Absorption of Energy by Frusta

Deformable energy absorbers are briefly introduced, and their relevance in crash protection systems is stressed. A general review of literature is presented on energy absorption by tubes of various cross sections. Work on quasi-static and impact-loaded hollow and capped, spun aluminum frusta is described. Experimental findings are reported that suggest that certain frusta may be used as active elements, and that in this respect frusta may be preferable to "constant-force energy absorbers" such as tubes. It is established for the inversion of stacked multi-element absorbers that the energy absorbed per gram is not affected by the series arrangement. It is further concluded that the amount of energy absorbed in inward inversion is more than twice that of outward inversion. It is pointed out that while tube inversion requires dies, the length of tube to be inverted has limitations, and that normally tube inversion is limited to about half the original tube, height, none of these shortcomings were encountered during the inversion of aluminum frusta.