A Constitutive Model for Progressive Compressive Failure of Composites

Abstract

A continuum damage mechanics model previously developed to model the tensile response of composites has been further enhanced to simulate their nonlinear constitutive behavior under compressive loading. The refinements were based on the behavior of an analog model, which was constructed to represent the complete force—displacement response of a representative volume element of the material. The updated constitutive model accounts for mechanisms considered to be characteristic of compressive damage growth in laminated composites, such as matrix cracking, fiber kinking, and delamination. The constitutive model was implemented in the commercial explicit finite element code, LS-DYNA, and is used here to predict the quasi-static compressive response of open-hole laminates as well as the dynamic axial crushing of braided composite tubes. It is shown that the model adequately captures: (1) the damage growth and local strain fields in open-hole specimens, and (2) the failure characteristics and energy absorption of braided composite tubes. This investigation demonstrated that the new model is capable of predicting the experimentally observed compressive response in these two rather different applications, and that it potentially offers an effective means of simulating the nonlinear damaging behavior of composite materials under a variety of loading conditions.