Effects of Weave Styles and Crimp Gradients on Damage Tolerance and Energy-Absorption Capacities of Woven Kevlar/Epoxy Composites
NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
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This research investigates the effects of weave styles and crimp gradients CGs on the damage-tolerance levels and energy-absorption capacities of woven fabric-reinforced polymer WFRP composites. A comparative study was conducted to determine the specific failure mechanisms including fibermatrix cohesive failures, matrix cracking, fiber breakage, and fiber buckling resulting from static and dynamic loading events. The tests Included flexure, short beam shear, drop impact, flexure-after-impact, ballistic impact, and split Hopkinson compression bar SHCB and were performed on 20-ply Kevlarepoxy WFRP laminates. Laminates of three different Kevlar fabric weave styles were fabricated using plain, 2x2 twill, and 4H satin weaves. A fourth fabricated laminate used a mixture of weave styles forming a hybrid CG construction. The experimental results demonstrated 1 that weave style selections and CGs can positively influence the spatial and temporal distributions of stress resulting from severe loading events and 2 that the fibermatrix cohesive zone stresses that often lead to delaminations can be reduced. Accordingly, the dependence of mechanical performance on weave styles, crimp contents, and CGs can be exploited to increase the damage-tolerance levels and energy-absorption capacities in WFRP composites.
- Laminates and Composite Materials