Flow analysis during compression of partially impregnated fiber preform under controlled force

Compression resin transfer molding (CRTM) is an alternative solution to conventional resin transfer molding processes. It offers the capability to produce net shape composites with fast cycle times making it conducive for high volume production. The resin flow during this process can be separated into three phases: (i) metered amount of resin injection into a partially closed mold containing dry fiber preform, (ii) closure of the mold until it is in contact with the fiber preform displacing all the resin into the preform and (iii) further mold closure to the desired thickness of the part compacting the preform and redistributing the resin. Understanding the flow behavior in every phase is imperative for predictive process modeling that guarantees full preform saturation within a given time and under specified force constraints. In this paper, the last phase of the resin flow during CRTM process is simplified and modeled as a one dimensional flow to obtain estimates for process time if the applied force is known. The constitutive equations describing the material used are discussed. Due to the non-linear nature of the formulated governing equations, a numerical solution is developed and the flow front progression and the change in preform thickness are experimentally verified. Finally, a non-dimensional analysis identifying the parameters involved in the process is presented. The impact of the main process parameter is then studied and conclusions regarding process feasibility and optimization are formulated.