Non-Linear Analysis Models for Design of Carbon-Carbon Components (MSC P4172)

Efficient use of two-dimensional (2D) and three-dimensional (3D) woven carbon-carbon (C/C) composite materials used in many thermal protection applications requires that onset and development of material non-linearity be accounted for during design. The theoretical framework and computational infrastructure to implement nonlinear material models into the finite element analysis code ABAQUS exists at Materials Sciences Corporation (MSC), including both stress-based and/or fracture-based failure analysis methods. Post-damage onset material response in the stress- or strain based ply level composite failure modeling approach is approximated as piece-wise linear and the continuum level response for the fiber bundle and woven composite is defined analytically based on homogenization theory. The fracture-based approach is referred to as the discrete damage space homogenization method, or DDSHM, since the damage state within a representative volume element is discretely modeled. The DDSHM approach can also calculate, directly and in a theoretically rigorous manner, changes in thermal expansion coefficients and thermal conductivity as damage evolves, which may be important for C/C materials. The link between constituent material properties, micro-structural features and measured response will be established under this program thus providing a path to a validated micromechanics modeling approach that can be used to support thermal protection component design.