The plastic collapse of sandwich beams with a metallic foam core

Plastic collapse modes of sandwich beams have been investigated experimenta lly and theoretically for the case of an aluminium alloy foam with cold-wor ked aluminium face sheets. Plastic collapse is by three competing mechanism s: face yield, indentation and core shear, with the active mechanism depend ing upon the choice of geometry and material properties. The collapse loads , as predicted by simple upper bound solutions for a rigid, ideally plastic beam, and by more refined finite element calculations are generally in goo d agreement with the measured strengths. However, a thickness effect of the foam core on the collapse strength is observed for collapse by core shear: the shear strength of the core increases with diminishing core thickness i n relation to the cell size. Limit load solutions are used to construct col lapse maps, with the beam geometrical parameters as axes. Upon displaying t he collapse load for each collapse mechanism, the regimes of dominance of e ach mechanism and the associate mass of the beam are determined. The map is then used in optimal design by minimising the beam weight for a given stru ctural load index, (C) 2001 Elsevier Science Ltd. All rights reserved.