Mechanical response of composite materials with through-the-thickness reinforcement

Abstract

An experimental investigation was conducted to identify the key geometrical parameters and quantify their influence on the mechanical response of through-the-thickness (TTT) reinforced composite materials. Composite laminates with TTT reinforcement fibers were fabricated using different TTT reinforcement materials and reinforcement methods and laminates were also fabricated of similar construction but without TTT reinforcement fibers. Coupon specimens were machined from these laminates and were destructively tested. TTT reinforcement yarns enhance damage tolerance and improve interlaminar strength. Thick-layer composites with TTT reinforcement yarns have equal or superior mechanical properties to thin-layer composites without TTT reinforcement yarns. A significant potential exists for fabrication cost reduction by using thick-layer composites with TTT reinforcement yarns. Removal of the surface loop of the TTT reinforcement improves compression strength. Stitching provides somewhat higher mechanical properties than integral weaving