Low cycle fatigue life prediction for 304 stainless steel under nonproportional loadings

A series of experiments on low cycle fatigue under nonproportional loading were conducted on tension-torsional fatigue facility for 304 stainless steel. Several multiaxial fatigue criteria in common use were analyzed. It shows that equivalent strain approaches based on uniaxial fatigue life analysis methods like maximum shear strain parameter and maximum normal strain parameter couldn't predict low-cycle fatigue lives under nonproportional cyclic loadin. Because of not considering of deformation behaviour under nonproportional loading, the unconservative predictions of the factor of five times are given. The predictions of SWT model based on tensile critical plane are generally within a factor of two scatter band, but some test points are on unsafe side. The Socie shear model based on critical plane approach gives better prediction when it is used to predict fatigue lives of 304 stainless steel under nonproportional loading. The predictions of Fatemi model based on shear critical plane approach are on conservative side.