Assessment of the influence of the mean shear stress on multiaxial high-cycle fatigue of metallic materials

Abstract

A study has been carried out to assess the influence of a superimposed mean shear stress on the capability of some multiaxial high cycle fatigue criteria. Five critical plane-based criteria, namely Matake (M), Susmel & Lazzarin (S&L), Findley (F), Carpinteri & Spagnoli (C&S) and Liu & Mahadevan (L&M) [1-5] were investigated deriving from their own equations the dependence of the fatigue resistance limit in shear stress loading as function of the mean shear stress. Seven different loading conditions reported in previous studies as critical relative to 42CrMo4 and 34Cr4 steel alloys have been considered [6]. Such loading conditions, which are expected to lead the materials to the threshold of failure in the order of one million cycles, were applied to the previously mentioned criteria (M, S&L, F, C&S and L&M), as well of being applied to a mesoscopic scale-based criterion proposed by Papadopoulos (P) [6]. Since Papadopoulos’ criterion, in agreement with well-established experimental observations [7-9], is independent of mean shear stress, it seems appropriate to conclude that the inclusion of the mean shear stress in the criteria should exert a negative influence on the fatigue behaviour predictive capability.