TOWARD A VIRTUAL MATERIAL FOR LIFETIME PREDICTION OF CMCs

The Snecma Propulsion Solide, SAFRAN Group Company, has developed a range of woven SiC/SiC composites designated as self-healing materials [1]. The composites are build up from woven yarns of SiC fibres infiltrated by a multi-layered ceramic matrix. During the load, a first crack network, perpendicular to the principal traction, appear in the matrix between yarns [2]. Once it is saturated, a second network, oriented by the fibres, appear in the yarns [2]. The self-healing process consists in filling these cracks with an oxide resulting from oxidation of certain components of the matrix, which limits the diffusion of oxygen toward fibres, that are the core of the material and might suffer from subcritical cracking under oxidizing atmosphere [3]. Therefore, this process leads to a great increase in the material’s lifetime. The challenge associated with the use of such materials for large industrial applications resides in the development of robust models of their mechanical and chemical behaviour up to failure, based on the physics of their micro-mechanisms so as to extrapolate their response even for very large lifetimes.