Crack Propagation in Low Cycle Fatigue of 7 : 3 Brass Specimens under Reversed Bending

Abstract

In this paper, the characteristics of crack propagation in low cycle fatigue were studied using electropolished 7 : 3 brass specimens. The method of loading is reversed bending. The following results were obtained. 1) The parameter deciding the rate of crack propagation is hθa1/2, where h is the minimum width of specimen, θ is the amplitude of bending angle and a is the effective crack length (the sum of crack length and notch depth). It is condidered that hθa1/2 represents the amplitude of reversed plastic strain at the root of crack. 2) The mean strain (the mean of maximum tensile and maximum compressive strains) near the root of crack is positive (that is, the grains near the root of crack have been extended under alternate bending). 3) One spacing of the fatigue striations in low cycle fatigue corresponds to one cycle of reversed bending.