ABSTRACT
Cellular structures comprising assemblies of metal tubes or honeycombs are effective impact energy absorbers because they permit gross plastic deformation and have long strokes that enable the designer to limit the decelerating forces. Recent work on the behaviour of such structures is reviewed, with particular emphasis on the localised deformation mechanisms that occur under dynamic loading conditions. Cellular materials comprising open cells deform through a variety of mechanisms governed by the sequential collapse of individual cells and layers of cells, which are reminiscent of those observed in cellular structures. The behaviour of wood is discussed as an example of cellular material behaviour. Experiments have demonstrated that the crushing strengths of wood both along the grain and across the grain change significantly with compression rate. This phenomenon is discussed, and simple models used in the analysis of cellular structures that attribute the stress enhancement to inertial effects are described. The distinctive roles of shock formation and microinertia are discussed.
