Programming of a Multiaxial Stress-Strain Model for Fatigue Analysis

The formulation of an isotropic-kinematic hardening model with a continuous yield surface field is briefly reviewed. Particular emphasis is focused on the redistribution of the yield surface field as a result of plastic loading. It is demonstrated that successive yield surface field redistributions can be concisely recorded by tracking the positions of a very small number of yield surfaces even under a complicated loading history. A FORTRAN program is then developed based on the model with the simple von Mises type of yield criterion. Applications to analysis of some biaxial tests on thin-walled tubes of SAE1045 steels show good agreements between the predicted and measured stress results.