Influence of the dry woven fabrics meso-structure on fabric/fabric contact behavior

The first stage of the RTM process concerns the preforming of the part. During the preforming of multilayered reinforcements, frictions between the plies occur. An experimental device designed to analyze the ply/ply, ply/tool, and yarn/yarn frictions has been built. Specific contact behavior for ply/ply friction is directly related to shocks taking place between overhanging yarns of each sample. Within the signal, two particular periods can be exhibited. This work shows for four different architecture woven fabrics that the two periods are directly related to the meso-architecture of the studied woven fabrics and more precisely to the characteristics of the fabric unit cell. The friction response appears to be very sensitive to the relative positioning and orientation of the samples. It can also lead to manufacturing defects such as unweaving or wrinkles. Up to now, finite element codes predicting the forming behavior of woven reinforcement fabrics do not take into account this friction coefficient evolution to model accurately the process. This point could therefore be addressed in future works on this topic with the view to optimize the multi-ply forming of composite parts.