Vibration And Acoustic Radiation Characteristics Of Cylindrical Shells On The Propulsion Motor

Cylindrical shell on the propulsion motor is the main structure part of underwater vehicle which includes torpedo and submarine, etc. Research of vibration and acoustic radiation characteristics of the shell will be helpful to investigate the mechanism of acoustic radiation. And it also has important value to improve concealment and to carry through lower noise design of underwater vehicle. The background of this thesis is the vibration and acoustic radiation from cylindrical shells on the propulsion motor. The vibration and acoustic radiation characteristics of the propulsion motor in air are analyzed by combing the finite element numerical simulation with the experimental methods, and it is discussed that vibration and acoustic radiation characteristics of cylindrical shells with ring stiffeners, damping layer thickness and excitation force characteristics.Method of single input single output (SISO) conducted on the simple model of cylindrical shells in air. The calculation of acoustic radiation is performed by using FEM/BEM on the model, and compared with experimental results. It shows that the numerical simulation results are accordant with the experimental data. Then research of vibration and acoustic radiation characteristics of cylindrical shells based on the FEM/BEM. The number and positional distribution of ring stiffeners have important effect on vibration and acoustic radiation characteristics of the shell. The calculation result shows that:the number of ring stiffeners has important effect on vibration and acoustic radiation characteristics, and the influence of the positional distribution of the same amount ring stiffeners is relatively lower. For the motor cabin of the prototype structure, the influences of the damping layer thickness and excitation force characteristics on vibration and acoustic radiation suppression are investigated. With the same analysis method of stiffened cylindrical shells, finite element method (FEM) and boundary element method (BEM) are combined to investigate the influences of the damping layer thickness and excitation force characteristics on vibration and acoustic radiation. The results showed that increased thickness of damping layer and reduced the radial excitation force value in the shell, can effectively suppress the vibration response and acoustic radiation of the shell, and they are significant for improving the concealment of underwater vehicle.This paper studies the vibration response and acoustic radiation characteristics of the simple model and cylindrical shells by combing the FEM/BEM with the experimental methods, and it is discussed that vibration and acoustic radiation characteristics of cylindrical shells with ring stiffeners, damping layer thickness and excitation force characteristics. These studies are valuable for researches on the vibration and acoustic radiation of motor cabin cylindrical shells underwater vehicle.