Knitted composites for energy absorption under tensile loading

A new class of knitted composites has been designed to maximize the total e nergy absorbed during tensile failure. Knitted loops of light, continuous f iber tows are configured in such a way that they must be drawn through rela tively large displacements before they come into direct contact with one an other. Upon loop contact, the material hardens locally, forcing further dam age to develop by the same process elsewhere. In this way the entire gauge section absorbs energy before ultimate failure. Levels of energy absorption per unit volume reach 40 MJ/m(3) and, per unit mass, 25 J/g. The mechanism s involved in damage delocalization and failure are detailed and modeled in a simple manner. While the current values of energy absorption are already attractive, the models indicate that much higher values could be attained with optimized composites. (C) 2000 Elsevier Science Ltd. All rights reserv ed.