The inversion processes of the proposed tubes under axial impact are simulated to investigate the detailed features of crushing process by using the explicit finite element FE code LS-DYNA. To validate the FE results, a new theoretical relation is developed . The validated FE model was then used for the parametric studies, to investigate the maximum crush distance and the effect of impact mass and the geometry parameters (i.e. wall thickness, foam density) on response of free inversion tubes under different strain rate loadings. Finally, a search algorithm combining Latin hypercube design (LHD) points and genetic algorithm is developed to carry out the multiobjective optimisation through the geometrical average method. The optimal design of the foam-filled free inversion tube demonstrates a significant improvement in the crashworthiness over the benchmark designs with the same loading conditions.
Free inversion;foam-filled tube;crashworthiness optimisation;dynamic loading;finite element analysis;circular tube;