Investigation into laminate design of open carbon–fibre/epoxy sections by quasi–static and dynamic crushing

The effect laminate design on the crush performance of carbon–fibre/epoxy “DLR” crush elements has been experimentally investigated. A quasi-isotropic lay-up was found to result in the highest Specific Energy Absorption (SEA) for Four-Harness (4HS) reinforced laminates; however a hybrid of unidirectional weave and 4HS fabric produced the highest SEA of 114 kJ/kg. Interleaving with thin thermoplastic films increased the steady state crushing force, however the increase in laminate density associated with the addition of the film caused no improvement and in some cases a reduction in SEA depending on material and lay-up. Dynamic crush testing of selected laminate designs resulted in a reduction in SEA of between 6% and 15% compared to the quasi–static case.