Parameter Analysis for Time-Dependent Low-Cycle Fatigue Life

1994 ◽  
Vol 116 (4) ◽  
pp. 479-482 ◽  
Author(s):  
Koji Yamaguchi ◽  
Kazuo Kobayashi ◽  
Kiyoshi Ijima ◽  
Satoshi Nishijima

Temperature and strain rate dependences of low-cycle fatigue life can be represented by a modified Larson-Miller parameter. The parameter P is written by P=T(logN25−Alog ε˙ + B), where T is temperature, N25 is fatigue life, ε˙ is strain rate, and A and B are constants. In the analysis, each data of several kinds of engineering materials from ferritic steels to austenitic stainless steels are used. These are the authors original data published in the documents of NRIM Fatigue Data Sheets. The result of 304 stainless steel has been compared with statistical analysis result by Diercks adopted in a design code. The fatigue life curves represented by the proposed parameter analysis fitted well test data in high-cycle region as well as ones in low-cycle region.

2010 ◽  
pp. 217-229
Author(s):  
Kuk-cheol Kim ◽  
Byeong-ook Kong ◽  
Min-soo Kim ◽  
Sung-tae Kang

2018 ◽  
Vol 165 ◽  
pp. 06002
Author(s):  
Golta Khatibi ◽  
Ali Mazloum-Nejadari ◽  
Martin Lederer ◽  
Mitra Delshadmanesh ◽  
Bernhard Czerny

In this study, the influence of microstructure on the cyclic behaviour and lifetime of Cu and Au wires with diameters of 25μm in the low and high cycle fatigue regimes was investigated. Low cycle fatigue (LCF) tests were conducted with a load ratio of 0.1 and a strain rate of ~2e-4. An ultrasonic resonance fatigue testing system working at 20 kHz was used to obtain lifetime curves under symmetrical loading conditions up to very high cycle regime (VHCF). In order to obtain a total fatigue life model covering the low to high cycle regime of the thin wires by considering the effects of mean stress, a four parameter lifetime model is proposed. The effect of testing frequency on high cycle fatigue data of Cu is discussed based on analysis of strain rate dependency of the tensile properties with the help of the material model proposed by Johnson and Cook.


1974 ◽  
Vol 96 (3) ◽  
pp. 171-176 ◽  
Author(s):  
J. D. Heald ◽  
E. Kiss

This paper presents the results of low-cycle fatigue testing and analysis of 26 piping components and butt-welded sections. The test specimens were fabricated from Type-304 stainless steel and carbon steel, materials which are typically used in the primary piping of light water nuclear reactors. Components included 6-in. elbows, tees, and girth butt-welded straight sections. Fatigue testing consisted of subjecting the specimens to deflection-controlled cyclic bending with the objective of simulating system thermal expansion type loading. Tests were conducted at room temperature and 550 deg F, with specimens at room temperature subjected to 1050 psi constant internal hydraulic pressure in addition to cyclic bending. In two tests at room temperature, however, stainless steel elbows were subjected to combined simultaneous cyclic internal pressure and cyclic bending. Predictions of the fatigue life of each of the specimens tested have been made according to the procedures specified in NB-3650 of Section III[1] in order to assess the code design margin. For the purpose of the assessment, predicted fatigue life is compared to actual fatigue life which is defined as the number of fatigue cycles producing complete through-wall crack growth (leakage). Results of this assessment show that the present code fatigue rules are adequately conservative.


Author(s):  
Takuma Sato ◽  
Yoshiharu Kariya ◽  
Kazuma Fukui

In this study, the effects of temperature and strain rate on low cycle fatigue life of Bi-Sn eutectic alloys have been studied. The fatigue life improves with the increasing of temperature and the decreasing of strain rate. This is a reverse phenomenon from characteristics found in general metals. As temperature increases and strain rate decreases, grin boundary sliding becomes the dominant deformation mechanism and the fatigue ductility coefficient increases, resulting in an improvement of fatigue life. To the extent of this study, dependence on temperature and strain rate can be expressed by Manson-Coffin’s law modified using Z-parameters.


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