Progressive Damage Modeling of Plain-Weave Composites using LS-Dyna Composite Damage Model MAT162

Abstract

Progressive damage of plain weave S-2 Glass/SC15 composites under in-plane tension, compression, and shear, through-thickness tension and compression, and transverse interlaminar and punch shear loading is presented for a unit single element using the MAT162 composite damage model in LS- Dyna. While the detail formulation of the MAT162 material model can be found in the Keyword user's manual [1], the main objective of this paper is to describe a methodology to determine a set of softening parameters using a unit single element analysis. The analytical formulation of post-yield damage softening is presented with stress-strain behavior of a single element under different loading conditions. Since MAT162 uses four different softening parameters, i.e., AM1 and AM2 for fiber damage along material directions 1 and 2, AM3 for fiber shear and crush, and AM4 for matrix crack and delamination; the choice of a set of these four AM values is not obvious. The stress-strain plots presented in this paper will serve as an additional user guide to select a set of AM values for a specific material and a specific application. Unlike linear-elastic design of composite structures with max-stress/strain or quadratic failure theories, modeling the post-yield softening behavior allows one to simulate the energy absorbing capabilities of a composite structure. It is important to choose a set of AM values which represent a material's behavior through single element analyses and validation of the model with other quasi-static and dynamic experiments. A poor choice of the AM values may lead to prediction of either higher or lower energy absorption capabilities of the composite structure. In order to accomplish this objective, the single element analysis is presented with appropriate loading and boundary conditions. Model validation studies simulating static and dynamic experiments can be found in [2], and further studies will be presented elsewhere