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.

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“…where: S is the stress in the outer fibers at mid-span (N/m 2 ), P -the load at a given point on the loaddeflection curve (N), L -the support span (m), b -the width of beam tested (m), d -the depth of beam tested (m), E -the modulus of elasticity in bending (N/m 2 ), m -the slope of the tangent to the initial straight-line portion of the load-deflection curve (N/m) of deflection, e -the bending deflection (%), Dl -the elongation (m) and l 0 -the initial length (m). The specific-bending strength (4), modulus (5) and deflection (6) were also calculated to evaluate the test results in normalized form based on both the measured density [37] and fiber volume fraction (V f ).…”

Applications of Glass Fibers in 3D Preform Composites

“…On the other hand, the warp and weft directional damaged areas of the unstitched composites are higher than multistitched and multistitched/nanocomposites. The addition of the nanosilica to the stitched structures increases the damage tolerance [72]. One of the critical property of the stitched composite is also through-the-thickness directional shearing.…”