Simulation Method and Coupled Response of Bow Skirt-Ramp Deployment in Hovercraft

Objectives To address the insufficient deployment efficiency and stability of bow landing ramps in hovercraft during landing operations under conditions such as restricted air exhaust, the dynamic response characteristics of the airbag–ramp coupled system are investigated, and effective approaches to enhance the reliable deployment capability of the ramp under abnormal conditions are explored. Methods Based on an explicit dynamic finite element approach, a rigid–flexible–fluid coupled numerical model of the bow skirt airbag–landing ramp system is established. The effects of different orifice area parameters on airbag internal pressure, exhaust mass flow rate, and ramp motion response during the ramp lowering process are systematically analyzed. For exhaust failure conditions, an equivalent mechanical transmission device is introduced to simulate the application of additional mechanical torque for actively driving ramp deployment. Results The results indicate that under normal exhaust conditions, the orifice area is the dominant parameter governing the airbag depressurization process and the dynamic behavior of ramp deployment. When the single orifice area increases from 0.1 m² to 0.45 m², the internal pressure decay rate is significantly accelerated, the transition to gravity-dominated motion occurs earlier, and the deployment time is reduced from 11.3 s to 2.6 s. Meanwhile, the peak angular velocity generally increases and exhibits a non-monotonic response characteristic. Fitting analysis further reveals a stable inverse correlation between the orifice area and ramp deployment time. In contrast, increasing the ramp mass from 6256 kg to 8181 kg shortens the deployment time by only about 0.5 s, indicating a limited influence on system response and a clear marginal effect. Under exhaust failure conditions, the introduction of an equivalent mechanical transmission device with controlled additional torque effectively shortens the deployment time and enhances motion stability. When the prescribed angular velocity increases from 0.14 rad/s to 0.22 rad/s, the maximum additional mechanical torque required to maintain uniform deployment increases from 1.16×10E6 N·m to 1.54×10E6·N·m, showing a stage-wise increasing trend during deployment and a positive correlation with angular velocity. Furthermore, stress analysis identifies the front folding region and lateral bulging region of the airbag as the primary zones of stress and deformation concentration. Conclusions By appropriately matching the airbag orifice parameters and ramp structural parameters, and employing mechanical transmission assistance under abnormal conditions, the reliability and operational efficiency of hovercraft landing ramp deployment can be effectively improved.