Crashworthiness optimal design of multi-cell triangular tubes under axial and oblique impact loading

This paper addresses multi-objective optimisation design for multi-cell structures under multiple loading angles. Triangular tubes with three different cross-sectional shapes are considered in this study. Numerical simulations are constructed via LS-DYNA to analyse the crashworthiness responses of the tubes where the accuracy of the numerical model is verified using experimental and theoretical techniques. It was observed that the global bending deformation mode occurs for all tubes at large loading angle whereas the progressive deformation mode is developed in some tubes under axial and oblique loading with small loading angles. Also, it was revealed that the load angle and number of cells have a significant effect on mean crushing force (MCF) where the impact of the number of cell on MCF is less than that of the load angle. A new kind of multiobjective optimisation for multiple loading cases (MOMLC) employing metamodeling and linear weighted average methods is presented. This optimisation strategy considers all impact loading cases simultaneously and thus it is effective for designing the multi-cell tubes under the multiple-loading case. The results exhibit that the optimal designs of the multi-cell tubes show better crashworthiness performance for multiple load cases.