The mechanical properties of 3D woven composites

In this work, three types of 3D woven fabric (orthogonal, angle interlock, and layer-to-layer) were used to study the effect of weaving architecture on processing and mechanical properties. In order to characterize the fabrics for liquid composite molding processes, the compaction and permeability characteristics of the reinforcements were measured as function of fiber volume fraction. High compaction pressures were required to achieve a target fiber volume fraction of 0.65, due to presence of through-thickness binder yarns that restricts fiber nesting. In-plane permeability experiments were completed and flow front patterns were obtained to understand the anisotropy in the laminates. The resin transfer molding process was then used to manufacture panels that were then tested under quasi-static flexure and low-velocity impact conditions. It was found that the flexural strength and modulus were higher along the weft direction, where high in-plane permeability of the reinforcement was observed, due to fiber alignment. Impact tests on composite plates based on the three types of fabric indicated that the orthogonal system offered a slightly higher perforation resistance and lower levels of damage at any given energy.