Protection Mechanism of Underwater Double-Hull Coated with Polyurea and UHMW-PE Subjected to Shock Waves and Bubble Loads

Naval ships are severely damaged in near-field underwater explosion. Therefore, it is significant to investigate the mechanism of destruction and protection. In the paper, the Coupled Eulerian–Lagrangian method (CEL) is utilized. The damage characteristics of blasting charge to the double-hull during the underwater explosion are analyzed. After that, protective materials are used in order to enhance the protective performance of the double-hull. Firstly, a numerical model of fluid–solid coupling is established. The complete physical process of double-hull being subjected to shock waves and bubble is simulated in this numerical model. Secondly, the damage characteristics of the double-hull are discussed associated with near-field underwater explosion. Next, the double-hull coated with polyurea (PU) or ultra-high molecular polyethylene (UHMW-PE) subjected to shock waves and bubble, respectively, are analyzed. Multifunctional integrated composite armor is designed according to the equal surface density theory. Finally, the optimal protection design of the double-hull is given. The results show that a small plastic deformation caused by shock waves is found on the outer and inner plates. A large plastic deformation of the outer plate is generated by bubble. Subsequently, the outer plate is sheared. Besides, the optimized double-hull is not sheared off by bubble, which can provide reference for naval ships protection design.