Numerical crashworthiness analysis of a novel functionally graded foam-filled tube

The thin-walled tubes used in the front rails of the vehicle’s body in white play a major role in absorbing the energy of the collision. In this work, the energy absorption characteristics of the functionally graded foam-filled thin-walled tubes are studied by using quasi-static finite element analysis. The simulation of all specimens has been conducted by utilizing finite element software ABAQUS/Explicit™. A high-precision constitutive equation is used to obtain mechanical properties of foam in different densities. Uniform density foam-filled and functionally graded foam-filled tubes with various gradient functions and configurations are simulated, and force–displacement and energy–displacement diagrams are extracted and compared to each other. The simulation carried out on the layered samples showed that the 13-layered sample is an appropriate approximation for the continuous variations of density along the axial direction. According to the results, linear variations have had better energy absorption characteristics compared to the samples with gradient exponent of m  = 2 and m  = 5 for an ascending density variation. In this study, the innovative density variation patterns as high-low-high and low-high-low are also simulated in which the high-low-high sample has better energy absorption than other specimens. It is shown for 13-layered samples, the specific energy absorption in the high-low-high design is 3 and 6.6% higher than the ascending pattern (m = 1) and the low-high-low samples, respectively.