Research On Vibration And Sound Radiation Of Pipe-shell Coupled Structures

In the acoustic stealth technology of underwater vehicles,pipeline vibration noise has become a major obstacle to the design of low-noise or quiet underwater vehicles.Therefore,it is necessary to carry out research on the prediction and control technology of pipeline system vibration and noise.The traditional fluid-structure interaction(FSI)calculation of ship pipeline usually only focuses on the vibration transmission characteristics of the pipeline system itself,and ignores the influence of the elastic foundation at the lower end of the support on the dynamic characteristics of the pipeline system.The actual ship pipeline system is usually connected to the ship hull through support,sea port,pump foundation,etc.Because of the coupling effect of elastic hull structure,its dynamic characteristics will show different mechanical characteristics from the single pipeline system.And the ultimate goal of the vibration and noise prediction of the pipeline system needs to be based on the underwater acoustic radiation characteristics of the ship hull.In this paper,an analytical numerical method is used to establish a three-dimensional fluid structure coupling model of the pipe system,and the underwater vehicle hull structure is simplified to a regular conical-cylinder-sphere combined shell structure.The main work of this paper is as follows:In chapter 1,the fluid-structure interaction of liquid filled pipes is reviewed,and the numerical calculation methods for the vibration problems of combined shells such as conical shells and cylindrical shells are summarized.The engineering requirements for the integrated modeling and calculation of pipeline and ship hull coupling are pointed out,and the application of periodic structures in the vibration control of liquid filled pipes is briefly introduced.In chapter 2,based on the FSI 14 equation model of the liquid-filled straight pipe,the three-dimensional impedance matrix is derived considering Poisson coupling and connection coupling to analyze its FSI parameters;the overall impedance matrix of elbow,branch pipe and space pipeline is assembled according to the boundary conditions of fluid continuity and force balance at the connection position of elbow,branch pipe and other accessories,and vibration transmission characteristics of typical pipe components are analyzed from the perspective of wave propagation;.In chapter 3,based on the exact solutions of the vibration governing equations of conical shells,cylindrical shells and annular plates,the impedance matrices are derived by using the impedance synthesis method.Annular plate is used to simulate the stiffened and bulkhead respectively,and the impedance matrix of conical-cylinder-sphere combined shell is established to simulate the hull structure.In chapter 4,the impedance admittance synthesis method is used to analyze the coupling vibration of pipeline and elastic foundation from the simple straight pipe plate coupling structure to the space pipeline and cylindrical shell coupling structure,and then to the complex space pipeline combined shell hull coupling structure.Finally,the coupling vibration and acoustic radiation characteristics of the pipeline and the hull finite element model under real working conditions are analyzed.In chapter 5,the band-pass characteristic of periodic structure is applied to the vibration control of pipeline.The relationship between wave vector and the displacement response propagation and attenuation area is studied.The composite laminated theory is combined with the band-pass characteristics of periodic structures.The mechanism of band gap formation of periodic structures is studied.In chapter 6,the experimental verification of the calculation method is carried out for the space pipeline,the conical-cylinder combined shell,the coupling structure of pipeline and combined shell,and the band gap control based on periodic structure proposed in the previous chapter.In chapter 7,a summary of the whole paper is made,and further feasible works are prospected.