Performance of flat-plate aluminum structures subjected to in-contact underwater explosions

This work investigates the effects of in-contact Underwater Explosion (UNDEX) on flat plates of various thicknesses. The interaction between generated bubbles and the plates is also studied. High-speed photography paired with digital image correlation (DIC) was used to capture full-field displacements, velocities, and strains on the plates during loading. Shockwave pressure was also recorded using pressure transducers strategically positioned in the water. The results show that, in the absence of rupture, thicker plates experience less deformation and allow the bubble to grow to a larger volume than the thinner plates, albeit smaller than that of a free field bubble. Bubbles generated in the vicinity of thicker plates also retain more energy. Contrary to cases of free field or near explosions which feature spherical and drifting bubbles, here the bubble assumes an ellipsoidal shape and attaches itself to the plate where it is confined to a more rapid cycle of collapse and regrowth before fully dissipating. When plate rupture does occur, it is immediate and is due to the initial shock. This structural failure drastically alters the behavior of the bubble.