Pii: S1359-6462(00)00460-7

Potential applications of metal foams include light weight cores for sandwich panels, shells and tubes where the foam can increase the resistance to local buckling, increase the impact resistance, and improve the energy absorbing capacity of the structure [1,2]. This latter property offers potential uses in transportation applications where, for example, foam-filling of the hollow sections of automobiles, such as fenders, may reduce damage and injuries resulting from impact accidents. For this type of application, aluminum foam is more suitable than a polymeric foam, because it deforms plastically under impact and with essentially no spring back, preventing further damage [3]. Other important advantages of using aluminum foams over polymeric foams include high fire resistance and insensitivity to cold and hot weather and humidity [3]. Impact accidents produce loading rates which are higher than those of static or quasi-static rates and which may significantly alter mechanical response of the materials. Therefore, in designing with metallic foams as energy absorbing fillers, mechanical properties are needed for strain rates corresponding to those created by impact events. Quasi-static mechanical behavior of metallic foams has been fairly extensively studied and reported, e.g. [3–5], but data concerning high strain rate mechanical behavior of these materials are, however, only just becoming available and are rather sparse [6,7]. This study was initiated, therefore, to study the high strain rate mechanical behavior of a range of metallic foams, and to compare it with quasi-static behavior and, hence, determine any effect on energy absorbing capacity. Microscopic observations were also made in order to clarify the deformation mechanisms involved during crushing of the foam.