Damage modeling at two scales for 4D carbon/carbon composites

Damage mechanisms and inelastic mechanical phenomena are modeled to the mac roscopic scale for multiaxial loading. The studied material made by Societe Europeenne de Propulsion (SEP) is a 4D carbon-carbon (C/C) composite compr ising four reinforcement directions. A very simple mathematical material mo del has been first derived for multiaxial loading as a consequence of some remarkable experimentally observed properties and the material geometry. Th e anisotropic continuum damage theory introduced by Ladeveze is used. To id entify the material constants and functions characterizing the studied 4D C IC material is a rather difficult task: fiber debonding near the edges is v ery important for tensile tests. This is due to an edge effect, which modif ies the local distribution of the stresses near a free surface. The study o f this phenomenon is made at a mesoscopic scale with three constituents: th e fibers, the matrix and the interfaces. A son-linear-damage model is intro duced for the interface. Large scale FE calculations are done using special numerical methods adapted to such problems: a domain decomposition approac h is associated with the LAnge Time INcrement (LATIN) method. Finally, the identified material model has been checked on various experiments. (C) 2000 Civil-Comp Ltd. and Elsevier Science Ltd. All rights reserved.