The Numerical Analysis Of Sound And Vibration From Cylindrical Shell

Research of the vibration and sound radiation of assembled structures with cylindrical shells has been increasingly become an advanced problems of noise and vibration control, just for the widely application of cylindrical shells in the common and national defense engineering. Predicting the noise and vibration of assembled structures with cylindrical shells is key points to realize low-noise design of structures and aircraft, especially for underwater vehicle.The noise due to the hull vibration, which is caused by the air noise from mechanical equipment, is one of the major sources of the underwater vehicle radiation noise. In this thesis, the main research contents are the numerical analysis of vibration and sound radiation from a ring-stiffened cylindrical shell excited by a point sound source. At medium and low frequency, finite element method and boundary element method are used to analyze vibration and sound radiation from underwater ring-stiffened cylindrical shell, and the influence of the source position on the acoustic radiation power from a shell and the mean-square velocity is also given. At medium and high frequency, statistical energy analyses are used to analyze vibration and sound radiation from underwater ring-stiffened cylindrical shell, and the influence of the damping treatment and the thickness of damping layer is also given.Characteristics of vibration in middle-high frequency for a ring stiffened cylinder by vibration measurement are predicted in this paper. In middle-high frequency,the vibration energy transfer function from the measured points to all subsystems is deduced by Statistical Energy Analysis. Further more mean square velocity of the shell can be obtained. Using the vibration signal of measured points as inputs, the mean square velocity of the shell is gotten by the deduced vibration energy transfer function in numerical calculation. The result shows that the Prediction method in this paper is feasible and more accurate by Comparing predict value of calculation with experimental value.