The Research On Acoustic Radiation Damping Of The Stiffened Structure

The ship structures work under the complicated conditions, it is significant to research the vibration and acoustic radiation characteristics to prove improve the ship's applicability and battle effectiveness.The researchers play much attention to the vibration and acoustic radiation of the structure in the engineering field. The theoretical method and numerical method are usually used to resolve the problems. The former method is applicable to the regular elastic structures with simple geometry, simple material characteristic and simple boundary conditions while the latter is applicable to the complicated elastic structures. The FEM, which is a numerical method often used, can also be adopted to resolve the vibration problem of structure with complicated surface. And the BEM shows unique advantage to deal with the infinite area problem.The fluid were considered as compressible and incompressible fluid model, based on the three basic equations of fluid mechanics, the fluid-structure coupled control equation was presented using the FEM/BEM. The iterative lanczos method was adopted to resolve the eigenvalue problem of the dissymmetrical, frequency relative matrix. And then, the acoustic radiation was calculated and the impact of the fluid's compressibility on the natural frequency, sound power, radiation direction and the radiation damping was showed. The compressible fluid model is suggested to be used.Both in light and heavy fluids, the impact of geometrical parameter of the elastic plate on its acoustic radiation damping was discussed. The solution method to the coupled vibro-acoustic problem was presented. Based on energy theory, the acoustic radiation damping of the elastic plate was defined and the numerical formula of the plate's acoustic radiation damping was educed. And then, with the FEM and BEM, the acoustic radiation damping of the elastic plate was calculated numerically. Finally, the conclusion was made. The acoustic radiation damping of the plate in water is far larger then in air; the impact of the thickness of the plate, the plate's size and the excitation location on its acoustic radiation damping was showed.