Multi-objective optimization of the design parameters in longitudinal corrugated tubes to improve crashworthiness performance

Longitudinal corrugated tubes (LCTs) are among the structures of interest to designers, because of their ability to improve the weaknesses of conventional simple tubes by reducing the maximum crushing force (F_max) and providing a controllable and predictable force-displacement curve during energy absorption. In this study using finite element (FE) simulations, the effect of design parameters of LCTs, i.e., amplitude and number of folds on the crashworthiness criteria, in different deformation modes has been investigated. Crushing parameters of some simple and corrugated tubes have been examined experimentally to validate the FE simulations. Results of 400 FE models, revealed some geometries in LCTs that, in addition to reducing F_max, can increase the specific energy absorption (SEA) compared to the simple tubes. Most of these geometries deform under compressive axial loading in the N-mode region. Using multi-objective optimization, specification of the optimal LCT, including number of folds and their amplitudes were determined. Then the optimal LCT was made by the ring-forming method and compared with the simple tube experimentally. The optimized LCT was experimentally evaluated and results showed that it can reduce F_max by 27.2% and increase SEA by 21.6% compared to the simple tube. The lower SEA of the LCTs is usually considered as a disadvantage for the LCTs compared to the simple tubes, which is violated in this research. Optimized LCT may be a new idea for aerospace applications as crash-resistant structures.