Optimization of hole height and wall thickness in perforated capped-end conical absorbers under axial quasi-static loading (using NSGA-III and MOEA/D algorithms)

In this study, a perforated capped-end conical steel absorber was investigated to optimize its wall thickness and hole height. The holes were worked out on the perimeter of the absorber to lower peak force at collapse. For this purpose, once finished with simulating the absorber utilizing LS-Dyna software and verifying the simulated model using experimental data, hole height and wall thickness of the absorber were optimized to achieve maximum energy absorption along with minimum peak force. A total of 96 different cases were simulated, of which 7 cases were subjected to experimental tests. The optimization was performed using NSGA-III and MOEA/D algorithms implemented in MATLAB software. Response surface methodology was used to determine input functions for these algorithms. Finally, optimal position for the holes in conical absorbers was found to be the nearest point to the upper base of the truncated cone. A relatively good agreement was observed between the results of NSGA-III and MOEA/D algorithms, and the algorithms could predict optimal wall thickness and hole position at an acceptable accuracy in some cases.