A stress-based multiaxial high-cycle fatigue damage criterion

A stress-based high-cycle fatigue damage criterion for multiaxial load cases is proposed and verified using published test results for mild steel, hard steel, cast iron and an aluminium alloy. The maximisation of the Damage Function, D(l,m,n)=[(τa(l,m,n)Te)2+k(σn,max(l,m,n)Se)2]12, yields damage resulting from combinations of shear stress amplitude and maximum normal stresses on critical planes defined by their vector normal directional cosines l, m and n. A ‘normal stress sensitivity’ factor, k, proportions the allowable maximum normal stress according to the endurance strength ratio, Te/Se. The results show accurate predictions of fatigue failure on the critical plane compared to McDiarmid's criterion and the combined WMPS/Carpinteri/Spagnoli method. The three-dimensional nature of the method does not limit the analysis to planes normal to the surface of the specimen, providing a more informative result.