We suggest a behavioural damage model. The model describes the principal phenomena observed in Ceramic Matrix Composites, namely: initial anisotropy, induced anisotropy, in other words the effects of damage on the elastic behaviour, default evolution law, closure effects in relation with residual strains. We have developed a formulation which allows to use damage variables both related to microcracks oriented by the constituents and microcracks oriented by the loading. It is now admitted that defects can either be oriented by the microstructure, and therefore expressed by a family of scalar variables, or by the loading, which leads to use tensorial variables. We show an application to the case of ceramic matrix composites (SiC/SiC) which presents two damage modes and requires to use both scalar and tensorial variables. We emphasise on the explicit feature of this model which simplifies the parameter identification and the implementation in finite element codes.
