Damage Modelling at the Mesoscopic Scale for 4D Carbon/Carbon Composites

摘要

The studied material produced by S.E.P. (Societe Europeenne de Propulsion) is a 4D Carbon-Carbon composite, therefore comprising four reinforcement directions. A very simple mathematical material model is initially derived for multiaxial loading, on the basis of some remarkable experimentally-observed properties, the material's geometry and the fiber yarns' orientations. Identifying the material constants and functions characterising the studied 4D C/C material is a rather difficult task: fiber debonding near the edges is very critical to tensile tests. In order to proceed further with the test analysis, large finite element computations have been performed by introducing a meso-model of the composite specimen, with the meso-contituents being the fiber yarns, the matrix blocks and the interfaces. For each meso-constituent (fiber yarns, matrix and interfaces), a material model is then derived. To construct a macroscopic behavior from the meso-model, a method based on the asymptotic development theory for periodic media is applied. Numerical results obtained are compared with experimental data, which allows validating the different choices made for the meso-model.