# Dynamic Response of Outer Windshield Structure in Different Schemes under Aerodynamic Load
## 5 Conclusions and Future Work  
The different geometric structures of the outer windshield section lead to a large difference in its stiffness and natural frequency, making the aerodynamic stability of the outer windshield for different structural schemes vary under the same application environment. In the present study, the FSI method is adopted to investigate the aerodynamic stability of three different schemes of rubber external windshield structure; the following conclusions are drawn:  
1. The airflow around the rubber external windshield at the end of the HST carriage is complex, and the air flows into the cavity along the outer windshield surface, resulting in an uneven pressure distribution on the outer surface of the rubber external windshield. The cavity interior generally maintains a positive pressure state. The outer side of the windshield on the leeward side is affected by negative pressure, and the outer wall of the windshield on the windward side is affected by positive pressure, resulting in an obvious force trend of relative dislocation, which is very unfavorable to the aerodynamic stability of the outer windshield.
2. By comparing the deformation form and vibration response frequency of the three rubber external windshield schemes, it can be concluded that the deformation of the rubber external windshield in Case 2 is significantly lower than the other two schemes, and the dynamic stability is also better. Increasing the thickness of the sidewall of the rubber external windshield can improve the stiffness of the outer windshield. However, when the distance between the sidewalls of the rubber external windshield increases, the insufficient thickness increase at the top of the arc causes greater deformation at the top of the arc.
3. By comparing the stress distribution of the structure response under the aerodynamic load of the outer windshield of the three schemes, it can be concluded that the stress in the outer windshield of Case 1 is mainly concentrated at the lower process hole and the fixed support during the vibration process. The stress value is significantly  
Figure 20: Fracture position in the rubber external windshield structure for Case 1.  
greater than the other two schemes, leading to the greatest risk for fatigue damage in the outer windshield.  
This research provides good support for evaluating the aerodynamic stability of rubber external HST windshields. The FSI method can accurately calculate the dynamic response characteristics for rubber external windshields in different structural schemes, which is of great significance for the optimal design of the outer windshield. In the next step, specific parametric research can be carried out on the shape and section size of the rubber external windshield, and the aerodynamic force can be reduced by optimizing the geometric shape of the windshield. By optimizing the structural section size parameters of the windshield, a better scheme to control the increase in the outer windshield mass while maximizing the stiffness and natural frequency of the rubber external windshield can be obtained.  
Conceptualization, M.-Z.T. and X.-B.L.; methodology, G.C. and M.Z.; formal analysis, J.Z. and B.S.; resources, X.-H.X.; writing--original draft, M.-Z.T.; writing--review and editing, X.-B.L.; supervision, X.-H.X.; funding acquisition, X.-H.X. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Key R&D program of China (grant no. 2020 YFA-0710903); the Natural Science Foundation of Hunan Province (grant no. 2021 JJ30849); the Graduate Student Independent Innovation Project of Hunan Province (grant no. CX20200196); and the Graduate Student Independent Innovation Project of Central South University (grant no. 2020 zzts111 and 2020 zzts117).  
Not applicable.  
The authors acknowledge the computational resources provided by the High-Performance Computing Center of Central South University, China.  
The authors declare no conflict of interest.