Braided composites for energy absorption under tensile loading

A new class of braided composites has been designed to maximise thetotal energy absorbed during tensile failure. Braided loops oflight, continuous fiber tows are configured in such a way that theymust be drawn through relatively large displacements before they comeinto direct contact with one another. Upon loop contact, thematerial hardens locally, forcing further damage to develop by thesame process elsewhere. In this way the entire gauge section absorbsenergy before ultimate failure. Levels of energy absorption per unitvolume reach 30 MJ/m3 and, per unit mass, 18 J/g. The mechanismsinvolved in damage delocalisation and failure are detailed andmodeled at a very simple level. While the current values of energyabsorption are already attractive, the simple models indicate muchhigher values for composites that have been optimised.