Study on the crashworthiness of windowed multi-cell square tubes under axial and oblique impact

The crumpling of aluminium alloy AA6060 T4 thin-walled tubes when subjected to axial and oblique impact is often experienced in collisions. Tubes with holes (so-called windows) and multi-cell tubes are efficient in terms of the structure's energy absorption. This paper proposes a combination of rectangular windows and multi-cell square tubes to improve the structure's crashworthiness. The advantages of the introduction of windows into the structure can diminish the initial peak collapsing load. This can also improve the crashworthiness performance and the mechanism of a folding formation. However, this introduction causes cracks in the tube and thus reduces the plastic zone area of the fold. The decrease in the plastic zone area and the cracks reduce the tube's energy absorption capacity. The specific energy absorption (SEA) and mean collapsing load (Pmcl) of WMCT-I and WMCT-III under axial impact is higher by about 20% and 16% compared to those of MCT-I and MCT-III, respectively. Relating to MCT-II having a wall-to-corner (WTC) one, the tube with holes does not improve in either case of axial and oblique impact. Extensive theoretical solutions are proposed to predict the mean collapsing loads of the windowed multi-cell tubes. The results of the theoretical predictions are compared to those of the numerical simulation. The Multi-Criteria Decision Making (MCDM) method is applied to select the better structure for the energy absorber application. Superscript/Subscript Available