A Dynamic Explanation of The Hybrid Effect

Abstract

A theoretical analysis has been performed to evaluate the dynamic stress concentration factor in hybrid composites composed of low elongation (LE) and high elongation (HE) fibers. At a fracture of a fiber, the present model predicts two stress waves propagating along each fiber in the hybrid. The phase difference of the dynamic responses contributed by these waves at the middle section of a fiber immediately adjacent to a fiber breakage is controll ed by the fiber mass per unit length. The magnitude of the dynamic responses is determined by the fiber extensional stiffness. The study concludes that hybrid effect always exists in a beneficial manner and the case of the parent LE fiber composite provides the upper bound for the dynamic stress concen tration factor in hybrids. The validity of the approximations made in the derivations has been examined.