THE USE OF KINEMATIC HARDENING MODELS IN MULTI-AXIAL CYCLIC PLASTICITY

Abstract— The use of kinematic hardening models are examined for tubes subjected to (a) cyclic plastic torsion with a sustained axial stress and (b) cyclic plastic tension-compression with a sustained hoop stress. It is shown that the kinematic model predicts a limit to the plastic strain accumulation resulting from the sustained loads. Experimental results show that the strain accumulation is not limited and that the mode of deformation within a cycle of plastic strain cannot be predicted using a kinematic hardening model. The development of the yield surface under cyclic loading is examined. The results indicate that contraction and expansion of the yield surface along the stress axes can occur and it is shown that the direction of the sustained stresses, relative to the direction of the cyclic stresses is an important factor in the development of any cumulative plastic strains.