Crashworthiness Research And Optimization Design Of Bionic Multi-cell Thin-walled Structures

Metal thin-walled structures are widely used in automotive crash energy dissipation systems due to their excellent energy absorption characteristics,light weight,and low cost.The problem of crashworthiness design and optimization of metal thin-walled tubes has also become a hot issue in the current automotive research field.In order to improve the crashworthiness of metal thin-walled tubes,this paper firstly explored the crashworthiness of traditional multi-cell thin-wall tubes through finite element simulation and theoretical analysis.Then,a series of bionic multi-cell thin-walled tubes were designed by imitating the microstructure of beetle forewings,and the crashworthiness of the bionic multi-cell thin-walled tubes and the traditional multi-cell thin-walled tubes was compared.Finally,the bionic multi-cell thin-walled tube with better energy absorption was optimized.The main research contents of this article include the following aspects:(1)Four kinds of octagonal multi-cell thin-walled tubes with different cross-sections were proposed,and a finite element simulation model of octagonal multi-cell thin-walled tubes was established.At the same time,the sled impact test was conducted,and the validity of the finite element model of the octagonal multi-cell thin-walled tube was verified by comparing the finite element simulation results with the sled impact test results.Based on the validated finite element model,the octagonal multi-cell thin-walled tubes with four different cross-sections were simulated by finite element analysis,and the crashworthiness of these four multi-cell thin-walled tubes was compared.The results show that the crashworthiness of the octagonal tubes with inner ribs connected at the mid-walls of the inner and outer tubes(W2W)is better than that of the other three sections.(2)Based on the Simplified Super Folding Element theory,the theoretical solutions of the average collision load of W2 W quadrilateral,hexagonal and octagonal multi-cell tube were deduced,and the derived theoretical solution expressions were compared.At the same time,the crashworthiness of W2 W quadrilateral,hexagonal and octagonal multi-cell tube under axial impact was compared and analyzed using finite element simulation.The theoretical and finite element analysis results show that the W2 W octagonal multi-cell tube has the best crashworthiness among the three structures,and the finite element simulation results have a high consistency with the theoretical prediction results.(3)By imitating the microstructure of beetle forewings,a series of novel bionic multi-cell thin-walled tubes were designed based on the W2 W multi-cell thin-walled tubes.Then,the crashworthiness of traditional multi-cell thin-walled tubes and bionic multi-cell thin-walled tubes under axial impact was compared and analyzed using finite element simulation.The results indicate that the bionic multi-cell tube O-BMCT-6 has the best crashworthiness in all the structures designed in this paper.(4)In order to further improve the crashworthiness of the bionic multi-cell tube O-BMCT-6,the bionic multi-cell tube O-BMCT-6 was optimized using full-factorial design and non-dominated sorting genetic algorithm NSGA-II.At the same time,the bionic multi-cell tube O-BMCT-6 was parametrically analyzed using the sample data of the full factorial design.Any solution on the Pareto frontier generated by multi-objective optimization is an optimal solution.Thin-wall tube designers can choose Pareto point according to actual engineering needs,thus effectively improving the crashworthiness of thin-walled tubes.