Effect of stepwise gradient on dynamic failure of composite sandwich beams with metal foam core subject to low-velocity impact

Abstract

Dynamic failure behaviors of fully clamped and simply supported composite sandwich beams with stepwise gradient foam cores subject to low-velocity impact have been investigated experimentally. The sandwich beams with uniform foam core, positive-gradient foam core and negative-gradient foam core are designed and manufactured. The experimental results show that the mass distributions of cores have significant effect on the failure modes. The low-density foam layer at the impact end would lead to local failure mode of indentation or face fracture, while the high-density foam layer at the impact end would bring about global failure mode of combined core shear and debonding. The simply supported graded sandwich beam exhibits softening post-failure behavior, while the fully clamped graded sandwich beam displays hardening post-failure behavior. The initial strengths of fully clamped and simply supported sandwich beams with negative-gradient foam core are the highest, while the subsequent strength of the fully clamped sandwich beams with positive-gradient foam core is the highest. Among all gradient distributions of foam cores, the impact resistance of the fully clamped composite sandwich beams with negative-gradient foam cores design is the highest.