An impregnation model for the consolidation of thermoplastic composites made from commingled yarns

A model for the consolidation of thermoplastic composites based on commingled yarns was developed. The evolution of composite void content during consolidation was related to the processing parameters and the material properties. Additionally, the analysis relied on experimental investigation of the yam structure, taking into account a distribution in dry fiber bundle sizes. Residual porosity was considered to result from pore closing at a given stage during fiber bundle impregnation. The accuracy of the model was assessed by conducting consolidation experiments using a unidirectional commingled yam fabric made of polyamide 12 resin and carbon fibers. Excellent correlation was found between predicted and experimental void contents. The model aided prediction of suitable processing conditions and identification of the main physical and geometrical parameters influencing the consolidation rate.