Study On The Load Characteristics Of Near Field Underwater Explosion And Its Damage Effect To Clamped Thin Plates

With the development of underwater precision guided weapons,the probability of ships being attacked by near-field underwater explosions is increasing.Near-field underwater explosions can cause devastating blows to ships and other maritime combat platforms.Therefore,the study of near-field underwater explosions has important strategic significance for modern marine warfare.Firstly,a series of research work has been carried out on the characteristics of the near-field underwater explosion load and its damage mechanism to the clamped thin plate.First,an underwater explosion experiment was carried out in which an explosive of 2.5 g TNT equivalent was detonated at the bottom of a fixed-supported square plate at different blasting distances.The experimental results show that the process of bubble collapse to form a water jet changes from "adsorption" to "non-adsorption" as the burst distance increases.Then based on the ABAQUS software,a series of numerical simulations were carried out using the CEL method.The results showed that when the burst distance is between 0.821 times the maximum bubble radius and 0.867 times the maximum bubble radius,there is a critical point for the conversion of the "adsorption" jet to the "non-adsorption" jet.Point;the fixed-supported square plate speeds up the process of bubble collapse.The smaller the distance between the explosive and the steel plate,the earlier the jet formation time;the maximum speed during the formation of the jet and the speed at which the jet hits the steel plate increase with the burst distance The increase first increases and then decreases,reaching the maximum near the critical point,the maximum jet velocity can reach 621 m/s,and the maximum jet velocity when it hits the steel plate can reach 269 m/s.Finally,the function relationship between the time when the jet starts to form,the maximum jet velocity,the time when the maximum jet velocity appears,the velocity of the jet hitting the steel plate,and the time and distance parameters of the jet hitting the steel plate are given.On this basis,a near-field underwater explosion experiment at the bottom of the clamped thin plate was carried out.The experimental results show that the final deformation of the thin plate is the result of the combined effect of shock waves,hysteresis flow,and multiple bubble pulsating pressures.Then,a related numerical simulation study was carried out.The numerical simulation results show that the lagging flow at the end of the underwater explosion bubble pulse will have a greater attraction to the structure,and its contribution to the damage of the structure is no less than the impact caused by the shock wave and the bubble pulse pressure.Finally,a series of numerical simulations of underwater explosions with different blast distances,different relative positions of explosives and plates,different lateral offset distances,square plates of different sizes and square plates of different materials are carried out,and the influence of each parameter on the damage effect is given.The above work provides a reference for the use of bubble jet phenomenon to damage and strike ships and other typical maritime targets.