Numerical Investigation on Axial Crushing of Double-Arrowed NPR Filled Thin-Walled Tubes 2021-01-0291

Thin-walled tubes have been mostly used in passive vehicle safety systems due to high crash energy absorption. The structures with negative Poisson’s ratio (NPR) property will contract to increase its stiffness. In this paper, a double-arrowed NPR structure is designed as a new energy-absorption filler for thin-walled tubes to apply as a novel crash energy absorber. Different beam thicknesses, angles and half cellular width are taken into account in the double-arrowed NPR filling tubes (DAFT) designing and the crashworthiness of the structures are analyzed by using validated nonlinear finite element method. The crashworthiness performances of DAFT are also compared with the singular NPR and hollow tube with the same outer dimension to show the efficiency of DAFT. Parameter analysis of DAFT crashworthiness are conducted by considering several crashworthiness indicators (e.g., the total energy absorption (EA), Peak crush force (PCF), mean crush force (MCF), specific energy absorption (SEA) and crush force efficiency (CFE)). The results reveal that the MCF of the singular NPR structure is 15.05kN, MCF of the square thin-walled tube is 9.12kN, and the MCF of the DAFT is 28.92kN, which is significantly larger than the sum of MCF for the singular NPR and square thin-walled tube. This is sufficient to illustrate the advantage of the filling tube in energy absorption. Analysis of the effect of the thickness and angles of beams on the crashworthiness performance is conducted. It is found that the crashworthiness performance of DAFT are more sensitive to the parameters of the long-inclined beam than those of the short one. Analysis of half cellular width shows that the change of half width will greatly affect PCF and SEA.