Energy absorption and topology optimization of self-similar inspired multi-cell square tubes

Due to their low cost and lightweight properties, multi-cell square tubes have been widely used in impact protection as energy absorbers. In this study, two kinds of multi-cell square tubes were constructed according to the local self-similar and global self-similar layout strategies. The experiments and numerical simulations were conducted to investigate their quasi-static compression deformation and energy absorption. The results demonstrated that self-similar layout strategies can significantly enhance the crashworthiness of multi-cell square tubes, and the global self-similar layout appears to be more effective at energy absorption. A simplified theoretical model for the mean crushing force (MCF) was developed for its constituent elements of the proposed square tubes. Furthermore, the COPRAS method and the non-dominated sorting genetic algorithm II (NSGA-II) were employed for optimal structure selection and multi-objective optimization. The results showed that the 2nd-order global self-similar multi-cell square tube (MSTG1-2) had prominent crashworthiness compared with some typical self-similar square tubes. The current optimization and topology design strategies can be used in other polygonal multi-cell tubes, which provides an effective guide for enhancing the crashworthiness of these multi-cell tubes.