Gholamreza Rashed - Department of Mechanical Engineering, Abadan Faculty of Petroleum, Petroleum University of Technology, Abadan, Iran

The ability to calculate elastic-plastic stress-strain relation is a prerequisite for achieving good fatigue life predictions. In this paper a parameter that includes normal and shear strain based on critical plane method is used to consider the additional hardening effect of the material due to nonproportional loading. Von Mises’ equivalent strain criterion is also used. The stress-strain relationship under multiaxial cyclic nonproportional loading is derived using the proportional loading stress-strain relationship.

Multiaxial, Nonproportional, Stress-strain relationship, additional hardenin, fatigue