Structure optimization design for pre-folded external double-layer biomimetic multi-cell thin-walled tubes

The multi-cell tube has been widely studied and applied in vehicle collision energy absorption due to its superior energy absorption capacity compared to traditional single tubes. The origami thin-walled structure is at the forefront of research on automotive energy absorption structures, thanks to its advantages such as low initial peak force, high energy absorption efficiency, and predictable deformation. In this study, a group of biologically inspired multi-cell tubes with origami-type outer walls was designed, and three design variables including the thickness of the outer wall, the ratio of outer to inner wall thickness, and the peak value ratio of the sine wave period were optimized. The design of experiment (DOE) was used to select the sample points needed to construct the surrogate model, and then a response surface model was built based on the criteria of minimum initial peak force (PCF) and maximum specific energy absorption (SEA). Finally, the non-dominated sorting genetic algorithm (NSGA-II) was used to optimize the design variables, resulting in a series of optimal solutions. The improved algorithm was used to select the best solution according to the requirements, and the optimization results were verified for their accuracy and reliability through simulation experiments. The results show that changing the values of the three design variables of the thin-walled tube will significantly affect the initial peak force and specific energy absorption. The optimal values after optimization were found to be 109.063 KN for PCF and 25.786 J/g for SEA.