Research On The Acoustic Characteristic Of Ribbed Double Cylindrical Shell Coated With Isolating Sound And Decoupled Tile

It is very important to hide itself for the submarine in modern war and finite cylindrical shells with stiffened ribs are major structure of cabin on the submerged or underwater vehicles. The noise of such structures roots in the shell vibration that drove by the inner engine, when coupled with the liquid medium, the noise will affect the performance of the vessels badly. Thus it has important theoretic value and practicality to research sound-vibration characteristic of the finite cylindrical shell with stiffened ribs. This paper researches the vibration and sound radiation of cylindrical shell.Based on classical mode theory, a FEM analyses model is set up by the FEM acoustic function. In the process of the FEM calculation, it uses limited truncation to substitute unlimited fluid domain. And the modal of the structure is analyzed.Based on FEM and BEM, the effect of structure parameters (the thickness of overpressure resistant plate, the arrangement of frames) on sound radiation is discussed using software ANSYS and SYSNOISE by changing the structure parameters of cylindrical shell, and finds the effect law of structure parameters on sound radiation.For the underwater ribbed double cylindrical shell's vibration and radiation, a kind of acoustic vibration test model for the 'structure-decoupled material-fluid' coupled action is set up, and based on this model it performed a model test. And this paper specifies the design and manufacturing of the model and the experimental contents and methods and so on. All of these are important for the completion of this test.By the analyses of the data, it finds out the rule of how much vibration and radiated noise the decoupled material can decrease, which is that the decoupled material can decrease the vibration and radiated noise clearly, and the function depends on the exciting frequency, how to coat the material and the structure form. By analyzing the structure radiation rule, it finds that the radiation has a clear directivity and part-coating can also decrease radiation clearly at special occasion.