Mesoscale modeling of ultra-thin woven fabric composite subjected to in-plane loading

Ultra-light composites are produced through the spread tow technology. The success of spread tow fabrics lies in their unique woven structure. By interlacing widespread thin flat tapes, instead of regular (and thicker) yarns, more straight fibers and thinner plies are obtained which leads to improvements in the mechanical performance in terms of both stiffness and strength. The available numerical studies on spread tow fabric composites are based on the approximation to equivalent thin ply laminates, where the key observations are dedicated to a delayed or suppressed microcracking. This paper helps to investigate the limitations of considering thin-ply spread tow composites as equivalent laminates, as well as to bring more understanding on how the tow thickness affect the sequence of failure mechanisms. As an aid to these investigations, a parameterized mesoscale model has been developed that preserves the complex geometry of the woven structure and can analyze the tow thickness effect down to 35 µm. By applying shifted periodic boundary conditions through the thickness, the effect of periodic layer shifting is also analyzed without having to discretize and model more than one layer of the composite.