Pressurised composite tubes as variable load energy absorbers

Internal pressurisation is presented as a method to vary the crushing force of the tubes. A novel sealing-crushing system was demonstrated to achieve a simultaneously crushing and pressurised tube. The tubes were then axially crushed at two internal pressure levels: 9 bar and 18 bar. It was found that the force due to internal pressure did contribute to the crushing force of the tubes and was a significant proportion of the unpressurised crush force (up to 60% in one case). The potential for an adaptable composite crushing element under a range of impact energy scenarios was also demonstrated for the development of a proposed variable load energy absorber for realistic crash conditions.