Theories relating to fatigue of materials under combinations of stress

Abstract

Analysis of available data suggests that the phenomenon of fatigue of materials results primarily from alternating shearing stress producing cracks along shear planes, and that the resistance to fatigue fracture is influenced by other factors. Some of these factors are: changes in structure of the material resulting from heat treatment, elastic distortion from applied stresses (or residual stresses), or plastic deformation; the mode of crack propagation (by shear or by separation); and the normal stress on planes of principal shear stress (called here the complementary normal stress).