Water-entry Stress Response and Damage Characteristics of Composite Shroud

To study the structural strength and impact resistance of a composite material vehicle shroud during water entry, a fluid-structure interaction numerical method was employed. This method was used to investigate the motion, stress and damage characteristics of a specific composite shroud design. The simulation results showed good agreement with experimental data, thereby verifying the feasibility and accuracy of the simulation. The findings indicate that the shroud primarily undergoes deceleration during water entry, with negligible deflection in its trajectory. Stress concentration occurs at the junction between the platform and the convex, as well as in the central region of the platform. As the water entry velocity increases, the overall stress in the composite material rises, with a more pronounced increase in the outer two layers compared to the inner two. The PMI60 foam material in the middle layer plays the role of energy absorption and stress redistribution. The damage to the composite shroud is mainly manifested as matrix failure. Material damage is more likely to occur around the top of the shroud and at the platform-convex junction. The maximum damage value in the outer two layers is significantly greater than that in the inner layers, while the foam layer exhibits the smallest damage value. Furthermore, the peak damage value increases exponentially with higher water entry velocities.