Energy absorption of foam-filled circular tubes with braided composite walls

Braided glass-fibre/epoxy circular tubes with polymer foam cores are loaded in tension and in compression, and the energy of deformation is measured. Theoretical models of tube deformation are developed, and are used to predict the energy absorption as a function of tube wall strength, the ratio of tube wall thickness to tube diameter, and the density of the foam. The energy per unit mass and energy per unit volume are optimised with respect to the relative density and geometry. It is found that foam-filled braided circular tubes exhibit promising energy absorbing characteristics, due to a combination of energy absorption by the polymeric foam core and by the glass/epoxy braided tube.