Modelling and characterization of porous fabric reinforcement permeability and compressibility in composite materials manufacturing

Through-thickness permeability of an E-glass non-crimp fabric (NCF) was modeled and characterized experimentally. Characterization setup used previously in various studies was modified. The number of layers used in an experiment was reduced and a new approach was designed to adjust the fiber volume fraction of the fabric preform. In-plane permeability components of a biaxial fabric was characterized by 2D (radial) flow experiment. Scatter between experimental results was observed similar to previous results in literature. Compressibility of a NCF was characterized using a vacuum infusion setup, pressure regulator and structured light scanning (SLS) system. Compared to previous study in our research lab, a new experimental SLS schedule was designed and tested for compressibility characterization. The accuracy of a single SLS measurement was low, however it was shown that repeated measurements had a better accuracy which made our SLS system suitable to monitor the part thickness variation with time. The variation of fiber volume fraction within the porous tows of a woven fabric was numerically investigated using ANSYS Fluent. In general, permeability of a tow assembly in a unit cell with spatially varying fiber volume fraction was lower than uniformly distributed fiber volume fraction. A dual scale model was prepared and verified by comparing its results with another study and its case studies available in the literature. Our model allows accounting any local variation in fiber volume fraction. This thesis contributes to the literature by presenting a new approach in modelling of fabric reinforcement permeability and compressibility which accounts for the non- uniformity of fiber distribution and the local variation of fiber volume fraction. Thus, it can be a guide to an appropriate model for different levels of fiber nesting of compacted fabric layers, as observed in composite manufacturing processes such as resin transfer molding and vacuum infusion.