Distribution characteristics of underwater explosion damage to ships

Underwater explosions pose a significant threat to ships and other waterborne structures, jeopardizing their integrity and combat readiness. When ships are subjected to attacks by underwater weapons such as torpedoes or mines, the resulted explosions propagate in multiple directions through the water, severely compromising the ability of the ship to remain afloat. To investigate the distribution characteristics of underwater explosion damage, a real-scale near-field underwater explosion test on a ship was conducted. The test results were analyzed focusing on the acceleration and strain measurements along the length of the ship. An acoustic-solid coupling method was employed to assess the cumulative shock wave and bubble jet load on the entire ship structure. The analysis reveals that the plastically deformed area of the ship exhibited a depression depth of 85 cm, with an L-shaped breach width of 30 cm and an area of 0.2 m2. The model was validated by comparing the experimental and simulation data, with breach size discrepancies below 20% and breach location alignment. Then, simulation calculations at varying blast distances were conducted to examine structural damage distribution patterns. A distributed damage pattern was identified to indicate not only overall structural fractures but also widespread small cracks in bulkheads and outer plate sections. As the impact factor decreases from 5.84 to 1.91, the bilge breach size reduces, alongside a decrease in overall breach size. This reduction validates the accuracy of the model. This model was further used to conduct explosion simulation calculations under different blast distances, and a distributed damage model of the barge under the near-field underwater explosion load was proposed. It is clarified that in addition to overall fracture and local large-scale breaches, the damage to the ship structure also occurs. There are widely distributed small cracks in bulkheads, side outer plating and other parts. When the impact factor decreases from 5.74 to 1.91, the size of the bilge breach decreases and the number of cracks in the cabin increases. When the impact factor is between 1.91 and 2.87, and the bilge damage is scattered small breaches. The connections between the sides, bulkheads and bilges are weak points with many small cracks, so protection can be focused on those weak points during the ship design process. © 2024 Explosion and Shock Waves. All rights reserved.