Research On The Damage And Energy Absorption Law And Rapid Calculation Method Of Warship Broadside Multicamerate Protection Structure Under The Action Of Underwater Contact Explosion

Underwater contact explosion generates several different forms of loads that act directly on the hull and cause serious damage to the military ship.The outboard structure is one of the important structures to resist underwater weapons,and large naval warships sacrifice space for protection,and adopt multicamerate protection system to make full use of space,media and structure to realize comprehensive protection for large naval warships.Therefore,this paper is an in-depth study of the destructive deformation and energy absorption of the ship side multicamerate protection structure under the effect of underwater contact explosion,which is of great significance to enhance the vitality of large naval warships,evaluate the performance of multicamerate protection system and optimize the design of compartment structure.Firstly,the physical phenomenon of underwater explosion and the characteristics of shock wave and bubble pulsation loads are described,and the prediction formula for the size of the breach produced by the structure under the action of underwater contact explosion is summarized,and the advantages and disadvantages between different prediction formulas are analyzed;the advantages and disadvantages of the energy analysis method applied in the underwater contact explosion of the multicamerate protection structure are analyzed,and the calculation formula for energy absorption of different damage modes of each structure is given.The ALE calculation method is discussed,and to ensure the effectiveness of the numerical algorithm in this paper,the classical empirical equation for shock wave loading is used to verify the grid density that meets the accuracy requirements and computational efficiency.On this basis,the effectiveness of the ALE method in the subsequent study is demonstrated by comparing with the numerical simulation results based on the typical multicamerate protection structure scaled-down ratio model tests.Based on the underwater contact explosion model test of the multi-compartment protection structure,the difference of the damage deformation mode between the three structural forms of the expansion chamber was analyzed,and the advantages and disadvantages of the protection performance of each structural form were studied.Secondly,a typical ship side multicamerate protection structure model was established to study the basic physical phenomena and dynamic response process under the action of underwater contact explosion load,analyze the damage deformation and energy absorption of each structure in the multicamerate protection system,and summarize its protection mechanism.The scaled-down model test of the multicamerate protection structure under the action of underwater contact explosion is carried out,and the energy absorption of each main structure is calculated by applying energy analysis method,which further verifies the validity of the research method from the perspective of total energy absorption and energy share of the structure.The multicamerate protection structure is divided into proximal and distal structures according to the distance from the center of the burst point,and the results are compared with those in several literatures,and the reasons behind them are investigated by analyzing the differences between different analysis methods for different structures.Extracting the energy distribution of the compartments at each level of the multicamerate protection structure,quantitatively analyzing the protection performance of the main components in the compartments using the energy flow method,and revealing the protection mechanism of the multicamerate protection structure.Then,analysis of the damage deformation and energy absorption law of multicamerate protection structure under the change of parameters such as different dosage and expansion chamber structure plate thickness,and obtained the mutual coupling relationship between the damage of outboard side plate,outboard inter-structure and outboard liquid chamber plate and their respective variables,mastered the damage deformation law of multicamerate protection structure,and established the rapid prediction formula of outboard side plate and outboard liquid chamber plate break area.According to the influence of each variable on the size of energy absorption of the expansion chamber structure,combined with the structural damage and deformation,the law of energry absorption of the outboard side plate,the inter-board structure and the liquid chamber outboard plate was obtained,and the rapid prediction formula of the specific energy absorption of the three structures was proposed.Simulations and fast calculations were designed for different dosage and expansion chamber structure plate thickness,and the accuracy of the fast prediction formula was further verified by comparing the results of both.Finally,in order to evaluate the absorption effect of the multicamerate protection structure on the high-speed fragments,the calculation methods of the main physical parameters of the fragment field formed by the combat parts of domestic and foreign anti-ship missiles are summarized,and the fragment mass,number distribution and initial velocity of the combat parts of four typical anti-ship missiles are obtained by the empirical formula of fragmentation,and the spatial distribution law of the number of fragments generated by the "Exocet" missile is studied.The penetration effect of fragments on thin metal plates and the velocity decay formula in fluid medium are discussed;from the empirical formula of fragmentation firing test,the penetration probability of fragment field on target plates is obtained,and then the effectiveness of fragment field on liquid compartment damage is studied,and the fast calculation formula of"safe quality" of fragmentation is established;combined with the damage probability model,the penetration probability of fragmentation on liquid compartment at different liquid compartment widths is analyzed.Combined with the damage probability model,the probability of penetration of the fragment into the inner plate of the liquid tank under different liquid tank widths is analyzed,the damage capability of the fragment field to the liquid tank protection structure is evaluated,and the fast calculation formula of the "safe width" of the liquid tank under different liquid tank plate thicknesses is given.