Finite element modeling of the time‐dependent behavior of nonlinear ductile polymers

Abstract

Abstract A finite element algorithm developed previously has been successfully extended to the study of nonlinear time‐dependent problems. Nonlinear viscoelastic and viscoplastic models have been used to study the time‐dependent deformation and failure of high density polyethylene (HDPE). Two classes of nonlinear models have been identified; those that allow stress redistribution with time under specified traction boundary conditions, and those that do not. The implications of using viscoelastic vs. viscoplastic models, as well as the specific mathematical form of the constitutive equations selected for use, have been studied. Strains predicted using the FE algorithm have been compared with experimental measurements for (i) a HDPE plate with a hole and (ii) a double edge notch HDPE specimen, both under remote tension. Excellent agreement was obtained between numerical predictions and the experimental values.