Warp–weft directional bending properties of multistitched biaxial woven E-glass/polyester nano composites

Abstract

The aim of this study was to understand the warp–weft directional bending properties of the developed two-dimensional multistitched multilayer E-glass/polyester woven nano composites. The warp–weft directional specific bending strengths and modulus of unstitched/nano composite structures were higher than those of the unstitched structures. Contrarily, the warp–weft directional specific bending strengths and modulus of unstitched structure were higher than those of the machine stitched and machine stitched/nano structures due to stitching caused filament breakages. When the stitching direction increased, the warp–weft directional bending strengths and modulus of the structures decreased. The warp–weft directional specific damaged areas of unstitched structure were higher than those of the multistitched and multistitched/nano structures. The addition of nano silica to the stitched structures improved their damage resistance slightly. It was generally found that when the number of stitching directions and stitching density in structures increased, the damaged areas of structures decreased. The failure of warp–weft directional multistitched and multistitched/nano woven E-glass/polyester composite structures was matrix breakages, partial and complete filaments, and yarn (tow) breakages in their surfaces. They had a local delamination in their cross-sections and the delamination did not propagate to the large areas due to multiple stitching. The failure was confined at a narrow area due to multistitching and resulted in the catastrophic fiber breakages. This was considered that the damage tolerance performance of the multistitched structures was enhanced due to stitching, in particular, at four directional stitching.