Dynamic response characteristics of an E-type impact isolation structure with a free mass constraint

In situations related to occupant impact protection, the free mass constraint of the occupants significantly influences the dynamic response characteristics of impact isolation structures. In this study, starting with the pre-bending deformation energy absorption mechanism, a static energy absorption prediction model for an E-type pre-bending folding deformation (E-PBFD) impact isolation structure was established. Based on the actual deformation state of the PBFD structure, the static energy absorption prediction theory was corrected, and quasi-static compression tests were conducted to validate the results of the corrected theoretical model. The smooth spline variance analysis method (SS-ANOVA) was used to determine the significance of high-dimensionality input variables in the theoretical prediction model. Finally, by combining the nonlinear kinematic equations of a free mass-constrained nonlinear vibration system and by considering the combined effects of the free mass constraint and the impact loading input, a theoretical dynamic energy absorption prediction model for the PBFD structure was developed. The NSGA-II algorithm was used to optimize the dynamic peak energy absorption of the structure, resulting in a 16.6% improvement in the peak energy absorption of the optimized structure. The results indicate that optimized parameters, which were based on the dynamic energy absorption theory, are conducive to fully exploiting the dynamic energy absorption characteristics of the PBFD structure. Additionally, parameter combinations that make the structure too soft or too rigid negatively affect the dynamic response behavior of the PBFD structure.