Research on the characteristics and similarity relationships of impact load reduction of a vehicle entering water

The strong, transient, and high-peak impact load caused by a vehicle entering water at high speed is the primary factor threatening its structural strength and equipment safety. One of the effective methods for water entry protection is to use head-mounted buffer components. To this end, based on the arbitrary Lagrangian-Eulerian method, a numerical model of impact load reduction of water entry was established in this study. The results showed that the impact load could be characterised by a narrow pulse width and a high peak value, which gradually stabilises in a fluctuating manner. Five typical stages in the failure process of the cushion foam and four typical stages in that of the nose cap were observed. The prediction accuracy decreased as the scaling ratio decreased. Furthermore, the buffer components increased the occurrence of an error in the prediction results of the scaling model. The primary causes are the strain-rate sensitivity of the foam and dissimilarity in the failure criteria, which lead to dissimilarities in the foam failure process after scaling. This research will be useful for the designing of water load reduction structures and scaled model experimental schemes.