Debond modeling for multidirectional composites

Damage mechanisms and inelastic mechanical phenomena are modeled at the mac roscopic scale for multiaxial loading. The studied material made by SEP (So ciete Europeenne de Propulsion) is a 4D Carbon-Carbon composite comprised o f four reinforcement directions. A very simple mathematical material model has been derived first for multiaxial loading as a consequence of some rema rkable experimentally observed properties and the material geometry. The an isotropic continuum damage theory introduced by Ladeveze is used. Identifyi ng the material constants and functions characterizing the studied 4D C/C m aterial is a rather difficult task: fiber debonding near the edges is very important for tensile tests. To go further in the test analysis, large fini te element computations have been performed and presented in this paper int roducing a meso-model of the composite specimen, the meso-constituents bein g the fiber yarns, the matrix blocks and the interfaces. Finally, the ident ified material model has been verified through various experiments. (C) 200 0 Elsevier Science S.A. All rights reserved.