Endochronic simulation for finite elasto-plastic deformation under cyclic torsion with pre-strain or pre-stress

By using the concept of the corotational stress rate, the constitutive equations of the endochronic theory are extended to simulate elasto-plastic deformation in the finite strain range. The endochronic theory incorporated with the Mandel stress rate is used for investigating the deformation of metal tubes subjected to finite cyclic torsion with pre-strain or pre-stress in this paper. Different formulation of the plastic spin, which can be used in Mandel stress rate, is also derived. Experimental data of 1100-O aluminum tested by Wu and Xu (1989) under finite cyclic torsion are used for comparison with the endochronic simulation. The result reveals that the axial effects caused by the cyclic torsion with pre-strain or pre-stress can be adequately described by the theory.