Endochronic simulation for finite viscoplastic deformation

The rate-sensitivity function of the endochronic theory proposed by Pan and Chern (1997) is modified herein to incorporate with the finite endochronic constitutive equations obtained by Pan et al. (1996) for simulating the material responses subjected to finite viscoplastic deformation. Explicit constitutive equations subjected to finite torsion with an axial pre-stress are derived in this study. Experimental data of iron (α-Fe) in simple torsion and commercial nickle (Ni-200) in torsion with an axial pre-stress for different shear strain-rates found in previous literature are used for comparison. It is shown that the simulated shear stress-strain responses and the axial effects caused by finite torsion correlate well with the experimental data.