Investigation On Vibration And Acoustic Radiation Characteristics Of A Complex Built-up Shell Structure

The complex built-up shell structure is one of important components of underwaterstructure. To ensure that the underwater structure has good quiet performance, vibro-acousticprediction is utterly necessary, not only we can evaluate structure characteristics, but alsodiscovering the key factor of vibration to improve structure. For vibro-acoustic prediction,there mainly exist analytical method, numerical method and test method. Analytical method iscommonly applied to simple structure. Test method depends on the external condition.Numerical method has been widely applied and is capable of solving large scale and complexstructure. Numerical methods mainly include FEM, BEM, SEA and some recently developedhybrid method, etc. In the thesis, the transfer path and contribution, numerical method,vibro-acoustic prediction in the low and intermediate frequency are investigated.Firstly, the numerical model of the complex built-up shell structure is modeled by finiteelement model, and validated through modal results obtained by modal test. Transferfunctions are obtained by test of vibration. For the region of obvious vibration, we applytransfer path analysis. Through loading transfer function of test experiment and numericalsimulation respectively, the contribution of the transmission path of the response spectrum iscalculated to trace the key problem of vibration.Fluid-structure interaction model is modeled, a comparison of vibration characteristicsin water and air is carried out. In the low-frequency band, different methods are employedincluding BEM, IFEM and AML, and compared by numerical analysis. The results show thatalthough the three methods can obtain satisfactory results, the AML method shows higherefficiency.In the low-frequency, acoustic radiation is predicted through loading identified force,providing the reference for noise in reality. In the intermediate-frequency, a hybrid FE-SEAmethod is employed to predict the vibro-acoustic of complex structure in the paper. With thesoftware of VA One, the vibration and acoustic radiation in the intermediate frequency iscalculated.