Effects of triggering and polyurethane foam on energy absorption of thin-walled circular tubes under the inversion process

Abstract

Abstract In this article, an attempt has been made to increase energy absorption and control suddenly applied load in the inversion process of both empty and foam-filled circular tubes. For this purpose, rigid steel die as a triggering mechanism is installed on the shock absorber. When the circular tube is subjected to axial compression, it is driven into the trigger and the empty tube is expanded or polyurethane foam is compressed as much as the trigger's length. In this new innovation process, the effects of triggering and polyurethane foam are investigated on specific energy absorption (SEA), initial peak load and inversion mechanism. To do so, numerical simulation is carried out to evaluate the shock absorber performance. To verify the results of numerical simulation, some quasi-static experimental tests are conducted. In the light of the results, employing a trigger at the bottom of the foam-filled tubes causing an increase in the energy absorption in comparison with the empty ones. In addition, the presence of trigger prevents the suddenly applied load to occupants and the main part of structures. Therefore, this mechanism could be a palatable alternative as an energy absorption system in structural safety design.