The static and impact behaviour of polymer composite sandwich beams

Abstract

The static and dropped weight impact performance of polymer composite sandwich beams has been investigated in a three-point bend configuration. The skin materials examined included woven fabrics of glass, carbon and aramid fibre, as well as glass chopped strand mat. The core materials were Coremat ™ (resin-impregnated non-woven polyester) and Aeroweb ™ aluminium honeycomb. Polyester and epoxy resin matrices were used. The static failure modes of beams with various core and skin combinations are discussed. The dominant failure modes for both glass/Coremat and glass/Aerolam ™ beams involved upper skin failure in the vicinity of the penetrator. The dropped weight impact performance of the latter two types of beam, at impact speeds of up to 7.5 m s −1, was investigated. The Coremat-cored beams showed marked rate dependence effects, with failure energies reducing to a minimum at a given drop height and then increasing again with increasing drop height. The honeycomb-cored beams showed only slight rate dependence. The dynamics of the beam tests are discussed in terms of mass spring models and times to failure in the upper skins highlighted.