Foam filling options for crashworthiness optimization of thin-walled multi-tubular circular columns

Abstract

There is an increasing trend in using aluminum foam-filled columns in crash management systems due to theirlight weight in automotive industry. The main goal of this study is to optimize the crashworthiness of aluminumfoam-filled thin-walled multi-tubular circular columns under quasi-static loading. The existing studies in theliterature considered only lateral foamfilling (the foam lateral dimension is variable and the foam height is equalto the column height). In the present study, we considered both lateral and axial foamfilling and compared theperformances of these two options. In optimization, the column thicknesses, taper angle, foam density, and foamheight/diameter are considered as design variables. The quasi-static responses of the columns are determinedthrough explicit dynamic Finite Element Analysis (FEA) using LS-DYNA software, and validated with quasi-statictests conducted in our facilities. Response surface based crashworthiness optimization of the columns formaximum Crush Force Efficiency (CFE) and maximum Specific Energy Absorption (SEA) is performed. It is foundthat lateral foamfilling is superior to axial foamfilling in terms of both CFE and SEA maximization. Themaximum CFE obtained through lateral foamfilling is 19% larger than the maximum CFE obtained through axialfoamfilling. Similarly, the maximum SEA obtained through lateral foamfilling is 6% larger than the maximumSEA obtained through axial foamfilling. For both CFE and SEA maximization, the columns should be tri-tubulartype and have a large thickness and a taper angle. To attain the maximum CFE, foam should be designed withlarge density and medium foam diameter. However, foam plays an adverse role in maximization of SEA becauseof its weight. The increase in energy absorption obtained by using foam does not compensate the additionalweight introduced by the foam