A New Criterion for the Strength of Metals under Combined Alternating Stresses

Abstract

Matsumura's theory of malleable materials, stating that “the elastic failure occurs in malleable materials when the maximum shear stress reaches a definite value depending on shear strain energy” is fairly well applicable to results of experiments, so far as the material is ductile; but the theory is not applicable to brittle materials. Extending Matsumura's theory to all materials, ductile and brittle, the authors propose now a new criterion and applying it to the case of fatigue, they think that “the fatigue failure occurs in ductile materials when the greatest maximum shear stress induced by combined repeated stresses reaches a definite value depending on shear strain energy at the instant, and that the fatigue occurs in brittle materials when the greatest maximum principal stress induced by the combined repeated stresses reaches a definite value depending also on shear strain energy at the instant.”From this new criterion on fatigue, they derive the conditions of fatigue failure under the combination of various stresses. Comparing the results of calculation with those of experiments, it is established that the new criterion is fairly well applicable to results of experiments in every case.