The energy-absorption characteristics of metal tube-reinforced polymer foams

This paper presents a study on the potential offered by lightweight energy-absorbing foam structures reinforced with aluminium and steel cylindrical tubes subjected to compressive crushing. Initially, attention was focused on establishing the influence of the length as well as the diameter to thickness ratio of the metal tubes on the specific energy absorption (SEA) characteristics. The metal tubes were then embedded in a range of cross-linked PVC foams to investigate how the stiffness of the foam influences the SEA of the tubes and the failure modes. The results show that aluminium tubes offer a superior energy-absorbing capability relative to their steel counterparts and the SEA of the metal tubes remains roughly constant with an increase in the tube length. The energy-absorbing capability of the two types of metal tubes increased with decreasing value of inner diameter/thickness ratio. Small D/t tubes were also embedded into a range of polymer foams and tested at both quasi-static and dynamic rates of strain. It has been shown that that the stiffness of the foam does not modify the energy-absorbing behaviour of the metal tubes. This evidence suggests that it should be possible to predict the response of an energy-absorbing system containing an array of tubes using a simple rule of mixtures approach. The output of this study provides useful data on core materials for sandwich construction.