Simulation of Impact Response of Polymer Composites Utilizing an Orthotropic Three-Dimensional Model with Tabulated Input

A material model which incorporates several key capabilities required for the predictive simulation of the impact response of composite materials has been developed. This model has been implemented into the commercial transient dynamic finite element code LS-DYNA as MAT 213. The deformation and damage modules of the material model utilize experimentally based tabulated input to define the evolution of plasticity and damage as opposed to specifying discrete input parameters (such as modulus and strength). The deformation module of the orthotropic, three-dimensional, macroscopic composite constitutive model is based on an extension of the Tsai-Wu composite failure model into a plasticity model including a generalized yield function with a nonassociative flow rule. For the damage module, a strain equivalent formulation is utilized to allow for the uncoupling of the deformation and damage analyses. The terms in the damage tensor are semicoupled such that the damage in a particular coordinate direction is a function of the stresses and plastic strains in all of the coordinate directions. For the failure module, a unique tabulated failure model has been developed which allows for arbitrarily shaped failure surfaces. A systematic series of validation and verification studies, at a variety of length scales ranging from single element simulations to simulations of a flat panel impact test, have been performed to fully exercise and evaluate the capabilities of the developed model.