Comparison of Equivalent Stress Methods with Critical Plane Approaches for Multiaxial High Cycle Fatigue Assessment

Abstract

Several equivalent stress methods and more advanced critical plane criteria are compared in terms of their performance in fatigue life estimations under uniaxial and biaxial loadings in which the effect of phase is investigated. For this purpose a MATLAB code is written which transforms the multiaxial cyclic stress state into a uniaxial cyclic stress to use with the equivalent stress based methods. For critical plane approaches the program searches a damage parameter on all material planes. The maximum damage parameter is then compared with a material allowable obtained from uniaxial fatigue tests for life estimation. In addition, various methods for calibration of the material coefficient k and prominent stress history enclosure methods to calculate the shear stress amplitude are also studied for determining their effect on the performance of critical plane approaches.