Fatigue of Metals Under Combinations of Stresses

Abstract Analysis of available information 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 cracking is influenced by other factors. Some of these factors are changes in structure of the material resulting from plastic and elastic stressing as well as heat-treatment; the mode of crack propagation and the complementary normal stress on planes of shear stress. Several theories of failure under combined stress are examined and modified to account for observed facts. A general design expression is proposed. The influence of mean stress (including extreme compression), yielding, complementary normal stress, and anisotropy are considered.