<p>The structural safety of high-speed trains is significantly endangered by increasing operating speeds. The objective of this research was to investigate the evolution of the flow field in trains passing through a tunnel while there is a strong crosswind at the tunnel entrance and exit. Moreover, the effect of aerodynamic pressure waves on structural strength was analyzed to evaluate the safety of the carbody. In this study, we selected the improved delayed detached-eddy simulation (IDDES) method as a turbulence model. The mechanism of interaction among the train, tunnel, and crosswind was evaluated through a complex computational fluid dynamics (CFD) model, simulating high-speed trains moving through tunnels at various crosswind speeds. Additionally, the dynamic stress response of the carbody was calculated using a sequential coupling approach, where integral aerodynamic forces were applied as substitutes for direct CFD pressure loads. We assessed the effect of aerodynamic loads on the dynamic stresses of the carbody at different crosswind velocities (0, 10, 15, and 20 m/s). The results indicate that crosswinds exert a substantial influence on the fluid structure surrounding the train. Consequently, the aerodynamic forces contribute significantly to potential damage to the carbody, posing increased safety risks for high-speed trains.</p>