Study On The Load And Damage Characteristics Of Underwater Near Field Explosion

According to a large number of research results at home and abroad,the damage caused by underwater near field explosion bubble jet load can not be ignored.Many scholars use the methods of experiment,numerical and theoretical analysis to study underwater explosion.Due to the difficulties of near field explosion test,such as high destruction,strong nonlinearity and high frequency of explosive load,the results of near field explosion are relatively imperfect.Such as near field explosion shock wave load size,bubble jet load size,damage to structure and plastic zone measurement method,as well as complex boundary conditions and multi-phase matter movement characteristics are not solved.Therefore,this paper studies the damage characteristics of underwater close-contact explosive bubble jet to multi-story frame structure by means of the double bottom model test and numerical calculation method.The main contents of this paper include the following three aspects:Firstly,the validity of the numerical algorithm was verified based on the shock wave empirical formula and the near-field explosion test.The solid supported back space stiffened square plate model is established to simulate the damage process of the underwater explosion shock wave to the frame structure.Several common damage modes are summarized and the break radius is calculated by the method of area equivalent,and through a large number of numerical calculations are carried out to sum up the change rules of the working condition parameters,such as burst distance,explosive equivalent,plate thickness,material and ao on,with the break radius of the structure,and get the break estimate formula,By this formula,and the engineering practice,we can predict the breach of the underwater close-contact explosion.Secondly,through numerical and model tests,the damage characteristics of laminates,the pressure characteristics inside the cavity and the movement characteristics of multi-phase material are studied.According to the failure results and the stress test results of the test and numerical model,the main causes of the failure of each layer are analyzed from the angle of energy absorption and pressure.Finally,the three-compartment models of single-section,double-layer rigid body and elasto-plastic section with initial breach are established,and the model is freely floated on the water surface by the additional mass method.The numerical calculation of the cabin structure under various loads dynamic response and damage situation,analysis of the model and detonation gas,water and air of multiphase material movement,and the effects of the dosage,the distance and the free surface effect of parameters such as energy absorption of bubble radius,period,jet velocity and structure.