Crystal-plasticity finite-element simulation of time-dependent springback in a commercially-pure titanium sheet

Abstract

A crystal-plasticity finite-element method was used to examine the deformation mechanism of time-dependent springback in a commercially-pure titanium sheet. To reproduce the viscoplastic behavior of the sheet, the material parameters were calibrated to reproduce the strain-rate dependency of the stress-strain curve under uniaxial tension. A two-dimensional draw bending process was simulated and the change in the sidewall curvature was evaluated. The simulation results showed that the curvature increased with the elapsed time after unloading, consistent with experimental results reported elsewhere. The deformation mechanism during the process was discussed in terms of evolution of stress and relative activities of slip and twinning systems.