This paper presents the performance of crashworthiness on multiple section bi-tubular thinwalled structures. The material of these models was from aluminum alloy 6060 and the structure consists of an outer tube and an inner tube with any one of various shapes such as triangle, square, hexagon, and octagon. The effect of different cross section of tube under dynamic axial impact is studied. As a result, the energy absorption capacity of various inner tubes was compared and it shows that octagonal inner tube has the better performance of crashworthiness than other inner tubes. Therefore, to get the optimal parameters, the Non Surrogate Genetic Algorithm II (NSGA II) focuses on achieving the maximum total energy absorption (TEA) and the minimum peak crushing force (PCF). During the process of multi objective optimization design, it was found to be accurate enough for engineering design of structures with inner tube by octagon.

Keywords : Crashworthiness; Double Tube; Dynamic Axial Impact.