Analytical formulation of (0°,±α°) braided composites and its application in crashworthiness simulations

New types of tridimensional composite materials have been developed during the last few pears. These new materials consist of braided, weft or warp knitted, and 3D woven composites preforms, and they present excellent out-of-plane mechanical properties. In this article, tubular energy absorbers, constituted of carbon-glass hybrid braided composites, are analyzed by means of the finite-element method, with explicit rime integration of the equations of motion. A nerv material model for (0 degrees, +/- alpha degrees) braided composites is introduced in a commercial finite-element code by means of user-developed subroutines. Braided materials with carbon fiber in the Or direction and glass fibers in the +/- alpha degrees directions are studied. Moreover, different fiber orientations and geometry of the triggering devices are analyzed in order to obtain the optimum configuration in terms of specific energy absorption.