Study On Dynamic Response And Residual Strength Of Hull Structure Under The Action Of Air Explosion Load

Ship is the main combat unit in modern maritime battlefield,it has important tasks such as fighting objectives and protecting crew safety.With the rapid development of modern science and technology,the hit precision,carrying dosage and concealment ability of antiship weapons have been rapidly improved,which poses a serious threat to ships.Different forms of anti-ship weapons from the air will cause different degrees of damage to the hull structure,resulting in a decline in the vitality of the ship,a serious threat to the ship's ability to continue to fight and the safety of the crew's life.In order to improve the effective vitality of ships in maritime warfare,large combat ships are mainly protected by the main deck with longitudinal box girder structure to ensure that the ship still has sufficient residual strength after being attacked by air weapons.Therefore,it is of great practical significance to study the damage process and residual limit strength of different forms of aerial weapons to ships,to evaluate the vitality of ships,to improve ship protection performance and to design a new main deck with longitudinal box girder structure.Based on the research of aerial shock wave and contact explosion theory,this paper studies the numerical simulation method of shock wave and typical thin plate under contact explosion,and gets the propagation law of shock wave and the hole size of typical thin plate,and compares it with the results of related empirical formula.The numerical simulation method of fluid-solid coupling in multi-Euclidean domain is determined.Furthermore,taking the different typical segments of a large surface combat warship in China as the research object,we study in detail the dynamic response process of the cabin structure under the action of air contact explosion load and the internal explosion load of the compartment,so as to obtain the failure mode and damage characteristics of the bulkhead structure under different forms of explosive load.On the basis of the above research,according to the research results of ship limit strength theory,the residual limit strength of the cabin segment after different damage has been studied,the collapse process and residual limit strength characteristics of the cabin segment with different damage effect are analyzed,and the important factors affecting the remaining limit strength of the cabin segment are obtained.Finally,on the premise of keeping the webs height of the profile unchanged,based on the evaluation criteria of the residual strength of the hull,the impact damage performance of the cabin section with the main deck structure of type I,Y and V type box girder structure under the internal explosion load of the compartment is compared and studied.Thus,a new main deck form of box girder structure which can effectively improve the residual strength of hull structure is obtained.The main research work of this paper is as follows:(1)Research on the theory and simulation method of shock wave and contact explosion.This paper studies the propagation process and parameter equation of aerial explosion shock wave,simulates the propagation process of aerial explosion shock wave under different mesh sizes,and gets a simulation method with high calculation accuracy.This paper studies the theoretical calculation method of the hole breaking size of the typical thin plate structure under the action of air contact explosion load,compares the numerical simulation results with the results of the literature theory,and verifies the reliability of the calculation accuracy of the finite element model,which provides the theoretical and technical basis for the subsequent research.(2)Research on the theory and simulation method of ship ultimate strength.This paper studies the different theoretical calculation methods and advantages and disadvantages of ship ultimate strength,uses different calculation methods to simulate the classical test model Reckling23 under different mesh sizes,and compares the numerical simulation results with the results of literature test.A simulation method with good computational efficiency and accuracy and mesh size are obtained,which provides the basis of theoretical and technical methods for the study of subsequent limit strength.(3)Study on the dynamic response of ship structures under the action of aerial explosion load.The dynamic response of several typical compartments of a large surface combat warship in China is numerically simulated under the two load modes of air contact explosion and internal explosion of the compartment,and the dynamic response characteristics such as shock wave propagation,damage deformation and structural deformation energy are analyzed,and then,The failure modes of different areas of typical segments under different load forms are revealed.Finally,the hole breaking size of the main deck under contact explosion and the prediction formula of the deformation energy of the compartment structure under different load forms are put forward.(4)Study on the residual strength of the cabin after air explosion load.Based on the numerical simulation results of the dynamic response of different typical cabins under different air explosion load forms and different explosive equivalent,the process of middle and vertical bending collapse of the complete typical cabin segment and the damage compartment section is studied,and the sensitive factors affecting the residual limit strength of the cabin segment are obtained,and the residual strength of the complete typical segment and the damage compartment is studied.The influence of different load forms and explosive equivalent on the vitality of the cabin segment is revealed.(5)Study on the protective properties of the new section with the main deck of the box girder structure.A new type of main deck with box girder structure,such as type I,Y type and V type,is proposed,and the impact damage performance of the new structural compartment is compared with the remaining strength of the cabin structure after the explosion load of the compartment under the condition that the height of the webs of the profile remains unchanged.A new type of main deck with box girder structure is obtained,which has the greatest increase in the remaining limit strength of the cabin segment.