Multi-objective crashworthiness optimization of thin-walled multi-cell tubes with different wall lengths

Thin-walled tubes are extensively used in the automotive industry because of their high energy absorption capacity and lightweight advantages. These structures are expected to have high energy absorption and low peak force during any collision. In this study, to obtain low peak crushing force, different wall lengths have applied to the thin-walled tubes. Different wall lengths have investigated using doubly-walled walled, inner multi-cell walled and multi-cell walled tubes obtained from square, hexagon, octagon and circle cross-sections. To evaluate crashworthiness performance dynamic impact analyses at a constant velocity are carried out using the non-linear explicit Finite Element (FE) code Radioss. According to the FE results, tubes with different wall lengths give lower peak crushing force (PCF) of up to 36% compared to normal tubes. On the other hand, in tubes with different wall lengths, there is a decrease of up to 6% in specific energy absorption (SEA) compared to normal tubes. Thus, considering the decrease of the PCF, the advantage of tubes with different wall lengths is presented. Optimization studies have carried out for the second type octagonal tube with different wall lengths (O2G) and the third type octagonal tube with different wall lengths (O3G) which give better SEA and PCF values between all tubes.