Application of Sandwich Structure on Ship Propulsion Damping System

• Main Authors: Chen, Yin-Min, 陳胤旻
• Other Authors: Chen, Yung-Wei
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/94k722

碩士 === 國立臺灣海洋大學 === 輪機工程學系 === 105 === In this thesis, we apply the macromolecule multilayer sandwich structure (MMSS) and different geometric design to reduce the radiation noise from submerged structure. Recently, it is very popular issue for under water noise and under water geometric design in the ocean engineering field. For the marine main engine, propeller, marine shafting, and wave, ones are main noisy sources, which cause the vibration and radiation noise under water. Therefore, it is our aim to set up macromolecule multilayer sandwich structures and to compute the radiation noise under water. Because the vibration and radiation of the submerged structures is different from in air, it is very difficult to deal with the coupling of the response of structure and fluid. Therefore, we propose the MMSS and geometrical structure, which used in shafting system to verify the radiation noise under water. The MMSS includes at least two types of material with the passive constrained layer (PCLD) and viscosity damping layer, and properties of PCLD and viscosity damping layer increase the stiffness and damping, respectively. When we apply the sandwich structure on submerged structure, the structure is subjected to the dynamic loading and deformed, the viscoelastic material dissipated energy and conversing kinetic energy to thermal energy; then, to reduce the vibration from the submerged structure further avoid the radiation noise. In this thesis we used the finite element method (FEM) solving the vibration natural modes (VNM), and coupled the VNM with the boundary element method (BEM) to compute the submerged structural responses. In order to verify the properties accuracy of FEM, we compared numerical solutions with experimental solutions. Numerical results show that the element properties by FEM is in agreement with experimental ones. Further, we apply the experimental parameters into full-scale submerged structure under different force tests. The results are shown that the proposed numerical procedure can efficiently reduce the amplitude of structural vibration and reduce sound radiation noise under water. Hence, the numerical results have value and its engineering application