This book is a comprehensive effort to quantify and characterize the influence of multilayer interlocked woven structure on the preform properties, resin impregnation behavior and low velocity impact properties of composites. A total of nine different multilayer interlocked woven fabrics consisting of 2-ply and 3-ply structures with different interlacement patterns have been developed for the present study. The structures of these multilayer fabrics were characterized using "Interlacement index". Influence of fabric structure in terms of interlacement index on the preform properties relevant for resin transfer moulding (RTM) of composite manufacture, such as compression, permeability and tensile behaviour have been incorporated. Resin flow through the porous reinforcement inside the moulds during RTM process was simulated using the permeability properties of these multilayer fabrics. Single-phase (resin only) and Multiphase (air and resin) flow models were developed for the simulation using CFD-Fluent software. Studies on the influence of interlacement in the multilayer fabrics on the low velocity impact properties of the composites reinforced with them have been carried out.