Intralaminar shear loading effects on the damage process of multiply composites at impact rates

Composite materials, when they are used as structural elements to ensure absorption energy during impacts, can give better results than those of steel. However, their energy absorption capacities can be reduced due to some damage mechanisms, like intralaminar shear, which induce a premature failure. The aim of this study is to investigate the intralaminar shear effects at fibre-matrix interfaces when composite materials are subjected to impacts. A servo-hydraulic testing machine and a Hopkinson bars tensile apparatus were improved to investigate, by using Damage Mechanics, the shear behaviour under high strain rates of E-glass reinforced epoxy crossply laminates. A microscopical analysis of the damage phenomena allows us to know the damage initiation and propagation processes.