引張圧縮低サイクル疲労試験片形状の問題点とその対策

概要

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We examined the low cycle fatigue behavior under axial loading with maximum 4% constant plastic strain range, and the effect of the shapes of specimens having various dimensions of the central part on fatigue behavior was investigated. The experimental results obtained from two types of specimens were also considered from values of elastic-plastic finite element analysis from the standpoint of the small crack growth law. The main results obtained are as follows : (1) To obtain the correct fatigue life, the ratio of length vs diameter of the parallel part has only to be more than 1.5 in the cylindrical specimens. (2) The fatigue life of hourglass specimens is longer than that of cylindrical ones and the rate of increase is 50〜70% at most. The main cause of the longer life is the value of the longitudinal tensile stress around the narrowest part of hourglass specimens being smaller than that of cylindrical ones under the same plastic strain range.
1994-03-25