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Sample records for fatigue test program

  1. 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.

  2. Multiaxial fatigue low cycle fatigue testing

    NASA Technical Reports Server (NTRS)

    Zamrik, S. Y.

    1985-01-01

    Multiaxial testing methods are reviewed. Advantages and disadvantages of each type test is discussed. Significant multiaxial data available in the literature is analyzed. The yield theories are compared for multiaxial fatigue analysis.

  3. Hydraulic Fatigue-Testing Machine

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    Fatigue-testing machine applies fluctuating tension to number of specimens at same time. When sample breaks, machine continues to test remaining specimens. Series of tensile tests needed to determine fatigue properties of materials performed more rapidly than in conventional fatigue-testing machine.

  4. Reversal bending fatigue testing

    SciTech Connect

    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. Programs For Predicting Fatigue And Creep-Fatigue Resistances

    NASA Technical Reports Server (NTRS)

    Saltsman, J. F.

    1994-01-01

    TS-SRP/PACK set of computer programs for characterizing and predicting fatigue and creep-fatigue resistances of metallic materials under isothermal and nonisothermal fatigue conditions in high-temperature, long-life regime. Programs implement total-strain version of strainrange-partitioning (TS-SRP) method. User should be thoroughly familiar with TS-SRP method before attempting to use any of these programs. Five programs included along with alloy data base. Four programs written in FORTRAN 77. One written in BASIC version 3.0.

  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. 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.

  10. 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.

  11. Fatigue tests on the ITER PF jacket

    NASA Astrophysics Data System (ADS)

    Qin, Jinggang; Weiss, Klaus-Peter; Wu, Yu; Wu, Zhixiong; Li, Laifeng; Liu, Sheng

    2012-10-01

    This paper focuses on fatigue tests on the ITER Poloidal Field (PF) jacket made of 316L stainless steel material. During manufacture, the conductor will be compacted and spooled after cable insertion. Therefore, sample jackets were prepared under compaction, bending and straightening in order to simulate the status of PF conductor during manufacturing and winding. The fatigue properties of materials were measured at T < 7 K, including S-N and fatigue crack growth rate (FCGR). The testing results show that the present Chinese PF jacket has good fatigue properties, which conclude that the results are accordant with the requirements of ITER.

  12. 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

  13. Computer controlled thermal fatigue test system

    SciTech Connect

    Schmale, D.T.; Jones, W.B.

    1986-01-01

    A servo-controlled hydraulic mechanical test system has been configured to conduct computer-controlled thermal fatigue tests. The system uses induction heating, a digital temperature controller, infrared pyrometry, forced air cooling, and quartz rod extensometry. In addition, a digital computer controls the tests and allows precise data analysis and interpretation.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Fatigue crack growth automated testing method

    SciTech Connect

    Hatch, P.W.; VanDenAvyle, J.A.; Laing, J.

    1989-06-01

    A computer controlled servo-hydraulic mechanical test system has been configured to conduct automated fatigue crack growth testing. This provides two major benefits: it allows continuous cycling of specimens without operator attention over evenings and weekends; and complex load histories, including random loading and spectrum loading, can be applied to the specimens to simulate cyclic loading of engineering structures. The software is written in MTS Multi-User Basic to control test machine output and acquire data at predetermined intervals. Compact tension specimens are cycled according to ASTM specification E647-86. Fatigue crack growth is measured via specimen compliance during the test using a compliance/crack length calibration determined earlier by visual crack length measurements. This setup was used to measure crack growth rates in 6063 aluminum alloy for a variety of cyclic loadings, including spectrum loads. Data collected compared well with tests run manually. 13 figs.

  19. Grip for fatigue testing pure aluminium

    NASA Astrophysics Data System (ADS)

    Lehmann, P.; Yuan, G. S.; Hartwig, K. T.

    A simple method of clamping pure aluminium for fatigue tests at cryogenic temperatures is described. Easily machined cylindrical specimens are aligned and held firmly by collet grips that counteract sample shrinkage during cooldown. Specimens are quickly mounted and removed after testing without distortion or thermal treatment 99.999% aluminium, aluminium alloys and copper were gripped successfully through tens of thousands of fully reversed tension-compression cycles at 295, 77 and 4.2 K.

  20. Material fatigue data obtained by card-programmed hydraulic loading system

    NASA Technical Reports Server (NTRS)

    Davis, W. T.

    1967-01-01

    Fatigue tests using load distributions from actual loading histories encountered in flight are programmed on punched electronic accounting machine cards. With this hydraulic loading system, airframe designers can apply up to 55 load levels to a test specimen.

  1. 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.

  2. 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.

  3. 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.

  4. Multi-axial fatigue testing machine

    SciTech Connect

    Sallberg, D.W.; Lawson, T.J.; Cardon, M.H.

    1989-02-07

    A testing machine is described for multi-axis fatigue testing of a component having inner and outer elements subject to linear and rotational forces about different axes comprising a base, first, second and third hydraulic actuators secured to the base, hydraulic pressure means and control means coupled to the actuators for controlled operation of the actuators, gimbal means comprising first and second gimbals mounted on the base and interconnected for rotation about mutually perpendicular axes, the first gimbal having means for attachment to one of the elements, means for substantially independently coupling the first and second actuators to the first and second gimbals respectively so that each actuator effects rocking movement of one gimbal without inputting torque about the axis of the other gimbal, and means for attaching the third actuator to the other of the elements, whereby the three actuators independently and controllably apply loads to the component about three axes of motion.

  5. [Impact of a fatigue management program in patients on hemodialysis].

    PubMed

    Merlin, Marjolaine Dionne; Gallant, Gemma

    2010-01-01

    The purpose of this study was to evaluate the impact of a fatigue management program on 25 hemodialysis patients regarding their level of fatigue and their rate of satisfaction towards knowledge. The study took place inside a hemodialysis unit in a health care facility located in New Brunswick. This research design was pre-experimental. The before-after design, with only one group of subjects, makes it possible to compare the level of fatigue, as well as the rate of satisfaction towards pre- and post-program knowledge. According to the results of our study, it seems that the subjects, after benefiting from a fatigue management program, managed to significantly decrease their level of fatigue and gain satisfaction related to the acquisition of knowledge. Even though our number of participants was small, our research supports the idea that a fatigue management program can meet the need of fatigue management in this population. The results of this study foresee the need to develop a fatigue management program in hemodialysis units and to evaluate its effectiveness in the medium or long term in selecting quasi-experimental studies, including a broader population of patients.

  6. 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.

  7. 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.

  8. Fatigue test of RC beams strengthened with prestressed CFLs

    NASA Astrophysics Data System (ADS)

    Guo, Xinyan; Huang, Peiyan; Liu, Guangwan; Xie, Jianhe

    2008-11-01

    Applying prestress to fiber reinforced polymer (FRP) can be used more efficiently since a greater portion energy of its tensile capacity is engaged. Based on carbon fiber laminate (CFL), fatigue tests are made to find out the fatigue behavior of reinforced concrete (RC) beams strengthened with prestressed CFL. The interfacial debonding is a main failure mode for RC beams strengthened with prestressed CFLs under the cyclic loading. Furthermore, it has been found that the stress value of CFLs decide whether the additional prestressing has a negative or positive effect on the fatigue behavior of the strengthened beam, and the excessive prestressing would reduce the fatigue life of the strengthened beam.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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, ...

  14. Hydraulic servo system increases accuracy in fatigue testing

    NASA Technical Reports Server (NTRS)

    Dixon, G. V.; Kibler, K. S.

    1967-01-01

    Hydraulic servo system increases accuracy in applying fatigue loading to a specimen under test. An error sensing electronic control loop, coupled to the hydraulic proportional closed loop cyclic force generator, provides an accurately controlled peak force to the specimen.

  15. Fatigue Tests with Random Flight Simulation Loading

    NASA Technical Reports Server (NTRS)

    Schijve, J.

    1972-01-01

    Crack propagation was studied in a full-scale wing structure under different simulated flight conditions. Omission of low-amplitude gust cycles had a small effect on the crack rate. Truncation of the infrequently occurring high-amplitude gust cycles to a lower level had a noticeably accelerating effect on crack growth. The application of fail-safe load (100 percent limit load) effectively stopped subsequent crack growth under resumed flight-simulation loading. In another flight-simulation test series on sheet specimens, the variables studied are the design stress level and the cyclic frequency of the random gust loading. Inflight mean stresses vary from 5.5 to 10.0 kg/sq mm. The effect of the stress level is larger for the 2024 alloy than for the 7075 alloy. Three frequencies were employed: namely, 10 cps, 1 cps, and 0.1 cps. The frequency effect was small. The advantages and limitations of flight-simulation tests are compared with those of alternative test procedures such as constant-amplitude tests, program tests, and random-load tests. Various testing purposes are considered. The variables of flight-simulation tests are listed and their effects are discussed. A proposal is made for performing systematic flight-simulation tests in such a way that the compiled data may be used as a source of reference.

  16. 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.

  17. 77 FR 55105 - Aging Airplane Program: Widespread Fatigue Damage; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-07

    ... establish a limit of validity of the engineering data that supports the structural maintenance program... tables. This document corrects the errors in those tables. DATES: This corrective action becomes... entitled ``Aging Airplane Program: Widespread Fatigue Damage'' (77 FR 30877), which corrected a final...

  18. 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).

  19. Various Fatigue Testing of Polycrystalline Silicon Microcantilever Beam in Bending

    NASA Astrophysics Data System (ADS)

    Hong; Hocheng; Hung, Jeng-Nan; Guu, Yunn-Horng

    2008-06-01

    With the vast potential of micro-electro-mechanical systems (MEMS) technology, the reliability is essential for the successful applications of microdevices. Polycrystalline silicon is one of the most often used structural materials in microdevices. Tension testing for fatigue life of this material has been investigated since past years. This paper presents a micro-actuator-based bending testing system as well as a MTS Tytron250 micro-tensile-force testing machine to study the fatigue of microbeams in bending. The polycrystalline silicon microcantilever beams are fabricated on silicon wafer. The influence of various dimensions and stress on the fatigue endurance is studied when an external force is loaded on the microcantilever beam. The flexural strength of beams are calculated by the ANSYS. Based on the experimental results and ANSYS analysis, it shows that the longer specimen reduces the stresses when the displacement, width and thickness are kept the same. When the width varies, the larger width results in higher stresses. The fatigue life lies between 9.1 ×105-1.53 ×107 cycles in use of the testing machine. For microactuator testing experiment, the fatigue life persists up to million cycles without failure. The obtained results are compared with the references of different testing methods.

  20. 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.

  1. 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.

  2. 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.

  3. 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. PMID:24918250

  4. Fatigue Testing of Wing Beam by the Resonance Method

    NASA Technical Reports Server (NTRS)

    Bleakney, William M

    1938-01-01

    Preliminary fatigue tests on two aluminum-alloy wing-beam specimens subjected to reversed axial loading are described. The motion used consists in incorporating one or two reciprocating motors in a resonance system of which the specimen is the spring element. A description is given of the reciprocating motors, and of the method of assembling and adjusting the vibrating system. The results indicate that the method is well adapted to fatigue tests of not only uniform wing beams but also wing beams with asymmetrical local reinforcements.

  5. Fatigue in the military: towards a fatigue detection test based on the saccadic velocity.

    PubMed

    Diaz-Piedra, Carolina; Rieiro, Héctor; Suárez, Juan; Rios-Tejada, Francisco; Catena, Andrés; Di Stasi, Leandro Luigi

    2016-09-01

    Fatigue is a major contributing factor to operational errors. Therefore, the validation of objective and sensitive indices to detect fatigue is critical to prevent accidents and catastrophes. Whereas tests based on saccadic velocity (SV) have become popular, their sensitivity in the military is not yet clear, since most research has been conducted in laboratory settings using not fully validated instruments. Field studies remain scarce, especially in extreme conditions such as real flights. Here, we investigated the effects of real, long flights on SV. We assessed five newly commissioned military helicopter pilots during their aviation training. Pilots flew Sikorsky S-76C helicopters, under instrumental flight rules, for more than 2 h (ca. 150 min). Eye movements were recorded before and after the flight with an eye tracker using a standard guided-saccade task. We also collected subjective ratings of fatigue. SV significantly decreased from the Pre-Flight to the Post-Flight session in all pilots by around 3% (range: 1-4%). Subjective ratings showed the same tendency. We provide conclusive evidence about the high sensitivity of fatigue tests based on SV in real flight conditions, even in small samples. This result might offer military medical departments a valid and useful biomarker of warfighter physiological state. PMID:27531394

  6. Flexural fatigue of hollow rolling elements. [fatigue tests on hollow cylindrical bars and bearings

    NASA Technical Reports Server (NTRS)

    Bamberger, E. N.; Parker, R. J.; Dietrich, M. W.

    1976-01-01

    Hollow cylindrical bars were tested in the rolling-contact fatigue tester to determine the effects of material and outside diameter to inside diameter (OD/ID) ratios of 2.0, 1.6, 1.4, and 1.2 on fatigue failure mode and subsequent failure propagation. The range of applied loads with these OD/ID ratios resulted in maximum tangential tensile stresses ranging from 165 to 655 megapascals (24,000 to 95,000 psi) at the bore surface. Flexural failures of the hollow test bars occurred when this bore stress was 490 megapascals (71,000 psi) or greater with AISI 52100 hollow bars and 338 megapascals (49,000 psi) or greater with AISI M-50 hollow bars. Good correlation was obtained in relating the failures of these hollow bars with flexural failures of drilled balls from previously published full scale bearing tests.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. High-strain fiber bragg gratings for structural fatigue testing of military aircraft

    NASA Astrophysics Data System (ADS)

    Davis, Claire; Tejedor, Silvia; Grabovac, Ivan; Kopczyk, James; Nuyens, Travis

    2012-09-01

    This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings (FBGs) for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.

  13. Fatigue testing of corrugated and Teflon hoses

    NASA Technical Reports Server (NTRS)

    Benner, Steve M.; Swanson, Theodore D.; Costello, Frederick A.

    1990-01-01

    Single and two-phase heat transport systems for the thermal control of large space facilities require fluid lines that traverse joints and either rotate or move in some other manner. Flexible hoses are being considered as one means of traversing these joints. To test the resilience of flexible hoses to bending stress, a test assembly was constructed to determine the number of flexing cycles the hoses could withstand before losing their ability to maintain a constant pressure. Corrugated metal hoses and Teflon hoses were tested at different pressures with nitrogen gas. The metal hoses had lives ranging from 30,000 to 100,000 flexing cycles. But, even after 400,000 cycles, the Teflon hoses remained essentially intact, though some leakage in the convoluted Teflon is noted.

  14. Fatigue

    MedlinePlus

    Bennett RM. Fibromyalgia, chronic fatigue syndrome, and myofascial pain. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 274. Thames TA, Karrh ...

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. School Hearing Test Program.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Washington, DC. Office of Noise Abatement and Control.

    The document offers guidelines for administration of the Hearing Test Noise Education Program, a program to teach students the harmful effects of excessive moise on their hearing and learning ability. Section 1 outlines the program strategy in terms of program initiation, suggested program coordination, suggested coordinator's responsibilities,…

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Cyclic fatigue testing of nickel-titanium endodontic instruments.

    PubMed

    Pruett, J P; Clement, D J; Carnes, D L

    1997-02-01

    Cyclic fatigue of nickel-titanium, engine-driven instruments was studied by determining the effect of canal curvature and operating speed on the breakage of Lightspeed instruments. A new method of canal curvature evaluation that addressed both angle and abruptness of curvature was introduced. Canal curvature was simulated by constructing six curved stainless-steel guide tubes with angles of curvature of 30, 45, or 60 degrees, and radii of curvature of 2 or 5 mm. Size #30 and #40 Light-speed instruments were placed through the guide tubes and the heads secured in the collet of a Mangtrol Dynamometer. A simulated operating load of 10 g-cm was applied. Instruments were able to rotate freely in the test apparatus at speeds of 750, 1300, or 2000 rpm until separation occurred. Cycles to failure were determined. Cycles to failure were not affected by rpm. Instruments did not separate at the head, but rather at the point of maximum flexure of the shaft, corresponding to the midpoint of curvature within the guide tube. The instruments with larger diameter shafts, #40, failed after significantly fewer cycles than did #30 instruments under identical test conditions. Multivariable analysis of variance indicated that cycles to failure significantly decreased as the radius of curvature decreased from 5 mm to 2 mm and as the angle of curvature increased greater than 30 degrees (p < 0.05, power = 0.9). Scanning electron microscopic evaluation revealed ductile fracture as the fatigue failure mode. These results indicate that, for nickel-titanium, engine-driven rotary instruments, the radius of curvature, angle of curvature, and instrument size are more important than operating speed for predicting separation. This study supports engineering concepts of cyclic fatigue failure and suggests that standardized fatigue tests of nickel-titanium rotary instruments should include dynamic operation in a flexed state. The results also suggest that the effect of the radius of curvature as an

  7. 77 FR 30877 - Aging Airplane Program: Widespread Fatigue Damage; Technical Amendment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ... Airplane Program: Widespread Fatigue Damage,'' (75 FR 69746). In that final rule the FAA revised the... actions (see Damage Tolerance Data for Repairs and Alterations, 72 FR 70486). Change to Table 1 of Sec... Administration 14 CFR Parts 26, 121, and 129 RIN 2120-AI05 Aging Airplane Program: Widespread Fatigue...

  8. 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.

  9. Effects of postpartum exercise program on fatigue and depression during "doing-the-month" period.

    PubMed

    Ko, Yi-Li; Yang, Chi-Li; Chiang, Li-Chi

    2008-09-01

    This study explored the effectiveness of an exercise program on reducing levels of fatigue and depression among postpartum women who were "doing-the-month" in a maternity center in Taiwan. Previous studies related to postpartum have focused on depression rather than women's feelings of fatigue, and no study related to exercise has previously been conducted in a Taiwan maternity center. A low-intensity exercise program was specifically designed and administered to 31 subjects in the study's intervention group. Another 30 subjects (the control group) followed a traditional, non-physically active postpartum care regimen. Those in the intervention group were required to participate in at least 6 exercise program sessions during their one month postpartum stay. All subjects were asked to fill out a fatigue and depression questionnaire before and after the program. A Fatigue Symptom Checklist (FSC) was used to measure fatigue, and the Center for Epidemiological Studies Depression (CESD) was used to confirm the development of depression. Results showed statistically significant differences between the two groups in terms of fatigue levels, with statistical improvements (p < .05) registered by the intervention group in terms of levels of physical and psychological fatigue and fatigue symptoms. However, no significant changes in depression between the two groups were found. Study results demonstrate that a low-intensity exercise program can offer a good platform for clinicians and researchers to help reduce fatigue in postpartum women. PMID:18792887

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

    NASA Technical Reports Server (NTRS)

    Schmidt, H.-J.; Nielsen, Thomas

    1994-01-01

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

  11. 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).

  12. Flexure fatigue testing of 90 deg graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Peck, Ann Nancy W.

    1995-01-01

    A great deal of research has been performed characterizing the in-plane fiber-dominated properties, under both static and fatigue loading, of advanced composite materials. To the author's knowledge, no study has been performed to date investigating fatigue characteristics in the transverse direction. This information is important in the design of bonded composite airframe structure where repeated, cyclic out-of-plane bending may occur. Recent tests characterizing skin/stringer debond failures in reinforced composite panels where the dominant loading in the skin is flexure along the edge of the frame indicate failure initiated either in the skin or else the flange, near the flange tip. When failure initiated in the skin, transverse matrix cracks formed in the surface skin ply closest to the flange and either initiated delaminations or created matrix cracks in the next lower ply, which in turn initiated delaminations. When failure initiated in the flanges, transverse cracks formed in the flange angle ply closest to the skin and initiated delamination. In no configuration did failure propagate through the adhesive bond layer. For the examined skin/flange configurations, the maximum transverse tension stress at failure correlates very well with the transverse tension strength of the composites. Transverse tension strength (static) data of graphite epoxy composites have been shown to vary with the volume of material stressed. As the volume of material stressed increased, the strength decreased. A volumetric scaling law based on Weibull statistics can be used to predict the transverse strength measurements. The volume dependence reflects the presence of inherent flaws in the microstructure of the lamina. A similar approach may be taken to determine a volume scale effect on the transverse tension fatigue behavior of graphite/epoxy composites. The objective of this work is to generate transverse tension strength and fatigue S-N characteristics for composite materials using

  13. Commerical module test program

    NASA Technical Reports Server (NTRS)

    Smokier, M. I.

    1986-01-01

    The results are presented for a program of qualification testing of commercial crystalline silicon modules from nine manufacturers in five countries. The outcome demonstrated the effective role of the Block 5 Qualification Tests in the development of reliable modules.

  14. Flexure fatigue testing of 90 deg graphite/epoxy composites

    SciTech Connect

    Peck, A.N.W.

    1995-12-01

    A great deal of research has been performed characterizing the in-plane fiber-dominated properties, under both static and fatigue loading, of advanced composite materials. To the author`s knowledge, no study has been performed to date investigating fatigue characteristics in the transverse direction. This information is important in the design of bonded composite airframe structure where repeated, cyclic out-of-plane bending may occur. Recent tests characterizing skin/stringer debond failures in reinforced composite panels where the dominant loading in the skin is flexure along the edge of the frame indicate failure initiated either in the skin or else the flange, near the flange tip. When failure initiated in the skin, transverse matrix cracks formed in the surface skin ply closest to the flange and either initiated delaminations or created matrix cracks in the next lower ply, which in turn initiated delaminations. When failure initiated in the flanges, transverse cracks formed in the flange angle ply closest to the skin and initiated delamination. In no configuration did failure propagate through the adhesive bond layer. For the examined skin/flange configurations, the maximum transverse tension stress at failure correlates very well with the transverse tension strength of the composites. Transverse tension strength (static) data of graphite epoxy composites have been shown to vary with the volume of material stressed. As the volume of material stressed increased, the strength decreased. A volumetric scaling law based on Weibull statistics can be used to predict the transverse strength measurements. The volume dependence reflects the presence of inherent flaws in the microstructure of the lamina. A similar approach may be taken to determine a volume scale effect on the transverse tension fatigue behavior of graphite/epoxy composites.

  15. Designing of a Testing Machine for Shear-Mode Fatigue Crack Growth

    NASA Astrophysics Data System (ADS)

    Kusaba, A.; Okazaki, S.; Endo, M.; Yanase, K.

    As recognized, flaking-type failure is one of the serious problems for railroad tracks and bearings. In essence, flaking-type failure is closely related to the growth of the shear-mode (Mode-II and Mode-III) fatigue crack. In our research group, it is demonstrated that a shear-mode fatigue crack can be reproduced for cylindrical specimens by applying the cyclic torsion in the presence of the static axial compressive stress. However, a biaxial servo-hydraulic fatigue testing machine is quite expensive to purchase and costly to maintain. The low testing speed (about 10Hz) of the testing machine further aggravates the situation. As a result, study on shear-mode fatigue crack growth is still in the nascent stage. To overcome the difficulties mentioned above, in this research activity, we developed a high-performance and cost-effective testing machine to reproduce the shear-mode fatigue crack growth by improving the available resonance-type torsion fatigue testing machine. The primary advantage of using the resonance-type torsion fatigue testing machine is cost-efficiency. In addition, the testing speed effectively can be improved, in comparison with that of a biaxial servo-hydraulic fatigue testing machine. By utilizing the newly-designed testing machine, we have demonstrated that we can successfully reproduce the shear-mode fatigue crack.

  16. Test-driven programming

    NASA Astrophysics Data System (ADS)

    Georgiev, Bozhidar; Georgieva, Adriana

    2013-12-01

    In this paper, are presented some possibilities concerning the implementation of a test-driven development as a programming method. Here is offered a different point of view for creation of advanced programming techniques (build tests before programming source with all necessary software tools and modules respectively). Therefore, this nontraditional approach for easier programmer's work through building tests at first is preferable way of software development. This approach allows comparatively simple programming (applied with different object-oriented programming languages as for example JAVA, XML, PYTHON etc.). It is predictable way to develop software tools and to provide help about creating better software that is also easier to maintain. Test-driven programming is able to replace more complicated casual paradigms, used by many programmers.

  17. Fatigue testing of laser treated endosseous implants with an internal trilobe connection.

    PubMed

    Berg, Robert W; Kurtz, Kenneth S; Griggs, Jason A; Watanabe, Ikuya; Coelho, Paulo G

    2011-03-01

    This study investigated the effect of laser treatment on the fatigue resistance of a 3.5-mm diameter implant with an internal trilobe connection. Twenty two implants were embedded into acrylic resin blocks. Half the specimens were used as control group, and the other half were laser treated circumferentially around the 1.5-mm polished collar with argon shielding. Implants were fatigue tested using a step-stress accelerated lifetime test in a servo-hydraulic test machine. Despite the trend pointing towards higher fatigue resistance of laser treated specimens versus controls, step-stress analysis did not determine significant differences in the fatigue lifetimes. PMID:21528680

  18. Tensile and fatigue qualification testing of ITER-CS conduit alloy JK2LB

    NASA Astrophysics Data System (ADS)

    Walsh, R. P.; McRae, D. M.; Han, K.; Martovetsky, N. N.

    2015-12-01

    The ITER Central Solenoid (CS) coils utilize cable-in-conduit conductor (CICC) and the conduit alloy is JK2LB. The production grade conduit alloy (and it's welds) must meet strict requirements for strength, toughness, fatigue crack resistance, and fabricability. The conduit alloy must retain good mechanical properties after additional fabrication steps such as welding, coil winding strain and exposure to the Nb3Sn superconductor's reaction heat treatment. Here we present data from cryogenic tensile, fracture toughness, fatigue crack growth rate, and axial fatigue tests of JK2LB alloy and conduit butt welds, before and after the exposure to the reaction heat treatment. The tests of specimens removed directly from the conduit provide confirmation of the materials properties and the effect of the cold work and aging. The 4 K fatigue performance is extremely important to the reliability of the CS and is covered both by axial cyclic fatigue tests and the fatigue crack growth rate measurements.

  19. Seat test program

    NASA Technical Reports Server (NTRS)

    Bricker, R. W.

    1979-01-01

    The test program has the objectives to: (1) evaluate severity of newspaper ignition source with contemporary seats (determine weight loss, visual damage, and if ignition source is severe enough to show improvement with new material configurations); (2) compare damage with jet A-1 ignition source; and (3) determine if materials for seat tests pass FAR 25 and obtain L01. Test configurations, data acquired, material test results, seat test results, and conclusions are presented.

  20. 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.

  1. 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. PMID:23556847

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

    NASA Astrophysics Data System (ADS)

    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.

  3. 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.

  4. 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.

  5. Drug testing programs.

    PubMed

    Willette, R E

    1986-01-01

    Many Federal agencies and private companies are conducting drug tests on job applicants and employees. Although the reasons for testing and the circumstances under which testing is conducted vary considerably, the main intent of these programs is to provide a drug-free environment for other employees and a safe service to the public. The programs that have been most successful usually include a clear communication to all employees and applicants as to the nature of the drug program and the consequences of detected drug use. Also, successful programs usually afford employees some type of assistance and a second chance. Finally, it is essential for successful programs to provide a reasonable and fair approach that includes procedures for due process, that is, a line of review and appeal. PMID:3127722

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

    PubMed

    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.

  7. 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

  8. Evaluation of a Fatigue Self-Management Program for People with Multiple Sclerosis

    PubMed Central

    Wilkinson, Amanda; Barclay, Amelia; Whiting, Hayley; Heynike, Christelle; Snowdon, Jessie

    2016-01-01

    Background: Fatigue is one of the most common and debilitating symptoms of multiple sclerosis (MS). The program “Minimise Fatigue, Maximise Life: Creating Balance with Multiple Sclerosis” (MFML) was created in New Zealand because of the lack of a fatigue management program for people with MS in that country. This program aims to empower individuals with MS to manage their own symptoms of fatigue. The objective of this study was to evaluate the MFML fatigue self-management program. Methods: Self-report questionnaires were used to measure impact of fatigue (5-item Modified Fatigue Impact Scale), self-efficacy (MS Self-efficacy Scale), and quality of life (12-item Short Form Health Status Survey [SF-12]) 1 month before (T1), at commencement of (T2) (to investigate the stability of questionnaire scores before the intervention), and at the end of (T3) the 6-week group-based program. Increased self-efficacy and quality of life scores and a decrease in reported impact of fatigue were the anticipated primary outcomes, with participants acting as their own controls. Results: Twenty-five women (aged 37–63 years) participated. Stability of scores for all the questionnaires was evidenced between T1 and T2. After the intervention (T3), scores showed a significant improvement in self-efficacy and impact of fatigue, with large effect sizes, but no change in either the physical or mental component summary of the SF-12. Conclusions: Despite the small sample size, this study showed an organized approach to the management of fatigue for people living with MS, and its outcomes demonstrated benefits for participants. PMID:27252598

  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. Perceived Impact of a Self-Management Program for Fatigue in Multiple Sclerosis

    PubMed Central

    Wilkinson, Amanda; Snowdon, Jessie

    2016-01-01

    Background: Fatigue in multiple sclerosis (MS) is reported to be one of its most debilitating symptoms, affecting personal, family, and community participation. Despite a high incidence of MS in New Zealand, there was no cohesive approach to support people with MS to manage their fatigue. This prompted the development of Minimise Fatigue, Maximise Life: Creating Balance with Multiple Sclerosis (MFML), a group-based, 6-week fatigue self-management program. This study explored the perceived impact of MFML for participants who attended the program. Methods: We undertook semistructured individual telephone interviews 1 (n = 23) and 3 (n = 11) months after delivery of the program. Data were analyzed for themes. Results: Two themes emerged from the data: achieving behavior change to manage fatigue and whole of life effects. These themes represent participants' perceived benefits of the program. Conclusions: This study provides evidence that the MFML fatigue self-management program positively affected the lives of participants. The findings suggest that participants had begun to successfully develop and integrate self-management skills into their everyday lives. This affected the individual personally and also their participation in family and community life. This study adds to the current knowledge and understanding of the positive effect that delivery of a fatigue self-management intervention can have for people with MS. PMID:26917995

  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. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. New techniques to test fatigue properties of coined sheet specimens. Part 4: Development of experimental techniques

    NASA Astrophysics Data System (ADS)

    Gustavsson, Anders; Melander, Arne

    1994-09-01

    The present work was directed to the development of laboratory specimens suitable for simulation of fatigue in coinings in sheet materials. This report describes the different steps taken to advance the test procedures towards the requirements formulated for the experiments. Two test geometries with corresponding test procedures were established. The two dimensional geometry loaded axially in the fatigue test benefits from its very simple form which results in ease of manufacture, testing and analysis. The more sophisticated three dimensional geometry developed resembles much of coinings in real automotive components - bending loading, geometry and similar fatigue failure site. However, due to its geometrical complexity it demands more when it comes to fatigue testing and analysis.

  19. 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

  20. 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.

  1. 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.

  2. Fatigue life prediction of liquid rocket engine combustor with subscale test verification

    NASA Astrophysics Data System (ADS)

    Sung, In-Kyung

    Reusable rocket systems such as the Space Shuttle introduced a new era in propulsion system design for economic feasibility. Practical reusable systems require an order of magnitude increase in life. To achieve this improved methods are needed to assess failure mechanisms and to predict life cycles of rocket combustor. A general goal of the research was to demonstrate the use of subscale rocket combustor prototype in a cost-effective test program. Life limiting factors and metal behaviors under repeated loads were surveyed and reviewed. The life prediction theories are presented, with an emphasis on studies that used subscale test hardware for model validation. From this review, low cycle fatigue (LCF) and creep-fatigue interaction (ratcheting) were identified as the main life limiting factors of the combustor. Several life prediction methods such as conventional and advanced viscoplastic models were used to predict life cycle due to low cycle thermal stress, transient effects, and creep rupture damage. Creep-fatigue interaction and cyclic hardening were also investigated. A prediction method based on 2D beam theory was modified using 3D plate deformation theory to provide an extended prediction method. For experimental validation two small scale annular plug nozzle thrusters were designed, built and tested. The test article was composed of a water-cooled liner, plug annular nozzle and 200 psia precombustor that used decomposed hydrogen peroxide as the oxidizer and JP-8 as the fuel. The first combustor was tested cyclically at the Advanced Propellants and Combustion Laboratory at Purdue University. Testing was stopped after 140 cycles due to an unpredicted failure mechanism due to an increasing hot spot in the location where failure was predicted. A second combustor was designed to avoid the previous failure, however, it was over pressurized and deformed beyond repair during cold-flow test. The test results are discussed and compared to the analytical and numerical

  3. Maglev program test plan

    NASA Astrophysics Data System (ADS)

    Debenedet, D.; Gilchrist, A. J.; Karanian, L. A.

    1992-07-01

    Maglev systems represent a promising evolution in the high-speed ground transportation, offering speeds in excess of 300 mph along with the potential for low operating costs and minimal environmental impact. The goal of this effort is to investigate the feasibility and viability of maglev systems in the United States. The emergence of a sophisticated technology such as maglev requires a need for a coordinated research test program and the determination of test requirements to identify and mitigate development risk and to maximize the use of domestic resources. The study is directed toward the identification and characterization of maglev systems development risks tied to a preliminary system architecture. Research objectives are accomplished by surveying experiences from previous maglev development programs both foreign and domestic, and interviews with individuals involved with maglev research and testing. Findings include ninety-four distinct development risks and twenty risk types. Planning and implementation requirements are identified for a maglev test program, including the development of a facilities strategy to meet any operational concept that evolves out of early development effort. Also specified is the logical development flow and associated long-lead support needs for sub-scale and full-scale testing.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    The monitoring of modulus decay during fatigue testing as an indicator of damage accumulation and incipient failure has frequently been postulated. The present study was designed to generate tensile fatigue data 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 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.

  5. Fatigue acceptance test limit criteria for larger diameter rolled thread fasteners

    SciTech Connect

    Kephart, A.R.

    1999-05-19

    This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches (25 mm) in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process.

  6. Resistance of three implant-abutment interfaces to fatigue testing

    PubMed Central

    RIBEIRO, Cleide Gisele; MAIA, Maria Luiza Cabral; SCHERRER, Susanne S.; CARDOSO, Antonio Carlos; WISKOTT, H. W. Anselm

    2011-01-01

    The design and retentive properties of implant-abutment connectors affect the mechanical resistance of implants. A number of studies have been carried out to compare the efficacy of connecting mechanisms between abutment and fixture. Objectives The aims of this study were: 1) to compare 3 implant-abutment interfaces (external hexagon, internal hexagon and cone-in-cone) regarding the fatigue resistance of the prosthetic screw, 2) to evaluate the corresponding mode of failure, and 3) to compare the results of this study with data obtained in previous studies on Nobel Biocare and Straumann connectors. Materials and Methods In order to duplicate the alternating and multivectorial intraoral loading pattern, the specimens were submitted to the rotating cantilever beam test. The implants, abutments and restoration analogs were spun around their longitudinal axes while a perpendicular force was applied to the external end. The objective was to determine the force level at which 50% of the specimens survived 106 load cycles. The mean force levels at which 50% failed and the corresponding 95% confidence intervals were determined using the staircase procedure. Results The external hexagon interface presented better than the cone-in-cone and internal hexagon interfaces. There was no significant difference between the cone-in-cone and internal hex interfaces. Conclusion Although internal connections present a more favorable design, this study did not show any advantage in terms of strength. The external hexagon connector used in this study yielded similar results to those obtained in a previous study with Nobel Biocare and Straumann systems. However, the internal connections (cone-in-cone and internal hexagon) were mechanically inferior compared to previous results. PMID:21710094

  7. Proficiency analytical testing program

    SciTech Connect

    Groff, J.H.; Schlecht, P.C.

    1994-03-01

    The Proficiency Analytical Testing (PAT) Program is a collaborative effort of the American Industrial Hygiene Association (AIHA) and researchers at the Centers for Disease Control and Prevention (CDC), National Institute for Occupational Safety and Health (NIOSH). The PAT Program provides quality control reference samples to over 1400 occupational health and environmental laboratories in over 15 countries. Although one objective of the PAT Program is to evaluate the analytical ability of participating laboratories, the primary objective is to assist these laboratories in improving their laboratory performance. Each calendar quarter (designated a round), samples are mailed to participating laboratories and the data are analyzed to evaluate laboratory performance on a series of analyses. Each mailing and subsequent data analysis are completed in time for participants to obtain repeat samples and to correct analytical problems before the next calendar quarter starts. The PAT Program currently includes four sets of samples. A mixture of 3 of the 4 possible metals, and 3 of the 15 possible organic solvents are rotated for each round. Laboratories are evaluated for each analysis by comparing their reported results against an acceptable performance limit for each PAT Program sample the laboratory analyses. Reference laboratories are preselected to provide the performance limits for each sample. These reference laboratories must meet the following criteria: (1) the laboratory was rated proficient in the last PAT evaluation of all the contaminants in the Program; and (2) the laboratory, if located in the United States, is AIHA accredited. Data are acceptable if they fall within the performance limits. Laboratories are rated based upon performance in the PAT Program over the last year (i.e., four calendar quarters), as well as on individual contaminant performance and overall performance. 1 ref., 3 tabs.

  8. Proficiency analytical testing program

    SciTech Connect

    Schlecht, P.C.; Groff, J.H.

    1994-06-01

    The Proficiency Analytical Testing (PAT) Program is a collaborative effort of the American Industrial Hygiene Association (AIHA) and researchers at the Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health (NIOSH). The PAT Program provides quality control reference samples to over 1400 occupational health and environmental laboratories in over 15 countries. Although one objective of the PAT Program is to evaluate the analytical ability of participating laboratories, the primary objective is to assist these laboratories in improving their laboratory performance. Each calendar quarter (designated a round), samples are mailed to participating laboratories and the data are analyzed to evaluate laboratory performance on a series of analyses. Each mailing and subsequent data analysis is completed in time for participants to obtain repeat samples and to correct analytical problems before the next calendar quarter starts. The PAT Program currently includes four sets of samples. A mixture of 3 of the 4 possible metals, and 3 of the 15 possible organic solvents are rotated for each round. Laboratories are evaluated for each analysis by comparing their reported results against an acceptable performance limit for each PAT Program sample the laboratory analyses. Reference laboratories are preselected to provide the performance limits for each sample. These reference laboratories must meet the following criteria: (1) the laboratory was rated proficient in the last PAT evaluation of all the contaminants in the Program; and (2) the laboratory, if located in the United States, is AIHA accredited. Data are acceptable if they fall within the performance limits. Laboratories are rated based upon performance in the PAT Program over the last year (i.e., four calendar quarters), as well as on individual contaminant performance and overall performance. 1 ref., 3 tabs.

  9. On the use of ultrasonic fatigue testing technique--variable amplitude loadings and crack growth monitoring.

    PubMed

    Müller, T; Sander, M

    2013-12-01

    In the very high cycle fatigue regime high-frequency testing techniques are required. Using the ultrasonic fatigue technique, testing time could be reduced significantly in comparison to conventional servo-hydraulic machines. An ultrasonic fatigue testing system developed by the BOKU Vienna with load frequencies of about 20kHz is used for variable amplitude loading investigations in the VHCF regime. Therefore, the amplitude level during fatigue tests is controlled by a PC using an own developed software. Additionally, an in situ reconstruction of a damage equivalent load spectrum based on a load time history is introduced schematically. To optimize the experimental procedure a temperature-controlled pulse-pause adaption has been developed and implemented into the software. For quantifying the influence of variable amplitude loadings on the fatigue life, e.g. load interaction effects, the crack growth is measured by using the potential drop technique that is adapted to the ultrasonic fatigue testing system. Finally, the results of two-step-block loading tests are presented. PMID:23597637

  10. 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.

  11. 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. PMID:21812824

  12. 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,...

  13. 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.

  14. The effects of testing methods on the flexural fatigue life of human cortical bone.

    PubMed

    Griffin, L V; Gibeling, J C; Martin, R B; Gibson, V A; Stover, S M

    1999-01-01

    A flexural model of four-point bending fatigue that has been experimentally validated for human cortical bone under load control was used to determine how load and displacement control testing affects the fatigue behavior of human cortical bone in three-point and symmetric four-point bending. Under load control, it was predicted that three-point bending produced no significant differences in fatigue life when compared to four-point bending. However, three-point bending produced less stiffness loss with increasing cycles than four-point bending. In four-point bending, displacement control was predicted to produce about one and a half orders of magnitude greater fatigue life when compared to load control. This prediction agrees with experimental observations of equine cannon bone tested in load and displacement control (Gibson et al., 1998). Displacement controlled three-point bending was found to produce approximately a 25% greater fatigue life when compared to load control. The prediction of longer fatigue life under displacement control may have clinical relevance for the repair of damaged bone. The model can also be adapted to other geometric configurations, including modeling of whole long bones, and with appropriate fatigue data, other cortical bone types.

  15. Fatigue acceptance test limit criterion for larger diameter rolled thread fasteners

    SciTech Connect

    Kephart, A.R.

    1997-05-01

    This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process. This criterion is derived from a stress dependent, room temperature air fatigue database for test studs having a 0.625 inch diameter threads of Alloys X-750 HTH and direct aged 625. Anticipated fatigue lives of larger threads are based on thread root elastic stress concentration factors which increase with increasing thread diameters. Over the thread size range of interest, a 30% increase in notch stress is equivalent to a factor of five (5X) reduction in fatigue life. The resulting diameter dependent fatigue acceptance criterion is normalized to the aerospace rolled thread acceptance standards for a 1.0 inch diameter, 0.125 inch pitch, Unified National thread with a controlled Root radius (UNR). Testing was conducted at a stress of 50% of the minimum specified material ultimate strength, 80 Ksi, and at a stress ratio (R) of 0.10. Limited test data for fastener diameters of 1.00 to 2.25 inches are compared to the acceptance criterion. Sensitivity of fatigue life of threads to test nut geometry variables was also shown to be dependent on notch stress conditions. Bearing surface concavity of the compression nuts and thread flank contact mismatch conditions can significantly affect the fastener fatigue life. Without improved controls these conditions could potentially provide misleading acceptance data. Alternate test nut geometry features are described and implemented in the rolled thread stud specification, MIL-DTL-24789(SH), to mitigate the potential effects on fatigue acceptance data.

  16. 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.

  17. 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.

  18. CELT site testing program

    NASA Astrophysics Data System (ADS)

    Schoeck, Matthias; Erasmus, D. Andre; Djorgovski, S. George; Chanan, Gary A.; Nelson, Jerry E.

    2003-01-01

    The California Extremely Large Telescope, CELT, is a proposed 30-m telescope. Choosing the best possible site for CELT is essential in order to extract the best science from the observations and to reduce the complexity of the telescope. Site selection is therefore currently one of the most critical pacing items of the CELT project. In this paper, we first present selected results from a survey of the atmospheric transparency at optical and infrared wavelengths over the southwestern USA and northern Mexico using satellite data. Results of a similar study of South America have been reported elsewhere. These studies will serve as the pre-selection criterion of the sites at which we will perform on-site testing. We then describe the current status of on-site turbulence evaluation efforts and the future plans of the CELT site testing program.

  19. 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.

  20. 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.

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

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1989-01-01

    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.

  2. Heat pipe testing program test plan

    SciTech Connect

    Bienert, W.B.

    1980-03-14

    A test plan is given which describes the tests to be conducted on several typical solar receiver heat pipes. The hardware to be used, test fixtures and rationale of the test program are discussed. The program objective is to perform life testing under simulated receiver conditions, and to conduct performance tests with selected heat pipes to further map their performance, particularly with regard to their transient behavior. Performance requirements are defined. Test fixtures designed for the program are described in detail, and their capabilities for simulating the receiver conditions and their limitations are discussed. The heat pipe design is given. (LEW)

  3. 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.

  4. 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.

  5. 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.

  6. Comparison of the Capacity of Different Jump and Sprint Field Tests to Detect Neuromuscular Fatigue.

    PubMed

    Gathercole, Rob J; Sporer, Ben C; Stellingwerff, Trent; Sleivert, Gord G

    2015-09-01

    Different jump and sprint tests have been used to assess neuromuscular fatigue, but the test with optimal validity remains to be established. The current investigation examined the suitability of vertical jump (countermovement jump [CMJ], squat jump [SJ], drop jump [DJ]) and 20-m sprint (SPRINT) testing for neuromuscular fatigue detection. On 6 separate occasions, 11 male team-sport athletes performed 6 CMJ, SJ, DJ, and 3 SPRINT trials. Repeatability was determined on the first 3 visits, with subsequent 3 visits (0-, 24-, and 72-hour postexercise) following a fatiguing Yo-Yo running protocol. SPRINT performance was most repeatable (mean coefficient of variation ≤2%), whereas DJ testing (4.8%) was significantly less repeatable than CMJ (3.0%) and SJ (3.5%). Each test displayed large decreases at 0-hour (33 of 49 total variables; mean effect size = 1.82), with fewer and smaller decreases at 24-hour postexercise (13 variables; 0.75), and 72-hour postexercise (19 variables; 0.78). SPRINT displayed the largest decreases at 0-hour (3.65) but was subsequently unchanged, whereas SJ performance recovered by 72-hour postexercise. In contrast, CMJ and DJ performance displayed moderate (12 variables; 1.18) and small (6 variables; 0.53) reductions at 72-hour postexercise, respectively. Consequently, the high repeatability and immediate and prolonged fatigue-induced changes indicated CMJ testing as most suitable for neuromuscular fatigue monitoring. PMID:26308829

  7. Comparison of the Capacity of Different Jump and Sprint Field Tests to Detect Neuromuscular Fatigue.

    PubMed

    Gathercole, Rob J; Sporer, Ben C; Stellingwerff, Trent; Sleivert, Gord G

    2015-09-01

    Different jump and sprint tests have been used to assess neuromuscular fatigue, but the test with optimal validity remains to be established. The current investigation examined the suitability of vertical jump (countermovement jump [CMJ], squat jump [SJ], drop jump [DJ]) and 20-m sprint (SPRINT) testing for neuromuscular fatigue detection. On 6 separate occasions, 11 male team-sport athletes performed 6 CMJ, SJ, DJ, and 3 SPRINT trials. Repeatability was determined on the first 3 visits, with subsequent 3 visits (0-, 24-, and 72-hour postexercise) following a fatiguing Yo-Yo running protocol. SPRINT performance was most repeatable (mean coefficient of variation ≤2%), whereas DJ testing (4.8%) was significantly less repeatable than CMJ (3.0%) and SJ (3.5%). Each test displayed large decreases at 0-hour (33 of 49 total variables; mean effect size = 1.82), with fewer and smaller decreases at 24-hour postexercise (13 variables; 0.75), and 72-hour postexercise (19 variables; 0.78). SPRINT displayed the largest decreases at 0-hour (3.65) but was subsequently unchanged, whereas SJ performance recovered by 72-hour postexercise. In contrast, CMJ and DJ performance displayed moderate (12 variables; 1.18) and small (6 variables; 0.53) reductions at 72-hour postexercise, respectively. Consequently, the high repeatability and immediate and prolonged fatigue-induced changes indicated CMJ testing as most suitable for neuromuscular fatigue monitoring.

  8. 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.

  9. Full-scale fatigue tests of CX-100 wind turbine blades. Part I: testing

    NASA Astrophysics Data System (ADS)

    Farinholt, Kevin M.; Taylor, Stuart G.; Park, Gyuhae; Ammerman, Curtt M.

    2012-04-01

    This paper overviews the test setup and experimental methods for structural health monitoring (SHM) of two 9-meter CX-100 wind turbine blades that underwent fatigue loading at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC). The first blade was a pristine blade, which was manufactured to standard specifications for the CX-100 design. The second blade was manufactured for the University of Massachusetts, Lowell with intentional simulated defects within the fabric layup. Each blade was instrumented with piezoelectric transducers, accelerometers, acoustic emission sensors, and foil strain gauges. The blades underwent harmonic excitation at their first natural frequency using the Universal Resonant Excitation (UREX) system at NREL. Blades were initially excited at 25% of their design load, and then with steadily increasing loads until each blade reached failure. Data from the sensors were collected between and during fatigue loading sessions. The data were measured over multi-scale frequency ranges using a variety of acquisition equipment, including off-the-shelf systems and specially designed hardware developed at Los Alamos National Laboratory (LANL). The hardware systems were evaluated for their aptness in data collection for effective application of SHM methods to the blades. The results of this assessment will inform the selection of acquisition hardware and sensor types to be deployed on a CX-100 flight test to be conducted in collaboration with Sandia National Laboratory at the U.S. Department of Agriculture's (USDA) Conservation and Production Research Laboratory (CPRL) in Bushland, Texas.

  10. 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.

  11. 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.

  12. 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

  13. The effect of isokinetic testing speed on the reliability of muscle fatigue indicators during a hip abductor-adductor fatigue protocol.

    PubMed

    Gautrey, C N; Watson, T; Mitchell, A

    2013-07-01

    The aim of this study was to investigate the reliability of fatigue indicators calculated from peak torque and total work during isokinetic speeds of 60, 90, 120 and 180° · s-1 during a hip fatigue protocol. 10 males suffering from a history of unilateral functional ankle instability and 10 male healthy controls performed 5 maximal concentric contractions on an isokinetic dynamometer. Following a 4 min rest period subjects were instructed to perform repeated maximal concentric contractions to fatigue, which was defined as 3 consecutive repetitions below 50% of the maximum peak torque value. Each testing speed was randomised with 24 h between speeds. The subjects were asked to return to the laboratory 7 days later to repeat the 4 speeds, with 24 h between speeds. Muscle fatigue was determined for each testing speed by the fatigue index, the percent decrease in performance and the slope of the regression equation. The most reliable fatigue determination method was the slope of the regression equation, when testing at a speed of 120° · s-1. It is recommended that future investigators examine and plot their data before choosing the slope of the regression equation as their fatigue indicator, as a linear model is required. PMID:23549692

  14. 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

  15. 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.

  16. 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.

  17. DC-10 composite vertical stabilizer ground test program

    NASA Technical Reports Server (NTRS)

    Palmer, J. M., Jr.; Stephens, C. O.; Sutton, J. O.

    1983-01-01

    A review of the structural configuration and ground test program is presented. Particular emphasis is placed on the testing of a full-scale stub box test subcomponent and full span ground test unit. The stub box subcomponent was tested in an environmental chamber under ambient, cold/wet, and hot/wet conditions. The test program included design limit static loads, fatigue spectrum loading to approximately two service lifetimes (with and without damage), design limit damage tolerance tests, and a final residual strength test to a structural failure. The first full-scale ground test unit was tested under ambient conditions. The test unit was to have undergone static, fatigue, and damage tolerance tests but a premature structural failure occurred at design limit load during the third limit load test. A failure theory was developed which explains the similarity in types of failure and the large load discrepancy at failure between the two test articles. The theory attributes both failures to high stress concentrations at the edge of the lower rear spar access opening. A second full-scale ground test unit has been modified to incorporate the various changes resulting from the premature failure. The article has been assembled and is active in the test program.

  18. 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.

  19. 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…

  20. 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.

  1. Aging test and dynamic fatigue test of apatite-wollastonite-containing glass ceramics and dense hydroxyapatite.

    PubMed

    Kitsugi, T; Yamamuro, T; Nakamura, T; Kakutani, Y; Hayashi, T; Ito, S; Kokubo, T; Takagi, M; Shibuya, T

    1987-04-01

    The purpose of this study is to examine the changes in mechanical strength of two bioactive ceramics in living tissue. An aging test and dynamic fatigue test were performed using apatite-wollastonite-containing glass ceramics (A X W-GC) and dense hydroxyapatite (HA). Specimens (5 mm X 5 mm X 25 mm, abraded with No. 2000 Al2O3 powder) were implanted into subcutaneous tissue of rats for varying periods of time. The bending strength of aged samples was measured by the three-point loading method. The bending strength of A X W-GC was greater than that of HA (P less than 0.001). There was no reduction in bending strength for both A X W-GC and HA in living tissue. The n value of both A X W-GC and HA did not decrease significantly after implantation as assessed by the results of the dynamic fatigue test according to analysis of covariance. SEM-EPMA showed that Si and Mg contents decreased, Ca content did not change, while P content increased in the surface of A X W-GC. The area where x-ray intensity changed increased moderately after implantation. There were no changes in Ca and P at the interface between HA and soft tissue. In macroscopic and microscopic observations, specimens were found to be encapsulated with a thin layer of connective tissue. Foreign body giant cells, osteoblasts, or osteoclasts were not observed in the soft tissue. There was no bonding between ceramics and soft tissue.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Strainrange partitioning: A tool for characterizing high temperature low cycle fatigue. [materials fatigue test

    NASA Technical Reports Server (NTRS)

    Hirschberg, M. H.; Halford, G. R.

    1975-01-01

    The basic concepts of strain range partitioning are reviewed and the areas requiring for expanded verification are detailed. A suggested cooperative evaluation program involves the verification of the four basic life relationships (for PP, CC, PC, and CP type inelastic strain ranges) for a variety of materials that are of direct interest to the participating organizations.

  7. Achievement Test Program.

    ERIC Educational Resources Information Center

    Ohio State Dept. of Education, Columbus. Trade and Industrial Education Service.

    The Ohio Trade and Industrial Education Achievement Test battery is comprised of seven basic achievement tests: Machine Trades, Automotive Mechanics, Basic Electricity, Basic Electronics, Mechanical Drafting, Printing, and Sheet Metal. The tests were developed by subject matter committees and specialists in testing and research. The Ohio Trade and…

  8. Implementation of a Two-Axis Servo-Hydraulic System for Full-Scale Fatigue Testing of Wind Turbine Blades

    SciTech Connect

    Hughes, S. D.; Musial, W. D.; Stensland, T.

    1999-09-09

    Recently, the blade fatigue testing capabilities at NREL were upgraded from single-axis to two-axis loading. To implement this, several practical challenges were addressed, as hardware complexity increased dramatically with two actuators applying the loads at right angles to each other. A custom bellcrank was designed and implemented to minimize the load angle errors and to prevent actuator side loading. The control system was upgraded to accept load and displacement feedback from two actuators. The inherent long strokes uniquely associated with wind turbine blade-tests required substantial real-time corrections for both the control and data systems. A custom data acquisition and control system was developed using a National Instruments LabVIEW platform that interfaces with proprietary servo-hydraulic software developed by MTS Corporation. Before testing, the program is run under quasi-static (slow speed) conditions and iterates to determine the correct operational control parameters for the controller, taking into consideration geometry, test speed, and phase angle errors between the two actuators. Comparisons are made between single-axis and two-axis test loads using actual test load data and load uncertainties are qualitatively described. To date, two fatigue tests have been completed and another is currently ongoing using NREL's two-axis capability.

  9. 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].

  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 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.

  12. 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.

  13. Fatigue fracture of the stem-cement interface with a clamped cantilever beam test.

    PubMed

    Heuer, D A; Mann, K A

    2000-12-01

    A clamped cantilever beam test was developed to determine the fatigue crack propagation rate of the CoCr alloy/PMMA cement interface at high crack tip phase angles. A combination of finite element and experimental methods was used to determine the fatigue crack growth rates of two different CoCr alloy/PMMA cement surfaces. A crack tip phase angle of 69 deg was found, indicating that loading at the crack tip was mixed-mode with a large degree of in-plane shear loading. The energy required to propagate a crack at the interface was much greater for the plasma-sprayed CoCr surface when compared to the PMMA-precoated satin finish (p < 0.001). Both interface surfaces could be modeled using a Paris fatigue crack growth law over crack propagation rates of 10(-4) to 10(-9) m/cycle.

  14. Effects on fatigue life of gate valves due to higher torque switch settings during operability testing

    SciTech Connect

    Richins, W.D.; Snow, S.D.; Miller, G.K.; Russell, M.J.; Ware, A.G.

    1995-12-01

    Some motor operated valves now have higher torque switch settings due to regulatory requirements to ensure valve operability with appropriate margins at design basis conditions. Verifying operability with these settings imposes higher stem loads during periodic inservice testing. These higher test loads increase stresses in the various valve internal parts which may in turn increase the fatigue usage factors. This increased fatigue is judged to be a concern primarily in the valve disks, seats, yokes, stems, and stem nuts. Although the motor operators may also have significantly increased loading, they are being evaluated by the manufacturers and are beyond the scope of this study. Two gate valves representative of both relatively weak and strong valves commonly used in commercial nuclear applications were selected for fatigue analyses. Detailed dimensional and test data were available for both valves from previous studies at the Idaho National Engineering Laboratory. Finite element models were developed to estimate maximum stresses in the internal parts of the valves and to identity the critical areas within the valves where fatigue may be a concern. Loads were estimated using industry standard equations for calculating torque switch settings prior and subsequent to the testing requirements of USNRC Generic Letter 89--10. Test data were used to determine both; (1) the overshoot load between torque switch trip and final seating of the disk during valve closing and (2) the stem thrust required to open the valves. The ranges of peak stresses thus determined were then used to estimate the increase in the fatigue usage factors due to the higher stem thrust loads. The usages that would be accumulated by 100 base cycles plus one or eight test cycles per year over 40 and 60 years of operation were calculated.

  15. 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.

  16. Development on the Tensile Fatigue Test Apparatus and Strength Evaluation of Thin Metal Films

    NASA Astrophysics Data System (ADS)

    Fukushi, Miyuki; Miyata, Hiroshi; Murakami, Akira

    Recently, development of medical devices such as catheter and stent are advanced in the low invasion medical field. Considering the functions of human body are affected severely by the medical devices, the high strength reliability of devices must be secured. In these circumstances, the thin metal film, which has high reliability of strength, is useful structural material for further development of low invasion medical device. As the strength characteristics of a thin film depend on thickness and formation process of itself, there is little strength database concerning a thin metal film. In this study, a tensile fatigue testing apparatus with cyclic loading frequency up to 30Hz and maximum loading 8 N for the thin metal film has been developed, and thin rolled films Ti and SUS304 were evaluated on tensile and load-controlled fatigue strength. The static tensile tests give that both are also over the twice of the bulk material on the tensile strength, and the proof stress is high-strength with over 90% of tensile strength respectively. The fatigue test shows that Ti thin film has long life in comparison with the bulk material, however, the fatigue characteristic itself is similar like that of bulk material.

  17. 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.

  18. 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.

  19. Loading frequencies up to 20Hz as an alternative to accelerate fatigue strength tests in a Y-TZP ceramic.

    PubMed

    Fraga, Sara; Pereira, Gabriel Kalil Rocha; Freitas, Mariana; Kleverlaan, Cornelis Johannes; Valandro, Luiz Felipe; May, Liliana Gressler

    2016-08-01

    Considering the interest of the research community in the fatigue behavior of all-ceramic restorations and the time consumed in low-frequency cyclic fatigue tests, this study aimed to investigate the influence of the loading frequency on the zirconia fatigue strength. The biaxial flexural fatigue strength of Y-TZP discs was determined by the staircase approach after 500,000 cycles. The investigated frequencies were 2Hz (control-simulation of the chewing activity; n=20), 10Hz (n=20), 20Hz (n=20), and 40Hz (n=21). The fatigue strength data were analyzed using one-way ANOVA and post-hoc Tukey׳s test (α=0.05). Pearson coefficient (r) was calculated to assess the existence of a correlation between fatigue strength and loading frequency. X-ray diffraction analysis was used to determine the relative amount of monoclinic phase under each fatigue test condition. The fatigue strength was significantly higher for 40Hz group (630.7±62.1MPa) and did not differ among the groups 2Hz (550.3±89.7MPa), 10Hz (574.0±47MPa) and 20Hz (605.1±30.7MPa). Pearson correlation coefficient indicated a significantly moderate correlation (r=0.57) between fatigue strength and loading frequency. The percentage of monoclinic phase was similar among the groups. Therefore, the use of loading frequencies up to 20Hz seems a good alternative to expedite the cycling strength fatigue tests in polycrystalline ceramics without significantly changing the fatigue behavior showed by zirconia in tests employing the frequency of the masticatory cycle. PMID:26849030

  20. Loading frequencies up to 20Hz as an alternative to accelerate fatigue strength tests in a Y-TZP ceramic.

    PubMed

    Fraga, Sara; Pereira, Gabriel Kalil Rocha; Freitas, Mariana; Kleverlaan, Cornelis Johannes; Valandro, Luiz Felipe; May, Liliana Gressler

    2016-08-01

    Considering the interest of the research community in the fatigue behavior of all-ceramic restorations and the time consumed in low-frequency cyclic fatigue tests, this study aimed to investigate the influence of the loading frequency on the zirconia fatigue strength. The biaxial flexural fatigue strength of Y-TZP discs was determined by the staircase approach after 500,000 cycles. The investigated frequencies were 2Hz (control-simulation of the chewing activity; n=20), 10Hz (n=20), 20Hz (n=20), and 40Hz (n=21). The fatigue strength data were analyzed using one-way ANOVA and post-hoc Tukey׳s test (α=0.05). Pearson coefficient (r) was calculated to assess the existence of a correlation between fatigue strength and loading frequency. X-ray diffraction analysis was used to determine the relative amount of monoclinic phase under each fatigue test condition. The fatigue strength was significantly higher for 40Hz group (630.7±62.1MPa) and did not differ among the groups 2Hz (550.3±89.7MPa), 10Hz (574.0±47MPa) and 20Hz (605.1±30.7MPa). Pearson correlation coefficient indicated a significantly moderate correlation (r=0.57) between fatigue strength and loading frequency. The percentage of monoclinic phase was similar among the groups. Therefore, the use of loading frequencies up to 20Hz seems a good alternative to expedite the cycling strength fatigue tests in polycrystalline ceramics without significantly changing the fatigue behavior showed by zirconia in tests employing the frequency of the masticatory cycle.

  1. 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.

  2. 75 FR 69745 - Aging Airplane Program: Widespread Fatigue Damage

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... airplanes to establish a limit of validity of the engineering data that supports the structural maintenance... validity of the engineering data that supports the structural maintenance program (LOV); 2. Demonstrate... 17, 2006. \\3\\ 71 FR 19928 The FAA proposed that design approval holders for those airplanes...

  3. 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).

  4. 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.

  5. 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.

  6. 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.

  7. Construct Validation of a Multidimensional Computerized Adaptive Test for Fatigue in Rheumatoid Arthritis

    PubMed Central

    Nikolaus, Stephanie; Bode, Christina; Taal, Erik; Vonkeman, Harald E.; Glas, Cees A. W.; van de Laar, Mart A. F. J.

    2015-01-01

    Objective Multidimensional computerized adaptive testing enables precise measurements of patient-reported outcomes at an individual level across different dimensions. This study examined the construct validity of a multidimensional computerized adaptive test (CAT) for fatigue in rheumatoid arthritis (RA). Methods The ‘CAT Fatigue RA’ was constructed based on a previously calibrated item bank. It contains 196 items and three dimensions: ‘severity’, ‘impact’ and ‘variability’ of fatigue. The CAT was administered to 166 patients with RA. They also completed a traditional, multidimensional fatigue questionnaire (BRAF-MDQ) and the SF-36 in order to examine the CAT’s construct validity. A priori criterion for construct validity was that 75% of the correlations between the CAT dimensions and the subscales of the other questionnaires were as expected. Furthermore, comprehensive use of the item bank, measurement precision and score distribution were investigated. Results The a priori criterion for construct validity was supported for two of the three CAT dimensions (severity and impact but not for variability). For severity and impact, 87% of the correlations with the subscales of the well-established questionnaires were as expected but for variability, 53% of the hypothesised relations were found. Eighty-nine percent of the items were selected between one and 137 times for CAT administrations. Measurement precision was excellent for the severity and impact dimensions, with more than 90% of the CAT administrations reaching a standard error below 0.32. The variability dimension showed good measurement precision with 90% of the CAT administrations reaching a standard error below 0.44. No floor- or ceiling-effects were found for the three dimensions. Conclusion The CAT Fatigue RA showed good construct validity and excellent measurement precision on the dimensions severity and impact. The dimension variability had less ideal measurement characteristics

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Nondestructive determination of fatigue crack damage in composites using vibration tests.

    NASA Technical Reports Server (NTRS)

    Dibenedetto, A. T.; Gauchel, J. V.; Thomas, R. L.; Barlow, J. W.

    1972-01-01

    The vibration response of glass reinforced epoxy and polyester laminates was investigated. The complex modulus and the damping capacity were measured as fatigue crack damage accumulated. Changes in the Young's modulus as well as the damping capacity correlated with the amount of crack damage. The damping was especially sensitive to debonding of the reinforcement from the resin matrix. Measurement of these vibration response changes shows promise as a means to nondestructively test the structural integrity of filament-reinforced composite structural members.

  17. Fatigue crack growth measurements in TMF testing of titanium alloys using an ACPD technique

    SciTech Connect

    Dai, Y.; Marchand, N.J.; Hongoh, M.

    1995-04-01

    A thermal-mechanical fatigue (TMF) testing system has been developed which is capable of studying the fatigue behaviors of gas turbine materials under simultaneous changes of temperatures and strains (or stresses). Furthermore, an advanced alternating current potential difference (ACPD) measurement technique has been developed successfully to perform on-line monitoring of fatigue crack initiation and growth in specimens tested under isothermal and TMF conditions. In this paper, the basic principles of the ACPD technique as well as all the relevant experimental procedures for performing ACPD measurements, including probe setup, choice of alternating currents (AC) and frequencies, noise rejection, data acquisition, and signal processing, are described. The linear relationship between ACPD signals and crack lengths, as well as the effects of thermal cycling on the ACPD signal, are presented and discussed. The capabilities of the TMF and ACPD systems are well illustrated by fatigue crack initiation and growth test results under isothermal and TMF conditions. These tests were performed on two titanium forgings, Ti-6Al-4V (Ti64) and Ti-6Al-2Sn-6Mo (Ti6246), respectively. Alloy Ti64 was TMF cycled between 150 and 400`C, while Ti6246 was cycled between 200 and 482 C. The resolution for detecting crack initiation at the root of notches was found to be 50 {mu}m with 95% confidence while the resolution for crack growth was 2 {mu}m per mV change of ACPD. An environmental assisted cracking model applied to TMF crack growth is proposed for rationalizing the data.

  18. Dynamic fatigue testing of Zerodur glass-ceramic

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.

    1988-01-01

    The inherent brittleness of glass invariably leads to a large variability in strength data and a time dependence in strength. Leading rate plays a large role in strength values. Glass is found to be weaker when supporting loads over long periods of time as compared to glass which undergoes rapid leading. These properties complicate the structural design allowables for the utilization of glass components in an application such as Advanced X-ray Astrophysics Facility (AXAF). The test methodology to obtain parameters which can be used to predict the reliability and life time of Zerodur glass-ceramic which is to be used for the mirrors in the AXAF is described.

  19. 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.

  20. Predicting in-service fatigue life of flexible pavements based on accelerated pavement testing

    NASA Astrophysics Data System (ADS)

    Guo, Runhua

    Pavement performance prediction in terms of fatigue cracking and surface rutting are essential for any mechanistically-based pavement design method. Traditionally, the estimation of the expected fatigue field performance has been based on the laboratory bending beam test. Full-scale Accelerated Pavement Testing (APT) is an alternative to laboratory testing leading to advances in practice and economic savings for the evaluation of new pavement configurations, stress level related factors, new materials and design improvements. This type of testing closely simulates field conditions; however, it does not capture actual performance because of the limited ability to address long-term phenomena. The same pavement structure may exhibit different response and performance under APT than when in-service. Actual field performance is better captured by experiments such as Federal Highway Administration's Long-Term Pavement Performance (LTPP) studies. Therefore, to fully utilize the benefits of APT, there is a need for a methodology to predict the long-term performance of in-service pavement structures from the results of APT tests that will account for such differences. Three models are generally suggested to account for the difference: shift factors, statistical and mechanistic approaches. A reliability based methodology for fatigue cracking prediction is proposed in this research, through which the three models suggested previously are combined into one general approach that builds on their individual strengths to overcome some of the shortcomings when the models are applied individually. The Bias Correction Factor (BCF) should account for all quantifiable differences between the fatigue life of the pavement site under APT and in-service conditions. In addition to the Bias Correction Factor, a marginal shifty factor, M, should be included to account for the unquantifiable differences when predicting the in-service pavement fatigue life from APT. The Bias Correction Factor

  1. Prediction of Frequency for Simulation of Asphalt Mix Fatigue Tests Using MARS and ANN

    PubMed Central

    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. PMID:24688400

  2. 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. PMID:27332924

  3. 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.

  4. 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.

  5. Effects of test sample shape and surface production method on the fatigue behaviour of PMMA bone cement.

    PubMed

    Sheafi, E M; Tanner, K E

    2014-01-01

    There is no consensus over the optimal criterion to define the fatigue life of bone cement in vitro. Fatigue testing samples have been made into various shapes using different surface preparation techniques with little attention being paid to the importance of these variations on the fatigue results. The present study focuses on the effect of test sample shape and surface production method on the fatigue results. The samples were manufactured with two cross sectional shapes: rectangular according to ISO 527 and circular according to ASTM F2118. Each shape was produced using two methods: direct moulding of the cement dough and machining from oversized rods. Testing was performed using two different bone cements: SmartSet GHV and DePuy CMW1. At least 10 samples of each category were tested, under fully reversed tension-compression fatigue stress at ±20MPa, to allow for Weibull analysis to compare results. The growth of fatigue cracks was observed by means of the changes in the absorbed energy and apparent modulus. It was found that fatigue crack growth can be altered by the sample shape and production method; however it is also dependent on the chemical composition of the cement. The results revealed that moulded samples, particularly those based on the ASTM F2118 standard, can lead to up to 5.5 times greater fatigue lives compared to the machined samples of the same cement. It is thus essential, when comparing the fatigue results of bone cement, to consider the effect of production method along with the shape of the test sample. PMID:24070780

  6. Motor-unit force potentiation in adult cats during a standard fatigue test.

    PubMed

    Gordon, D A; Enoka, R M; Stuart, D G

    1990-02-01

    1. The purpose of this study was to examine the time course of tetanic force during a standard fatigue test and to distinguish between the appearance of potentiation and fatigue among the four motor-unit types of a cat hindlimb muscle. 2. Motor units of the tibialis posterior muscle in the adult cat were assigned to four categories (i.e. types S, FR, FI, FF) based on conventional criteria (Burke, Levine, Tsairis & Zajac, 1973). The mean (+/- S.D.) time course of peak force was constructed for each motor-unit type and, within each type, for those units that potentiated (a greater than 3% increase in peak force compared to the initial value) and those that did not potentiate. 3. The average time courses of force differed between motor-unit types. There was, however, considerable variability within each motor-unit type. For the same relative force output, the forces exerted by slow-twitch units were less variable than those exerted by fast-twitch units. In addition, the variability among slow-twitch units was relatively constant during the fatigue test while variability among fast-twitch units either increased or decreased with time. 4. For a given motor-unit type, the average time course of force did not depend on whether force in each tetanus was expressed as a peak value, an average peak value, or a force-time integral. 5. Some motor units within each type exhibited potentiation. Most of the variability in the time course of the peak force for each motor-unit type could be accounted for by the potentiating units. Motor units that exhibited only force decline (i.e. fatigue), regardless of unit type, had less variable time courses of peak force. Since potentiation was transient in some unit types, it was assumed that at least two opposing processes (i.e. fatigue and potentiation) occurred simultaneously in these units (see also, Krarup, 1981; Rankin, Enoka, Volz & Stuart, 1988; Garner, Hicks & McComas, 1989). 6. It is concluded that the expression of force

  7. Fatigue life estimation program for Part 23 airplanes, `AFS.FOR`

    SciTech Connect

    Kaul, S.K.

    1993-12-31

    The purpose of this paper is to introduce to the general aviation industry a computer program which estimates the safe fatigue life of any Federal Aviation Regulation (FAR) Part 23 airplane. The algorithm uses the methodology (Miner`s Linear Cumulative Damage Theory) and the various data presented in the Federal Aviation Administration (FAA) Report No. AFS-120-73-2, dated May 1973. The program is written in FORTRAN 77 language and is executable on a desk top personal computer. The program prompts the user for the input data needed and provides a variety of options for its intended use. The program is envisaged to be released through issuance of a FAA report, which will contain the appropriate comments, instructions, warnings and limitations.

  8. 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

  9. 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.

  10. 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.

  11. Back and hip extensor muscles fatigue in healthy subjects: task-dependency effect of two variants of the Sorensen test

    PubMed Central

    Champagne, Annick; Descarreaux, Martin

    2008-01-01

    Paraspinal muscle fatigability during various trunk extension tests has been widely investigated by electromyography (EMG), and its task-dependency is established recently. Hip extensor muscle fatigability during the Sorensen test has been reported. The aim of the present experiments was to evaluate the task-dependency of back and hip extensor muscle fatigue during two variants of the Sorensen test. We hypothesized that the rate of muscular fatigue of the hip and back extensor muscles varies according to the test position. Twenty healthy young males with no history of low back pain volunteered to participate in this cross-sectional study. They were asked to perform two body weight-dependent isometric back extension tests (S1 = Sorensen test; S2 = modified Sorensen on a 45° Roman chair). Surface EMG activity of the paraspinal muscles (T10 and L5 levels) and hip extensor muscles (gluteus maximus; biceps femoris) was recorded, and muscular fatigue was assessed through power spectral analysis of the EMG data by calculating the rate of median power frequency change. We observed hip extensor muscle fatigue simultaneously with paraspinal muscle fatigue during both Sorensen variants. However, only L5 level EMG fatigue indices showed a task-dependency effect between S1 and S2. Hip extensor muscles appear to contribute to load sharing of the upper body mass during both Sorensen variants, but to a different extent because L5 level fatigue differs between the Sorensen variants. Our findings suggest that task-dependency has to be considered when EMG variables are compared between two types of lumbar muscle-fatiguing tasks. PMID:18813961

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

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

    DOE PAGESBeta

    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 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

  18. 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.

  19. 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.

  20. Cognitive and Physical Fatigue Tasks Enhance Pain, Cognitive Fatigue and Physical Fatigue in People with Fibromyalgia

    PubMed Central

    Dailey, Dana L; Keffala, Valerie J; Sluka, Kathleen A

    2014-01-01

    Objective Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task and a dual fatigue task. Methods Twenty four people with fibromyalgia and 33 healthy controls completed pain, fatigue and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue and perceived physical fatigue were assessed during each task using visual analogue scales. Function was assessed with shoulder range of motion and grip. Results People with fibromyalgia had significantly higher increases in pain, cognitive fatigue and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (p<0.01). People with fibromyalgia performed equivalently on measures of physical performance and cognitive performance on the physical and cognitive fatigue tasks, respectively. Conclusions These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation. PMID:25074583

  1. Comparison of uncertainty in fatigue tests obtained by the Monte Carlo method in two softwares

    NASA Astrophysics Data System (ADS)

    Trevisan, Lisiane; Kapper Fabricio, Daniel Antonio; Reguly, Afonso

    2016-07-01

    The Supplement 1 to the “Guide to the expression of uncertainty in measurement” indicates the Monte Carlo method for calculating the expanded measurement uncertainty. The objective of this work is to compare the measurement uncertainty values obtained via Monte Carlo method through two commercial softwares (Matlab® and Crystal Ball®) for the parameter ‘adjusted strain’, obtained from fatigue tests. Simulations were carried out using different number of iterations and different levels of confidence. The results showed that there are short differences between the measurement uncertainty values generated by different software.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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...

  7. 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...

  8. A unique elevated-temperature tension-torsion fatigue test rig

    NASA Astrophysics Data System (ADS)

    Jordan, E. H.; Chan, C. T.

    1987-06-01

    A unique tension-torsion fatigue test set up is described that allows strain-controlled tests at temperatures exceeding 649 C. The machine uses a large die set as a load frame resulting in lower cost and superior parallel positioning of the crossheads. Disposable weld-on grips were found to be cost effective for elevated-temperature testing. A new extensometer using commercially available capacitance probes was developed which can operate at the elevated temperature without cooling. Capacitance ring probes were utilized in an attempt to measure through-thickness strains. The characteristic behavior of the ring probes is discussed. Design modifications needed to make a successful measurement of through-thickness strains at elevated temperatures are presented.

  9. A novel noncontact electromagnetic field-based sensor for the monitoring of resonant fatigue tests

    NASA Astrophysics Data System (ADS)

    Nam, Si-Byung; Yun, Gun Jin; Carletta, Joan; Kim, Dong-Han; Binienda, Wieslaw

    2011-03-01

    In this paper, a prototype of an electromagnetic field-based (EFB) vibration sensor that uses a novel sensing technique to monitor the resonant fatigue testing of a conductive and/or ferromagnetic target specimen is presented. The distance from the target to a coil within the sensor affects the impedance of the coil. The electronic circuitry for the sensor consists of a relaxation oscillator, an embedded microprocessor module and a high-speed digital-to-analog converter. The impedance of the coil determines the frequency of oscillation of the relaxation oscillator's output, so that vibration of the target causes changes in the oscillation frequency. A timer in the embedded microprocessor module is used to count the oscillations, producing a digital signal that indicates the coil-to-target distance. The digital signal is instantaneously converted to an analog signal to produce the sensor's output. The key technologies proposed include: (1) a novel timer counting method using the input capture functionality and timer of the embedded microprocessor module and (2) significant simplification of the analog electronic circuitry. The performance of the proposed sensor has been verified using AISI 1095 carbon steel and Al6061-T6 aluminum alloy specimens during resonant fatigue tests. The sensor shows a good linearity between displacement amplitudes and output voltages.

  10. 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.

  11. Physical activity, smoking, and exercise-induced fatigue.

    PubMed

    Hughes, J R; Crow, R S; Jacobs, D R; Mittelmark, M B; Leon, A S

    1984-06-01

    This study determined whether persons with coronary risk factors have increased fatigue during or after exercise. Ratings of perceived exertion were first shown to be a valid measure of fatigue; i.e., ratings of perceived exertion correlated with heart rate both during and after exercise and at each of three exercise tests (all within-subjects r greater than 0.88). Physical inactivity and smoking were associated with increased fatigue. Inactive men and smokers had higher levels of fatigue during both exercise and recovery conditions and at each of three exercise test. The increased fatigue of men who were inactive and smoked was not entirely due to their lower level of fitness. The risk factors of age, Type A behavior pattern, blood pressure, serum cholesterol, serum high-density lipoprotein, and obesity were not associated with increased fatigue. The increased fatigue experienced by inactive persons and smokers may account for their decreased compliance to exercise programs.

  12. 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

  13. Six-Minute Walk Test demonstrates motor fatigue in spinal muscular atrophy

    PubMed Central

    Montes, J.; McDermott, M. P.; Martens, W. B.; Dunaway, S.; Glanzman, A. M.; Riley, S.; Quigley, J.; Montgomery, M. J.; Sproule, D.; Tawil, R.; Chung, W. K.; Darras, B. T.; De Vivo, D. C.; Kaufmann, P.; Finkel, R. S.

    2010-01-01

    Background: In spinal muscular atrophy (SMA), weakness, decreased endurance, and fatigue limit mobility. Scales have been developed to measure function across the wide spectrum of disease severity. However, these scales typically are observer dependent, and scores are based on sums across Likert-scaled items. The Six-Minute Walk Test (6MWT) is an objective, easily administered, and standardized evaluation of functional exercise capacity that has been proven reliable in other neurologic disorders and in children. Methods: To study the performance of the 6MWT in SMA, 18 ambulatory participants were evaluated in a cross-sectional study. Clinical measures were 6MWT, 10-m walk/run, Hammersmith Functional Motor Scale–Expanded (HFMSE), forced vital capacity, and handheld dynamometry. Associations between the 6MWT total distance and other outcomes were analyzed using Spearman correlation coefficients. A paired t test was used to compare the mean distance walked in the first and sixth minutes. Results: The 6MWT was associated with the HFMSE score (r = 0.83, p < 0.0001), 10-m walk/run (r = −0.87, p < 0.0001), and knee flexor strength (r = 0.62, p = 0.01). Gait velocity decreased during successive minutes in nearly all participants. The average first minute distance (57.5 m) was significantly more than the sixth minute distance (48 m) (p = 0.0003). Conclusion: The Six-Minute Walk Test (6MWT) can be safely performed in ambulatory patients with spinal muscular atrophy (SMA), correlates with established outcome measures, and is sensitive to fatigue-related changes. The 6MWT is a promising candidate outcome measure for clinical trials in ambulatory subjects with SMA. GLOSSARY FVC = forced vital capacity; HFMSE = Hammersmith Functional Motor Scale–Expanded; HHD = handheld dynamometry; 6MWT = Six-Minute Walk Test; SMA = spinal muscular atrophy. PMID:20211907

  14. Lunar mass spectrometer test program

    NASA Technical Reports Server (NTRS)

    Torney, F. L.; Dobrott, J. R.

    1972-01-01

    The procedures are described along with results obtained in a test program conducted to demonstrate the performance of a candidate lunar mass spectrometer. The instrument was designed to sample and measure gases believed to exist in the lunar atmosphere at the surface. The subject instrument consists of a cold cathode ion source, a small quadrupole mass analyzer and an off axis electron multiplier ion counting detector. The major program emphasis was placed on demonstrating instrument resolution, sensitivity and S/N ratio over the mass range 0-150 amu and over a partial pressure range from 10 to the minus 9th power to 10 to the minus 13th power torr. Ultrahigh vacuum tests were conducted and the minimum detectable partial pressure for neon, argon, krypton and xenon was successfully determined for the spectrometer using isotopes of these gases. With the exception of neon, the minimum detectable partial pressure is approximately 4 x 10 to the minus 14th power torr for the above gases.

  15. 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.

  16. 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

  17. Influence of successive bouts of fatiguing exercise on perceptual and physiological markers during an incremental exercise test.

    PubMed

    Coquart, Jeremy B J; Legrand, Renaud; Robin, Sophie; Duhamel, Alain; Matran, Regis; Garcin, Murielle

    2009-01-01

    The purpose of this study was to examine the effects of a succession of fatiguing stages, on ratings of perceived exertion (RPE) and estimated time limits (ETL) during an incremental exercise test. Twenty-seven cyclists performed a continuous incremental test and a discontinuous test with randomized workloads. A linear mixed model was used to compare the RPE, ETL, respiratory gas, heart rate, and blood data obtained during the two exercise tests. RPE and ETL were not significantly different between the tests. Ventilation, breathing frequency, heart rate, and blood lactate concentration were significantly higher during the last incremental test workloads. In conclusion, although the incremental exercise test generated higher cardiorespiratory and muscular workloads than observed during the randomized exercise test, most likely due to a greater fatiguing process, these higher workloads did not influence the perceptual response.

  18. 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.

  19. 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.

  20. Low cycle fatigue

    NASA Technical Reports Server (NTRS)

    Solomon, H. D. (Editor); Kaisand, L. R. (Editor); Halford, G. R. (Editor); Leis, B. N. (Editor)

    1988-01-01

    The papers contained in this volume focus on various aspects of low cycle fatigue, including cyclic deformation, crack propagation, high-temperature low cycle fatigue, microstructural defects, multiaxial and variable amplitude loading, and life prediction. Papers are presented on the low cycle fatigue of some aluminum alloys, prediction of crack growth under creep-fatigue loading conditions, high-temperature low cycle fatigue behavior and lifetime prediction of a nickel-base ODS alloy, and an integrated approach to creep-fatigue life prediction. Other topics discussed include thermal fatigue testing of coated monocrystalline superalloys, low cycle fatigue of Al-Mg-Si alloys, and the effect of superimposed stresses at high frequency on low cycle fatigue.

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

    DOE PAGESBeta

    Niezrecki, Christopher; Avitabile, Peter; Chen, Julie; Sherwood, James; Lundstrom, Troy; LeBlanc, Bruce; Hughes, Scott; Desmond, Michael; Beattie, Alan; Rumsey, Mark; et al

    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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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...

  11. 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...

  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, 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...

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

    PubMed

    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.

  15. 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.

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

    PubMed

    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. PMID:26520994

  17. 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)

  18. 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.

  19. 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.

  20. Fatigue Testing of Metallurgically-Bonded EBR-II Superheater Tubes

    SciTech Connect

    Terry C. Totemeier

    2006-12-01

    Fatigue crack growth tests were performed on 2¼Cr-1Mo steel specimens machined from ex-service Experimental Breeder Reactor – II (EBR-II) superheater duplex tubes. The tubes had been metallurgically bonded with a 100 µm thick Ni interlayer; the specimens incorporated this bond layer. Tests were performed at room temperature in air and at 400°C in air and humid Ar; cracks were grown at varied levels of constant ?K. Crack growth tests at a range of ?K were also performed on specimens machined from the shell of the superheater. In all conditions the presence of the Ni interlayer was found to result in a net retardation of growth as the crack passed through the interlayer. The mechanism of retardation was identified as a disruption of crack planarity and uniformity after passing through the porous interlayer. Full crack arrest was only observed in a single test performed at near-threshold ?K level (12 MPa?m) at 400°C. In this case the crack tip was blunted by oxidation of the base steel at the steel-interlayer interface.

  1. Apollo experience report: Certification test program

    NASA Technical Reports Server (NTRS)

    Levine, J. H.; Mccarty, B. J.

    1972-01-01

    A review of the Apollo spacecraft certification (qualification) test program is presented. The approach to devising the spectrum of dynamic and climatic environments, the formulation of test durations, and the relative significance of the formal certification test program compared with development testing and acceptance testing are reviewed. Management controls for the formulation of test requirements, test techniques, data review, and acceptance of test results are considered. Significant experience gained from the Apollo spacecraft certification test program which may be applicable to future manned spacecraft is presented.

  2. 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.

  3. Neuromuscular characteristics and fatigue in endurance and sprint athletes during a new anaerobic power test.

    PubMed

    Paavolainen, L; Häkkinen, K; Nummela, A; Rusko, H

    1994-01-01

    The purpose of this study was to investigate neuromuscular and energy performance characteristics of anaerobic power and capacity and the development of fatigue. Ten endurance and ten sprint athletes performed a new maximal anaerobic running power test (MARP), which consisted of n x 20-s runs on a treadmill with 100-s recovery between the runs. Blood lactate concentration [la-]b was measured after each run to determine submaximal and maximal indices of anaerobic power (P3 mmol.l-1, P5 mmol.l-1, P10 mmol.l-1 and Pmax) which was expressed as the oxygen demand of the runs according to the American College of Sports Medicine equation: the oxygen uptake (ml.kg-1.min-1) = 0.2 x velocity (m.min-1) + 0.9 x slope of treadmill (frac) x velocity (m.min-1) + 3.5. The height of rise of the centre of gravity of the counter movement jumps before (CMJrest) and during (CMJ) the MARP test, as well as the time of force production (tF) and electromyographic (EMG) activity of the leg muscles of CMJ performed after each run were used to describe the neuromuscular performance characteristics. The maximal oxygen uptake (VO2max), anaerobic and aerobic thresholds were determined in the VO2max test, which consisted of n x 3-min runs on the treadmill.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. 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

  5. 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

  6. Effects of a short-term exercise training program on aerobic fitness, fatigue, health perception and activity level of subjects with multiple sclerosis.

    PubMed

    Mostert, S; Kesselring, J

    2002-04-01

    Multiple sclerosis (MS) patients of an inpatient rehabilitation program have been randomly assigned to an exercise training (MS-ET) or nontraining group (MS-NI). Before and after 4 weeks of aerobic exercise training, a graded maximal exercise test with measurement of gas exchange and a lung function test was administered to all 26 patients fulfilling the inclusion criteria. Activity level, fatigue and health perception were measured by means of questionnaires. Twenty-six healthy persons served as control group and were matched in respect of age, gender and activity level. Training intervention consisted of 5x30 min sessions per week of bicycle exercise with individualised intensity. Compared with baseline, the MS training group demonstrated a significant rightward placement of the aerobic threshold (AT) (VO2+13%; work rate [WR])+11%), an improvement of health perception (vitality+46%; social interaction+36%), an increase of activity level (+17%) and a tendency to less fatigue. No changes were observed for the MS-NI group and the control groups. Maximal aerobic capacity and lung function were not changed by either training or nontraining in all four groups. Overall compliance to the training program was quite low (65%), whereas incidence of symptom exacerbation by physical activity has been lower than expected (6%). PMID:11990874

  7. Effects of soluble milk protein or casein supplementation on muscle fatigue following resistance training program: a randomized, double-blind, and placebo-controlled study

    PubMed Central

    2014-01-01

    Background The effects of protein supplementation on muscle thickness, strength and fatigue seem largely dependent on its composition. The current study compared the effects of soluble milk protein, micellar casein, and a placebo on strength and fatigue during and after a resistance training program. Methods Sixty-eight physically active men participated in this randomized controlled trial and underwent 10 weeks of lower-body resistance training. Participants were randomly assigned to the Placebo (PLA), Soluble Milk Protein (SMP, with fast digestion rate) or Micellar Casein (MC, with slow digestion rate) group. During the 10-week training period, participants were instructed to take 30 g of the placebo or protein twice a day, or three times on training days. Tests were performed on quadriceps muscles at inclusion (PRE), after 4 weeks (MID) and after 10 weeks (POST) of training. They included muscle endurance (maximum number of repetitions during leg extensions using 70% of the individual maximal load), fatigue (decrease in muscle power after the endurance test), strength, power and muscle thickness. Results Muscle fatigue was significantly lower (P < 0.05) in the SMP group at MID and POST (-326.8 ± 114.1 W and -296.6 ± 130.1 W, respectively) as compared with PLA (-439.2 ± 153.9 W and -479.2 ± 138.1 W, respectively) and MC (-415.1 ± 165.1 W and -413.7 ± 139.4 W, respectively). Increases in maximal muscle power, strength, endurance and thickness were not statistically different between groups. Conclusions The present study demonstrated that protein composition has a large influence on muscular performance after prolonged resistance training. More specifically, as compared with placebo or micellar casein, soluble milk protein (fast digestible) appeared to significantly reduce muscle fatigue induced by intense resistance exercise. PMID:25057266

  8. 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.

  9. Evaluation of the New B-REX Fatigue Testing System for Multi-Megawatt Wind Turbine Blades: Preprint

    SciTech Connect

    White, D.; Musial, W.; Engberg, S.

    2004-12-01

    The National Renewable Energy Laboratory (NREL) recently developed a new hybrid fatigue testing system called the Blade Resonance Excitation (B-REX) test system. The new system uses 65% less energy to test large wind turbine blades in half the time of NREL's dual-axis forced-displacement test method with lower equipment and operating costs. The B-REX is a dual-axis test system that combines resonance excitation with forced hydraulic loading to reduce the total test time required while representing the operating strains on the critical inboard blade stations more accurately than a single-axis test system. The analysis and testing required to fully implement the B-REX was significant. To control unanticipated blade motion and vibrations caused by dynamic coupling between the flap, lead-lag, and torsional directions, we needed to incorporate additional test hardware and control software. We evaluated the B-REX test system under stable operating conditions using a combination of various sensors. We then compared our results with results from the same blade, tested previously using NREL's dual-axis forced-displacement test method. Experimental results indicate that strain levels produced by the B-REX system accurately replicated the forced-displacement method. This paper describes the challenges we encountered while developing the new blade fatigue test system and the experimental results that validate its accuracy.

  10. 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.

  11. Creep-fatigue response of structural ceramics: 1, Comparison of flexure, tension, and compression testing

    SciTech Connect

    Ferber, M.K.; Jenkins, M.G.; Nolan, T.A.; Yeckley, R.

    1990-12-31

    The stress sensitivities of the creep rates of commercially available Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} ceramics were measured at elevated temperatures using tension, compression, and flexure specimens. Pronounced differences in creep deformation behavior in compression and tension were observed for both ceramics. These differences were attributed to the generation of a creep-induced damage zone under tensile loading which accelerated the creep rate. The evolution of this damage zone was confirmed by (1) fractographic studies of failed tensile samples and (2) the observed stress-dependence of the creep failure strain. The creep rate-stress data generated fromn the flexure creep testing were found to be in fair agreement with results predicted from a creep deformation model. Differences between experimental and predicted creep behavior were attributed to the failure of the model to account for primary creep. This model was also capable of describing differences in the fatigue-life characteristics of a silicon nitride measured in flexure and tension.

  12. Creep-fatigue response of structural ceramics: 1, Comparison of flexure, tension, and compression testing

    SciTech Connect

    Ferber, M.K.; Jenkins, M.G.; Nolan, T.A. ); Yeckley, R. )

    1990-01-01

    The stress sensitivities of the creep rates of commercially available Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} ceramics were measured at elevated temperatures using tension, compression, and flexure specimens. Pronounced differences in creep deformation behavior in compression and tension were observed for both ceramics. These differences were attributed to the generation of a creep-induced damage zone under tensile loading which accelerated the creep rate. The evolution of this damage zone was confirmed by (1) fractographic studies of failed tensile samples and (2) the observed stress-dependence of the creep failure strain. The creep rate-stress data generated fromn the flexure creep testing were found to be in fair agreement with results predicted from a creep deformation model. Differences between experimental and predicted creep behavior were attributed to the failure of the model to account for primary creep. This model was also capable of describing differences in the fatigue-life characteristics of a silicon nitride measured in flexure and tension.

  13. Developing a corporate drug testing program

    SciTech Connect

    Hanrath, D.A. )

    1990-10-01

    Management reaction to employee drug abuse at a gas distribution company resulted in the development and implementation of a corporate drug testing program before DOT mandated drug testing. The author explains the background, planning, operation and communication work involved.

  14. Implementing an Adaptive Testing Program in an Instructional Programs Environment.

    ERIC Educational Resources Information Center

    McKinley, Robert L.; Reckase, Mark D.

    The purpose of this paper is to identify and discuss some of the problems presented by the use of computerized adaptive testing (CAT) in an instructional programs environment versus large scale testing applications, and to describe an actual implementation of CAT in an instructional programs setting. This particular application is in the…

  15. Anti-buckling fatigue test assembly. [for subjecting metal specimen to tensile and compressive loads at constant temperature

    NASA Technical Reports Server (NTRS)

    Eichenbrenner, F. F.; Imig, L. A. (Inventor)

    1974-01-01

    An antibuckling fatigue test assembly is described for holding a metal specimen which is subjected to compression and to rapid cyclical heating and cooling while permitting visual observation. In an illustrative embodiment of this invention, the anti-buckling fatigue test apparatus includes first and second guide members between which the metal specimen is disposed and held, a heating assembly comprising a suitable heating source such as a quartz lamp and a reflecting assembly directing the heat onto the specimen, and a cooling assembly for directing a suitable cooling fluid such as air onto the specimen. The guide members each have a passage to permit the heat to be directed onto the specimen. An opening is provided in the reflecting assembly to permit visual inspection of that region of the specimen adjacent to the opening onto which the heat is directed.

  16. 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…

  17. 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.

  18. 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

  19. 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

  20. 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 information on…

  1. Probabilistic Failure Assessment For Fatigue

    NASA Technical Reports Server (NTRS)

    Moore, Nicholas; Ebbeler, Donald; Newlin, Laura; Sutharshana, Sravan; Creager, Matthew

    1995-01-01

    Probabilistic Failure Assessment for Fatigue (PFAFAT) package of software utilizing probabilistic failure-assessment (PFA) methodology to model high- and low-cycle-fatigue modes of failure of structural components. Consists of nine programs. Three programs perform probabilistic fatigue analysis by means of Monte Carlo simulation. Other six used for generating random processes, characterizing fatigue-life data pertaining to materials, and processing outputs of computational simulations. Written in FORTRAN 77.

  2. 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.

  3. Fatigue of die cast zinc alloys

    SciTech Connect

    Schrems, K.K.; Dogan, O.N.; Goodwin, F.E.

    2006-04-01

    The rotating bending fatigue limit of die cast zinc alloy 2, alloy 3, alloy 5, AcuZinc 5, and ZA-8 were determined as a part of an on-going program by ILZRO into the mechanical properties of die cast zinc. The stress-life (S-N) curves of alloys 3, 5, AcuZinc 5, and ZA-8 were determined previously. This presentation reports the results of the S-N curve for Alloy 2 and the calculated fatigue limits for all five alloys. During the previous stress-life testing, the samples were stopped at 10 million cycles and the fatigue limit for alloy 3, alloy 5, and AcuZinc 5 appeared to be higher and the fatigue limit for ZA-8 appeared to be lower than the values reported in the literature. This was further investigated in alloy 5 and ZA-8 by testing continuous cast bulk alloy 5 and ZA-8.

  4. Fatigue-test acceleration with flight-by-flight loading and heating to simulate supersonic-transport operation

    NASA Technical Reports Server (NTRS)

    Imig, L. A.; Garrett, L. E.

    1973-01-01

    Possibilities for reducing fatigue-test time for supersonic-transport materials and structures were studied in tests with simulated flight-by-flight loading. In order to determine whether short-time tests were feasible, the results of accelerated tests (2 sec per flight) were compared with the results of real-time tests (96 min per flight). The effects of design mean stress, the stress range for ground-air-ground cycles, simulated thermal stress, the number of stress cycles in each flight, and salt corrosion were studied. The flight-by-flight stress sequences were applied to notched sheet specimens of Ti-8Al-1Mo-1V and Ti-6Al-4V titanium alloys. A linear cumulative-damage analysis accounted for large changes in stress range of the simulated flights but did not account for the differences between real-time and accelerated tests. The fatigue lives from accelerated tests were generally within a factor of two of the lives from real-time tests; thus, within the scope of the investigation, accelerated testing seems feasible.

  5. Space station structures and dynamics test program

    NASA Technical Reports Server (NTRS)

    Bugg, Frank M.; Ivey, E. W.; Moore, C. J.; Townsend, John S.

    1987-01-01

    The design, construction, and operation of a low-Earth orbit space station poses challenges for development and implementation of technology. One specific challenge is the development of a dynamics test program for defining the space station design requirements, and identifying and characterizing phenomena affecting the space station's design and development. The test proposal, as outlined, is a comprehensive structural dynamics program to be launched in support of the space station (SS). Development of a parametric data base and verification of the mathematical 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 four test phases planned are discussed: testing of SS applicable structural concepts; testing of SS prototypes; testing of actual SS structural hardware; and on-orbit testing of SS construction.

  6. 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

  7. Influence of test specimen fabrication method and cross-section configuration on tension-tension fatigue life of PMMA bone cement.

    PubMed

    Sheafi, E M; Tanner, K E

    2015-11-01

    Different cyclic loading modes have been used in in vitro fatigue studies of PMMA bone cement. It is unclear which loading mode is most appropriate from the perspective of the in vivo loading experienced by the cement in a cemented arthroplasty. Also, in different in vitro fatigue studies, different test specimen configurations have been used. The present work considers the influence of test specimen fabrication method (direct moulding vs moulding followed by machining) and cross-section shape (rectangular vs circular) on the tension-tension fatigue performance of two bone cement brands (SmartSet GHV and CMW1), under force control conditions. Two trends were consistent: 1) for each of the cements, for moulded specimens, a longer fatigue life was obtained with circular cross-sectioned specimens and, 2) for either rectangular or circular CMW1 specimens, a longer fatigue life was obtained using machined specimens. A comparison of the present results to those reported in our previous work on fully-reversed tension-compression loading under force control showed that, regardless of the test specimen fabrication method or cross-section configuration used, the fatigue life was considerably shorter under tension-compression than tension-tension loading. This finding highlights the fact that the presence of the compression portion in the loading cycle accelerates fatigue failure.

  8. 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.

  9. A MODIFIED PMMA CEMENT (SUB-CEMENT) FOR ACCELERATED FATIGUE TESTING OF CEMENTED IMPLANT CONSTRUCTS USING CADAVERIC BONE

    PubMed Central

    Race, Amos; Miller, Mark A.; Mann, Kenneth A.

    2008-01-01

    Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress intensity factor, fatigue crack propagation rates for sub-cement were higher by a factor of 25 ± 19. When tested in a simplified 2 1/2D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models. PMID:18774136

  10. A modified PMMA cement (Sub-cement) for accelerated fatigue testing of cemented implant constructs using cadaveric bone.

    PubMed

    Race, Amos; Miller, Mark A; Mann, Kenneth A

    2008-10-20

    Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress-intensity factor, fatigue crack propagation rates for Sub-cement were higher by a factor of 25+/-19. When tested in a simplified 2 1/2-D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models.

  11. 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

  12. Bithermal fatigue - A link between isothermal and thermomechanical fatigue

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Mcgaw, Michael A.; Bill, Robert C.; Fanti, Paolo D.

    1988-01-01

    A technique for bithermal fatigue testing is presented in which the tensile and compressive halves of the cycle are conducted isothermally at two significantly different temperatures. With reference to experimental results obtained for a nickel-base superalloy, B1900 + Hf, it is shown that bithermal fatigue testing is a simple alternative to thermomechanical fatigue and can provide a conservative determination of thermomechanical fatigue life for creep damage dominated failure modes. Bithermal fatigue results can be directly related to thermomechanical fatigue results through the use of an appropriate damage rule.

  13. Electrical Arc Ignition Testing for Constellation Program

    NASA Technical Reports Server (NTRS)

    Sparks, Kyle; Gallus, Timothy; Smith, Sarah

    2009-01-01

    NASA Johnson Space Center (JSC) Materials and Processes Branch requested that NASA JSC White Sands Test Facility (WSTF) perform testing for the Constellation Program to evaluate the hazard of electrical arc ignition of materials that could be in close proximity to batteries. Specifically, WSTF was requested to perform wire-break electrical arc tests to determine the current threshold for ignition of generic cotton woven fabric samples with a fixed voltage of 3.7 V, a common voltage for hand-held electrical devices. The wire-break test was developed during a previous test program to evaluate the hazard of electrical arc ignition inside the Extravehicular Mobility Unit [1].

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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.

  19. Pilot study investigating the utility of a specialized online symptom management program for individuals with myalgic encephalomyelitis/chronic fatigue syndrome as compared to an online meditation program

    PubMed Central

    Arroll, Megan A; Attree, Elizabeth A; Marshall, Clare L; Dancey, Christine P

    2014-01-01

    Background Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a long-term, debilitating condition that impacts numerous areas of individuals’ lives. The two predominant treatment options for ME/CFS are cognitive behavioral therapy and graded exercise therapy; however, many people have found these techniques unacceptable or even damaging. This pilot study aimed to evaluate the utility of a specialized online symptom management program for ME/CFS in comparison to an online meditation program in an effort to ascertain whether this tool could be a further option for those with ME/CFS. Methods This experimental design consisted of two interventions: a specialized online symptoms management program (N=19) and a control intervention based on an online meditation website (N=9). A battery of questionnaires, including measures of multidimensional fatigue, illness-specific symptoms, perceived control, and mindful awareness, were completed before the participants commenced use of the programs and following 8 weeks’ use. Results Significant differences were found in the areas of chance and powerful others’ locus of control, and sleeping difficulties, but not in ME/CFS symptomatology overall. Conclusion The specialized online program described in this study warrants further investigation, as it appears to influence perceived control and key ME/CFS symptoms over time. PMID:25214803

  20. 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.

  1. 2006 GED Testing Program Statistical Report

    ERIC Educational Resources Information Center

    GED Testing Service, 2007

    2007-01-01

    The 2006 GED[R] Testing Program Statistical Report is the 49th annual report in the program's 65-year history of providing a second opportunity to adults without a high school diploma to earn their jurisdiction's General Educational Development (GED) credential, and, as a result, advance their educational, personal, and professional aspirations.…

  2. 2007 GED Testing Program Statistical Report

    ERIC Educational Resources Information Center

    GED Testing Service, 2008

    2008-01-01

    The "2007 GED[R] Testing Program Statistical Report" is the 50th annual report in the program's 66-year history of providing a second opportunity for adults without a high school diploma to earn their jurisdiction's GED credential, and, as a result, advance their educational, personal, and professional aspirations. Section I, "Who Lacks a High…

  3. Program Helps Design Tests Of Developmental Software

    NASA Technical Reports Server (NTRS)

    Hops, Jonathan

    1994-01-01

    Computer program called "A Formal Test Representation Language and Tool for Functional Test Designs" (TRL) provides automatic software tool and formal language used to implement category-partition method and produce specification of test cases in testing phase of development of software. Category-partition method useful in defining input, outputs, and purpose of test-design phase of development and combines benefits of choosing normal cases having error-exposing properties. Traceability maintained quite easily by creating test design for each objective in test plan. Effort to transform test cases into procedures simplified by use of automatic software tool to create cases based on test design. Method enables rapid elimination of undesired test cases from consideration and facilitates review of test designs by peer groups. Written in C language.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. The insulation irradiation test program for the Compact Ignition Tokamak

    SciTech Connect

    McManamy, T.J. ); Kanemoto, G. ); Snook, P. )

    1990-01-01

    The electrical insulation for the toroidal field coils of the Compact Ignition Tokamak (CIT) is expected to be exposed to radiation doses on the order of 10{sup 10} rad with {approx}90% of the dose from neutrons. The coils are cooled to liquid nitrogen temperature and then heated during the pulse to a peak temperature >300 K. In a program to evaluate the effects of radiation exposure on the insulators, three types of boron-free insulation were irradiated at room temperature in the Advanced Technology Reactor (ATR) and tested at the Idaho National Engineering Laboratory. The materials were Spaulrad-S, Shikishima PG5-1, and Shikishima PG3-1. The first two use a bismaleimide resin and the third an aromatic amine hardened epoxy. Spaulrad-S is a two-dimensional (2-D) weave of S-glass, while the others are 3-D weaves of T-glass. Flexure and shear/compression samples were irradiated to approximately 5 {times} 10{sup 9} rad and 3 {times} 10{sup 10} rad with 35 to 40% of the total dose from neutrons. The shear/compression samples were tested in pairs by applying an average compression of 345 MPa and then a shear load. After static tests were completed, fatigue testing was done by cycling the shear load for up to 30,000 cycles with a constant compression. The static shear strength of the samples that did not fail was then determined. Generally, shear strengths on the order of 120 MPa were measured. The behavior of the flexure and shear/compression samples was significantly different; large reductions in the flexure strength were observed, while the shear strength stayed the same or increased slightly. The 3-D weave material demonstrated higher strength and significantly less radiation damage than the 2-D material in flexure but performed nearly identically when tested with combined shear and compression. The epoxy system was much more sensitive to fatigue damage than the bismaleimide materials. 9 refs., 5 figs.

  9. 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.

  10. An EMG frequency-based test for estimating the neuromuscular fatigue threshold during cycle ergometry.

    PubMed

    Camic, Clayton L; Housh, Terry J; Johnson, Glen O; Hendrix, C Russell; Zuniga, Jorge M; Mielke, Michelle; Schmidt, Richard J

    2010-01-01

    The purposes of this investigation were twofold: (1) to determine if the model used for estimating the physical working capacity at the fatigue threshold (PWC(FT)) from electromyographic (EMG) amplitude data could be applied to the frequency domain of the signal to derive a new fatigue threshold for cycle ergometry called the mean power frequency fatigue threshold (MPF(FT)), and (2) to compare the power outputs associated with the PWC(FT), MPF(FT), ventilatory threshold (VT), and respiratory compensation point (RCP). Sixteen men [mean (SD) age = 23.4 (3.2) years] performed incremental cycle ergometer rides to exhaustion with bipolar surface EMG signals recorded from the vastus lateralis. There were significant (p < 0.05) mean differences for PWC(FT) [mean (SD) = 168 (36) W] versus MPF(FT) [208 (37) W] and VT [152 (33) W] versus RCP [205 (84) W], but no mean differences for PWC(FT) versus VT or MPF(FT) versus RCP. The mean difference between PWC(FT) and MPF(FT) may be due to the effects of specific metabolites that independently influence the time and frequency domains of the EMG signal. These findings indicated that the PWC(FT) model could be applied to the frequency domain of the EMG signal to estimate MPF(FT). Furthermore, the current findings suggested that the PWC(FT) may demarcate the moderate from heavy exercise domains, while the MPF(FT) demarcates heavy from severe exercise intensities.

  11. 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.

  12. Short-crack growth behaviour in an aluminum alloy: An AGARD cooperative test program

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Edwards, P. R.

    1988-01-01

    An AGARD Cooperative Test Program on the growth of short fatigue cracks was conducted to define the significance of the short-crack effect, to compare test results from various laboratories, and to evaluate an existing analytical crack-growth prediction model. The initiation and growth of short fatigue cracks (5 micrometer to 2 mm) from the surface of a semi-circular notch in 2024-T3 aluminum alloy sheet material were monitored under various load histories. The cracks initiated from inclusion particle clusters or voids on the notch surface and generally grew as surface cracks. Tests were conducted under several constant-amplitude (stress ratios of -2, -1, 0, and 0.5) and spectrum (FALSTAFF and Gaussian) loading conditions at 3 stress levels each. Short crack growth was recorded using a plastic-replica technique. Over 250 edge-notched specimens were fatigue tested and nearly 950 cracks monitored by 12 participants from 9 countries. Long crack-growth rate data for cracks greater than 2 mm in length were obtained over a wide range in rates (10 to the -8 to 10 to the -1 mm/cycle) for all constant-amplitude loading conditions. Long crack-growth rate data for the FALSTAFF and Gaussian load sequences were also obtained.

  13. 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

  14. Peach Bottom test element program. Final report

    SciTech Connect

    Saurwein, J.J.; Holzgraf, J.F.; MIller, C.M.; Myers, B.F.; Wallroth, C.F.

    1982-11-01

    Thirty-three test elements were irradiated in the Peach Bottom high-temperature gas-cooled reactor (HTGR) as part of the testing program for advanced HTGRs. Extensive postirradiation examinations and evaluations of 21 of these irradiation experiments were performed. The test element irradiations were simulated using HTGR design codes and data. Calculated fuel burnups, power profiles, fast neutron fluences, and temperatures were verified via destructive burnup measurements, gamma scanning, and in-pile thermocouple readings corrected for decalibration effects. Analytical techniques were developed to improve the quality of temperature predictions through feedback of nuclear measurements into thermal calculations. Dimensional measurements, pressure burst tests, diametral compression tests, ring-cutting tests, strip-cutting tests, and four-point bend tests were performed to measure residual stress, strain, and strength distributions in H-327 graphite structures irradiated in the test elements.

  15. 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.

  16. Surface contact fatigue and flexural fatigue of dental restorative materials.

    PubMed

    McCabe, J F; Wang, Y; Braem, M

    2000-06-01

    Antagonistic contact on a dental restoration may produce surface and subsurface stresses leading to fatigue wear as well as to bulk stressing, eventually causing catastrophic failure. It was the aim of the present work to study the outcome of two different approaches to fatigue testing of materials involving either surface contact fatigue or flexural fatigue mechanisms. A range of materials was tested, including conventional glass-ionomers, resin-modified glass-ionomers, poly-acid modified composites, and composites. Materials were prepared and tested using both surface contact and flexural fatigue. The results show that conventional glass-ionomers have the least resistance to fatigue under both regimes while composites have the longest fatigue lives and the highest values of flexural fatigue limit. However, the results also support the fact that catastrophic failure should be investigated separately from surface contact fatigue. Within the group of composite products tested, a hybrid composite material had a significantly greater flexural fatigue limit than a microfilled one, but the latter material had a significantly greater surface contact fatigue life, indicating that wear behavior cannot be predicted from bulk fracture characteristics and vice versa. The process of wear occurs by a combination of a number of fundamental processes, and the contribution fatigue makes will vary according to the environment and nature of the material.

  17. 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.

  18. 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 shall ensure that fatigue assessments are conducted under the following conditions: (1) For cause....

  19. 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 shall ensure that fatigue assessments are conducted under the following conditions: (1) For cause....

  20. 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 shall ensure that fatigue assessments are conducted under the following conditions: (1) For cause....

  1. 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 shall ensure that fatigue assessments are conducted under the following conditions: (1) For cause....

  2. 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.

  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. 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%.

  5. Fitness for duty: A 3 minute version of the Psychomotor Vigilance Test predicts fatigue related declines in luggage screening performance

    PubMed Central

    Basner, Mathias; Rubinstein, Joshua

    2011-01-01

    Objective To evaluate the ability of a 3-min Psychomotor Vigilance Test (PVT) to predict fatigue related performance decrements on a simulated luggage screening task (SLST). Methods Thirty-six healthy non-professional subjects (mean age 30.8 years, 20 female) participated in a 4 day laboratory protocol including a 34 hour period of total sleep deprivation with PVT and SLST testing every 2 hours. Results Eleven and 20 lapses (355 ms threshold) on the PVT optimally divided SLST performance into high, medium, and low performance bouts with significantly decreasing threat detection performance A′. Assignment to the different SLST performance groups replicated homeostatic and circadian patterns during total sleep deprivation. Conclusions The 3 min PVT was able to predict performance on a simulated luggage screening task. Fitness-for-duty feasibility should now be tested in professional screeners and operational environments. PMID:21912278

  6. 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.

  7. 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).

  8. Altering Work to Rest Ratios Differentially Influences Fatigue Indices During Repeated Sprint Ability Testing.

    PubMed

    La Monica, Michael B; Fukuda, David H; Beyer, Kyle S; Hoffman, Mattan W; Miramonti, Amelia A; Riffe, Josh J; Baker, Kayla M; Fragala, Maren S; Hoffman, Jay R; Stout, Jeffrey R

    2016-02-01

    This study examined the influence of recovery time on fatigue indices, performance (total work [TW], peak power [PP], and mean power [MP]), and oxygen consumption during repeated sprint ability (RSA) on a cycle ergometer. Eight recreationally-trained men performed 3 RSA protocols consisting of 10 × 6 s sprints with 12 s, 18 s, and 24 s rest intervals between each sprint. Fatigue indices were determined as percent decrement (%Dec) and rate of decline using either a log transform method or standard slope approach for TW, PP, and MP during respective RSA protocols. The maximal VO2 value in response to given sprint intervals and the minimal VO2 value in response to given rest periods (VO2 work and VO2 rest, respectively) were recorded. A repeated measures analysis of variance was used to analyze all variables. Average VO2 work was not different among rest interval trials. Average VO2 rest with 12 s rest was greater than 18 s and 24 s (2.16 ± 0.17 L · min(-1), 1.91 ± 0.18 L · min(-1), 1.72 ± 0.15 L · min(-1), respectively), while 18 s was greater than 24 s. Average TW and MP were greater with 24 s rest than 12 s (4,604.44 ± 915.98 J vs. 4,305.46 ± 727.17 J, respectively), with no differences between RSA protocols for PP. No differences in %Dec were observed. Both methods of calculating rates of decline per sprint for PP and TW were greater during 12 s than 18 s or 24 s. Since changes were only noted between the 12 s and 24 s protocols, a 6 s differential in rest intervals may not be enough to elicit alterations in TW, PP, MP, or %Dec in RSA performance. Rate of decline may be a more sensitive measure of fatigue than %Dec.

  9. 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.

  10. Prediction of fatigue life of plain concrete beams from fracture tests

    SciTech Connect

    Ramsamooj, D.V. )

    1994-05-01

    A mathematical model, based on the principles of fracture mechanics, is proposed for the prediction of the flexural fatigue life of plain concrete beams. The model predictions are compared with about 400 experimental data from four separate collections, published earlier, covering materials with wide ranges of compressive strengths, 20 Mpa to 44.8 MPa, stress range ratios (minimum/maximum bending stress) of 0 to 0.75, and flexing frequencies of 1 to 20 Hz. There is good agreement between the model and the regression lines fitted to the experiment data.

  11. The NASA atomic oxygen effects test program

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Brady, Joyce A.

    1988-01-01

    The NASA Atomic Oxygen Effects Test Program was established to compare the low earth orbital simulation characteristics of existing atomic oxygen test facilities and utilize the collective data from a multitude of simulation facilities to promote understanding of mechanisms and erosion yield dependence upon energy, flux, metastables, charge, and environmental species. Four materials chosen for this evaluation include Kapton HN polyimide, FEP Teflon, polyethylene, and graphite single crystals. The conditions and results of atomic oxygen exposure of these materials is reported by the participating organizations and then assembled to identify degrees of dependency of erosion yields that may not be observable from any single atomic oxygen low earth orbital simulation facility. To date, the program includes 30 test facilities. Characteristics of the participating test facilities and results to date are reported.

  12. THAI Multi-Compartment Containment Test Program

    SciTech Connect

    Kanzleiter, T.; Poss, G.; Funke, F.; Allelein, H.J.

    2006-07-01

    The THAI experimental programme includes combined-effect investigations on thermal hydraulics, hydrogen, and fission product (iodine and aerosols) behaviour in LWR containments under severe accident conditions. An overview on the experiments performed up to now and on the future test program is presented, in combination with a selection of typical results to illustrate the versatility of the test facility and the broad variety of topics investigated. (authors)

  13. 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.

  14. 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.

  15. 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…

  16. 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…

  17. 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…

  18. 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.

  19. Maglev program test plan. Final report

    SciTech Connect

    deBenedet, D.; Gilchrist, A.J.; Karanian, L.A.

    1992-07-01

    Maglev systems represent a promising evolution in the high-speed ground transportation, offering speeds in excess of 300 mph along with the potential for low operating costs and minimal environmental impact. The goal of this effort is to investigate the feasibility and viability of maglev systems in the United States. The emergence of a sophisticated technology such as maglev requires a need for a coordinated research test program and the determination of test requirements to identify and mitigate development risk and to maximize the use of domestic resources. The study is directed toward the identification and characterization of maglev systems development risks tied to a preliminary system architecture. Research objectives are accomplished by surveying experiences from previous maglev development programs, both foreign and domestic, and interviews with individuals involved with maglev research and testing. Findings include ninety-four distinct development risks and twenty risk types. Planning and implementation requirements are identified for a maglev test program, including the development of a facilities strategy to meet any operational concepts that evolve out of early development effort. Also specified is the logical development flow and associated long-lead support needs for sub-scale and full-scale testing.

  20. 42 CFR 493.905 - Nonapproved proficiency testing programs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false Nonapproved proficiency testing programs. 493.905... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION LABORATORY REQUIREMENTS Proficiency Testing Programs for Nonwaived Testing § 493.905 Nonapproved proficiency testing programs. If a proficiency testing program...

  1. 42 CFR 493.905 - Nonapproved proficiency testing programs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 5 2011-10-01 2011-10-01 false Nonapproved proficiency testing programs. 493.905... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION LABORATORY REQUIREMENTS Proficiency Testing Programs for Nonwaived Testing § 493.905 Nonapproved proficiency testing programs. If a proficiency testing program...

  2. 42 CFR 493.905 - Nonapproved proficiency testing programs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 5 2012-10-01 2012-10-01 false Nonapproved proficiency testing programs. 493.905... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION LABORATORY REQUIREMENTS Proficiency Testing Programs for Nonwaived Testing § 493.905 Nonapproved proficiency testing programs. If a proficiency testing program...

  3. 42 CFR 493.905 - Nonapproved proficiency testing programs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 5 2013-10-01 2013-10-01 false Nonapproved proficiency testing programs. 493.905... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION LABORATORY REQUIREMENTS Proficiency Testing Programs for Nonwaived Testing § 493.905 Nonapproved proficiency testing programs. If a proficiency testing program...

  4. 42 CFR 493.905 - Nonapproved proficiency testing programs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 5 2014-10-01 2014-10-01 false Nonapproved proficiency testing programs. 493.905... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION LABORATORY REQUIREMENTS Proficiency Testing Programs for Nonwaived Testing § 493.905 Nonapproved proficiency testing programs. If a proficiency testing program...

  5. 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.

  6. Hand calculator programs for stack particulate tests

    SciTech Connect

    Fay, W.A.; Jones, B.J.

    1983-01-01

    Those familiar with particulate stack testing understand that a great deal of number-crunching is necessary to generate end results. Two hand calculator programs, one designed for a Texas Instruments Programmable 57 and the other for a Hewlett-Packard 33E, have been developed to ease this workload and provide quick turnaround when results are required in a hurry. These two programs calculate all the variables surrounding a stack test except isokinetics. As such these programs are intended to be used as a supplement to, and not a replacement of, more advanced computer programs that calculate all the variables and provide hard copy documentation of raw data and end results. Each calculator program has been divided into two parts. The first part uses the equations presented in EPA's Reference Method 5-Determination of Particulate Emissions from Stationary Sources to calculate particulate concentration, dry and wet gas volumes and moisture content. The second part uses the results of the first part and equations presented in EPA Reference Method 2-Determination of Stack Gas Velocity and Volumetric Flow Rate to calculate volumetric flow rate, emission rate and velocity.

  7. Fatigue behavior of continuous fiber silicon-carbide-aluminum composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Wallis, R. R.

    1984-01-01

    Four lay-ups of continuous fiber silicon carbide (SCS2) fiber/aluminum matrix composites were tested to assess fatigue mechanisms including stiffness loss when cycled below their respective fatigue limits. The lay-ups were 0 (sub 8), 0(sub 2)/ + or - 45 (sub 2s), 0/90 (sub 2s),and 0/ + or 45/90 (subs). The data were compared with predictions from the author's previously published shakedown model which predicts fatigue-induced stiffness loss in metal matrix composites. A fifth lay-up, + or - 45 (sub 2s), was tested to compare shakedown and fatigue limits. The particular batch of silicon-carbide fibers tested in this program had a somewhat lower modulus (340 GPa) than expected and displayed poor bonding to the aluminum matrix. Good agreement was obtained between the stiffness loss model and the test data. The fatigue damage below the fatigue limit was primarily in the form of matrix cracking. The fatigue limit corresponded to the laminate shakedown for the + or - 45 (sub 2s) laminate.

  8. 14 CFR 117.7 - Fatigue risk management system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... fatigue risk management policy. (2) An education and awareness training program. (3) A fatigue reporting system. (4) A system for monitoring flightcrew fatigue. (5) An incident reporting process. (6) A performance evaluation....

  9. Plutonium Immobilization Program cold pour tests

    SciTech Connect

    Hovis, G.L.; Stokes, M.W.; Smith, M.E.; Wong, J.W.

    1999-07-01

    The Plutonium Immobilization Program (PIP) is a joint venture between the Savannah River Site, Lawrence Livermore National Laboratory, Argonne National Laboratory, and Pacific Northwest National Laboratory to carry out the disposition of excess weapons-grade plutonium. This program uses the can-in-canister (CIC) approach. CIC involves encapsulating plutonium in ceramic forms (or pucks), placing the pucks in sealed stainless steel cans, placing the cans in long cylindrical magazines, latching the magazines to racks inside Defense Waste Processing Facility (DWPF) canisters, and filling the DWPF canisters with high-level waste glass. This process puts the plutonium in a stable form and makes it attractive for reuse. At present, the DWPF pours glass into empty canisters. In the CIC approach, the addition of a stainless steel rack, magazines, cans, and ceramic pucks to the canisters introduces a new set of design and operational challenges: All of the hardware installed in the canisters must maintain structural integrity at elevated (molten-glass) temperatures. This suggests that a robust design is needed. However, the amount of material added to the DWPF canister must be minimized to prevent premature glass cooling and excessive voiding caused by a large internal thermal mass. High metal temperatures, minimizing thermal mass, and glass flow paths are examples of the types of technical considerations of the equipment design process. To determine the effectiveness of the design in terms of structural integrity and glass-flow characteristics, full-scale testing will be conducted. A cold (nonradioactive) pour test program is planned to assist in the development and verification of a baseline design for the immobilization canister to be used in the PIP process. The baseline design resulting from the cold pour test program and CIC equipment development program will provide input to Title 1 design for second-stage immobilization. The cold pour tests will be conducted in two

  10. 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.

  11. MTI compact electronic meter testing program

    SciTech Connect

    O`Rourke, E.L.

    1995-12-31

    MTI has completed an extensive test program to ensure a new compact electronic gas meter meets all specifications and standards customarily employed by the U.S. gas industry. Thirty (30) test plans were developed to cover all American National Standards Institute (ANSI) performance requirements. (1) The prototype meters have met or exceeded the ANSI B109.1 standards. (2) The prototype meters have demonstrated the feasibility of GRI`s decision to seek a compact meter for early market entry. (3) Several leading U.S. utilities have participated in sponsoring the project and have expressed keen interest in field testing the compact meter. (4) American Meter Company (AMC), the predominant U.S. meter manufacturer, has participated in the sponsorship and testing of the compact meter and has formed a joint venture with Select Corporation to bring the meter to the U.S. and world-wide marketplace. (5) The meter generates the necessary electronic output for either telephonic or radio based automatic meter reading (AMR). The pre-production meters for the North American market are being fabricated currently by AMC. Following their completion, an extensive field test program will take place. Three hundred units will be installed at ten to fifteen utilities and tested for a period of up to one year.

  12. 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.

  13. 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. PMID:26194655

  14. Relay test program. Series 2 tests: Integral testing of relays and circuit breakers

    SciTech Connect

    Bandyopadhyay, K.K.; Kunkel, C.; Shteyngart, S.

    1994-02-01

    This report presents the results of a relay test program conducted by Brookhaven National Laboratory (BNL) under the sponsorship of the US Nuclear Regulatory Commission (NRC). The program is a continuation of an earlier test program the results of which were published in NUREG/CR-4867. The current program was carried out in two phases: electrical testing and vibration testing. The objective was primarily to focus on the electrical discontinuity or continuity of relays and circuit breaker tripping mechanisms subjected to electrical pulses and vibration loads. The electrical testing was conducted by KEMA-Powertest Company and the vibration testing was performed at Wyle Laboratories, Huntsville, Alabama. This report discusses the test procedures, presents the test data, includes an analysis of the data and provides recommendations regarding reliable relay testing.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Optical fiber fatigue behavior over very extended periods at low stress levels in the field and in laboratory tests

    NASA Astrophysics Data System (ADS)

    Stockton, David J.; Mayhew, Andi J.

    1999-12-01

    The reliability of optical fiber exposed to relatively high static strains (> 2%) has been extensively modelled and investigated by experiment. Fatigue `knees' have been demonstrated predicting the premature fracture of fiber particularly where elevated temperatures and relatively large volumes of water have been used to soak the samples. The cause has been attributed to simultaneous stress- assisted and stress-free corrosion of the fiber surface. In this paper we show that, a t more moderate strains (1 to 2%) and using a limited volume of water, there is evidence of a strength recovery caused either by a healing process or the observance of some form of lower strain threshold. The expected strength reduction of the fiber, from contemporary models is contrasted to that observed. The unusually high strength retention shown by the test fiber in water is shown to have important implications for optical cable design and for the bending of fiber within joint housings.

  20. 47 CFR 74.14 - Service or program tests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Service or program tests. 74.14 Section 74.14... Services in Part 74 § 74.14 Service or program tests. (a) Upon completion of construction of a radio... Commission, conduct service or program tests. (b) Program test authority for stations authorized under...

  1. 47 CFR 74.14 - Service or program tests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Service or program tests. 74.14 Section 74.14... Services in Part 74 § 74.14 Service or program tests. (a) Upon completion of construction of a radio... Commission, conduct service or program tests. (b) Program test authority for stations authorized under...

  2. 47 CFR 74.14 - Service or program tests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Service or program tests. 74.14 Section 74.14... Services in Part 74 § 74.14 Service or program tests. (a) Upon completion of construction of a radio... Commission, conduct service or program tests. (b) Program test authority for stations authorized under...

  3. 47 CFR 74.14 - Service or program tests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Service or program tests. 74.14 Section 74.14... Services in Part 74 § 74.14 Service or program tests. (a) Upon completion of construction of a radio... Commission, conduct service or program tests. (b) Program test authority for stations authorized under...

  4. Designing a respirator fit testing program.

    PubMed

    Murphy, D C

    1992-11-01

    The requirements for adequate respiratory protection for the employees of this agency vary. Therefore, accurate, updated job descriptions are a critical piece of information. Although the agency has made an effort to establish a respiratory protection program, a number of limitations exist when compared to the program components defined in ANSI, NIOSH, and OSHA guidance documents. In response to a request from the agency, the nurse consultant evaluated the existing respiratory protection program and made specific recommendations for improvement. At this time, the agency has signed a formal agreement with the Division of Federal Occupational Health to request continued assistance with "overhauling" their program. Top management has begun assigning responsibilities for the program to specific individuals, and a centralized database is being set up. The agency has implemented two new DFOH developed forms to improve the testing process, and the nurse consultant has revised the educational/training session to more adequately meet the needs of the work force. The Agency and DFOH are collaborating on reassessment of employees to correctly assign them to appropriate respiratory risk categories. This will, in turn, affect the medical monitoring needs as well as the educational needs of each individual.

  5. Fatigue and thermal fatigue of Pb-Sn solder joints

    SciTech Connect

    Frear, D.; Grivas, D.; McCormack, M.; Tribula, D.; Morris, J.W. Jr.

    1987-01-01

    This paper presents a fundamental investigation of the fatigue and thermal fatigue characteristics, with an emphasis on the microstructural development during fatigue, of Sn-Pb solder joints. Fatigue tests were performed in simple shear on both 60Sn-40Pb and 5Sn-95Pb solder joints. Isothermal fatigue tests show increasing fatigue life of 60Sn-40Pb solder joints with decreasing strain and temperature. In contrast, such behavior was not observed in the isothermal fatigue of 5Sn-95Pb solder joints. Thermal fatigue results on 60Sn-40Pb solder cycled between -55/sup 0/C and 125/sup 0/C show that a coarsened region develops in the center of the joint. Both Pb-rich and Sn-rich phases coarsen, and cracks form within these coarsened regions. The failure mode 60Sn-40Pb solder joints in thermal and isothermal fatigue is similar: cracks form intergranularly through the Sn-rich phase or along Sn/Pb interphase boundaries. Extensive cracking is found throughout the 5Sn-95Pb joint for both thermal and isothermal fatigue. In thermal fatigue the 5Sn-95Pb solder joints failed after fewer cycles than 60Sn-40Pb.

  6. 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.

  7. Axial Fatigue Tests at Zero Mean Stress of 24S-T and 75S-T Aluminum-alloy Strips with a Central Circular Hole

    NASA Technical Reports Server (NTRS)

    Brueggeman, W C; Mayer, M JR

    1948-01-01

    Axial fatigue tests at zero mean stress have been made on 0.032- and 0.064-inch 24S-T and 0.032-inch 75S-T sheet-metal specimens 1/4, 1/2, 1, and 2 inches wide without a hole and with central holes giving a range of hole diameter D to specimen width W from 0.01 to 0.95. No systematic difference was noted between the results for the 0.032-inch and the 0.064-inch specimens although the latter seemed the more consistent. In general the fatigue strength based on the minimum section dropped sharply as the ration D/W was increased from zero to about 0.25. The plain specimens showed quite a pronounced decrease in fatigue strength with increasing width. The holed specimens showed only slight and rather inconclusive evidence of this size effect. The fatigue stress-concentration factor was higher for 75S-T than for 24S-T alloy. Evidence was found that a very small hole would not cause any reduction in fatigue strength.

  8. Low-cycle fatigue of TiNi shape memory alloy and formulation of fatigue life

    SciTech Connect

    Tobushi, Hisaaki; Nakahara, Takafumi; Shimeno, Yoshirou; Hashimoto, Takahiro

    2000-04-01

    The low-cycle fatigue of a TiNi shape memory alloy was investigated by the rotating-bending fatigue tests in air, in water and in silicone oil. (1) The influence of corrosion fatigue in water does not appear in the region of low-cycle fatigue. (2) The temperature rise measured through an infrared thermograph during the fatigue test in air is four times as large as that measured through a thermocouple. (3) The fatigue life at an elevated temperature in air coincides with the fatigue life at the same elevated temperature in water. (4) The shape memory processing temperature does not affect the fatigue life. (5) The fatigue equation is proposed to describe the fatigue life depending on strain amplitude, temperature and frequency. The fatigue life is estimated well by the proposed equation.

  9. F-15 flight flutter test program

    NASA Technical Reports Server (NTRS)

    Katz, H.; Foppe, G. F.; Grossman, D. T.

    1976-01-01

    The modes to be observed during the F-15 flight flutter test program were selected on the basis of the results of analytical studies, wind tunnel tests, and ground vibration tests. The modes (both symmetrical and antisymmetrical) tracked on this basis were: fin first bending, fin torsion, fin tip roll, stabilator bending, stabilator pitch, boom lateral bending, boom torsion, boom vertical bending, wing first bending, wing second bending, wing first torsion, outer wing torsion, and aileron rotation. Data obtained for these various modes were evaluated in terms of damping versus airspeed at 1525 m (5000 ft), damping versus altitude at the cross-section Mach numbers (to extrapolate to the damping value to be expected at sea level), and flutter boundaries on the basis of flutter margin of various modal pairs representing potential flutter mechanisms. Results of these evaluations are summarized in terms of minimum predicted flutter margin for the various mechanisms.

  10. AMTEC RC-10 Performance Evaluation Test Program

    NASA Astrophysics Data System (ADS)

    Schuller, Michael; Reiners, Elinor; Lemire, Robert; Sievers, Robert

    1994-07-01

    The Phillips Laboratory Power and Thermal Management Division (PL/VTP), in conjunction with ORION International Technologies, initiated the Alkali Metal Thermal to Electric Conversion (AMTEC), Remote Condensed-10% efficient (RC-10) Performance Evaluation Test Program to investigate cell design variations intended to increase efficiency in AMTEC cells. The RC-10 cell, fabricated by Advanced Modular Power Systems, uses a remote condensing region to reduce radiative heat losses from the electrode. The cell has operated at 10% efficiency. PL/VTP tested the RC-10 to evaluate its performance and efficiency. The impact of temperature variations along the length of the cell wall on performance were evaluated. Testing was performed in air, with a `` guard heater'' surrounding the cell to simulate the system environment of the cell.

  11. 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.

  12. 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.

  13. 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.

  14. Common aperture multispectral sensor flight test program

    SciTech Connect

    Bird, R.S.; Kaufman, C.S.

    1996-11-01

    This paper will provide an overview of the Common Aperture Multispectral Sensor (CAMS) Hardware Demonstrator. CAMS is a linescanning sensor that simultaneously collected digital imagery over the Far-IR (8 to 12 {mu}m) and visible spectral (0.55 to 1.1 PM) spectral bands, correlated at the pixel level. CAMS was initially sponsored by the U.S. Naval Air System Commands F/A-18 program office (PMA-265). The current CAMS field tests are under the direction of Northrop-Grumman for the Defense Nuclear Agency (DNA) in support of the Follow-On Open Skies Sensor Evaluation Program (FOSEP) and are scheduled to be conducted in April 1996. 8 figs., 4 tabs.

  15. 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.

  16. A mammography quality assurance test program.

    PubMed

    Burgess, A

    1979-11-01

    The design and implementation of a program to investigate remote quality assurance testing for film mammography is described. The measurements included tube output, x-ray machine and processor stability, and film quality. Mammography phantoms and film sensitometric strips were distributed monthly to 24 regional hospitals. Most of the hospital processors and x-ray machines performed in a stable manner during the 12-month test period. It was found that x-ray machine useful beams could be reliably measured using nonscreen films. The main utility of the phantom was to identify cases of poor image quality. The measurements performed on the phantom image could not be used to diagnose specific causes of poor images. PMID:493542

  17. 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.

  18. Fretting fatigue of 2XXX series aerospace aluminum alloys

    NASA Astrophysics Data System (ADS)

    Giummarra, Cindie

    Fretting is a wear mechanism that occurs at the contact region between two materials subject to minute cyclic relative motion. Fretting causes the initiation of surface cracks within the first few thousand cycles, which in the presence of a fatigue stress, grow to cause material failure approximately 10 to 100 times earlier than expected under standard fatigue conditions. Examples of fretting fatigue have been seen in joints in aircraft, and the aerospace industry acknowledges the possibility of catastrophic failure from this mechanism. Improvements in a material's resistance to fretting would benefit aluminum alloys in aerospace applications. This research investigated the effect of microstructural properties on the fretting response in 2XXX series aerospace aluminum alloys. Fretting wear and fretting fatigue tests were conducted to determine the influence of slip characteristics, alloy purity, grain orientation and yield strength on fretting crack initiation and growth. Crack length measurements and micrographs of the fretting indicated there was no significant difference in the fretting response of these alloys based on their microstructural characteristics. Results showed that fretting initiated cracks in the first 1--8% of the life while standard fatigue initiation took around 90% of the life. This reduction in initiation resulted in a shorter life under fretting conditions. Additionally, fretting normalized the initiation time in all alloys which eliminated any intrinsic initiation resistance. The alloys with the highest stress-life (S-N) fatigue properties exhibiting a greater reduction in fatigue strength under fretting conditions. The fretting stresses appeared to influence the crack growth to a distance below the surface of approximately 17mum under fretting fatigue conditions, after which some cracks changed direction and propagated under the influence of the fatigue stress. Under fretting wear conditions, the cracks tended to arrest at a depth of 8

  19. 40 CFR 88.205-94 - California Pilot Test Program Credits Program.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false California Pilot Test Program Credits...) AIR PROGRAMS (CONTINUED) CLEAN-FUEL VEHICLES California Pilot Test Program § 88.205-94 California Pilot Test Program Credits Program. (a) General. (1) The Administrator shall administer this...

  20. 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.

  1. High strain FBG sensors for structural fatigue testing of military aircraft

    NASA Astrophysics Data System (ADS)

    Tejedor, S.; Kopczyk, J.; Nuyens, T.; Davis, C.

    2012-02-01

    This paper reports on a series of tests investigating the performance of Draw Tower Gratings (DTGs) combined with custom-designed broad area packaging and bonding techniques for high-strain sensing applications on Defence platforms. The sensors and packaging were subjected to a series of high-strain static and cyclic loading tests and a summary of these results is presented.

  2. Fatigue of fiberglass beam substructures

    SciTech Connect

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

    1995-09-01

    Composite material beams representative of wind turbine blade substructure have been designed, fabricated, and tested under constant amplitude flexural fatigue loading. Beam stiffness, strength, and fatigue life are predicted based on detailed finite element analysis and the materials fatigue database developed using standard test coupons and special high frequency minicoupons.Beam results are in good agreement with predictions when premature adhesive and delamination failures are avoided in the load transfer areas. The results show that fiberglass substructures can be designed and fabricated to withstand maximum strain levels on the order of 8,000 microstrain for about 10{sup 6} cycles with proper structural detail design and the use of fatigue resistant laminate constructions. The study also demonstrates that the materials fatigue database and accurate analysis can be used to predict the fatigue life of composite substructures typical of blades.

  3. 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.

  4. Effects of Materials Parameters and Design Details on the Fatigue of Composite Materials for Wind Turbine Blades

    SciTech Connect

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

    1999-03-04

    This paper presents an analysis of the results of nine years of fatigue testing represented in the USDOE/Montana State University (DOE/MSU) Composite Materials Fatigue Database. The focus of the program has been to explore a broad range of glass-fiber-based materials parameters encompassing over 4500 data points for 130 materials systems. Significant trends and transitions in fatigue resistance are shown as the fiber content and fabric architecture are varied. The effects of structural details including ply drops, bonded stiffeners, and other geometries that produce local variations in fiber packing and geometry are also described. Fatigue tests on composite beam structures are then discussed; these show generally good correlation with coupon fatigue data in the database. Goodman diagrams for fatigue design are presented, and their application to predicting the service lifetime of blades is described.

  5. 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.

  6. 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.

  7. 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.

  8. Social Support in Relation to Fatigue Symptoms Among Patients with Multiple Sclerosis

    PubMed Central

    Aghaei, Naiereh; Karbandi, Soheila; Gorji, Mohammad Ali Heidari; Golkhatmi, Maryam Bidgoli; Alizadeh, Batul

    2016-01-01

    Background and Aim: The psychological changes and physiological limitations during multiple sclerosis (MS) disease diminish the social relations. Consequently, losing social supports leads to more physical and psychological complications such as fatigue syndromes. Therefore, this study aimed to investigate the relationship of social support and fatigue syndromes in MS patients. Methods: This study was a descriptive-analytic which randomly selected 46 patients with MS. The patients evaluated through demographic information, standard modified social support scale, fatigue severity scale, modified fatigue impact scale, and fatigue descriptive scale. Gathered data analyzed using descriptive and inferential statistical Pearson's correlation coefficient. Results: Mean score for variables were as following: Fatigue severity 4/3 ± 1/6, perceived fatigue 34/6 ± 19/5, quality of fatigue 62 ± 3/9, and social support 65/6 ± 23/1, respectively. According to the Pearson statistical test, there was signification association between social support with fatigue severity (P = 0.002 and r = −0.474), fatigue perception (P = 0.001 and = −0.478), and fatigue perception sub-scales, i.e. physical (P = 0.005, r = −0.432), cognitive (P = 0.003, r = −0.0457), and psychosocial (P = 0.009, r = −0.341), respectively. However, there was not significant relationship between social support and fatigue quality (P = 0.59). Conclusion: According to the results of current study, all aspects of social support can impact fatigue symptoms in MS patients. Therefore, it is suggested to develop educational programs for caregivers of patients to improve the mental and physical quality of life of patients. PMID:27162427

  9. 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

  10. 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…

  11. a Development of Multi Purpose Testing Machine for Friction, Wear and Rolling Contact Fatigue

    NASA Astrophysics Data System (ADS)

    Choi, Gab-Su; Pyun, Young-Sik; Kim, Jun-Hyoung; Kim, Hak-Doo; Tominaga, Yasutoshi; Darisuren, Shirmendagwa

    In this paper, the newly developed tribometer was introduced. Ball-on-disk, pin-on-disk, small-sized journal and thrust bearings tests on friction and wear were carried out using a newly developed tribometer which is built up according to the ASTM G99. Those friction and wear test results were compared with the friction results which were approved by Korean (KOLAS) and CSM Instruments. The comparison revealed that friction characteristics and trends of three different tribometers were similar to each other. The objective of this paper is to demonstrate the capability of the newly developed tribometer. As a result, the newly developed tribometer is capable of performing friction tests using pin-on-disk, disk-on-disk, journal and thrust bearings configurations.

  12. 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... insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is one which demonstrates with reasonable certainty that insulation certified to comply with the standard...

  13. 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... insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is one which demonstrates with reasonable certainty that insulation certified to comply with the standard...

  14. 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... insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is one which demonstrates with reasonable certainty that insulation certified to comply with the standard...

  15. 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... insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is one which demonstrates with reasonable certainty that insulation certified to comply with the standard...

  16. 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... insulation. (b) Requirements of testing program. A reasonable testing program for cellulose insulation is one which demonstrates with reasonable certainty that insulation certified to comply with the standard...

  17. A MODEL FOR THE EVALUATION OF A TESTING PROGRAM.

    ERIC Educational Resources Information Center

    COX, RICHARD C.; UNKS, NANCY J.

    THE EVALUATION OF AN EDUCATIONAL PROGRAM TYPICALLY IMPLIES MEASUREMENT. MEASUREMENT, IN TURN, IMPLIES TESTING IN ONE FORM OR ANOTHER. IN ORDER TO CARRY OUT THE TESTING NECESSARY FOR THE EVALUATION OF AN EDUCATIONAL PROGRAM, RESEARCHERS OFTEN DEVELOP A COMPLETE TESTING SUB-PROGRAM. THE EVALUATION OF THE TOTAL PROJECT MAY DEPEND UPON THE TESTING…

  18. 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... 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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... 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...

  3. 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.

  4. 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.

  5. Cesium chloride compatibility testing program: Final report

    SciTech Connect

    Bryan, G.H.

    1989-11-01

    The US Department of Energy is considering the geologic disposal of the doubly encapsulated cesium chloride (CsCl) produced at the Waste Encapsulation and Storage Facility (WESF). Reliable estimates of long-term corrosion of the inner capsule material by the CsCl under repository storage conditions are needed to assess the hazards associated with geologic disposal of the fission product Cs. The Cesium Chloride Compatibility Program was carried out at PNL to obtain the short-term corrosion data required to accurately estimate long-term attack. In the compatibility tests six standard WESF CsCl capsules were placed vertically in individual insulated containers and allowed to self-heat to a nominal maximum 316L SS/CsCl interface temperature of 450{degree}C. The capsules were held at temperature for times ranging from 0.25 to 6 years. When a test was completed, the capsule was removed from the container and sectioned. Four samples were cut from the inner capsule at prescribed locations and subjected to metallographic examination. Corrosion was determined from photomicrographs of the samples. 16 refs., 41 figs., 16 tabs.

  6. 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…

  7. 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.

  8. 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.

  9. 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.

  10. Fatigue loading of tendon

    PubMed Central

    Shepherd, Jennifer H; Screen, Hazel R C

    2013-01-01

    Tendon injuries, often called tendinopathies, are debilitating and painful conditions, generally considered to develop as a result of tendon overuse. The aetiology of tendinopathy remains poorly understood, and whilst tendon biopsies have provided some information concerning tendon appearance in late-stage disease, there is still little information concerning the mechanical and cellular events associated with disease initiation and progression. Investigating this in situ is challenging, and numerous models have been developed to investigate how overuse may generate tendon fatigue damage and how this may relate to tendinopathy conditions. This article aims to review these models and our current understanding of tendon fatigue damage. We review the strengths and limitations of different methodologies for characterizing tendon fatigue, considering in vitro methods that adopt both viable and non-viable samples, as well as the range of different in vivo approaches. By comparing data across model systems, we review the current understanding of fatigue damage development. Additionally, we compare these findings with data from tendinopathic tissue biopsies to provide some insights into how these models may relate to the aetiology of tendinopathy. Fatigue-induced damage consistently highlights the same microstructural, biological and mechanical changes to the tendon across all model systems and also correlates well with the findings from tendinopathic biopsy tissue. The multiple testing routes support matrix damage as an important contributor to tendinopathic conditions, but cellular responses to fatigue appear complex and often contradictory. PMID:23837793

  11. Fatigue behavior of a single-crystal superalloy

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Mcgaw, Michael A.

    1989-01-01

    A single-crystal superalloy, PWA 1480 is under consideration as a replacement material for the turbine blades of the high pressure fuel turbopump (HPFTP) of the space shuttle main engine (SSME). Three separate experimental programs were conducted to characterize the fatigue behavior of this alloy. Fatigue tests were conducted at room temperature (in air) and at 1000 F (in vacuum) on smooth specimens machined from both cast bars and slabs. The data from all of these programs are consolidated to provide a broader characterization of the fatigue behavior of the single crystal PWA 1480. The zero-mean-stress fatigue relationships are expressed in terms of stress range versus cyclic life lines on log-log plots. Characterization of the fatigue behavior of (001) oriented PWA 1480 single crystal under conditions of tensile mean stress was performed by using the unified approach proposed by Heidmann. In this approach the fatigue life is modified by a mean stress parameter so that a single life relationship can be used to represent both zero and tensile mean stress data.

  12. Evaluation of Ratnaprash for its effect on strength, stamina and fatigue using swim endurance test and biochemical estimation in swiss albino mice

    PubMed Central

    Gupta, Arun; Kumar, Satyendra; Rajput, Rashmi; Srivastava, Ruchi; Rai, Rajiv K.; Sastry, J. L. N.

    2015-01-01

    Context: Traditional medicines have been considered as important resources for postponing fatigue, accelerating elimination of fatigue related metabolites and improving physical ability. Rasāyanās or rejuvenative therapies are mentioned as one of the eight clinical specialties in Ayurveda for attaining longevity, healthy life and regulation of bodily balance. Eventhough more detailed studies are needed to confirm the claims of benefits in the light of evidence based research, Ratnaprash, a herbo-mineral rasāyana formulation, is proposed here to be an antifatigue supplement that is good in promoting strength and stamina. Materials and Methods: In the present study, anti fatigue, strength and stamina enhancing properties of Ratnaprash were examined based on swim endurance capacity and the change in biochemical parameters in Swiss Albino mice. Treatment groups were orally administered Ratnaprash at various test doses (500, 1000, 2000 mg/Kg per day), while the control group received distilled water at similar dose volumes. Effect of therapy was evaluated after 28 days of treatment. Results: At the end of study period, the swimming times to exhaustion were longer in the treated groups than in the control group. Plasma lactate levels of treated groups were lower than those of the control group (P < 0.05) while tissue ATP levels were higher. These effects were dose dependent and the strongest effect was seen in groups treated at 1000 mg/Kg. Conclusion: Ratnaprash enhanced the forced swimming capacity of mice and exhibited elevated anti-fatigue activity, reduced blood lactate levels and increased tissue ATP levels in preclinical models in comparison to vehicle control, exhibiting possible role in increasing strength and stamina and contributing anti-fatigue activity. PMID:26600664

  13. 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

  14. Stability of external and internal implant connections after a fatigue test

    PubMed Central

    Feitosa, Paulo Cesar Pinheiro; de Lima, Ana Paula Barbosa; Silva-Concílio, Laís Regiane; Brandt, William Cunha; Neves, Ana Christina Claro

    2013-01-01

    Objective: The objective of this study was to compare the torque and detorque values of screw intermediates of external hexagon, internal hexagon, and Morse taper implants in single restorations before and after mechanical cycling. Materials and Methods: The study sample was divided into three groups (n = 10) as follows: group EH – external hexagon implant, group IH – internal hexagon implant, and group MT – Morse taper implant. Universal abutments were screwed on the implants, and metal crowns were cemented onto the abutment. The samples were submitted to a mechanical testing of 1 million cycles, with a frequency of 8 cycles per second under a 400 N load. The application and registration of the screw torque (T0) and detorque (T1) values of the intermediate were performed before and after the test. The results were statistically evaluated by analysis of variance (ANOVA) and Tukey's test (α = 0.05). Results: There was no difference between the values of T0 and T1 in the intra-group samples. However, the inter-group difference in T0 between the EH (12.8 N cm) and MT (18.6 N cm) groups and in T1 between the EH (10.4 N cm) and IH (13.8 N cm), EH and MT (19.4 N cm), and MT and IH (P = 0.001) groups were significant. The MT group showed a lower variation of T0 and T1. Conclusion: The internal implants, particularly MT, showed better stability in these cases when used for single restorations. PMID:24926204

  15. Fatigue resistance of duralumin

    NASA Technical Reports Server (NTRS)

    1922-01-01

    Where, in the following report, mention is made of fatigue, it always refers to the weakening of the material produced by rapidly changing stresses below the point of elasticity. The alternating stress was obtained by a test bar which was held at one end and subjected to rotation. Most of the tests were conducted on connecting rods.

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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.

  2. 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.

  3. 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.

  4. Proceedings of the 2000 International Conference on Fatigue of Reactor Components (MRP-46): PWR Materials Reliability Program (PWRMRP)

    SciTech Connect

    2001-05-01

    This report contains information presented at the First International Conference on Fatigue of Reactor Components held July 31-August 2, 2000, in Napa, California. The conference--sponsored by EPRI, the Organisation for Economic Co-operation and Development Nuclear Energy Agency/Committee on the Safety of Nuclear Installations (OECD NEA/CSNI), and the U.S. Nuclear Regulatory Commission (U.S. NRC)--provided a forum for the technical discussion of fatigue issues that affect the integrity and operation of light water reactor components. Approximately 90 fatigue experts, representing 12 countries, participated in the conference. Strong representation was shown by nuclear operators, vendors, regulatory agencies, research and development organizations, and other experts.

  5. Bithermal fatigue: A simplified alternative to thermomechanical fatigue

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.

    1988-01-01

    A bithermal fatigue test technique was proposed as a simplified alternative to the thermomechanical fatigue test. Both the thermomechanical cycle and the bithermal technique can be used to study nonisothermal fatigue behavior. The difference between the two cycles is that in a conventional thermomechanical fatigue cycle the temperature is continuously varied concurrently with the applied mechanical strains, but in the bithermal fatigue cycle the specimen is held at zero load during the temperature excursions and all the loads are applied at the two extreme temperatures of the cycle. Experimentally, the bithermal fatigue test technique offers advantages such as ease in synchronizing the temperature and mechanical strain waveforms, in minimizing temperature gradients in the specimen gauge length, and in reducing and interpreting thermal fatigue such as the influence of alternate high and low temperatures on the cyclic stress-strain response characteristics, the effects of thermal state, and the possibility of introducing high- and low-temperature deformation mechanisms within the same cycle. The bithermal technique was used to study nonisothermal fatigue behavior of alloys such as single-crystal PWA 1480, single-crystal Rene N4, cast B1900+Hf, and wrought Haynes 188.

  6. 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.

  7. 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...

  8. 49 CFR 219.601 - Railroad random drug testing programs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 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...

  9. 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...

  10. 49 CFR 219.601 - Railroad random drug testing programs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. 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. PMID:25362435

  16. "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…

  17. A FORTRAN program for testing trend and homogeneity in proportions.

    PubMed

    Thakur, A K; Berry, K J; Mielke, P W

    1985-01-01

    A FORTRAN program is provided for testing linear trend and homogeneity in proportions. Trend is evaluated by the Cochran-Armitage method and homogeneity is tested by an overall X2 test as well by multiple pairwise comparisons by the Fisher-Irwin exact method. The program should be easy to implement on any size of computer with a FORTRAN compiler.

  18. Low-cycle fatigue of thermal-barrier coatings at 982 deg C

    NASA Technical Reports Server (NTRS)

    Kaufman, A.; Liebert, C. H.; Nachtigall, A. J.

    1978-01-01

    The low-cycle fatigue lives of ZrO2-NiCrAlY and Al2O3-ZrO2-NiCrAlY thermal-barrier coatings in air at 982 C were determined from cyclic flexural tests of coated TAZ-8A strips. Strains were computed as a function of specimen displacements from a nonlinear, three-dimensional stress analysis program. Fatigue resistances of thermal-barrier coatings applied to the strips were compared with those of uncoated and NiCrAlY-coated strips. The results indicate that ZrO2 is about four times greater in fatigue life than TAZ-8A at 982 C, that ZrO2 would probably retain that fatigue strength up to 1316 C, and that adding an outer coat of Al2O3 to ZrO2 is neither beneficial nor detrimental to fatigue resistance.

  19. 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.

  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. 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 ...

  2. Fatigue testing of electron beam-melted Ti-6Al-4V ELI alloy for dental implants.

    PubMed

    Joshi, Gaurav V; Duan, Yuanyuan; Neidigh, John; Koike, Mari; Chahine, Gilbert; Kovacevic, Radovan; Okabe, Toru; Griggs, Jason A

    2013-01-01

    Customized one-component dental implants have been fabricated using Electron Beam Melting(®) (EBM(®)), which is a rapid prototyping and manufacturing technique. The goal of our study was to determine the effect of electron beam orientation on the fatigue resistance of EBM Ti-6Al-4V ELI alloy. EBM technique was used to fabricate Ti-6Al-4V ELI alloy blocks, which were cut into rectangular beam specimens with dimensions of 25 × 4 × 3 mm, such that electron beam orientation was either parallel (group A) or perpendicular (group B) to the long axis of the specimens. The specimens were subjected to cyclic fatigue (R = 0.1) in four-point flexure under ambient conditions using various stress amplitudes below the yield stress. The fatigue lifetime data were fit to an inverse power law-Weibull model to predict the peak stress corresponding to failure probabilities of 5 and 63% at 2M cycles (σ(max, 5%) and σ(max, 63%)). Groups A and B did not have significantly different Weibull modulus, m (p > 0.05). The specimens with parallel orientation showed significantly higher σ(max, 63%) (p ≤ 0.05), but there was no significant difference in the σ(max, 5%) (p > 0.05). Thus, it can be concluded that the fatigue resistance of the material was greatest when the electron beam orientation was perpendicular to the direction of crack propagation.

  3. 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.

  4. Constellation Program Flight Test Methodology and Strategy

    NASA Technical Reports Server (NTRS)

    Vigil, Art; Rivas, Mauricio; Moses, Robert

    2008-01-01

    Main projects elements: a) Orion & Ares b) New & Modified heritage hardware. c) Shuttle retirement in 2010. Methodology: a) Flight test objectives. b) Risk reduction. Strategy a) Mapping Flight Test Objectives. b) Build incremental capability.

  5. Progeria Research Foundation Diagnostic Testing Program

    MedlinePlus

    ... PRF By The Numbers Medical Database Cell & Tissue Bank Diagnostic Testing Research Funding Opportunities Scientific Meetings Scientific ... New in Progeria Research Medical Database Cell & Tissue Bank Diagnostic Testing Research Funding Opportunities Scientific Meetings Scientific ...

  6. 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.

  7. Fatigue: an overview.

    PubMed

    Rosenthal, Thomas C; Majeroni, Barbara A; Pretorius, Richard; Malik, Khalid

    2008-11-15

    Fatigue, a common presenting symptom in primary care, negatively impacts work performance, family life, and social relationships. The differential diagnosis of fatigue includes lifestyle issues, physical conditions, mental disorders, and treatment side effects. Fatigue can be classified as secondary to other medical conditions, physiologic, or chronic. The history and physical examination should focus on identifying common secondary causes (e.g., medications, anemia, pregnancy) and life-threatening problems, such as cancer. Results of laboratory studies affect management in only 5 percent of patients, and if initial results are normal, repeat testing is generally not indicated. Treatment of all types of fatigue should include a structured plan for regular physical activity that consists of stretching and aerobic exercise, such as walking. Caffeine and modafinil may be useful for episodic situations requiring alertness. Short naps are proven performance enhancers. Selective serotonin reuptake inhibitors, such as fluoxetine, paroxetine, or sertraline, may improve energy in patients with depression. Patients with chronic fatigue may respond to cognitive behavior therapy. Scheduling regular follow-up visits, rather than sporadic urgent appointments, is recommended for effective long-term management. PMID:19035066

  8. 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…

  9. 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.

  10. Fatigue Fractures

    PubMed Central

    Morris, James M.

    1968-01-01

    Fatigue (or stress) fracture of bone in military recruits has been recognized for many years. Most often it is a metatarsal bone that is involved but the tarsal bones, calcaneus, tibia, fibula, femur, and pelvis are occasionally affected. Reports of such fractures in the ribs, ulna and vertebral bodies may be found in the literature. In recent years, there has been increasing awareness of the occurrence of fatigue fractures in the civilian population. Weekend sportsmen, athletes in an early phase of training, and persons engaged in unaccustomed, repetitive, vigorous activity are potential victims of such a fracture. The signs and symptoms, roentgenographic findings, treatment and etiology of fatigue fractures are dealt with in this presentation. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6. PMID:5652745

  11. 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.

  12. Small crack test program for helicopter materials

    NASA Astrophysics Data System (ADS)

    Annigeri, Bal; Schneider, George

    1994-09-01

    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.

  13. 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.

  14. 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.

  15. CIT photoheliograph functional verification unit test program

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Tests of the 2/3-meter photoheliograph functional verification unit FVU were performed with the FVU installed in its Big Bear Solar Observatory vacuum chamber. Interferometric tests were run both in Newtonian (f/3.85) and Gregorian (f/50) configurations. Tests were run in both configurations with optical axis horizontal, vertical, and at 45 deg to attempt to determine any gravity effects on the system. Gravity effects, if present, were masked by scatter in the data associated with the system wavefront error of 0.16 lambda rms ( = 6328A) apparently due to problems in the primary mirror. Tests showed that the redesigned secondary mirror assembly works well.

  16. 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.

  17. 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...

  18. Intercity rail-passenger car ride quality test program

    NASA Technical Reports Server (NTRS)

    Scharr, R. L.; Owings, R. P.

    1975-01-01

    The Federal Railroad Administration's research and development program relating to intercity rail-passenger ride quality focuses on developing ride quality design criteria and specifications. The FRA ride quality test program and some of the techniques being used to analyze and evaluate the design criteria of the program are discussed.

  19. 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 community.…

  20. 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)

  1. 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.

  2. 78 FR 12259 - Unmanned Aircraft System Test Site Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-22

    ... Privacy Act Statement can be found in the Federal Register published on April 11, 2000 (65 FR 19477-19478... 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...

  3. 78 FR 41999 - Combined Drug and Alcohol Testing Programs

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-15

    ..., final rule titled ``Drug and Alcohol Testing Program'' (74 FR 22653). 3. It reorganizes existing rule... Proposed Rulemaking (NPRM) (77 FR 39194), entitled ``Combined Drug and Alcohol Testing Programs.'' The..., the National Air Tour Safety Standards rule (72 FR 6884, February 13, 2007) established a...

  4. Recent wake turbulence flight test programs

    NASA Technical Reports Server (NTRS)

    Tymczyszyn, J. J.; Barber, M. R.

    1974-01-01

    In early flight tests the size and intensity of the wake vortexes generated by aircraft ranging in size from the Learjet to the C-5A and the B-747 were studied to determine the effects of aircraft configuration, weight, and speed. Early problems were related to vortex marking, the measurement of separation distance, and test techniques. Recent tests conducted with B-747 showed that vortexes were alleviated by reducing the deflection of the outboard flaps. It was found that a more rapid dissipation of the vortex system can be obtained through alterations in the span lift distribution.

  5. 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.

  6. Space shuttle cavity assessment test program

    NASA Technical Reports Server (NTRS)

    Scheps, P. B.

    1976-01-01

    In order to obtain basic radiation properties of the radiator/payload bay door cavity, three tests were conducted on a full-size structural simulator of the cavity. There were three tests conducted: (1) CATA used for determination of exchange factors, absorbed solar flux, and door covering influences, (2) quartz lamp array calibrated to provide IR flux distribution on CATA, and (3) retest with radiometer array for background flux measurement.

  7. The Savvy Caregiver Program: Developing and Testing a Transportable Dementia Family Caregiver Training Program

    ERIC Educational Resources Information Center

    Hepburn, Kenneth W.; Lewis, Marsha; Sherman, Carey Wexler; Tornatore, Jane

    2003-01-01

    Purpose: This article reports on the development and field testing of the Savvy Caregiver Program, the transformation of a successful, academic-based caregiver psychoeducational program into a self-contained program that can be adopted in other locations. Design and Methods: Program development began with a prototype of a 12-hr course with the…

  8. A new quantitative indicator of visual fatigue

    NASA Technical Reports Server (NTRS)

    Goussard, Yves; Martin, Bernard; Stark, Lawrence

    1987-01-01

    Ocular-motor correlates of visual fatigue have remained elusive. Performance of ocular-motor tracking with a wide-band white noise input and the response of the dual-mode, smooth pursuit-saccadic eye movement system as output was used to test visual fatigue. A new visual fatigue indicator, VFI, was defined as the nonlinear remnant after subtracting an identified impulse response contribution to the output. Subjects were required to perform very fatiguing CRT screen reading tasks, and the VFI correlated well with the subjective reports of visual fatigue.

  9. METC Fluid-bed Test Rigs/Test Program

    SciTech Connect

    Walczak, S.C.; Rockey, J.M.; Rutten, J.

    1993-09-01

    Since its last runs in December 1989, the 6-inch gasifier has been modified to enlarge the reactor inside diameter to 10 inches. Recent runs have shown stable operation and increased carbon conversion with the new gasifier size. As a 10-inch reactor, the METC FBG has logged over 150 hours online with Montana Rosebud coal. Table 2 shows typical solids analyses for an April 1993 run. A series of hot gas desulfurization tests using a batch-mode, fluidized bed to contact the coal gas with sulfur capturing sorbent marked the last integrated runs with the 6-inch, fluid-bed gasifier [2]. Table 3 shows typical coal gas composition before and after the fluid-bed, hot gas desulfurization reactor. Shakedown tests of the MGCR were performed in April and May 1993. These tests were performed primarily to obtain the characteristics of a candle filter created by the Shell Development Company as part of a Cooperative Research and Development Agreement (CRADA). The April run was a 4-day test using a 30-lb batch of zinc ferrite desulfurization sorbent. A plot of the sulfur removal in this run compared with one in 1989 [3] is shown in Figure 5. It is obvious from this figure that the MGCR has performed consistently despite a 4-year hiatus.

  10. 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.

  11. 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.

  12. Fatigue of niobium. Technical progress report

    SciTech Connect

    Stoloff, N. S.

    1980-01-31

    Tests to determine the effects of frequency, test temperature, and hydrogen content on the fatigue life and crack propagation behavior of polycrystalline niobium are described. Unalloyed niobium is nearly insensitive to test frequency at 25/sup 0/C, while hydrided alloys exhibit a strong frequency effect. Increasing test temperature decreases fatigue life, consistent with decreasing tensile strength. A brief survey of irradiation effects on fatigue of refractory metal alloys suggests that fatigue resistance of irradiated niobium should increase in proportion to effects on strength.

  13. 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.

  14. Technical bases for the DWPF testing program

    SciTech Connect

    Plodinec, M.J.

    1990-09-17

    The Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) will be the first production facility in the United States for the immobilization of high-level nuclear waste. Production of DWPF canistered wasteforms will begin prior to repository licensing, so decisions on facility startup will have to be made before the final decisions on repository design are made. The Department of Energy's Office of Civilian Radioactive Waste Management (RW) has addressed this discrepancy by defining a Waste Acceptance Process. This process provides assurance that the borosilicate-glass wasteform, in a stainless-steel canister, produced by the DWPF will be acceptable for permanent storage in a federal repository. As part of this process, detailed technical specifications have been developed for the DWPF product. SRS has developed detailed strategies for demonstrating compliance with each of the Waste Acceptance Process specifications. An important part of the compliance is the testing which will be carried out in the DWPF. In this paper, the bases for each of the tests to be performed in the DWPF to establish compliance with the specifications are described, and the tests are detailed. The results of initial tests relating to characterization of sealed canisters are reported.

  15. Technical bases for the DWPF testing program

    SciTech Connect

    Plodinec, M.J.

    1990-09-17

    The Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) will be the first production facility in the United States for the immobilization of high-level nuclear waste. Production of DWPF canistered wasteforms will begin prior to repository licensing, so decisions on facility startup will have to be made before the final decisions on repository design are made. The Department of Energy`s Office of Civilian Radioactive Waste Management (RW) has addressed this discrepancy by defining a Waste Acceptance Process. This process provides assurance that the borosilicate-glass wasteform, in a stainless-steel canister, produced by the DWPF will be acceptable for permanent storage in a federal repository. As part of this process, detailed technical specifications have been developed for the DWPF product. SRS has developed detailed strategies for demonstrating compliance with each of the Waste Acceptance Process specifications. An important part of the compliance is the testing which will be carried out in the DWPF. In this paper, the bases for each of the tests to be performed in the DWPF to establish compliance with the specifications are described, and the tests are detailed. The results of initial tests relating to characterization of sealed canisters are reported.

  16. 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.

  17. 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.

  18. 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.

  19. Creep fatigue life prediction for engine hot section materials (isotropic)

    NASA Technical Reports Server (NTRS)

    Moreno, Vito; Nissley, David; Lin, Li-Sen Jim

    1985-01-01

    The first two years of a two-phase program aimed at improving the high temperature crack initiation life prediction technology for gas turbine hot section components are discussed. In Phase 1 (baseline) effort, low cycle fatigue (LCF) models, using a data base generated for a cast nickel base gas turbine hot section alloy (B1900+Hf), were evaluated for their ability to predict the crack initiation life for relevant creep-fatigue loading conditions and to define data required for determination of model constants. The variables included strain range and rate, mean strain, strain hold times and temperature. None of the models predicted all of the life trends within reasonable data requirements. A Cycle Damage Accumulation (CDA) was therefore developed which follows an exhaustion of material ductility approach. Material ductility is estimated based on observed similarities of deformation structure between fatigue, tensile and creep tests. The cycle damage function is based on total strain range, maximum stress and stress amplitude and includes both time independent and time dependent components. The CDA model accurately predicts all of the trends in creep-fatigue life with loading conditions. In addition, all of the CDA model constants are determinable from rapid cycle, fully reversed fatigue tests and monotonic tensile and/or creep data.

  20. Fatigue properties of acrylic denture base resins.

    PubMed

    Fujii, K

    1989-12-01

    Observations were made of fractured surfaces caused by flexural and tensile fatigue tests made in polymethyl methacrylate denture base resins (PMMA). In addition, the changes in dynamic viscoelastic and tensile properties of the materials along with fatigue propagation were investigated. In the tensile and flexural fatigue tests, both the fractured surfaces, which had striations on their surfaces and cracks near the fractured section, closely resembled each other in appearance. On the other hand, all of the tensile properties, such as elastic modulus, toughness and tensile strength, decreased with the increase of the number of stress cycles in the fatigue test. The storage modulus (E') of the material decreased gradually along with fatigue propagation over the whole range of temperatures tested. The loss modulus (E") and mechanical loss tangent (tan delta) increased slightly. The fatigue limit of four commercial denture base resins varied widely from one product to another.

  1. 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.

  2. 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.

  3. Space shuttle galley water system test program

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A water system for food rehydration was tested to determine the requirements for a space shuttle gallery flight system. A new food package concept had been previously developed in which water was introduced into the sealed package by means of a needle and septum. The needle configuration was developed and the flow characteristics measured. The interface between the food package and the water system, oven, and food tray was determined.

  4. Initial Mirror Coalignment (IOT test program)

    NASA Astrophysics Data System (ADS)

    Friedman, Scott

    A series of 25 arcsec slews is executed in a spiral pattern about the LWRS aperture to try to find light in all four channels for the first time. This will be done as a single time-tag exposure. The primary data source is the detector counters. The default detector mask must be loaded prior to executing this program. This is followed by a one day interval to calculate the mirror movements required to co-align the channels to an accuracy of 25 arcsec. Finally, the target is recentered in the LWRS aperture. Then two series of linear slews are done, first in the X direction then in the Y direction. Each of these consists of 7 dwells separated by six slews, with each slew 5 arcsec in size. This will locate the edge of the slit to an accuracy of about 5 arcsec. A separate time-tag exposure will be taken during each of these linear slew sequences.

  5. 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.

  6. Test Pac: A Program for Comprehensive Item and Reliability Analysis.

    ERIC Educational Resources Information Center

    Luecht, Richard M.

    1987-01-01

    Test Pac, a test scoring and analysis computer program for moderate-sized sample designs using dichotomous response items, performs comprehensive item analyses and multiple reliability estimates. It also performs single-facet generalizability analysis of variance, single-parameter item response theory analyses, test score reporting, and computer…

  7. Drug Testing in a University Athletic Program: Protocol and Implementation.

    ERIC Educational Resources Information Center

    Rovere, George D.; And Others

    1986-01-01

    An athletic drug education, counseling, and screening program at Wake Forest University is described. Decisions regarding which athletes to test, which drugs to test for and how to test for them, how to collect urine samples, and measures taken for a positive result are discussed. (MT)

  8. Fatigue case study and loading spectra for wind turbines

    SciTech Connect

    Sutherland, H.J.

    1994-05-01

    The paper discusses two aspects of Sandia`s Wind Energy Program. The first section of the paper presents a case study of fatigue in wind turbines. This case study was prepared for the American Society of Testing Material`s (ASTM) Standard Technical Publication (STP) on fatigue education. Using the LIFE2 code, the student is lead through the process of cumulative damage summation for wind turbines and typical data are used to demonstrate the range of life estimates that will result from typical parameter variations. The second section summarizes the results from a workshop held by Sandia and the National Renewable Energy Laboratory (NREL) to discuss fatigue life prediction methodologies. This section summarizes the workshop discussions on the use of statistical modeling to deduce the shape and magnitude of the low-probability-of-occurrence, high-stress tail of the load distribution on a wind turbine during normal operation.

  9. Fatigue case study and loading spectra for wind turbines

    NASA Astrophysics Data System (ADS)

    Sutherland, H. J.

    The paper discusses two aspects of Sandia's Wind Energy Program. The first section of the paper presents a case study of fatigue in wind turbines. This case study was prepared for the American Society of Testing Material's (ASTM) Standard Technical Publication (STP) on fatigue education. Using the LIFE2 code, the student is lead through the process of cumulative damage summation for wind turbines and typical data are used to demonstrate the range of life estimates that will result from typical parameter variations. The second section summarizes the results from a workshop held by Sandia and the National Renewable Energy Laboratory (NREL) to discuss fatigue life prediction methodologies. This section summarizes the workshop discussions on the use of statistical modeling to deduce the shape and magnitude of the low-probability-of-occurrence, high-stress tail of the load distribution on a wind turbine during normal operation.

  10. Dynamic fatigue testing of candidate ceramic materials for turbine engines to determine slow-crack-growth parameters

    SciTech Connect

    Osborne, N.R.; Graves, G.A.; Ferber, M.K.

    1997-04-01

    The purpose of this study was to evaluate the mechanical strength and slow-crack-growth parameter values for two commercially available silicon nitrides, SN-88 and NT164, at three high-temperature conditions. Weibull analysis and dynamic fatigue slow-crack-growth parameters were used to characterize the material strength and resistance to slow crack growth at high temperatures for use in life prediction models. Although both materials are commercially available Si{sub 3}N{sub 4}, their high-temperature behavior was found to be significantly different.

  11. Thin polymer icemaker development and test program

    SciTech Connect

    Leigh, R.W. )

    1991-08-01

    We have constructed and tested a small device to produce ice in ice/water mixtures using a cold fluid as the heat sink. The device is a flexible heat exchanger constructed from a thin film of a suitable polymer. When filled with circulating liquid coolant the heat exchanger consists of an inflated series of parallel tubes; ice forms on the outside in complementary half cylinders. When the circulation is cut off, gravity drains the coolant and the static head of the water bath crushes the tubes, freeing them from the ice which floats to the surface. Brine circulation is then re-started and the cycle begins again. Here we report recent testing of this device: it makes ice readily under water and easily sheds the semi-cylinders of ice over many cycles of operation. It produces ice at a rate of 10 kg/m{sup 2}-hour. It offers substantial benefits in simplicity and reliability over mechanical harvester ice making systems, and the potential for significant improvements in energy efficiency compared to systems which use a re-heat cycle to harvest the ice. A reliable method of leak detection has been developed. The device should be of substantial value to systems where efficiency and reliability are at a premium, such as slush ice for district cooling.

  12. DOE Field Operations Program EV and HEV Testing

    SciTech Connect

    Francfort, James Edward; Slezak, L. A.

    2001-10-01

    The United States Department of Energy’s (DOE) Field Operations Program tests advanced technology vehicles (ATVs) and disseminates the testing results to provide fleet managers and other potential ATV users with accurate and unbiased information on vehicle performance. The ATVs (including electric, hybrid, and other alternative fuel vehicles) are tested using one or more methods - Baseline Performance Testing (EVAmerica and Pomona Loop), Accelerated Reliability Testing, and Fleet Testing. The Program (http://ev.inel.gov/sop) and its nine industry testing partners have tested over 30 full-size electric vehicle (EV) models and they have accumulated over 4 million miles of EV testing experience since 1994. In conjunction with several original equipment manufacturers, the Program has developed testing procedures for the new classes of hybrid, urban, and neighborhood EVs. The testing of these vehicles started during 2001. The EVS 18 presentation will include (1) EV and hybrid electric vehicle (HEV) test results, (2) operating experience with and performance trends of various EV and HEV models, and (3) experience with operating hydrogen-fueled vehicles. Data presented for EVs will include vehicle efficiency (km/kWh), average distance driven per charge, and range testing results. The HEV data will include operating considerations, fuel use rates, and range testing results.

  13. FATIGUE OF DENTAL CERAMICS

    PubMed Central

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-01-01

    Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. PMID:24135295

  14. Using Wii Fit to reduce fatigue among African American women with systemic lupus erythematosus: a pilot study.

    PubMed

    Yuen, H K; Holthaus, K; Kamen, D L; Sword, D O; Breland, H L

    2011-10-01

    Fatigue and physical deconditioning are common, difficult to treat conditions among patients with systemic lupus erythematosus (SLE). The aim of this pilot study was to evaluate the effectiveness of a home-based exercise program using the Wii Fit system in patients with SLE. Fifteen sedentary African American women with SLE experiencing moderate to severe fatigue participated in a home exercise program using the Wii Fit 3 days a week for 30 minutes each for 10 weeks. A one-group pretest-post test design was used to evaluate the effectiveness of this program. Primary outcome measure was severity of fatigue. Secondary outcome measures were body weight, waist circumference, fatigue-related symptoms of distress, activity level, and physical fitness. At the completion of the 10-week Wii Fit exercise program, participants perceived fatigue severity as measured by the Fatigue Severity Scale to be significantly decreased (p = 0.002), and body weight and waist circumference were significantly reduced (p = 0.01). In addition, anxiety level, as measured by Hospital Anxiety and Depression Scale, and overall intensity of total pain experience, as measured by Short-form of the McGill Pain Questionnaire, were also significantly reduced (p < 0.05). Findings provide preliminary evidence that the Wii Fit motivates this population to exercise, which leads to alleviation of fatigue and reduced body weight, waist circumference, anxiety level, and overall intensity of total pain experience.

  15. 7075-T6 and 2024-T351 Aluminum Alloy Fatigue Crack Growth Rate Data

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Wright, Christopher W.; Johnston, William M., Jr.

    2005-01-01

    Experimental test procedures for the development of fatigue crack growth rate data has been standardized by the American Society for Testing and Materials. Over the past 30 years several gradual changes have been made to the standard without rigorous assessment of the affect these changes have on the precision or variability of the data generated. Therefore, the ASTM committee on fatigue crack growth has initiated an international round robin test program to assess the precision and variability of test results generated using the standard E647-00. Crack growth rate data presented in this report, in support of the ASTM roundrobin, shows excellent precision and repeatability.

  16. Manipulator Comparative Testing Program: Final report

    SciTech Connect

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

    1987-02-01

    The manipulator systems tested included the Meidensha BILARM 83A, the Central Research Laboratories Model M-2, and the GCA PaR Systems Model 6000. Six manipulator and control mode combinations were evaluated: (1) the BILARM in master/slave mode without force reflection, (2) the BILARM in master/slave mode with force reflection, (3) the Model M-2 in master/slave mode without force reflection, (4) the Model M-2 in master/slave mode with force reflection, (5) the BILARM with switchbox controls, and (6) the PaR 6000 with switchbox controls. The experiments examined differences between master/slave systems with and without force reflection and differences between master/slave systems and switchbox-controlled systems. A fourth experiment examined the relative contributions of the remote viewing system and the manipulator system to the performance of remote handling tasks. Results of the experiments showed that operators using the Model M-2 in master/slave mode had significantly faster times to completion than operators using the BILARM in master/slave mode, with about the same error rate per trial. Operators were slower using the BILARM with force reflection than without it, and they committed more errors. There was no statistically significant difference between force-reflection and nonforce-reflection conditions for the M-2 manipulator for any of the performance criteria. Tasks and procedures used in this testing were not sensitive to differences within any single system. No inferences about the effect of force reflection on remote task performance should be made from these data. The two manipulator systems in switchbox mode had significantly slower times to completion than any system in master/slave mode, with approximately the same error rate per trial. There were no significant differences between the BILARM in switchbox mode and the PaR arm.

  17. Prototype steam generator test at SCTI/ETEC. Acoustic program test plan. [LMFBR

    SciTech Connect

    Greene, D.A.; Thiele, A.; Claytor, T.N.

    1981-10-01

    This document is an integrated test plan covering programs at General Electric (ARSD), Rockwell International (RI) and Argonne National Laboratory (CT). It provides an overview of the acoustic leak detection test program which will be completed in conjunction with the prototype LMFBR steam generator at the Energy Technology Engineering Laboratory. The steam generator is installed in the Sodium Components Test Installation (SCTI). Two acoustic detection systems will be used during the test program, a low frequency system developed by GE-ARSD (GAAD system) and a high frequency system developed by RI-AI (HALD system). These systems will be used to acquire data on background noise during the thermal-hydraulic test program. Injection devices were installed during fabrication of the prototype steam generator to provide localized noise sources in the active region of the tube bundle. These injectors will be operated during the steam generator test program, and it will be shown that they are detected by the acoustic systems.

  18. TESTER: A Computer Program to Produce Individualized Multiple Choice Tests.

    ERIC Educational Resources Information Center

    Hamer, Robert; Young, Forrest W.

    1978-01-01

    TESTER, a computer program which produces individualized objective tests from a pool of items, is described. Available in both PL/1 and FORTRAN, TESTER may be executed either interactively or in batch. (Author/JKS)

  19. Sheath insulator final test report, TFE Verification Program

    SciTech Connect

    Not Available

    1994-07-01

    The sheath insulator in a thermionic cell has two functions. First, the sheath insulator must electrically isolate the collector form the outer containment sheath tube that is in contact with the reactor liquid metal coolant. Second, The sheath insulator must provide for high uniform thermal conductance between the collector and the reactor coolant to remove away waste heat. The goals of the sheath insulator test program were to demonstrate that suitable ceramic materials and fabrication processes were available, and to validate the performance of the sheath insulator for TFE-VP requirements. This report discusses the objectives of the test program, fabrication development, ex-reactor test program, in-reactor test program, and the insulator seal specifications.

  20. Test Program Seeks to Lower School Heating Costs.

    ERIC Educational Resources Information Center

    School Business Affairs, 1980

    1980-01-01

    As part of the second year of its Schoolhouse Energy Efficiency Demonstration (SEED) program, Tenneco, Inc. recently began a test of experimental window insulation material in three of the schools audited last year. (Author/MLF)

  1. Dish stirling solar receiver combustor test program

    NASA Technical Reports Server (NTRS)

    Bankston, C. P.; Back, L. H.

    1981-01-01

    The operational and energy transfer characteristics of the Dish Stirling Solar Receiver (DSSR) combustor/heat exchanger system was evaluated. The DSSR is designed to operate with fossil fuel augmentation utilizing a swirl combustor and cross flow heat exchanger consisting of a single row of 4 closely spaced tubes that are curved into a conical shape. The performance of the combustor/heat exchanger system without a Stirling engine was studied over a range of operating conditions and output levels using water as the working fluid. Results show that the combustor may be started under cold conditions, controlled safety, and operated at a constant air/fuel ratio (10 percent excess air) over the required range of firing rates. Furthermore, nondimensional heat transfer coefficients based on total heat transfer are plotted versus Reynolds number and compared with literature data taken for single rows of closely spaced tubes perpendicular to cross flow. The data show enhanced heat transfer for the present geometry and test conditions. Analysis of the results shows that the present system meets specified thermal requirements, thus verifying the feasibility of the DSSR combustor design for final prototype fabrication.

  2. Component test program for variable-cycle engines

    NASA Technical Reports Server (NTRS)

    Powers, A. G.; Whitlow, J. B.; Stitt, L. E.

    1976-01-01

    Variable cycle engine (VCE) concepts for a supersonic cruise aircraft were studied. These VCE concepts incorporate unique critical components and flow path arrangements that provide good performance at both supersonic and subsonic cruise and appear to be economically and environmentally viable. Certain technologies were identified as critical to the successful development of these engine concepts and require considerable development and testing. The feasibility and readiness of the most critical VCE technologies, was assessed, a VCE component test program was initiated. The variable stream control engine (VSCE) component test program, tested and evaluated an efficient low emission duct burner and a quiet coannular ejector nozzle at the rear of a rematched F100 engine.

  3. Startup of the FFTF sodium cooled reactor. [Acceptance Test Program

    SciTech Connect

    Redekopp, R.D.; Umek, A.M.

    1981-03-01

    The Fast Flux Test Facility (FFTF), located on the Department of Energy (DOE) Hanford Reservation near Richland, Washington, is a 3 Loop 400 MW(t) sodium cooled fast reactor with a primary mission to test fuels and materials for development of the Liquid Metal Fast Breeder Reactor (LMFBR). Bringing FFTF to a condition to accomplish this mission is the goal of the Acceptance Test Program (ATP). This program was the mechanism for achieving startup of the FFTF. Highlights of the ATP involving the system inerting, liquid metal and inerted cell testing and initial ascent to full power are discussed.

  4. Rocky Flats plant qualification testing for PRES Program

    SciTech Connect

    Kautz, D.D.; Tanaka, G.J.

    1994-06-24

    The authors recently completed several tests for EG&G - Rocky Flats, Inc. (RFP) to qualify welding procedures for the PRESS program. The welds that were tested were the Monel 400 to vanadium friction weld used in the Sail-A and the vanadium electron beam welds from the Mast Inner Subassembly. Tests were performed to determine the structural properties of the parts under conditions similar to those encountered in a weapons handling and storage environment. These tests included impact, tensile and pressure loading. Metallographic analysis was done where appropriate to document weld quality. All results were satisfactory for PRESS program purposes.

  5. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... audiologist, otolaryngologist, or other physician who has experience and expertise in hearing and hearing loss... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests... who are required by § 227.107 to be included in a hearing conservation program. (1) New employees....

  6. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... audiologist, otolaryngologist, or other physician who has experience and expertise in hearing and hearing loss... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests... who are required by § 227.107 to be included in a hearing conservation program. (1) New employees....

  7. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... audiologist, otolaryngologist, or other physician who has experience and expertise in hearing and hearing loss... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests... who are required by § 227.107 to be included in a hearing conservation program. (1) New employees....

  8. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... audiologist, otolaryngologist, or other physician who has experience and expertise in hearing and hearing loss... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests... who are required by § 227.107 to be included in a hearing conservation program. (1) New employees....

  9. 49 CFR 227.109 - Audiometric testing program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... audiologist, otolaryngologist, or other physician who has experience and expertise in hearing and hearing loss... be included in a hearing conservation program pursuant to § 227.107. (b) Cost. The audiometric tests... employees who are required by § 227.107 to be included in a hearing conservation program. (1) New...

  10. Evaluation Report: Early Childhood Education Program, 1969 Field Test.

    ERIC Educational Resources Information Center

    Appalachia Educational Lab., Charleston, WV.

    Reported are findings from the first year's field test of the home-oriented Appalachia Educational Laboratory (AEL) Early Childhood Education Program for 3-, 4-, and 5-year-olds. The program consists of a 30-minute daily television lesson, a weekly home visit by a paraprofessional, and group instruction once a week in a mobile classroom. The…

  11. 42 CFR 493.901 - Approval of proficiency testing programs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... scientific problems about program operations; (c) Meet the specific criteria for proficiency testing programs... performance problems in a timely manner; (b) Demonstrate to HHS that it has— (1) The technical ability... the appropriate good manufacturing practices required in 21 CFR parts 606, 640, and 820; and...

  12. 42 CFR 493.901 - Approval of proficiency testing programs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... scientific problems about program operations; (c) Meet the specific criteria for proficiency testing programs... performance problems in a timely manner; (b) Demonstrate to HHS that it has— (1) The technical ability... the appropriate good manufacturing practices required in 21 CFR parts 606, 640, and 820; and...

  13. 75 FR 25884 - NIJ Body Armor Compliance Testing Program Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-10

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Office of Justice Programs NIJ Body Armor Compliance Testing Program Workshop AGENCY: National Institute of Justice. ACTION: Notice of meeting. SUMMARY: The National Institute of Justice (NIJ) is hosting a...

  14. NCAA Drug-Testing Program 2010-11

    ERIC Educational Resources Information Center

    National Collegiate Athletic Association (NJ1), 2010

    2010-01-01

    The National Collegiate Athletic Association (NCAA) Drug-Testing Program was created to protect the health and safety of student-athletes and to ensure that no one participant might have an artificially induced advantage or be pressured to use chemical substances. This publication describes this program in the following chapters: (1) NCAA…

  15. NCAA[R] Drug-Testing Program, 1999-2000.

    ERIC Educational Resources Information Center

    Halpin, Ty, Ed.

    The drug testing program supports NCAA's goal to protect the health and safety of student-athletes competing for their institutions, while reaffirming the organization's commitment to fair and equitable competition. Proposal Nos. 30 and 52-54 provide a program for the NCAA's members to ensure that no one athlete has a chemically-induced advantage…

  16. A BASIC Microcomputer Program for Estimating Test Reliability.

    ERIC Educational Resources Information Center

    Cobern, William W.

    This computer program, written in BASIC, performs three different calculations of test reliability: (1) the Kuder-Richardson method; (2); the "common split-half" method; and (3) the Rulon-Guttman split-half method. The program reads sequential access data files for microcomputers that have been set up by statistical packages such as STATPAC. The…

  17. U.S. field testing programs and results

    SciTech Connect

    Wicks, G.G.

    2000-06-09

    The United States has been active in four major international in-situ or field testing programs over the past two decades, involving the burial of simulated high-level waste forms and package components. These programs are designed to supplement laboratory testing studies in order to obtain the most complete and realistic picture possible of waste glass behavior under realistic repository-relevant conditions.

  18. General test plan redundant sensor strapdown IMU evaluation program

    NASA Technical Reports Server (NTRS)

    Hartwell, T.; Irwin, H. A.; Miyatake, Y.; Wedekind, D. E.

    1971-01-01

    The general test plan for a redundant sensor strapdown inertial measuring unit evaluation program is presented. The inertial unit contains six gyros and three orthogonal accelerometers. The software incorporates failure detection and correction logic and a land vehicle navigation program. The principal objective of the test is a demonstration of the practicability, reliability, and performance of the inertial measuring unit with failure detection and correction in operational environments.

  19. Energy efficient engine sector combustor rig test program

    NASA Technical Reports Server (NTRS)

    Dubiel, D. J.; Greene, W.; Sundt, C. V.; Tanrikut, S.; Zeisser, M. H.

    1981-01-01

    Under the NASA-sponsored Energy Efficient Engine program, Pratt & Whitney Aircraft has successfully completed a comprehensive combustor rig test using a 90-degree sector of an advanced two-stage combustor with a segmented liner. Initial testing utilized a combustor with a conventional louvered liner and demonstrated that the Energy Efficient Engine two-stage combustor configuration is a viable system for controlling exhaust emissions, with the capability to meet all aerothermal performance goals. Goals for both carbon monoxide and unburned hydrocarbons were surpassed and the goal for oxides of nitrogen was closely approached. In another series of tests, an advanced segmented liner configuration with a unique counter-parallel FINWALL cooling system was evaluated at engine sea level takeoff pressure and temperature levels. These tests verified the structural integrity of this liner design. Overall, the results from the program have provided a high level of confidence to proceed with the scheduled Combustor Component Rig Test Program.

  20. Three Essays on Teacher Education Programs and Test-Takers' Response Times on Test Items

    ERIC Educational Resources Information Center

    Qian, Hong

    2013-01-01

    This dissertation includes three essays: one essay focuses on the effect of teacher preparation programs on teacher knowledge while the other two focus on test-takers' response times on test items. Essay One addresses the problem of how opportunities to learn in teacher preparation programs influence future elementary mathematics teachers'…