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Effects of Environment on the Low-Cycle Fatigue Behavior of Type 304 Stainless Steel

Description: The low-cycle fatigue behavior of Type 304 stainless steel has been investigated at 593 degrees C in a dynamic vacuum of better than 1.3 x 10⁻⁶ Pa (10⁻⁸ torr). The results concerning the effects of strain range, strain rate and tensile hold time on fatigue life are presented and compared with results of similar tests performed in air and sodium environments. Under continuous symmetrical cycling, fatigue life is significantly longer in vacuum than in air; in the low strain range regime, the effect of sodium on fatigue life appears to be similar to that of vacuum. Strain rate (or frequency) strongly influences fatigue life in both air and vacuum. In compressive hold-time tests, the effect of environment on life is similar to that in a continuous-cycling test. However, tensile hold times are nearly as damaging in vacuum as in air. Thus, at least for austenitic stainless steels, the influence of the environment of fatigue life appears to depend on the loading waveshape.
Date: December 1979
Creator: Argonne National Laboratory. Materials Science Division.
Partner: UNT Libraries Government Documents Department

Fatigue and Recuperation Curves under Varying Lengths of Intertrial Recovery Periods

Description: The purposes of this study were to investigate the effect that strength level had upon fatigue and recuperation under the two conditions of five- and thirty-second interval duration periods. Another purpose was to compare the results of this study to similar studies using male subjects in order to determine if women's response patterns to tests of strength were similar to those of men.
Date: August 1968
Creator: Osborne, Jacquelyn
Partner: UNT Libraries

Low-Frequency Fatigue-Crack Propagation in Type 304 Stainless Steel at 482 and 593°C

Description: This report presents results from an investigation on the low-frequency fatigue-crack growth behavior of Type 304 stainless steel at 482 and 593 C. Included were continuous-cycling tests with a triangular loading waveform, waveshape-effects tests employing slow-fast, fast-slow and square waveforms, creep-crack growth rate tests, and a block-loading test. The results are compared with similar test data from the literature, and the block-loading test results are compared with results predicted by integrating the relations for da/dN obtained under constant conditions.
Date: June 1980
Creator: Raske, D. T.
Partner: UNT Libraries Government Documents Department

An analysis of the fatigue life of an airplane wing structure under overload conditions

Description: From Introduction: "Fatigue life expectancy in normal transport operations was investigated in reference 1 and was found to be of equal importance with single-gust life. The effect of overload operation of transport airplanes on the probability of encountering single critical gusts was investigated in reference 2 and the frequency of critical gusts was found to increase rapidly with overload. The effect of overload operation on fatigue strength, however, has not heretofore been evaluated, hence the investigations of references 1 and 2 are combined herein to permit such evaluation and to determine the relative importance of fatigue and single-gust failures under conditions of overload operation."
Date: February 1946
Creator: Reisert, Thomas D
Partner: UNT Libraries Government Documents Department

Bending Fatigue Tests on Flattened Strand Wire Rope at High Working Loads

Description: Abstract: The U.S. Bureau of Mines established a wire rope research laboratory to examine the factors that affect the safety and the useful life of wire rope. In the most recent work, two 32-mm 6x27H flattened strand ropes were degraded on a bending fatigue machine. The two tests were run at constant loads of 285 and 347 kN or safety factors of 2.5 and 2. Nondestructive and tensile strength tests were performed on samples of the ropes to determine the relationship between rope deterioration and rope breaking strength. Neither the area loss nor the number of broken wires measured from nondestructive tests could be used as clear indicators of the loss of strength. However, it was found from the tensile tests for both rope specimens that the strength loss was associated with the reduction of breaking strain. This suggests that measuring the strain of many short sections of a rope in the elastic region may locate the high stress sections and thus determine the condition of the rope.
Date: 1995
Creator: Wang, Richard C. & Shapiro, David E.
Partner: UNT Libraries Government Documents Department

Bilinear Cyclic Stress-Strain Parameters for Types 304 and 316 Stainless Steel

Description: The bilinear cyclic stress-strain parameters for Types 304 and 316 stainless steel are described. The bilinear properties of solution-annealed and aged Type 304 stainless steel (heat 9T2796) and solution-annealed Type 3l6 stainless steel (heat 8092297) under cyclic-loading conditions at a strain rate of 8.6 x 10⁵ s⁻¹, total strain range between 0.2 and 0.8 percent, and temperatures from 22 to 593 degrees C were determined. The dependence of bilinear parameters on maximum strain epsilon and temperature is discussed.
Date: July 1978
Creator: Maiya, P. S.
Partner: UNT Libraries Government Documents Department

Mechanism of fatigue in micron-scale films of polycrystalline silicon for microelectromechanical applications

Description: Reported nearly a decade ago, cyclic fatigue failure in silicon thin films has remained a mystery. Silicon does not display the room temperature plasticity or extrinsic toughening mechanisms necessary to cause fatigue in either ductile (e.g., metals) or brittle (e.g., ceramics and ordered mintermetallic) materials.
Date: August 2, 2001
Creator: Muhlstein, C.L.; Stach, E.A. & Ritchie, R.O.
Partner: UNT Libraries Government Documents Department

Determining worst-case fatigue thresholds for grain-bridging ceramics

Description: A method for determining worst-case cyclic fatigue thresholds in grain-bridging ceramics by quantifying the role of bridging is demonstrated for a model alumina. Crack-growth properties for both long and short (< 2 mm) cracks emanating from machined notches (root radii, (rho) {approx}; 15 - 150 (mu)m) were investigated. When compared as a function of the applied stress-intensity range (delta K), growth rates (da/dN) were far higher and fatigue thresholds (Delta)KTH were markedly lower with short cracks, with growth being observable at the lowest driving forces for short cracks emanating from razor micronotches ((rho)is approximately equal to 15 (mu)m). For growth rates < 10-8 m/cycle, da/dN vs. (delta)K data for short cracks merged with the steady-state data for long cracks after {approx}2 mm of extension.
Date: October 7, 2002
Creator: Kruzic, J.J.; Yuan, R.; Canon, R.M. & Ritchie, R.O.
Partner: UNT Libraries Government Documents Department

Fatigue case study and reliability analyses for wind turbines

Description: Modern wind turbines are fatigue critical machines used to produce electrical power. To insure long term, reliable operation, their structure must be optimized if they are to be economically viable. The fatigue and reliability projects in Sandia`s Wind Energy Program are developing the analysis tools required to accomplish these design requirements. The first section of the paper formulates the fatigue analysis of a wind turbine using a cumulative damage technique. The second section uses reliability analysis for quantifying the uncertainties and the inherent randomness associated with turbine performance and the prediction of service lifetimes. Both research areas are highlighted with typical results.
Date: December 31, 1994
Creator: Sutherland, H.J. & Veers, P.S.
Partner: UNT Libraries Government Documents Department

Biaxial Creep-Fatigue Behavior of Type 316H Stainless Steel Tube

Description: Biaxial creep-fatigue test data for Type 316 stainless steel tubes at 1100*Y are presented. The specimens were subjected to constant internal pressure and fluctuating axial strain with and without hold times in tension as well as compress ion. The results show that internal pressure significantly affects diametral ratchetting and axial stress range. Axial tensile hold is found to he more damaging than axial compressive hold even cinder a biaxial state of stress.
Date: April 1979
Creator: Majumdar, S.
Partner: UNT Libraries Government Documents Department

Comparison of 43Sn/43Pb/14Bi Solder and Standard 60Sn/40Pb Solder by Thermocyclic Fatigue Analysis

Description: The thermocyclic fatigue behavior of the low-melting solder 43Sn/43Pb/14Bi has been investigated and compared to that of standard 60Sn/4OPb solder via metallographic analysis (using scanning electron microscopy) and evaluation of the degree of fatigue development (using a fatigue scale as a function of thermocycles). Specimens were subjected to shearing strains imposed by several hundred fatigue thermocycles. Both solder types fatigue by the same microstructural failure mechanism as described by other workers. The mechanism is characterized by a preferential coarsening of the solder joint microstructure at the region of maximum stress concentration where cracks originate.
Date: August 1991
Creator: Calderon, Jose Guadalupe
Partner: UNT Libraries

Failure by fracture and fatigue in 'NANO' and 'BIO'materials

Description: The behavior of nanostructured materials/small-volumestructures and biologi-cal/bio-implantable materials, so-called "nano"and "bio" materials, is currently much in vogue in materials science. Oneaspect of this field, which to date has received only limited attention,is their fracture and fatigue properties. In this paper, we examine twotopics in this area, namely the premature fatigue failure ofsilicon-based micron-scale structures for microelectromechanical systems(MEMS), and the fracture properties of mineralized tissue, specificallyhuman bone.
Date: December 19, 2003
Creator: Ritchie, R.O.; Muhlstein, C.L. & Nalla, R.K.
Partner: UNT Libraries Government Documents Department

Novel Experiments to Characterize Creep-Fatigue Degradation in VHTR Alloys

Description: It is well known in energy systems that the creep lifetime of high temperature alloys is significantly degraded when a cyclic load is superimposed on components operating in the creep regime. A test method has been developed in an attempt to characterize creep-fatigue behavior of alloys at high temperature. The test imposes a hold time during the tensile phase of a fully reversed strain-controlled low cycle fatigue test. Stress relaxation occurs during the strain-controlled hold period. This type of fatigue stress relaxation test tends to emphasize the fatigue portion of the total damage and does not necessarily represent the behavior of a component in-service well. Several different approaches to laboratory testing of creep-fatigue at 950°C have been investigated for Alloy 617, the primary candidate for application in VHTR heat exchangers. The potential for mode switching in a cyclic test from strain control to load control, to allow specimen extension by creep, has been investigated to further emphasize the creep damage. In addition, tests with a lower strain rate during loading have been conducted to examine the influence of creep damage occurring during loading. Very short constant strain hold time tests have also been conducted to examine the influence of the rapid stress relaxation that occurs at the beginning of strain holds.
Date: October 1, 2013
Creator: Wright, J. K.; Simpson, J. A.; Carroll, L. J.; Wright, R. N. & Sham, T.-L.
Partner: UNT Libraries Government Documents Department

Oxygen Uptake Kinetics in Severe Intensity Exercise

Description: The purpose of this study was to describe mathematically the oxygen uptake kinetics during cycle ergometry, and to examine the effect of intensity on the kinetic responses within the severe domain. Sixteen volunteers performed a series of exercise tests at a range of intensities selected to elicit fatigue in ~3 to 10 min. A simple mono-exponential model effectively described the response across all intensities. There was a positive correlation between the response time and the time to fatigue, demonstrating that the maximal oxygen uptake was achieved faster at higher intensities within the severe domain. Models incorporating two components effectively described the responses only in tests lasting 8 min or more. It was concluded that there is a second, slow component in the oxygen uptake response only at the lower intensities within the severe domain.
Date: May 2000
Creator: Blumoff, Sonja
Partner: UNT Libraries

Fatigue Related Changes in the Body Motion and Force Application During the Performance of Consecutive Chin-ups

Description: The purpose of this study was to examine the effects of fatigue on force application and resulting movement patterns during the performance of consecutive chin-ups. Special attention was directed toward relating any fatigue effects to upper limb strength dominance. Twenty male adult subjects each performed one trial. Each trial consisted of consecutive chin-ups. Fatigue caused changes in the movement patterns, duration of movement and force applied through the supporting hands. Throughout the performance greater vertical forces were applied through the dominant upper limb segment with the application of these forces resulting in horizontal displacement of the total body center of gravity toward the dominant hand.
Date: December 1984
Creator: Hong, Der-Ming
Partner: UNT Libraries

The Effect of the Tonic Neck Reflex upon Fatigue of the Extensor Leg Muscles

Description: The purpose of the investigation was to determine the effect of the tonic neck posture upon fatigue induced by exhaustive exercise of the knee extensor muscles of college women. The subjects were college females enrolled in physical education activity classes at North Texas State University. The F ratio was used to determine significance of the difference in fatigue measures in the three head positions. The results of the present investigation revealed no statistically significant difference between the three head positions with respect to their influence on endurance of the leg extensors. Conclusions were that the tonic neck reflex does not facilitate or inhibit leg extensor endurance.
Date: August 1974
Creator: Cate, Susan Carol
Partner: UNT Libraries

Small fatigue cracks: mechanics, mechanisms and engineering applications

Description: Damage-tolerant design and life-prediction methodologies have been practiced for metallic structures for decades, although their application to brittle materials, such as ceramics, and intermetallic alloys, still poses particular problems, primarily because of their extreme flaw-sensitivity.
Date: May 1, 2001
Creator: Ritchie, R.O. & Peters, J.O.
Partner: UNT Libraries Government Documents Department