INTRALAMINAR SHEAR LOADING EFFECTS ON THE DAMAGE PROCESS OF MULTIPLY COMPOSITES AT IMPACT RATES

Composite materials, when they are used as structural elements to ensu re absorption energy during impacts, can give better results than thos e 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 intra laminar shear effects at fibre-matrix interfaces when composite materi als are subjected to impacts. A servo-hydraulic testing machine and a Hopkinson bars tensile apparatus were improved to investigate, by usin g Damage Mechanics, the shear behaviour under high strain rates of E-g lass reinforced epoxy crossply laminates. A microscopical analysis of the damage phenomena allows us to know the damage initiation and propa gation processes.