Finite element analysis for time-dependent inelastic material behavior

Abstract

A representation of inelastic, time-dependent material behavior, due to Bodner and Partom, in which both elastic and inelastic deformations are considered to be present at all stages of loading and unloading, is shown to be well-suited to structural analyses using finite element modeling techniques and high speed digital computation methods. The formulation considerably simplifies the computational logic for non-monotonic and cyclic loading problems since no special unloading criteria or yield conditions are required. Examples demonstrating strain-rate sensitivity, work-hardening, and reversed loading behavior are given for problems in the small strain range. Experimental results for a titanium tensile specimen subjected to changes in crosshead velocity are compared with predictions based on a plane stress finite element model. Numerical analyses using axisymmetric, solid of revolution finite element models are presented for unstiffened and ring-stiffened cyclindrical shells subjected to time-dependent external pressure.