The energy absorbed during the axial collapse of a variety of structures made in steel, aluminium alloy, and glass fiber reinforced plastic (GFRP) was examined with respect to changes produced by foam filling reinforcement. A simple model was devised which permits reasonable estimates of the axial collapse load for a structure and an assessment of the weight-effectiveness of foam filling for that structure. Design charts are given, from which the dimensions can be derived for sections made in either steel or aluminium alloys of any particular strength level, in order to establish foam weight-effectiveness. Foam filling is primarily of value only in sections made from high density, low strength materials, e.g. mild steel. It becomes weight-effective in sections having a thickness-to-section size ratio of less than about .02. In the case of brittle materials (e.g. GFRP), foam filling promotes the crush stability of the structure. Such stability improvements may be the major need for foam filling in these sections and also in large, thin-wall metal sections.
Abstract