Axial Crushing Analysis of Sandwich Thin-walled Tubes using Experimental and Finite Element Simulation

Application of impact energy absorption systems in different industries is of special significance. Thin-walled tubes, due to their lightness, high energy absorption capacity, long crushing length and the high ratio of energy absorption to weight, have found ever-increasing application as one of the most effective energy absorption systems. In this research, through  carrying out experimental tests and finite element simulation, the crushing mechanism of  hollow & solid (filled with polyurethane foam), sandwiched, thin-walled structures under the influence of axial, quasi-static loading has been studied.  The tested cylindrical samples are made using extrusion method. These samples are compressed between two rigid plates under quasi-static loading conditions, and then the collapse mechanism, the crushing force fluctuations and absorbed energy are determined.  A numerical model is presented based on the finite element analysis to simulate the collapse process, considering the non-linear responses of material behavior, contact surface and large deformation effects.  Simulation of tested specimen has been executed by ABAQUS software in 3- dimensional models through explicit method. Comparison of numerical and experimental results showed that the present model provided an appropriate procedure to determine the collapse mechanism, crushing load and the amount of energy absorption. The model is used to evaluate the thickness effects of the tube, material quality, imperfection and density of the foam on the mean crush load, energy absorption capacity, and collapse mechanism of cylindrical shells. Research results showed that the existence of foam increases the amount of energy absorbtion in the structures. Increase of energy absorbtion and also increase of average crushing force, in foams with higher density is more evident.