T.; Maciuca, C.; McAssey, E.V. Jr.; Reddy, D.G.; Yang, B.W.

    1991-07-01

    This report presents results for the steady state portion of the finless single annulus test program. The objective of the experimental study was to investigate the onset of flow instability in an annular geometry similar to the MARK 22 reactor. The test program involved testing of both a finless or ribless heater and a ribbed heater. The latter program is currently underway and will be reported separately. For finless heater, testing was conducted in both a steady state and transient mode. The present report presents steady state results for a series of experiments with uniform and asymmetric heating. The demand curves obtained under uniform heating yielded OFI flow-rates which were slightly below those obtained for a circular tube geometry with the same L/D ratio; however, the single annulus had a hydraulic diameter which was approximately fifty percent larger than the circular tube. The asymmetric heating cases were selected to provide the same average power input as the uniform cases. The results for these tests indicated that the flow-rate at OFI increased with the degree of asymmetry.

  18. Creep, fatigue and creep-fatigue interactions in modified 9% Chromium - 1% Molybdenum (P91) steels

    NASA Astrophysics Data System (ADS)

    Kalyanasundaram, Valliappa

    Grade P91 steel, from the class of advanced high-chrome ferritic steels, is one of the preferred materials for many elevated temperature structural components. Creep-fatigue (C-F) interactions, along with oxidation, can accelerate the kinetics of damage accumulation and consequently reduce such components' life. Hence, reliable C-F test data is required for meticulous consideration of C-F interactions and oxidation, which in turn is vital for sound design practices. It is also imperative to develop analytical constitutive models that can simulate and predict material response under various long-term in-service conditions using experimental data from short-term laboratory experiments. Consequently, the major objectives of the proposed research are to characterize the creep, fatigue and C-F behavior of grade P91 steels at 625 C and develop robust constitutive models for simulating/predicting their microstructural response under different loading conditions. This work will utilize experimental data from 16 laboratories worldwide that conducted tests (creep, fatigue and C-F) on grade P91 steel at 625°C in a round-robin (RR) program. Along with 7 creep deformation and rupture tests, 32 pure fatigue and 46 C-F tests from the RR are considered in this work. A phenomenological constitutive model formulated in this work needs just five fitting parameters to simulate/predict the monotonic, pure fatigue and C-F behavior of grade P91 at 625 C. A modified version of an existing constitutive model is also presented for particularly simulating its isothermal creep deformation and rupture behavior. Experimental results indicate that specimen C-F lives, as measured by the 2% load drop criterion, seem to decrease with increasing strain ranges and increasing hold times at 625°C. Metallographic assessment of the tested specimens shows that the damage mode in both pure fatigue and 600 seconds hold time cyclic tests is predominantly transgranular fatigue with some presence of

  19. Program documentation for the space environment test division post-test data reduction program (GNFLEX)

    NASA Technical Reports Server (NTRS)

    Jones, L. D.

    1979-01-01

    The Space Environment Test Division Post-Test Data Reduction Program processes data from test history tapes generated on the Flexible Data System in the Space Environment Simulation Laboratory at the National Aeronautics and Space Administration/Lyndon B. Johnson Space Center. The program reads the tape's data base records to retrieve the item directory conversion file, the item capture file and the process link file to determine the active parameters. The desired parameter names are read in by lead cards after which the periodic data records are read to determine parameter data level changes. The data is considered to be compressed rather than full sample rate. Tabulations and/or a tape for generating plots may be output.

  20. A pilot study to test psychophonetics methodology for self-care and empathy in compassion fatigue, burnout and secondary traumatic stress

    PubMed Central

    Butler, Nadine

    2013-01-01

    Abstract Background Home-based care is recognised as being a stressful occupation. Practitioners working with patients experiencing high levels of trauma may be susceptible to compassion fatigue, with the sustained need to remain empathic being a contributing factor. Objectives The aim of this research was to evaluate psychophonetics methodology for self-care and empathy skills as an intervention for compassion fatigue. Objectives were to measure levels of compassion fatigue pre-intervention, then to apply the intervention and retest levels one month and six months post-intervention. Method The research applied a pilot test of a developed intervention as a quasi-experiment. The study sample comprised home-based carers working with HIV-positive patients at a hospice in Grabouw, a settlement in the Western Cape facing socioeconomic challenge. Results The result of the pilot study showed a statistically-significant improvement in secondary traumatic stress, a component of compassion fatigue, measured with the ProQOL v5 instrument post-intervention. Conclusion The results gave adequate indication for the implementation of a larger study in order to apply and test the intervention. The study highlights a dire need for further research in this field.

  1. Effect of Load History on Fatigue Life.

    DTIC Science & Technology

    1980-06-01

    A number of different loading histories will be investigated to determine their effects on constant amplitude fatigue properties of the selected...previous test results, and at each of the two R ratios. The effect of overloads on constant ampli- tude fatigue life and damage will be investigated ...be investigated . 5.1 FATIGUE TEST RESULTS Constant amplitude fatigue tests were conducted at four R ratios (+0.5, 0.0, -0.5, -1.0) using the

  2. Wiring test program insulation material related properties

    NASA Technical Reports Server (NTRS)

    Reher, Heinz-Josef

    1995-01-01

    This viewgraph presentation provides an overview of activities at DASA-RI concerning the testing of wires for manned spacecraft, including test facilities, arc-tracking tests, flammability tests, microgravity tests, and standardization, and outlines future activities.

  3. Fatigue experience from tests carried out with forged beam and frame structures in the development of the Saab aircraft Viggen

    NASA Technical Reports Server (NTRS)

    Larsson, S. E.

    1972-01-01

    A part of the lower side of the main wing at the joint of the main spar with the fuselage frame was investigated. This wing beam area was simulated by a test specimen consisting of a spar boom of AZ 74 forging (7075 aluminum alloy modified with 0.3 percent Ag) and a portion of a honeycomb sandwich panel attached to the boom flange with steel bolts. The cross section was reduced to half scale. However, the flange thickness, the panel height, and the bolt size were full scale. Further, left and right portions of the fuselage frame intended to carry over the bending moment of the main wing were tested. Each of these frame halves consisted of a forward and a rear forging (7079 aluminum alloy, overaged) connected by an outer and inner skin (Alclad 7075) creating a box beam. These test specimens were full scale and were constructed principally of ordinary aircraft components. The test load spectrum was common to both types of specimens with regard to percentage levels. It consisted of maneuver and gust loads, touchdown loads, and loads due to ground roughness. A load history of 200 hours of flight with 15,000 load cycles was punched on a tape. The loads were randomized in groups according to the flight-by-flight principle. The highest positive load level was 90 percent of limit load and the largest negative load was -27 percent. A total of 20 load levels were used. Both types of specimens were provided with strain gages and had a nominal stress of about 300 MN/sq m in some local areas. As a result of the tests, steps were taken to reduce the risk of fatigue damage in aircraft. Thus stress levels were lowered, radii were increased, and demands on surface finish were sharpened.

  4. Improving turbine blade fatigue life

    NASA Technical Reports Server (NTRS)

    Buddenbohm, H. W.

    1988-01-01

    Turbine airfoil design, materials, and cooling system management are variables which, when optimized, can contribute to longer turbine component lives. These advancements have been identified as redesign techniques to improve the turbine fatigue life of the SSME High Pressure Fuel Turbopump. This paper discusses the general program approach toward improving turbine fatigue life.

  5. Fatigue in advanced cancer: a prospective study.

    PubMed

    Hauser, Katherine; Walsh, Declan; Rybicki, Lisa A; Davis, Mellar P; Seyidova-Khoshknabi, Dilara

    2008-01-01

    Fatigue is a common advanced cancer symptom. Clinical features are not well known. The authors surveyed consecutive patients admitted to a palliative medicine program to identify clinical correlates of fatigue. Data collected included age, sex, performance status, primary site, prior chemotherapy/radiation therapy, and blood transfusions. Visual analogue scales assessed fatigue, quality of life, and ability to perform daily activities. Weight change was estimated. Laboratory results including lactate dehydrogenase and hemoglobin were recorded. Fatigue severity was associated with brain metastases, poor performance status, poor quality of life, and reduced ability to perform activities. Prior radiation therapy was associated with less severe fatigue. Age, sex, and hemoglobin level were not associated with fatigue. Fatigue was universal on referral. Brain metastases and poor quality of life independently predicted severity. Hemoglobin level did not predict fatigue. Further studies are necessary to define the clinical features and relationships of fatigue.

  6. Fatigue test load identification using weighted modal filtering based on stress

    NASA Astrophysics Data System (ADS)

    Wentzel, Henrik

    2013-11-01

    Laboratory reliability testing is an important part of the vehicle development process. Test rigs are designed to reproduce accelerations or other sensor readings in a controlled environment and criteria on the duration of testing without failure are used to assure quality. An apparent difficulty of this procedure is that the damage at a point is only indirectly coupled to the accelerations measured in other points. In this paper, it is proposed to use a modal shape filter, and control the test such that the shapes that are generating stress in critical points are reproduced. A selective weighting of the mode shapes allows for accurate reproduction of the stress, and hence the damage, also in circumstances when the exact location of the excitation force cannot be reconstructed in the test. The proposed procedure is applied in two different experiments; the first aiming to reproduce the stress in a cantilever beam, and the second aiming to reproduce the stress in a truck cabin suspension.

  7. 78 FR 68360 - Unmanned Aircraft System Test Site Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-14

    ... Federal Aviation Administration 14 CFR Part 91 Unmanned Aircraft System Test Site Program AGENCY: Federal... unmanned aircraft system (``UAS'') test site program; response to comments. SUMMARY: On February 22, 2013... Privacy Requirements'') for UAS test sites (the ``Test Sites'') that the FAA will establish pursuant...

  8. 46 CFR 16.205 - Implementation of chemical testing programs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Implementation of chemical testing programs. 16.205... CHEMICAL TESTING Required Chemical Testing § 16.205 Implementation of chemical testing programs. (a) When a...) Upon written request of an employer, Commandant (CG-INV) will review the employer's chemical...

  9. 46 CFR 16.205 - Implementation of chemical testing programs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Implementation of chemical testing programs. 16.205... CHEMICAL TESTING Required Chemical Testing § 16.205 Implementation of chemical testing programs. (a) When a...) Upon written request of an employer, Commandant (CG-INV) will review the employer's chemical...

  10. 46 CFR 16.205 - Implementation of chemical testing programs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Implementation of chemical testing programs. 16.205... CHEMICAL TESTING Required Chemical Testing § 16.205 Implementation of chemical testing programs. (a) When a...) Upon written request of an employer, Commandant (CG-INV) will review the employer's chemical...

  11. 46 CFR 16.205 - Implementation of chemical testing programs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Implementation of chemical testing programs. 16.205... CHEMICAL TESTING Required Chemical Testing § 16.205 Implementation of chemical testing programs. (a) When a...) Upon written request of an employer, Commandant (CG-545) will review the employer's chemical...

  12. 46 CFR 16.205 - Implementation of chemical testing programs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Implementation of chemical testing programs. 16.205... CHEMICAL TESTING Required Chemical Testing § 16.205 Implementation of chemical testing programs. (a) When a...) Upon written request of an employer, Commandant (CG-545) will review the employer's chemical...

  13. Structural Technology Evaluation Analysis Program (STEAP). Task Order 0029: Thermal Stability of Fatigue Life-Enhanced Structures

    DTIC Science & Technology

    2012-01-01

    more likely to come from the development of new processes to enhance the properties and resistance to damage of current materials during typical...studies to date have revealed that LSP leads to a dramatic improvement in the fatigue strength, life, and resistance to crack propagation in materials and...burnishing used originally for refinement of surface finishes, has similar effects on enhancing the fatigue properties and corrosion resistance of a

  14. Pulsed Ejector Wave Propogation Test Program

    NASA Technical Reports Server (NTRS)

    Fernandez, Rene; Slater, John W.; Paxson, Daniel E.

    2003-01-01

    The development of, and initial test data from, a nondetonating Pulse Detonation Engine (PDE) simulator tested in the NASA Glenn 1 x 1 foot Supersonic Wind Tunnel (SWT) is presented in this paper. The concept is a pulsed ejector driven by the simulated exhaust of a PDE. This pro- gram is applicable to a PDE entombed in a ramjet flowpath, i.e., a PDE combined-cycle propulsion system. The ejector primary flow is a pulsed, uiiderexpanded, supersonic nozzle simulating the supersonic waves ema- nating from a PDE, while the ejector secondary flow is the 1 x 1 foot SWT test section operated at subsonic Mach numbers. The objective is not to study the detonation details, but the wave physics including t,he start- ing vortices, the extent of propagation of the wave front, the reflection of the wave from the secondary flowpath walls, and the timing of these events of a pulsed ejector, and correlate these with Computational Fluid Dynamics (CFD) code predictions. Pulsed ejectors have been shown to result in a 3 to 1 improvement in LID (length-to-diameter) and a near 2 to 1 improvement in thrust augmentation over a steady ejector. This program will also explore the extent of upstream interactions between an inlet and large, periodically applied, backpressures to the inlet as would be present due to combustion tube detonations in a PDE. These interactions could result in inlet unstart or buzz for a supersonic mixed compression inlet. The design of the present experiment entailed the use of an 2-t diagram characteristics code to study the nozzle filling and purging timescales as well as a series of CFD analyses conducted using the WIND code. The WIND code is a general purpose CFD code for solution of the Reynolds averaged Navier-Stokes equations and can be applied to both steady state and time-accurate calculations. The first, proof-of-concept, test entry (spring 2001) pressure distributions shown here indicate the simulation concept was successful and therefore the experimental

  15. A Session with TINKER: Interleaving Program Testing With Program Design.

    DTIC Science & Technology

    1980-09-01

    Smith’s Pygmalion , which pioneered the idea of menu-oriented programming. Our techniques of displaying examples and source code for programs...slimilar in spirit to Pygmalion , and both these systems made interesting use of graphical rather than textual representations of programs, which we have not...demionstrating his Pygmalion 1 * ,ti to uts and discussing it with us on a visit to Xerox PARC, and G. J. Curry’ for leiiding uts a \\ideoiaped demonstration of

  16. Pioneer Robot Testing Program and Status

    SciTech Connect

    Herndon, J.N.

    2001-02-02

    The U.S. Department of Energy (USDOE) and Ukraine established a joint program in 1997 to address the need for remotely operated systems for unstructured environments in Ukraine such as the highly hazardous conditions inside the failed Chernobyl Nuclear Power Plant (ChNPP) Unit 4, or Shelter Object. The environment inside Shelter Object is extremely hazardous due to ionizing radiation fields, high airborne contamination, and major industrial safety issues. Although Ukrainian workers have explored and mapped much of the internals of Unit 4 in the time since the accident during the morning hours of April 26, 1986, there remain areas where humans have not entered to this date. Based on the agreement between USDOE and Ukraine, the USDOE, in cooperation with the U.S. National Aeronautics and Space Administration (NASA), developed the Pioneer Robot and has provided it to the ChNPP within the framework of international technical assistance. Pioneer is capable of mobile platform movement and manipulation under teleoperated control, 3-dimensional mapping, and environmental data collection. The Pioneer is radiation hardened for conditions like those of Shelter Object. Pioneer has been evaluated on site in Ukraine for use in both the Shelter Object environment and the more general conditions of ChNPP decommissioning. This paper summarizes the results of these testing activities and describes the status and near-term activities in support of the Pioneer Robot integration into Ukraine.

  17. Fatigue life of laser cut metals

    NASA Technical Reports Server (NTRS)

    Martin, M. R.

    1986-01-01

    Fatigue tests were conducted to determine the actual reduction in fatigue life due to weight removal for balancing by: hand grinding, low power (20 watt) Nd:glass laser, and high power (400 watt) Nd:YAG laser.

  18. Elevated Temperature Fatigue Endurance of Three Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Verrilli, Michael J.

    2007-01-01

    High-cycle fatigue endurance of three candidate materials for the acoustic liners of the Enabling Propulsion Materials Nozzle Program was investigated. The ceramic matrix composite materials investigated were N720/AS (Nextel 720, 3M Corporation), Sylramic S200 (Dow Corning), and UT 22. High-cycle fatigue tests were conducted in air at 910 C on as-machined specimens and on specimens subjected to tensile cyclic load excursions every 160 hr followed by thermal exposure at 910 C in a furnace up to total exposure times of 2066 and 4000 hr. All the fatigue tests were conducted in air at 100 Hz with a servohydraulic test machine. In the as-machined condition, among the three materials investigated only the Sylramic S200 exhibited a deterministic type of high-cycle fatigue behavior. Both the N720/AS and UT-22 exhibited significant scatter in the experimentally observed high-cycle fatigue lives. Among the thermally exposed specimens, N720/AS and Sylramic S200 materials exhibited a reduction in the high-cycle fatigue lives, particularly at the exposure time of 4000 hr.

  19. Statistical complex fatigue data for SAE 4340 steel and its use in design by reliability

    NASA Technical Reports Server (NTRS)

    Kececioglu, D.; Smith, J. L.

    1970-01-01

    A brief description of the complex fatigue machines used in the test program is presented. The data generated from these machines are given and discussed. Two methods of obtaining strength distributions from the data are also discussed. Then follows a discussion of the construction of statistical fatigue diagrams and their use in designing by reliability. Finally, some of the problems encountered in the test equipment and a corrective modification are presented.

  20. LANCE Q-flex accelerometer qualification test program

    NASA Astrophysics Data System (ADS)

    Hunter, J. S.; Mitchell, J. N.; Hester, T.; Searcy, D.

    1982-03-01

    This report covers the performance obtained on six Sundstrand Q-Flex accelerometers during the qualification test program for the LANCE missile. The Qualification Test Program was divided into three parts: (1) Flight Assurance Tests (FAT), (2) Storage and Transportation Tests (SATT), and (3) Reliability Overstress Tests (ROT). All testing was performed in accordance with Vought accelerometer procurement specification 704-166C dated 8 June 1978.

  1. An overview of fatigue failures at the Rocky Flats Wind System Test Center

    NASA Technical Reports Server (NTRS)

    Waldon, C. A.

    1981-01-01

    Potential small wind energy conversion (SWECS) design problems were identified to improve product quality and reliability. Mass produced components such as gearboxes, generators, bearings, etc., are generally reliable due to their widespread uniform use in other industries. The likelihood of failure increases, though, in the interfacing of these components and in SWECS components designed for a specific system use. Problems relating to the structural integrity of such components are discussed and analyzed with techniques currently used in quality assurance programs in other manufacturing industries.

  2. Thermal fatigue of beryllium

    SciTech Connect

    Deksnis, E.; Ciric, D.; Falter, H.

    1995-09-01

    Thermal fatigue life of S65c beryllium castellated to a geometry 6 x 6 x (8-10)mm deep has been tested for steady heat fluxes of 3 MW/m{sup 2} to 5 MW/m{sup 2} and under pulsed heat fluxes (10-20 MW/m{sup 2}) for which the time averaged heat flux is 5 MW/m{sup 2}. These tests were carried out in the JET neutral beam test facility A test sequence with peak surface temperatures {le} 600{degrees}C produced no visible fatigue cracks. In the second series of tests, with T{sub max} {le} 750{degrees}C evidence for fatigue appeared after a minimum of 1350 stress cycles. These fatigue data are discussed in view of the observed lack of thermal fatigue in JET plasma operations with beryllium PFC. JET experience with S65b and S65c is reviewed; recent operations with {Phi} = 25 MW/m{sup 2} and sustained melting/resolidification are also presented. The need for a failure criterion for finite element analyses of Be PFC lifetimes is discussed.

  3. 49 CFR 219.601 - Railroad random drug testing programs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Railroad random drug testing programs. 219.601 Section 219.601 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Programs § 219.601 Railroad random drug testing programs. (a) Submission. Each railroad must submit for...

  4. 49 CFR 219.601 - Railroad random drug testing programs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Railroad random drug testing programs. 219.601 Section 219.601 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Programs § 219.601 Railroad random drug testing programs. (a) Submission. Each railroad must submit for...

  5. 49 CFR 219.607 - Railroad random alcohol testing programs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Railroad random alcohol testing programs. 219.607 Section 219.607 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Programs § 219.607 Railroad random alcohol testing programs. (a) Each railroad must submit for FRA...

  6. 49 CFR 219.607 - Railroad random alcohol testing programs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Railroad random alcohol testing programs. 219.607 Section 219.607 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Programs § 219.607 Railroad random alcohol testing programs. (a) Each railroad must submit for FRA...

  7. 49 CFR 219.601 - Railroad random drug testing programs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Railroad random drug testing programs. 219.601 Section 219.601 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Programs § 219.601 Railroad random drug testing programs. (a) Submission. Each railroad must submit for...

  8. Evaluation of verification and testing tools for FORTRAN programs

    NASA Technical Reports Server (NTRS)

    Smith, K. A.

    1980-01-01

    Two automated software verification and testing systems were developed for use in the analysis of computer programs. An evaluation of the static analyzer DAVE and the dynamic analyzer PET, which are used in the analysis of FORTRAN programs on Control Data (CDC) computers, are described. Both systems were found to be effective and complementary, and are recommended for use in testing FORTRAN programs.

  9. Test Length and Cognitive Fatigue: An Empirical Examination of Effects on Performance and Test-Taker Reactions

    ERIC Educational Resources Information Center

    Ackerman, Phillip L.; Kanfer, Ruth

    2009-01-01

    Person and situational determinants of cognitive ability test performance and subjective reactions were examined in the context of tests with different time-on-task requirements. Two hundred thirty-nine first-year university students participated in a within-participant experiment, with completely counterbalanced treatment conditions and test…

  10. Design of a Data Acquisition and Reduction System for Fatigue Testing.

    DTIC Science & Technology

    1981-09-01

    Jerry Wayne Dalton Lieutenant, United States Navy B.S., University of Texas at Austin, 1975 Submitted in partial fulfillment of the requirements for...specimen (Fig. 1) to be used in the full scale tests. These material parameters and properties are: 34 80 70 60 so ~40/ n30 / 20/ 10 / 2 4 6 8 10 12 STRAIN

  11. Fatigue Lives Of Laser-Cut Metals

    NASA Technical Reports Server (NTRS)

    Martin, Michael R.

    1988-01-01

    Fatigue lives made to approach those attainable by traditional grinding methods. Fatigue-test specimens prepared from four metallic alloys, and material removed from specimens by manual grinding, by Nd:glass laser, and by Nd:YAG laser. Results of fatigue tests of all specimens indicated reduction of fatigue strengths of laser-fired specimens. Laser machining holds promise for improved balancing of components of gas turbines.

  12. 40 CFR 88.205-94 - California Pilot Test Program Credits Program.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false California Pilot Test Program Credits...) AIR PROGRAMS (CONTINUED) CLEAN-FUEL VEHICLES California Pilot Test Program § 88.205-94 California... program to enable vehicle manufacturers who are required to participate in the California Pilot...

  13. 40 CFR 88.205-94 - California Pilot Test Program Credits Program.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false California Pilot Test Program Credits...) AIR PROGRAMS (CONTINUED) CLEAN-FUEL VEHICLES California Pilot Test Program § 88.205-94 California... program to enable vehicle manufacturers who are required to participate in the California Pilot...

  14. 40 CFR 88.205-94 - California Pilot Test Program Credits Program.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true California Pilot Test Program Credits...) AIR PROGRAMS (CONTINUED) CLEAN-FUEL VEHICLES California Pilot Test Program § 88.205-94 California... program to enable vehicle manufacturers who are required to participate in the California Pilot...

  15. 40 CFR 88.205-94 - California Pilot Test Program Credits Program.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false California Pilot Test Program Credits...) AIR PROGRAMS (CONTINUED) CLEAN-FUEL VEHICLES California Pilot Test Program § 88.205-94 California... program to enable vehicle manufacturers who are required to participate in the California Pilot...

  16. Study on the Temperature Field Loaded by a Shaped Laser Beam on the Top Surface of a Cylinder Head for Thermal Fatigue Test

    NASA Astrophysics Data System (ADS)

    Nie, S.-Z.; Yu, J.; Yu, G.; Tan, Q.-F.; Fan, Z.-W.

    2014-09-01

    In thermal fatigue test, the key point is whether the temperature field on the top surface of cylinder head induced by the heat source can well match it in real service. In order to produce the target temperature field in service which is measured by thermocouples, shaped laser beam generated by diffractive optics element (DOE) is chosen as the heat source to irradiate on the top surface of cylinder head. The DOE is designed based on the Gerchberg-Saxton (GS) algorithm and the simulated temperature field is calculated by finite element model (FEM). The results show that the simulated and experimental temperature field can well match the target one which demonstrates that this method is feasible to produce the target temperature field and can be used in thermal fatigue test.

  17. The Citywide Standardized Testing Program for Middle and High Schools (A Testing Manual).

    ERIC Educational Resources Information Center

    Stratton, Julius A.

    The relationship between the Instructional Process, Instructional Objectives, and Assessment Tasks, identified at the School City of Gary, Indiana, necessitate an effective testing program. Four characteristics perceived crucial to a sound program were: (1) The program should be continuous, (2) The testing program should be comprehensive, (3)…

  18. Equating in Small-Scale Language Testing Programs

    ERIC Educational Resources Information Center

    LaFlair, Geoffrey T.; Isbell, Daniel; May, L. D. Nicolas; Gutierrez Arvizu, Maria Nelly; Jamieson, Joan

    2017-01-01

    Language programs need multiple test forms for secure administrations and effective placement decisions, but can they have confidence that scores on alternate test forms have the same meaning? In large-scale testing programs, various equating methods are available to ensure the comparability of forms. The choice of equating method is informed by…

  19. 78 FR 54510 - New Entrant Safety Assurance Program Operational Test

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-04

    ... TRANSPORTATION Federal Motor Carrier Safety Administration New Entrant Safety Assurance Program Operational Test... Motor Carrier Safety Administration (FMCSA) announces an operational test of procedural changes to the New Entrant Safety Assurance Program. The operational test began in July 2013 and will be in...

  20. Definition study of a Variable Cycle Experimental Engine (VCEE) and associated test program and test plan

    NASA Technical Reports Server (NTRS)

    Allan, R. D.

    1978-01-01

    The Definition Study of a Variable Cycle Experimental Engine (VCEE) and Associated Test Program and Test Plan, was initiated to identify the most cost effective program for a follow-on to the AST Test Bed Program. The VCEE Study defined various subscale VCE's based on different available core engine components, and a full scale VCEE utilizing current technology. The cycles were selected, preliminary design accomplished and program plans and engineering costs developed for several program options. In addition to the VCEE program plans and options, a limited effort was applied to identifying programs that could logically be accomplished on the AST Test Bed Program VCE to extend the usefulness of this test hardware. Component programs were provided that could be accomplished prior to the start of a VCEE program.

  1. Probabilistic Fatigue: Computational Simulation

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2002-01-01

    Fatigue is a primary consideration in the design of aerospace structures for long term durability and reliability. There are several types of fatigue that must be considered in the design. These include low cycle, high cycle, combined for different cyclic loading conditions - for example, mechanical, thermal, erosion, etc. The traditional approach to evaluate fatigue has been to conduct many tests in the various service-environment conditions that the component will be subjected to in a specific design. This approach is reasonable and robust for that specific design. However, it is time consuming, costly and needs to be repeated for designs in different operating conditions in general. Recent research has demonstrated that fatigue of structural components/structures can be evaluated by computational simulation based on a novel paradigm. Main features in this novel paradigm are progressive telescoping scale mechanics, progressive scale substructuring and progressive structural fracture, encompassed with probabilistic simulation. These generic features of this approach are to probabilistically telescope scale local material point damage all the way up to the structural component and to probabilistically scale decompose structural loads and boundary conditions all the way down to material point. Additional features include a multifactor interaction model that probabilistically describes material properties evolution, any changes due to various cyclic load and other mutually interacting effects. The objective of the proposed paper is to describe this novel paradigm of computational simulation and present typical fatigue results for structural components. Additionally, advantages, versatility and inclusiveness of computational simulation versus testing are discussed. Guidelines for complementing simulated results with strategic testing are outlined. Typical results are shown for computational simulation of fatigue in metallic composite structures to demonstrate the

  2. Test Builder Program Instructions. IBM Version.

    ERIC Educational Resources Information Center

    Patton, Jan; Steffee, John

    This document provides printed instructions for teachers to use with an IBM-compatible microcomputer to construct tests and then have the computer give the tests, grade them, and print the test results. Computerized tests constructed in this way may contain true-false questions, multiple-choice questions, or a combination of both. The questions…

  3. Fatigue and Barkhausen effect

    NASA Astrophysics Data System (ADS)

    Tong, Wei

    Piezomagnetism designates a change in the magnetization of materials induced by mechanical actions such as tension or compression. The type of Barkhausen effect that occurs in this work consists of sudden, discontinuous jumps in a material's magnetization that appear in response to smooth (continuous) stress variations. A series of strain controlled fatigue tests with an alternating sinusoidal waveform were carried out to study the relationship between the endurance limit and the Barkhausen effect. Results of fatigue tests on steel specimens exhibiting Barkhausen pulses at various stages are reported and a threshold-crossing analysis is applied to the test results. These studies show that when the fatigue limit is approached, the Barkhausen pulses become, in general, more intense in amplitude and quantity than at other stress levels. A hypothetical mechanism is proposed that relates the intensity of the Barkhausen response to the inception of micro-cracking and rearrangements of the mechanical lattice at the microscopic level.

  4. Determination of Rolling-Element Fatigue Life From Computer Generated Bearing Tests

    NASA Technical Reports Server (NTRS)

    Vlcek, Brian L.; Hendricks, Robert C.; Zaretsky, Erwin V.

    2003-01-01

    Two types of rolling-element bearings representing radial loaded and thrust loaded bearings were used for this study. Three hundred forty (340) virtual bearing sets totaling 31400 bearings were randomly assembled and tested by Monte Carlo (random) number generation. The Monte Carlo results were compared with endurance data from 51 bearing sets comprising 5321 bearings. A simple algebraic relation was established for the upper and lower L(sub 10) life limits as function of number of bearings failed for any bearing geometry. There is a fifty percent (50 percent) probability that the resultant bearing life will be less than that calculated. The maximum and minimum variation between the bearing resultant life and the calculated life correlate with the 90-percent confidence limits for a Weibull slope of 1.5. The calculated lives for bearings using a load-life exponent p of 4 for ball bearings and 5 for roller bearings correlated with the Monte Carlo generated bearing lives and the bearing data. STLE life factors for bearing steel and processing provide a reasonable accounting for differences between bearing life data and calculated life. Variations in Weibull slope from the Monte Carlo testing and bearing data correlated. There was excellent agreement between percent of individual components failed from Monte Carlo simulation and that predicted.

  5. Corrosion-fatigue of laser-repaired commercially pure titanium and Ti-6Al-4V alloy under different test environments.

    PubMed

    Zavanelli, R A; Guilherme, A S; Pessanha-Henriques, G E; de Arruda Nóbilo, M Antônio; Mesquita, M F

    2004-10-01

    This study evaluated the corrosion-fatigue life of laser-repaired specimens fabricated from commercially pure titanium (CP Ti) and Ti-6Al-4V alloy, tested under different storage conditions. For each metal, 30 dumbbell rods with a central 2.3 mm diameter were prepared by lost-wax casting with the Rematitan System. Simulating the failure after service, corrosion-fatigue life in different media at room temperature (air, synthetic saliva and fluoride synthetic saliva) was determined at a testing frequency of 10 Hz for intact specimens and after laser repairing, using a square waveform with equal maximum tensile and compressive stress that was 30% lower than the 0.2% offset yield strength. For laser welding, the fractured specimens were rejoined using a jig to align the sections invested in type-IV dental stone. The adjacent areas of the gap was air-abraded with 100 microm aluminum oxide, laser welded and retested under the same conditions as the initial intact specimens. The number of cycles at failure was recorded, and the fracture surface was examined with a scanning electron microscope (SEM). The number of cycles for failure of the welded and intact specimens was compared by anova and the Tukey test at a 5% probability level. Within the limitations of this study, the number of cycles required for fracture decreased in wet environments and the laser repairing process adversely affected the life of both metals under the corrosion-fatigue conditions.

  6. High Voltage Testing. Volume 1. Test Program Report

    DTIC Science & Technology

    1982-07-15

    Discharges 44 6.3.7.1 Procedure 6.3.7.2 Instruments "vi TABLE OF CONTENTS (Continued) ,E;CTION PAGE 6.4 Test Data 45 6.4.1 Insulation Resistance 45...Partial Discharge Test 56 6.5 Discussion of Test Results 59 6.5.1 Test Objectives 63 6.5.2 Insulation Resistance 63 6.5.3 Capacitance and Dielectric...and DC Partial Discharge Test Data 61 6.4-17 Pulse Transformer AC Partial Discharge Test Data 62 6.5-1 Insulation Resistance 64 6.5-2 Dielectric

  7. Axial-torsional fatigue: A study of tubular specimen thickness effects

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1990-01-01

    A room-temperature experimental program was conducted on AISI type 316 stainless steel to determine the effect of wall thickness on the cyclic deformation behavior and fatigue life of thin-wall, tubular, axial-torsional fatigue specimens. The following experimental variables were examined in this study: the depth of the surface work-hardened layer produced in specimen machining, and the effects of strain range and axial-torsional strain phasing. Tubular fatigue specimens were fabricated with wall thicknesses of 1.5, 2.0, and 2.5 mm. One as-fabricated specimen from each wall thickness was sectioned for microstructural examination and microhardness measurement. A specimen of each wall thickness was tested at each of three conditions - high strain range in-phase, low strain range in-phase, and low strain range out-of-phase - for a total of nine axial-torsional fatigue experiments. The machining-induced work-hardened zone, as a percentage of the gage section material, was found to have a minimal effect on both deformation behavior and fatigue life. Also, little or no variation in fatigue life or deformation behavior as a function of wall thickness was observed. Out-of-phase fatigue tests displayed shorter fatigue lives and more cyclic hardening than in-phase tests.

  8. Investigation of thermal fatigue in fiber composite materials. [(thermal cycling tests)

    NASA Technical Reports Server (NTRS)

    Fahmy, A. A.; Cunningham, T. G.

    1976-01-01

    Graphite-epoxy laminates were thermally cycled to determine the effects of thermal cycles on tensile properties and thermal expansion coefficients of the laminates. Three 12-ply laminate configurations were subjected to up to 5,000 thermal cycles. The cumulative effect of the thermal cycles was determined by destructive inspection (electron micrographs and tensile tests) of samples after progressively larger numbers of cycles. After thermal cycling, the materials' tensile strengths, moduli, and thermal expansion coefficients were significantly lower than for the materials as fabricated. Most of the degradation of properties occurred after only a few cycles. The property degradation was attributed primarily to the progressive development of matrix cracks whose locations depended upon the layup orientation of the laminate.

  9. Detailed Test Plan Redundant Sensor Strapdown IMU Evaluation Program

    NASA Technical Reports Server (NTRS)

    Hartwell, T.; Miyatake, Y.; Wedekind, D. E.

    1971-01-01

    The test plan for a redundant sensor strapdown inertial measuring unit evaluation program is presented. The subjects discussed are: (1) test philosophy and limitations, (2) test sequence, (3) equipment specifications, (4) general operating procedures, (5) calibration procedures, (6) alignment test phase, and (7) navigation test phase. The data and analysis requirements are analyzed.

  10. Pre-crack fatigue life assessment of relevant aircraft materials using fractal analysis of eddy current test data

    NASA Astrophysics Data System (ADS)

    Schreiber, Jürgen; Cikalova, Ulana; Hillmann, Susanne; Meyendorf, Norbert; Hoffmann, Jochen

    2013-01-01

    Successful determination of residual fatigue life requires a comprehensive understanding of the fatigue related material deformation mechanism. Neither macroscopic continuum mechanics nor micromechanic observations provide sufficient data to explain subsequent deformation structures occurring during the fatigue life of a metallic structure. Instead mesomechanic deformation on different scaling levels can be studied by applying fractal analysis of various means of nondestructive inspection measurements. The resulting fractal dimension data can be correlated to the actual material damage states, providing an estimation of the remaining residual fatigue life before macroscopic fracture develops. Recent efforts were aimed to apply the fractal concept to aerospace relevant materials AA7075-T6 and Ti-6Al-4V. Proven and newly developed fractal analysis methods were applied to eddy current (EC) measurements of fatigued specimens, with the potential to transition this approach to an aircraft for an in-situ nondestructive inspection. The occurrence of mesomechanic deformation at the material surface of both AA7075-T6 and Ti-6Al-4V specimens could be established via topography images using confocal microscopy (CM). Furthermore, a pulsed eddy current (PEC) approach was developed, combined with a sophisticated new fractal analysis algorithm based on short pulse excitation and evaluation of EC relaxation behavior. This paper presents concept, experimental realization, fractal analysis procedures, and results of this effort.

  11. Alternative filtration testing program: Pre-evaluation of test results

    SciTech Connect

    Georgeton, G.K.; Poirier, M.R.

    1990-09-28

    Based on results of testing eight solids removal technologies and one pretreatment option, it is recommended that a centrifugal ultrafilter and polymeric ultrafilter undergo further testing as possible alternatives to the Norton Ceramic filters. Deep bed filtration should be considered as a third alternative, if a backwashable cartridge filter is shown to be inefficient in separate testing.

  12. An Experimental Investigation of Transverse Tension Fatigue Characterization of IM6/3501-6 Composite Materials Using a Three-Point Bend Test

    NASA Technical Reports Server (NTRS)

    Peck, Ann W.

    1998-01-01

    As composites are introduced into more complex structures with out-of-plane loadings, a better understanding is needed of the out-of-plane, matrix-dominated failure mechanisms. This work investigates the transverse tension fatigue characteristics of IM6/3501 composite materials. To test the 90 degree laminae, a three-point bend test was chosen, potentially minimizing handling and gripping issues associated with tension tests. A finite element analysis was performed of a particular specimen configuration to investigate the influence of specimen size on the stress distribution for a three-point bend test. Static testing of 50 specimens of 9 different sized configurations produced a mean transverse tensile strength of 61.3 Mpa (8.0 ksi). The smallest configuration (10.2 mm wide, Span-to-thickness ratio of 3) consistently exhibited transverse tensile failures. A volume scale effect was difficult to discern due to the large scatter of the data. Static testing of 10 different specimens taken from a second panel produced a mean transverse tensile strength of 82.7 Mpa (12.0 ksi). Weibull parameterization of the data was possible, but due to variability in raw material and/or manufacturing, more replicates are needed for greater confidence. Three-point flex fatigue testing of the smallest configuration was performed on 59 specimens at various levels of the mean static transverse tensile strength using an R ratio of 0.1 and a frequency of 20 Hz. A great deal of scatter was seen in the data. The majority of specimens failed near the center loading roller. To determine whether the scatter in the fatigue data is due to variability in raw material and/or the manufacturing process, additional testing should be performed on panels manufactured from different sources.

  13. A test program for solar collectors

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Rigorous environmental and performance tests qualify solar collector for use in residential solar-energy systems. Testing over 7 month period examined pressurized effects, wind and snow loading, hail damage, solar and thermal degradation, effects of pollutants, efficiency, and outgassing. Test procedures and results are summarized in tables, graphs, and text.

  14. Characterization of micro-contact resistance between a gold nanocrystalline line and a tungsten electrode probe in interconnect fatigue testing.

    PubMed

    Ling, Xue; Wang, Yusheng; Li, Xide

    2014-10-01

    An electromechanically-coupled micro-contact resistance measurement system is built to mimic the contact process during fatigue testing of nanoscale-thickness interconnects using multiple probe methods. The design combines an optical microscope, high-resolution electronic balance, and micromanipulator-controlled electric probe, and is coupled with electrical measurements to investigate microscale contact physics. Experimental measurements are performed to characterize the contact resistance response of the gold nanocrystalline pad of a 35-nm-thick interconnect under mechanical force applied by a tungsten electrode probe. Location of a stable region for the contact resistance and the critical contact force provides better understanding of micro-contact behavior relative to the effects of the contact force and the nature of the contact surface. Increasing contact temperature leads to reduced contact resistance, softens the pad material, and modifies the contact surface. The stability of both contact resistance and interconnect resistance is studied under increasing contact force. Major fluctuations emerge when the contact force is less than the critical contact force, which shows that temporal contact resistance will affect interconnect resistance measurement accuracy, even when using the four-wire method. This performance is demonstrated experimentally by heating the Au line locally with a laser beam. Finally, the contact resistances are calculated using the LET (Li-Etsion-Talke) model together with combined Holm and Sharvin theory under various contact forces. Good agreement between the results is obtained. This research provides a way to measure change in interconnect line resistance directly under a stable contact resistance regime with a two-wire method that will greatly reduce the experimental costs.

  15. Characterization of micro-contact resistance between a gold nanocrystalline line and a tungsten electrode probe in interconnect fatigue testing

    NASA Astrophysics Data System (ADS)

    Ling, Xue; Wang, Yusheng; Li, Xide

    2014-10-01

    An electromechanically-coupled micro-contact resistance measurement system is built to mimic the contact process during fatigue testing of nanoscale-thickness interconnects using multiple probe methods. The design combines an optical microscope, high-resolution electronic balance, and micromanipulator-controlled electric probe, and is coupled with electrical measurements to investigate microscale contact physics. Experimental measurements are performed to characterize the contact resistance response of the gold nanocrystalline pad of a 35-nm-thick interconnect under mechanical force applied by a tungsten electrode probe. Location of a stable region for the contact resistance and the critical contact force provides better understanding of micro-contact behavior relative to the effects of the contact force and the nature of the contact surface. Increasing contact temperature leads to reduced contact resistance, softens the pad material, and modifies the contact surface. The stability of both contact resistance and interconnect resistance is studied under increasing contact force. Major fluctuations emerge when the contact force is less than the critical contact force, which shows that temporal contact resistance will affect interconnect resistance measurement accuracy, even when using the four-wire method. This performance is demonstrated experimentally by heating the Au line locally with a laser beam. Finally, the contact resistances are calculated using the LET (Li-Etsion-Talke) model together with combined Holm and Sharvin theory under various contact forces. Good agreement between the results is obtained. This research provides a way to measure change in interconnect line resistance directly under a stable contact resistance regime with a two-wire method that will greatly reduce the experimental costs.

  16. Characterization of micro-contact resistance between a gold nanocrystalline line and a tungsten electrode probe in interconnect fatigue testing

    SciTech Connect

    Ling, Xue; Wang, Yusheng; Li, Xide

    2014-10-15

    An electromechanically-coupled micro-contact resistance measurement system is built to mimic the contact process during fatigue testing of nanoscale-thickness interconnects using multiple probe methods. The design combines an optical microscope, high-resolution electronic balance, and micromanipulator-controlled electric probe, and is coupled with electrical measurements to investigate microscale contact physics. Experimental measurements are performed to characterize the contact resistance response of the gold nanocrystalline pad of a 35-nm-thick interconnect under mechanical force applied by a tungsten electrode probe. Location of a stable region for the contact resistance and the critical contact force provides better understanding of micro-contact behavior relative to the effects of the contact force and the nature of the contact surface. Increasing contact temperature leads to reduced contact resistance, softens the pad material, and modifies the contact surface. The stability of both contact resistance and interconnect resistance is studied under increasing contact force. Major fluctuations emerge when the contact force is less than the critical contact force, which shows that temporal contact resistance will affect interconnect resistance measurement accuracy, even when using the four-wire method. This performance is demonstrated experimentally by heating the Au line locally with a laser beam. Finally, the contact resistances are calculated using the LET (Li–Etsion–Talke) model together with combined Holm and Sharvin theory under various contact forces. Good agreement between the results is obtained. This research provides a way to measure change in interconnect line resistance directly under a stable contact resistance regime with a two-wire method that will greatly reduce the experimental costs.

  17. Halogen Occultation Experiment (HALOE) gas cell life test program

    NASA Technical Reports Server (NTRS)

    Sullivan, E. M.; Thompson, R. E.; Harvey, G. A.; Park, J. H.; Richardson, D. J.

    1983-01-01

    The Halogen Occultation Experiment (HALOE) will use gas filter correlation radiometry to measure the atmospheric concentration profiles of HCl, HF, NO, and CH4 from the Upper Atmosphere Research Satellite. The need to contain the gases for the gas filter measurements has resulted in the development of gas cells and the need for a life test program to demonstrate that the gas cells will perform their functions for extended periods (several years) of time. This report describes the tests in the life test program, the test apparatus used, and the analysis techniques developed. The report also presents data obtained during the first 14 months of the test program.

  18. High Alpha Technology Program (HATP) ground test to flight comparisons

    NASA Technical Reports Server (NTRS)

    Hall, R. M.; Banks, D. W.; Fisher, David F.; Ghaffari, F.; Murri, D. G.; Ross, J. C.; Lanser, Wendy R.

    1994-01-01

    This status paper reviews the experimental ground test program of the High Alpha Technology Program (HATP). The reasons for conducting this ground test program had their origins during the 1970's when several difficulties were experienced during the development programs of both the F-18 and F-16. A careful assessment of ground test to flight correlations appeared to be important for reestablishing a high degree of confidence in our ground test methodology. The current paper will then focus on one aspect of the HATP program that is intended to improve the correlation between ground test and flight, high-alpha gritting. The importance of this work arises from the sensitivity of configurations with smooth-sided forebodies to Reynolds number. After giving examples of the effects of Reynolds number, the paper will highlight efforts at forebody gritting. Finally, the paper will conclude by summarizing the charter of the HATP Experimental Aerodynamics Working Group and future experimental testing plans.

  19. 76 FR 59574 - Procedures for Transportation Workplace Drug and Alcohol Testing Programs: Federal Drug Testing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-27

    ... Office of the Secretary 49 CFR Part 40 RIN 2105-AE13 Procedures for Transportation Workplace Drug and Alcohol Testing Programs: Federal Drug Testing Custody and Control Form; Technical Amendment AGENCY... of a new Federal Drug Testing Custody and Control Form (CCF) in its drug testing program. Use of...

  20. "A Group of Me's": Adult Learning through Group Process: The Experiences of Participants in a Teleconference Delivered Multiple Sclerosis Fatigue Management Program

    ERIC Educational Resources Information Center

    Preissner, Katharine L.

    2013-01-01

    Multiple sclerosis (MS) is a chronic, progressive neurological disorder that affects approximately 2.1 million people worldwide. Fatigue is one of the most common and most disabling symptoms of MS. One well-established approach to address fatigue is fatigue management education provided by an occupational therapist. Fatigue management education is…

  1. Terminal configured vehicle program: Test facilities guide

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The terminal configured vehicle (TCV) program was established to conduct research and to develop and evaluate aircraft and flight management system technology concepts that will benefit conventional take off and landing operations in the terminal area. Emphasis is placed on the development of operating methods for the highly automated environment anticipated in the future. The program involves analyses, simulation, and flight experiments. Flight experiments are conducted using a modified Boeing 737 airplane equipped with highly flexible display and control equipment and an aft flight deck for research purposes. The experimental systems of the Boeing 737 are described including the flight control computer systems, the navigation/guidance system, the control and command panel, and the electronic display system. The ground based facilities used in the program are described including the visual motion simulator, the fixed base simulator, the verification and validation laboratory, and the radio frequency anechoic facility.

  2. Methodology for Predicting the Onset of Widespread Fatigue Damage in Lap-Splice Joints

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Harris, C. E.; Piascik, R. S.; Dawicke, D. S.

    1998-01-01

    NASA has conducted an Airframe Structural Integrity Program to develop the methodology to predict the onset of widespread fatigue damage to lap-splice joints of fuselage structures. Several stress analysis codes have been developed or enhanced to analyze the lap-splice-joint configuration. Fatigue lives in lap-splice-joint specimens and fatigue-crack growth in a structural fatigue test article agreed well with calculations from small-crack theory and fatigue-crack growth analyses with the FASTRAN code. Residual-strength analyses of laboratory specimens and wide stiffened panels were predicted quite well from the critical crack-tip-opening angle (CTOA) fracture criterion and elastic-plastic finite-element analyses (two- or three-dimensional codes and the STAGS shell code).

  3. Small crack test program for helicopter materials

    NASA Technical Reports Server (NTRS)

    Annigeri, Bal; Schneider, George

    1994-01-01

    Crack propagation tests were conducted to determine crack growth behavior in five helicopter materials for surface cracks between 0.005 to 0.020 inches in depth. Constant amplitude tests were conducted at stress ratios R equals 0.1 and 0.5, and emphasis was placed on near threshold data (i.e., 10-8 to 10-6 inches/cycle). Spectrum tests were conducted using a helicopter spectrum. The test specimen was an unnotched tension specimen, and cracks were initiated from a small EDM notch. An optical/video system was used to monitor crack growth. The material for the test specimens was obtained from helicopter part forgings. Testing was conducted at stresses below yield to reflect actual stresses in helicopter parts.

  4. F-14A Fire Protection Test Program

    DTIC Science & Technology

    1977-02-01

    Nacelle Fuel Leak/Ignitor Simulator Mockup .. ........ .37 13. Test Preparations for Full-Scale Airflow Tests ........ ..40 14. Pitot Tube Array Used for...the engine-caused failure simulation. A simulator mockup was designed and fabricated for use in conducting the leak simulator/fuel ignition tests. The...basic design of the boiler plate mockup representing the engine fan area of an F-14A right-hand engine nacelle is shown in Figure 12. Fancase rupture

  5. EPA's New Oil and Dispersant Testing Program

    EPA Science Inventory

    The U.S. EPA has initiated a new component of its oil spills research program to develop baseline data on the ecotoxicity of selected petroleum products and toxicity and efficacy of dispersant agents. Two diluted bitumens (dilbits) from the Alberta Tar Sands are currently being t...

  6. Development of a Program Specific Locator Test. Final Report.

    ERIC Educational Resources Information Center

    Benn, Robert J.

    A project was undertaken to develop a series of program-specific vocational locator tests (PSVLTs) that would consist of subject-specific questions in three academic disciplines--writing, reading, and mathematics--for use in predicting vocational students' success in their vocational programs. As a prelude to constructing the tests, project staff…

  7. Test program for 4-K memory card, JOLT microprocessor

    NASA Technical Reports Server (NTRS)

    Lilley, R. W.

    1976-01-01

    A memory test program is described for use with the JOLT microcomputer 4,096-word memory board used in development of an Omega navigation receiver. The program allows a quick test of the memory board by cycling the memory through all possible bit combinations in all words.

  8. An Education Program to Reduce Unnecessary Laboratory Tests by Residents.

    ERIC Educational Resources Information Center

    Dowling, Patrick T.; And Others

    1989-01-01

    A program at an inner-city community health center involving 20 family practice residents provided an educational intervention concerning the use of laboratory tests based on quality of care, not cost containment. During the program, the use of thyroid stimulating hormone test declined, while complete blood counts ordered did not. (MSE)

  9. Testing Programs in Schools: What's New? A Special Issue.

    ERIC Educational Resources Information Center

    Walter, L. James; And Others

    1981-01-01

    This special issue of "Catalyst", entitled Testing Programs in Schools: What's New?, was published jointly by the Nebraska Council of School Administrators and the Nebraska Association for Supervision and Curriculum. The articles emphasize desirability of designing testing programs to meet the information needs of educators and the…

  10. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests shall be provided at no cost to employees. (c) Tests. Audiometric tests shall be performed by: (1) An...) Where mobile test vans are used to meet the requirement in paragraph (e)(1)(i), the railroad...

  11. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests shall be provided at no cost to employees. (c) Tests. Audiometric tests shall be performed by: (1) An... duty. (ii) Where mobile test vans are used to meet the requirement in paragraph (e)(1)(i), the...

  12. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests shall be provided at no cost to employees. (c) Tests. Audiometric tests shall be performed by: (1) An... duty. (ii) Where mobile test vans are used to meet the requirement in paragraph (e)(1)(i), the...

  13. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests shall be provided at no cost to employees. (c) Tests. Audiometric tests shall be performed by: (1) An...) Where mobile test vans are used to meet the requirement in paragraph (e)(1)(i), the railroad...

  14. Contractor point of view for system development and test program

    NASA Technical Reports Server (NTRS)

    Koide, F. K.; Ringer, D. E.; Earl, C. E.

    1981-01-01

    Industry's practice of testing space qualified hardware is examined. An overview of the Global Positioning System (GPS) Test Program is discussed from the component level to the sub-system compatibility tests with the space vehicle and finally to the launch site tests, all related to the Rubidium clock.

  15. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests shall be provided at no cost to employees. (c) Tests. Audiometric tests shall be performed by: (1) An...) Measurements of background sound pressure levels in the audiometric test room as required in appendix D of...

  16. Berthing mechanism final test report and program assessment

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The purpose is to document the testing performed on both hardware and software developed under the Space Station Berthing Mechanisms Program. Testing of the mechanism occurred at three locations. Several system components, e.g., actuators and computer systems, were functionally tested before assembly. A series of post assembly tests were performed. The post assembly tests, as well as the dynamic testing of the mechanism, are presented.

  17. Damage Tolerance Assessment Handbook. Volume 1. Introduction Fracture Mechanics Fatigue Crack Propagation

    DTIC Science & Technology

    1993-10-01

    Volume ,: Introduction NJ 08405 Fracture Mechanics Fatigue Crack Propagation Research and Special Programs Administration John A. Volpe National...Load-displacement plot [Adapted from John M. Barson/Stanley T. Rolfe, Fracture and Fatigue Control in Structures. Applications of Fracture Mechanics...Methods ASTM STP 527, American Society for Testing and Materials, Philadelphia, PA, 1973. 2-19. Ratwani, M.M. and Wilhem , DP. Develonment and EvaluAtion of

  18. Strip cell test and evaluation program

    NASA Technical Reports Server (NTRS)

    Gitlow, B.; Bell, W. F.; Martin, R. E.

    1978-01-01

    The performance characteristics of alkaline fuel cells to be used for space power systems were tested. Endurance tests were conducted on the cells during energy conversion operations. A feature of the cells fabricated and tested was the capability to evaporate the product water formed during the energy conversion reaction directly to space vacuum. A fuel cell powerplant incorporating these cells does not require a condenser and a hydrogen recirculating pump water separator to remove the product water. This simplified the fuel cell powerplant system, reduced the systems weight, and reduced the systems parasite power.

  19. Chronic Fatigue Syndrome

    MedlinePlus

    Chronic fatigue syndrome (CFS) is a disorder that causes extreme fatigue. This fatigue is not the kind of tired feeling that ... activities. The main symptom of CFS is severe fatigue that lasts for 6 months or more. You ...

  20. Apollo experience report: Electronic systems test program accomplishments and results

    NASA Technical Reports Server (NTRS)

    Ohnesorge, T. E.

    1972-01-01

    A chronological record is presented of the Electronic Systems Test Program from its conception in May 1963 to December 1969. The original concept of the program, which was primarily a spacecraft/Manned Space Flight Network communications system compatibility and performance evaluation, is described. The evolution of these concepts to include various levels of test detail, as well as systems level design verification testing, is discussed. Actual implementation of these concepts is presented, and the facility to support the program is described. Test results are given, and significant contributions to the lunar landing mission are underlined. Plans for modifying the facility and the concepts, based on Apollo experience, are proposed.

  1. Shift work and employee fatigue: implications for occupational health nursing.

    PubMed

    Yumang-Ross, Doreen J; Burns, Candace

    2014-06-01

    Long work hours and irregular shifts are part of the nation's 24-hour society and contribute to employee fatigue. Factors affecting employee fatigue are circadian rhythm, sleep quality and quantity, individual health, the environment, and work tasks. Employee fatigue contributes to accidents and injuries, and affects occupational performance, safety, and health. These findings should be used by occupational health nurses to address fatigue management and develop comprehensive fatigue management programs.

  2. Fatigue life of high-speed ball bearings with silicon nitride balls

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.

    1974-01-01

    Evaluation of hot-pressed silicon nitride as a rolling-element bearing material. Two grades of hot-pressed silicon nitride balls were tested under rolling contact conditions in a five-ball fatigue tester. A digital computer program was used to predict the dynamic performance characteristics and fatigue life of high-speed ball bearings with silicon nitride balls relative to that with bearings containing steel balls. The results obtained include the finding that fatigue spalls on silicon nitride balls are similar in appearance to those obtained with typical bearing steels.

  3. Accelerated Leach Test(s) Program: Annual report

    SciTech Connect

    Dougherty, D.R.; Pietrzak, R.F.; Fuhrmann, M.; Colombo, P.

    1986-09-01

    A computerized data base of LLW leaching data has been developed. Long-term tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms containing simulated wastes are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms.

  4. Incompatibility and Mental Fatigue

    ERIC Educational Resources Information Center

    Herzog, Thomas R.; Hayes, Lauren J.; Applin, Rebecca C.; Weatherly, Anna M.

    2011-01-01

    A straightforward prediction from attention restoration theory is that the level of incompatibility in a person's life should be positively correlated with that person's level of mental (or directed attention) fatigue. The authors tested this prediction by developing a new self-report measure of incompatibility in which they attempted to isolate…

  5. Cosmic ray simulation and testing program

    NASA Technical Reports Server (NTRS)

    Kolasinski, W. A.; Koga, R.; King, C. G.; Imamoto, S. I.

    1985-01-01

    Single event upset (SEU) and latchup vulnerabilities were determined for a number of parts of interest to NASA space programs. In cases where a threshold linear energy transfer (LET) for SEU could be measured, an upset rate in a low inclination Space Shuttle orbit was computed. The predicted upset rates are extremely low, except for the devices with LET thresholds below the geomagnetic cutoff for altitude and inclination of the Space Shuttle orbit. While some of the devices do exhibit latchup, the cross sections and threshold LETs are such that the risk associated with flying these devices in low, near equatorial orbits is small if not negligible.

  6. High Energy Storage Flywheel Test Program.

    DTIC Science & Technology

    1980-01-28

    or Lo < 4A, LLU o ~* C3 C), C) o D I~le CD CV C -9- CD oD "N LU ’-Z I-- I 0 3 U )jC I- < LU j4c Lai C OW 0 Uc . U)0: ==~ = N L-s LU ) LL = _j .j LU(LU...continued to be elastic at the peak speeds of Test E-2 and E-3. Vibration levels continued to be extremely low and non-resonant in nature confirming...display elastic properties at the rated 30 KWH design speed of 14,500 rpm. Test F-2 was conducted three days later, on 29 November 1979. Test F-2

  7. Biosphere 2 test module experimentation program

    NASA Technical Reports Server (NTRS)

    Alling, Abigail; Leigh, Linda S.; Maccallum, Taber; Alvarez-Romo, Norberto

    1990-01-01

    The Biosphere 2 Test Module is a facility which has the capability to do either short or long term closures: five month closures with plants were conducted. Also conducted were investigations of specific problems, such as trace gas purification by bioregenerative systems by in-putting a fixed concentration of a gas and observing its uptake over time. In other Test Module experiments, the concentration of one gas was changed to observe what effects this has on other gases present or on the system. The science of biospherics which encompasses the study of closed biological systems provides an opening into the future in space as well as in the Earth's biosphere.

  8. Dynamic Test Generation for Large Binary Programs

    DTIC Science & Technology

    2009-11-12

    Dalal and Mallows framed this question as a size-dependent sequential search problem, in which each bug has a different probability of being found, or...observed size for each bug. We could then derive for each test run the cutoff according to the Dalal and Mallows rule, then run for, say, twice that number...Software En- gineering). ACM, May 2005. [27] S. R. Dalal and C. L. Mallows . When should one stop testing software. j-J-AM-STAT- ASSOC, 83(403):872–879

  9. Verification of phylogenetic inference programs using metamorphic testing.

    PubMed

    Sadi, Md Shaik; Kuo, Fei-Ching; Ho, Joshua W K; Charleston, Michael A; Chen, T Y

    2011-12-01

    Many phylogenetic inference programs are available to infer evolutionary relationships among taxa using aligned sequences of characters, typically DNA or amino acids. These programs are often used to infer the evolutionary history of species. However, in most cases it is impossible to systematically verify the correctness of the tree returned by these programs, as the correct evolutionary history is generally unknown and unknowable. In addition, it is nearly impossible to verify whether any non-trivial tree is correct in accordance to the specification of the often complicated search and scoring algorithms. This difficulty is known as the oracle problem of software testing: there is no oracle that we can use to verify the correctness of the returned tree. This makes it very challenging to test the correctness of any phylogenetic inference programs. Here, we demonstrate how to apply a simple software testing technique, called Metamorphic Testing, to alleviate the oracle problem in testing phylogenetic inference programs. We have used both real and randomly generated test inputs to evaluate the effectiveness of metamorphic testing, and found that metamorphic testing can detect failures effectively in faulty phylogenetic inference programs with both types of test inputs.

  10. Prediction of the Low Cost Fatigue Life of HY-100 Undermatched Welds in Marine Structure (The National Shipbuilding Research Program)

    DTIC Science & Technology

    1993-11-01

    predict the low cycle fatigue life of undermatched (lower yield strength) weldments of HY- 100 steel . The objective was to determine the feasibility of...strength steel naval structures. The high yield strength of the weld metal, in comparison to that of the base metal, ensures adequate strength and...to be adequate. However, for high strength steels , such as HY-1OO and above, the welding process envelope is severely restricted. For this reason, and

  11. Next Generation Drivetrain Development and Test Program

    SciTech Connect

    Keller, Jonathan; Erdman, Bill; Blodgett, Doug; Halse, Chris; Grider, Dave

    2015-11-03

    This presentation was given at the Wind Energy IQ conference in Bremen, Germany, November 30 through December 2, 2105. It focused on the next-generation drivetrain architecture and drivetrain technology development and testing (including gearbox and inverter software and medium-voltage inverter modules.

  12. New Testing Standard For European Programs

    NASA Astrophysics Data System (ADS)

    Giordano, P.

    2004-08-01

    Standardization is a key aspect of the production business committed to the optimization of the product development and cost. In the Space field, American industries and Government organizations have developed since several decades Space standards like the MIL series, deriving them from the aircraft and military fields, or the NASA standards. The same happened later in other countries like Russia, Japan and China. In the last years most of those standards were revised to cope with the emerging needs of the market. In Europe, the Space activities were generally managed by a set of ESA standards, the PSS, which covered some aspects of these activities and reflected the up-to-date approaches and common practices. But, in the last years an initiative was also promoted by ESA, National Agencies and Space Organizations, named ECSS (European Cooperation for Space Standardization), with the aim to develop a coherent, single set of user-friendly standards for use in all European space activities. European industries supported this initiative, including a deep involvement of Alenia Spazio and, sometime through a suitable revision of the old PSS documents, new standards were defined, as for the "Testing" (ECSS-E-10-03A, now published). The ECSS-E-10-03A provides standard environmental and performance test requirements for space products (systems and their constituents) which are generally applicable to all projects. Scope of this paper is to present the status of the worldwide initiatives in the testing standardization, the major contents of the European ECSS Testing standard and the possibilities for tailoring. Differences in requirement definition with other international testing standards and proposals for further ECSS optimization are presented on the basis of Alenia Spazio experience in supporting the above initiatives.

  13. Rubidium frequency standard test program for NAVSTAR GPS

    NASA Technical Reports Server (NTRS)

    Koide, F.; Dederich, D. J.

    1978-01-01

    Test data of the RFS Program in the Production phase and computer automation are presented, as an essential element in the evaluation of the RFS performance in a simulated spacecraft environment. Typical production test data will be discussed for stabilities from 1 to 100,000 seconds averaging time and simulated time error accumulation test. Also, design considerations in developing the RFS test systems for the acceptance test in production are discussed.

  14. SRM propellant and polymer materials structural test program

    NASA Technical Reports Server (NTRS)

    Moore, Carleton J.

    1988-01-01

    The SRM propellant and polymer materials structural test program has potentially wide application to the testing and structural analysis of polymer materials and other materials generally characterized as being made of viscoelastic materials. The test program will provide a basis for characterization of the dynamic failure criteria for Solid Rocket Motor (SRM) propellant, insulation, inhibitor and liners. This experimental investigation will also endeavor to obtain a consistent complete set of materials test data. This test will be used to improve and revise the presently used theoretical math models for SRM propellant, insulators, inhibitor, liners, and O-ring seals.

  15. Instrumentation system to implement leak test program

    SciTech Connect

    Turner, W.J.; Brown, R.; Rael, D.

    1997-05-01

    HVAC equipment, gloveboxes, and other types of enclosures are required to meet rigid well-defined leak rates when they are to be installed in a nuclear facility. This paper describes two implementations of an instrumentation system that is used to test leak rates on heating, ventilation, and air conditioning (HVAC) plenums, gloveboxes, and experimental chambers, etc. One of the implementations used a programmable logic controller (PLC). The other used what is probably a simpler system based on FlexNet{reg_sign} modules. The emphasis on both systems was on automatic data collection, automatic report generation, and validation of the test results to ERDA 76-21 and ASME-N510. The data are collected using input modules connected to the PLC in one case. In the other case the data are collected using the FlexNet{reg_sign} modules. In both cases, the data are stored and the reports are generated in a spreadsheet.

  16. Aircraft Cargo Compartment Fire Test Simulation Program

    NASA Technical Reports Server (NTRS)

    Blumke, R. E.

    1977-01-01

    The objective of the test was to assess fire containment and fire extinguishment in the cargo by reducing the ventilation through the cargo compartment. Parameters which were measured included ignition time, burnthrough time, and physical damage to the cargo liner, composition of selected combustible gases, temperature-time histories, heat flux, and detector response. The ignitor load was made of a typical cargo consisting of filled cardboard cartons occupying 50% of the compartment volume.

  17. Maximum Likelihood Program for Sequential Testing Documentation

    DTIC Science & Technology

    1983-03-01

    Research Laboratory AREA 6 WORK UNIT NUMBERS ,ATITN: DRDAR-BLB Aberdeen Proving Ground. MD 21005 RDT&E 1L162618AH80 It. CONTROLLING OFFICE No,,4E...Availability Codes ist~ Special,-----vail and/or Jo I. INTRODUCTION The Army has used sensitivity testing for many years, especially in the areas of...response distribucion when the data do not meet the requirements for the DiDonato and Jarnagin procedure. Examples are provided for each of these

  18. Vuilleumier Cooler Wear Rate Test Program

    DTIC Science & Technology

    1976-12-01

    such combination would be a silicon carbide or chromium silicide rider sliding against a hardcoated Inconel 718 liner. If rider wear is excessive, the...rupture energy These properties are related to experimental parameters that are easily measured. The elastic energy potential of a material is...ultimate strength. It is only necessary to realize that these bulk material properties depend on test conditions such as deformation rate and temperature

  19. Use of Psychological Tests in an Administrative Staff Improvement Program.

    ERIC Educational Resources Information Center

    Johnson, Richard W.; North, Stewart D.

    All School Administrators and Nominees for administrative positions enrolled in an Administrative Staff Improvement Program at Green Bay, Wisconsin, completed a battery of psychological tests (Miller Analogies Test, Concept Mastery Test, and Strong Vocational Interest Blank). The enrollees scored above average on the MAT compared with graduate…

  20. Validation tests of the thermal analysis research program

    SciTech Connect

    Walton, G.N.; Cavanaugh, K.

    1985-09-01

    In the study analytical and empirical tests were performed using the Thermal Analysis Research Program (TARP). TARP was found to be very accurate relative to the analytical tests (calculations for simplified conditions) which covered steady and transient conduction, internal radiant interchange, latent loads, and clear sky solar gains. Six one-room buildings with different wall constructions provided data for the empirical tests.