## 6 Conclusions  
In this paper, a novel double-layer square tube composite anti-climb energy-absorbing device filled with honeycomb aluminum blocks was designed. A collision finite element model was established using LS-DYNA to study the impact of different connecting diaphragm thicknesses, thin-walled outer tubes, thin-walled inner tubes, and yield strengths of the honeycomb aluminum on the crashworthiness of the anti-climb energy-absorbing device. Furthermore, with the specific energy absorption and peak force as the optimization objectives, the response surface method and a multi-island genetic algorithm were employed to identify the optimal wall thickness combinations within the design space, leading to the following conclusions:  
1. Regarding the influence of the connecting diaphragm thickness, thin-walled inner and outer tubes, and yield strength of the honeycomb aluminum on the crashworthiness of the anti-climb energy-absorbing device, the connecting diaphragm thickness and the yield strength of the honeycomb aluminum have a relatively minor impact on energy absorption. The connecting diaphragm thickness has a more pronounced effect on the maximum peak force, while the thickness of the thin-walled tubes significantly affects both the energy absorption and the maximum peak force.
2. The polynomial surrogate model established based on the response surface method can effectively predict the energy absorption and maximum peak force of the anti-climb energy-absorbing device under collision impact, providing a reference for structural crashworthiness research in the field of engineering.
3. An optimization analysis was conducted on the influencing factors of the anti-climb energy-absorbing device, such as the connecting diaphragm thickness, thin-walled outer tube thickness, thin-walled inner tube thickness, and yield strength of the honeycomb aluminum, using a multi-island genetic algorithm. The optimization was significant, with the optimized structural parameters leading to a substantial increase in energy absorption and specific energy absorption, while the maximum peak force increased by only 6.7%.  
Conceptualization, S.X., T.Z. and L.X.; Methodology, Y.L.; validation, H.Z.; Investigation, J.X. and G.Z.; Writing--original draft preparation, Y.L.; Writing--review and editing, Y.L.; funding acquisition, S.X., T.Z. and Y.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the National Natural Science Foundation Project of China (grant numbers 52175123 and 52172409), by Key Technologies R&D Program of Henan Province (grant number 232102240092), by Heilongjiang Province Postdoctoral Foundation Project (grant number LBH-Z23041), and by the 2023 Special Project for the Cultivation of Original Technology Decade (grant number 2022 CYY007).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors on request.  
**Acknowledgments:** Thanks to [PERSON] for funding the project (2022 CYY007) and their support of this paper.  
**Conflicts of Interest:** Author [PERSON] was employed by the company CRRC Qiqihar Rolling Stock Co., Ltd. The remaining authors declare that the re-search was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.