Gh.R Rashed - Associate Professor, Department of Mechanical Engineering, Petroleum University of Technology, Abadan Faculty of Petroleum, P. O. Box ۶۱۹, Abadan, Iran

The ability to calculate elastic-plastic stress-strain relation is a prerequisite for achieving good fatigue life predictions. Determination of a multiaxial stress-strain relationship for multiaxial cyclic loading has been studied 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 hardening