Crashworthiness investigation of bitubal columns reinforced with several inside ribs under axial and oblique impact loads

This paper deals with the crashworthiness capability of newly designed bitubal columns with different polygonal cross-sections (i.e. triangular, square, hexagonal, octagonal, decagonal and circular) reinforced with several inside ribs. A large number of finite element analyses were performed on these columns under axial and oblique impact loads using LS-DYNA to find the crashworthiness indicators. These columns were studied with five different size ratios (the ratios of the perimeter a of the inner tube to the perimeter b of the outer tube), namely a/b = 0, 0.25, 0.5, 0.75 and 1. A decision-making method, which in this case is the technique for ordering preferences by similarity to the ideal solution, was then employed to select the better columns which possessed a higher energy absorption and a lower peak force. The bitubal columns with size ratios a/b of 0.5, 0.25 and 0.75 were generally found to be the best cases. Furthermore, the multi-cell columns with the decagonal and octagonal cross-sectional shapes were selected as the best energy absorbers.