Finite Element Method for an Incremental Viscoplasticity Theory Based on Overstress.

摘要

A one-step time integration method is developed for Krempl's viscoplasticity theory based on overstress. Differential growth laws for the tensorial and scalar state variables are included in the constitutive model. This time integration method leads to explicit symmetric tangent operators which are suitable for finite element implementation. An adaptive time-stepping scheme has been developed for the incremental finite element procedure. Finite element calculations which simulate homogeneous deformation state in 304 stainless steel and 6061 T6 aluminium alloy under various strain and stress rate histories are performed. The accuracy and robustness of the algorithm are assessed by comparing the finite element results with solution obtained from the stiff ordinary differential equation solver. The numerical experiments show that the use of simple integration formulas together with adaptive time-stepping procedure provide a satisfactory for general stress analysis in viscoplastic solids. Reprints. (jhd)