Computation of Vibration and Sound Radiation from Double Cylindrical Shell Coupled with Frame

The vibration and sound radiation of double cylindrical shell reinforced with and coupled with ribs including frame are considered. Fltigge equation is used to describe the vibration of the shell. The shell is coupled with the frame structure by the discrete nodes of the contact surface. FEM (finite element method) is used for calculation of the forces acted on the shell by frame structure, which induces the forces into the vibration equation. The vibration equation coupled by the sound fluid structure is solved in the end. Theoretical results of radiated power, radial quadratic velocity are presented. The results show that the level of vibration and sound radiation is reduced due to the existing of frame, and increasing the thickness of the frame＇s panel or the length of the frame can reduce the radiation noise effectively. These are important for the design of noise reduction of underwater structure.