Investigation into the changes in bending stiffness of a textile reinforced composite due to in-plane fabric shear: Part 1 – Experiment

A study to investigate the factors that contribute to the variation among the stiffnesses of consolidated composite plates reinforced by plain-weave fabrics with various degrees of in-plane shear is presented. The first part of the two-part study focuses on the experiments performed. Three-point bend tests were used to measure the effective stiffness of the composite plates along the global X and Y axes, which were aligned with the weft and warp orientations, respectively, in the undeformed configuration at 0° of shear. The warp yarns were sheared 0°, 10°, 20°, 25° and 30° toward the weft yarns. It was observed that as the shear angle in the plates increased, the thickness of the plates also increased. An increase in stiffness for bending in X-direction with increasing shear angle was observed as was expected, but the change in stiffness for bending in Y-direction was observed to be inconsistent with the expected decrease with increasing degree of shear.