Modified hyper-viscoelastic damage evolution constitutive model for polyurethane materials - an experimental and numerical investigation

Elastomeric materials are widely used in different industries due to their excellent capability to withstand different loading types. There are significant challenges to the efficient design of elastomeric structures because of the rate-dependent and highly nonlinear behavior of this type of material. In this study, a damage zone model was employed to simulate the material behavior and damage evolution in polyurethane (PU) elastomers with different shore hardness. This model consists of three sections, hyper viscoelastic constitutive model, damage initiation, and damage evolution using a hyper viscoelastic traction-separation law. To simulate the nonlinear behavior of PU, a dynamic increase factor (DIF) implemented into the Mooney-Rivlin strain density function with 9 parameters. The material characteristics are specified by performing the experimental tests for three different shore hardness. In this study, a user-defined subroutine (VUMAT) was developed to predict the damage evolution in the pure shear tearing specimen of PU elastomers. The results verification proves a good agreement between the FEA simulation and experimental data. Therefore, the developed numerical analysis procedure can be used to investigate the damage initiation and evolution in elastomeric materials.