Research On Damage Mechanism Of Cylindrical Shell Structure Induced By Shock Wave Thick Wave Head

The damage mechanism of the underwater vehicle under the action of the underwater noncontact explosion shock wave load is not only related to the structural form and material parameters,but also closely related to the input load characteristics.The shock wave load of the underwater thick wave head has the load characteristics of high peak value and long pulse width,and different deformation and failure effects will occur during the coupling process with the cylindrical shell structure of the submarine.The cost of actual ship experiments is high,and scaled model experiments are generally used to predict damage effects.Therefore,the similarity criterion between the model and the prototype is very important.In this paper,underwater explosion loads,plate structure,cabin structure,stiffened cylindrical shell structure and underwater unmanned vehicle are the research objects,and the method of combining scale test and numerical research is used to study the similarity of underwater explosion model test.And the damage characteristics of the cylindrical shell structure under the action of the shock wave load of the thick wave head.Firstly,the physical process of underwater explosion,shock wave propagation theory and numerical simulation method of underwater explosion based on ALE algorithm are introduced.Then combined with the theoretical research on the damage characteristics of the underwater explosion shock wave to the flat/cylindrical shell structure,the numerical method is used to calculate the dynamic response test of the stiffened cylindrical shell model,and the simulation and experimental data are compared to verify the reliability of the numerical method.Finally,the spatial distribution characteristics of the explosive shock wave load are discussed through the charge shape parameters,and the shock wave of the small equivalent cone charge at the detonation end has the characteristics of thick wave head shock wave load.Secondly,aiming at the similarity problem of the underwater non-contact explosion scale model test,this paper adopts Buckingham’s π theorem to discuss the influence of the single value physical quantity on the underwater explosion impact factor under the premise of satisfying the single value condition.A new type of shock factor under the condition of plane wave effect of underwater non-contact explosion shock wave is derived from the angle of similar single value.Taking the typical flat plate,stiffened plate frame and midship section structure of a certain type of ship as the research object,the method of combining numerical value and experiment is adopted.Under the condition of different scale ratios,the deformation deflection and deformation speed of the target structure are measured.Assess the effectiveness of the new shock factor.Then,based on the study of the propagation characteristics of the shock wave load on the surface of the cylindrical shell structure under underwater explosion conditions,numerical methods are used to analyze the spatial distribution characteristics of the underwater explosion shock wave on the surface of the single/double-layer tightened cylindrical shell structure.Under the condition of satisfying the new shock factor,a reduced ratio model of the cylindrical shell was designed based on the mid-section structure of a certain type of submarine.Damage characteristics.Finally,by analyzing the coupling response test of the shock wave of the thick wave head and the reduced ratio model of the backside plate frame,it is proposed that the damage mode of the backside plate frame structure is plastic deformation when the burst distance meets certain conditions.Combined with the internal design structure of the underwater vehicle,the shock spectrum theory is used to assess the severity of the impact environment of the underwater vehicle,and the influence of the shock wave load of the thick wave head on the impact environment is analyzed.The impact of load characteristics on the impact environment of the structure is calculated,and on this basis,the idealized thick wave head shock wave load analysis is designed to affect the impact environment of the underwater vehicle.