Governing mechanisms of structural damage from underwater contact explosions induced by shock-wave and bubble loading

Abstract

Underwater contact explosions involve complex multi-phase moving interfaces under elastoplastic and damage-induced conditions. This study investigates shock wave propagation, bubble pulsation, and progressive damage evolution in plate structures subjected to underwater contact explosions. An experimental setup was established in a dedicated explosion water tank equipped with synchronized high-speed imaging and pressure sensors, complemented by arbitrary Lagrangian-Eulerian (ALE) simulations that account for fluid-structure interaction. The shock wave and bubble pulsation behaviors were compared between damaged and purely elastoplastic boundary conditions. The results show that both the reflection coefficient and impulse of the shock wave at the structural surface decay rapidly with decreasing stand-off distance, a trend that diminishes when the dimensionless stand-off distance γ exceeds 0.2. Plate rupture leads to bubble venting through the resulting cracks, which reduces internal pressure and attenuates secondary pulsation amplitude. Structural deformation and damage are primarily driven by shock-wave loading, while bubble-induced loads contribute up to 17% at a stand-off of γ = 0.21. These findings provide valuable insights for enhancing the safety design and shock resilience of underwater structures.