Amelioration du procede RTM par l'optimisation des parametres d'injection

Liquid Composite Molding (LCM) regroups a number of well known manufacturing techniques of polymer composites based on resin injection through fibrous reinforcements. LCM processes such as RTM (Resin Transfer Molding) have been increasingly used to manufacture parts for a wide range of industrial applications and were shown to be cost-effective in the low to medium range of volume production. To improve the performance of these processes, more scientific knowledge of the impregnation phenomena is required. In LCM processing, injection pressure dominates the impregnation of the fibers. It was recently observed that the local resin velocity is key for proper impregnation of the fibrous reinforcement. From this observation, mechanical properties of composites are highly dependent of void content since voids are sites of residual stresses. Formation of macro/micro voids entrapped between or within the fiber tows is a function of the capillary pressure of the resin, the porosity of the fiber bed and the local fluid velocity. An optimum resin velocity exists so as to minimize the content of macro and micro voids during resin impregnation.; Presented in this thesis, an experimental analysis is carried out on different types of fibrous reinforcements to identify the optimal impregnation velocity. Experimental injections were carried out at constant flow rate and constant pressure. The content of macro/micro voids was related to the local capillary number and also their presence was also studied to measure their effects on mechanical properties of the composite.