Bending crashworthiness performance of square beams with holes and metallic foam filler

Abstract

Several parameters affect the crashworthiness performance of thin-walled structures. However, geometrical imperfections are particularly relevant since they can trigger deformation. Based on this idea, the current article explores the use of holes as imperfections to improve the bending crashworthiness of square profiles in a first stage. Parameters such as position, shape, and size of the holes are investigated numerically. The reliability of the numerical results was confirmed by experimental validation of the first model, which included ductile and shear damage criteria. The second part of the article explores the use of metallic foam filler to further increase the energy absorption performance of the profiles. In all cases, the structures were made of aluminum alloy 6063-T5 and numerically evaluated by a three-point bending test. Compared to a typical square tube, drilling holes at the upper corners increased the crush force efficiency (CFE) by 10.12%. The effectiveness of circular holes was demonstrated over other shapes, since it provides a better distribution of the load. Additionally, a hole size analysis allowed to increase the crashworthiness performance of the tubes even more. The optimal scale factor = 1.20 yielded a CFE improvement of 21%. From this analysis, a useful expression for the hole size limit is presented. Lastly, the relevance of foam fillers and holes demonstrated improvements in CFE of up to 68% which were obtained on drilled tubes compared with typical square tubes.