Evaluation of the Performance of Initiator on Energy Absorption of Foam-Filled Rectangular Tubes: Experimental and Numerical Assessment

In this paper, the effect of initiator on axial crushing response of partially foam-filled and foam-filled rectangular tubes was investigated. For this purpose, an initiator was placed at the top of the filling rectangular tube with rigid polyurethane foam to prevent a suddenly applied force to the main part of the structure when the accident occurs. In this new idea, the process of axial crushing was carried out in two steps. In the first step, the initiator crushed the foam core as much as the initiator length, and, the second step, the initiator simultaneously crushed the thin-walled rectangular tube and the foam core. In this research, a number of numerical simulations were performed to study the dissipated energy of the rectangular tubes with initiator. To verify these numerical findings, some quasi-static experimental tests were conducted to explain energy absorption, initial peak load and crush force efficiency. Moreover, load-displacement curves and deformation mechanism of this shock absorber with different length of initiators were described. The results showed that, in the considered material and geometry, the design with an initiator on partially foam-filled and foam filled rectangular tube have superior performance rather than the specimen without an initiator. In addition, selecting the appropriate length of initiator for the specimens of partially foam-filled and foam-filled resulted in an increase in the energy absorption. Besides, the results showed that the increase in the absorbed energy in the foam-filled specimen was more than that of the partially foam-filled specimens. Therefore, by applying the initiator on the top of the tube, it would be help to reduce the occupant injury and main structure in a collision.