Effect of Stitch Orientation on Tensile and Flexural Bending Mechanical Properties and Damage Mechanisms of Glass/Epoxy Composites Laminate

Abstract

This study aims to investigate the effect of stitch row directions on tensile and flexural bending mechanical properties of composite laminates reinforced by glass-fabric. For the fabrication of stitched laminates, a polyester thread was used to stitch the dry fabric glass in fourth cases (longitudinal stitch 0°, transversal stitch 90°, multi-stitching 0°/90°, and 45°/-45° stitch) with 4 mm stitch spacing. The responses of stitched laminates specimens subject to the tests mentioned were compared to the unstitched laminates and discussed. According to our results, the effect of stitching plays opposite roles on the tensile property by decreasing of about 45% and 36% in tensile strength and longitudinal modulus compared to unstitched specimens, respectively. However, an increasing approximately 11.69% to 20.25% in flexural strength found in samples stitched along 0° and multi-stitching 0°/90°, due to the stitch lines through-thickness by arrests temporally of cracks propagation and the delamination progressively propagate between layers.