Application of Sandwich Structures on the Vibration Reducing for Dynamic Response

• Main Authors: Chang, Yi, 張逸
• Other Authors: Soon, Shin-Ping
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/20079240158331689955

碩士 === 國立臺灣海洋大學 === 輪機工程學系 === 104 === In this thesis, we apply the sandwich structure to reduce the radiation noise from the submerged structure. Recently, it is very popular issue for controlling radiation and scattering noise from the submerged structure especially in the ocean engineering. Because the vibration and radiation of the submerged structure under water are different in air, it is very difficult to deal with the coupling of the responses of structure and fluid. Therefore, we propose the sandwich structure to verify the radiation noise under water. The sandwich structure includes at least two types of material with the passive constrained layer (PCLD) and viscos damping layer, and properties of PCLD and viscosity damping layer increase the stiffness and damping, respectively. When the submerged structure is subjected to the dynamic loading and deformed, the viscoelastic material at the same time dissipated energy and conversing kinetic energy to thermal energy; then, to reduce the vibration from the submerged structure further avoid the radiation noise. Therefore, in this thesis we used fem/bem solving for low frequency domain, and applied the vibration natural modes (VNM) for the displacement expansions and coupling with bem to compute the submerged structural responses. In order to verfied the numerical accuracy and stability, we compared numercial solutions with analytical solutions. The results are shown that the present methods have good computational efficiency and high accuracy. Hence, the numerical results have value and its engineering application.