Fluid-structure interaction between shaped charge underwater explosion and sandwich composite panels

Shaped charges pose a severe threat to Unmanned Underwater Vehicle (UUV) or Autonomous Underwater Vehicles (AUV). Ultra-high molecular weight polyethylene (UHMWPE) exhibit significant application prospects due to their excellent anti-blast performance. However, underwater explosions (UNDEX) of shaped charges generate shockwave-projectile-bubble damage elements across multi-scale spatiotemporal domains. It presents challenges to numerical calculations of interaction between damage elements and structures. Therefore, the application of UHMWPE in underwater anti-blast scenarios is limited. In this study, UNDEX experiments were conducted. A sandwich target (SPS) was designed. The full physical process of shaped charge UNDEX and the damage condition of the targets were obtained. Based on the experiment, the research on the damage mechanism of shaped charge UNDEX was carried out. The whole physical process of shaped charge UNDEX was divided into shockwave phase (SP), projectile phase (PP), and bubble phase (BP). The damage modes and the target response in each phase were obtained. Finally, the protective capability of the SPS target under damage elements with different intensities was investigated. The intensity was controlled by the distance parameter γ . The damage conditions of the SPS target and the Q235 target with equal areal density were compared. It shows that the SPS target still maintains protective characteristics under different γ . This study can provide experimental data for underwater anti-blast verification and offer references for the protective design.