A similitude approach towards the understanding of low velocity impact characteristics of bi-layered hybrid composite structures

This article discusses the impact behavioral responses of opaque bi-layered metal bonded hybrid composites from geometrically equivalent transparent plastic specimens. Low velocity drop weight impact experiments were conducted on bi-material laminated plates made of brittle acrylic sheet adhesively bonded with ductile polycarbonate layer by a compatible room temperature cure epoxy. Depending on the nature of impact face (brittle or ductile) battered by the impactor, the induced impact damage are characterized either as partial or complete interface failure that leads to formation of radial cracks or spalling fracture in the acrylic layer. The influence of relative constituent thickness towards impact damage resistance and the resultant structural integrity are extensively discussed. The obtained results from similitude study made it possible to understand the behavior of geometrically equivalent bi-layered fibre metal laminates under similar impact conditions. In addition through numerical simulations, the energy dissipated via plastic work by the ductile layers was found to be dominant and the only source that create significant difference in energy absorption between hard and soft side impact samples.