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Bilateral Contracts and Grants with Industry
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Section: New Results

Virtual self-healing composite for aeronautic propulsion

Participants : Mathieu Colin [Corresponding member] , Xi Lin, Gregory Perrot, Mario Ricchiuto.

As a composite material having excellent properties, Ceramic-matrix composites (CMCs) comprise a ceramic matrix reinforced by a refractory fiber such as silicon carbide fiber. Due to the self-healing process (which consists in filling cracks produced by oxydation by an oxide formed in-situ), CMCs have extremely long lifetimes even under severe mechanical and chemical solicitations. These time spans make most full-scale experimental investigations impractical : laboratory tests have necessarily to be replaced by predictions based on numerical models. Initial results have already been obtained by in the past with simplified crack averaged models based on simple potential approximations of the flow field of the oxide. In this direction, Xi Lin has developed new asymptotic models by creating a hierarchy inside two different families : the Saint-Venant equations and the thin film equations. The hierarchy is based on the use of several different boundary conditions. The main goal is to obtain more accurate hydrodynamic models accounting for surface tension and viscous effects which may be very important for the oxide evolution.

In parallel, we have made great progress in the coupling of the chemistry module with the structural mechanics solver of the LCTS laboratory in Bordeaux. The first fully coupled simulations of a fatigue test for a so-called mini-composite (on single fibre tow). The simulations have allowed to reproduce the gradual breaking mechanism typical of these materials, allowing to reproduce numerically the delayed rupture observed in practice.