NONLINEAR MECHANICS OF TWO-DIMENSIONAL CARBON-CARBON COMPOSITE STRUCTURES AND MATERIALS

The inelastic mechanics of isotropic materials are usually modeled by scalar functions of the material stress or strain state. Simple effective stress-strain models work well because of the material symmetry and homogeneity usually found in structural materials, and because of a single deformation mechanism accounts for inelastic strain behavior. In contrast, laminated carbon-carbon composites are anisotropic with a weak matrix phase and exhibit at least two inelastic deformation mechanisms in coupon tests. The present paper describes results froma program that developed and demonstrated a nonlinear model for two-dimensional carbon-carbon composites based directly on coupon stress-strain data. A low modulus bidirectional material, K-KARB, was used to validate the model in room temperature tests. Refs.