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Vibration Isolation Analysis and Application of Viscoelastic Materials
|Authors: ||Wei-Hong Lin|
|Contributors: ||NTOU:Department of Systems Engineering and Naval Architecture|
viscoelastic material;loss factor;complex modulus;mobility;resonance;isolation
|Issue Date: ||2011-06-30T07:33:15Z
|Abstract: ||黏彈性材料之隔振特性分析與應用 林威宏 摘要 黏彈性材料因同時具有彈性及黏性，當其有動態應力時，可由該材料之彈性而吸收振動能量，同時由材料之黏性而消耗振動能量，因此黏彈性材料可用作隔振材料。黏彈性材料之隔振特性係以材料之損失因子作為評估指標。損失因子是材料動態應力與動態應變比值(即複變模數)之虛部與實部之比。 本文即在建立黏彈性材料損失因子之量測方法，並以此方法對八種黏彈性材料試片進行複變模數量測，並分別算出損失因子。顯示其在0.0362 ~0.0925之範圍。再以黏彈性材料之損失因子作為輸入資料，以ANSYS有限元素分析軟體進行簡單結構之動性函數分析，並與實驗值比較，以確定材料損失因子量測之正確性。 對黏彈性材料損失因子之量測，應用了Nielsen理論將材料損失因子之振動頻率相關性予以剔除，使得到單獨材料之損失因子值是本研究之特點。同時就試片面積大小、應力變化幅度大小對黏彈性材料損失因子是量測值之影響，進行敏感度分析，得知黏彈性材料損失因子值之量測受應力變化幅度之影響較顯著，當應力變化幅度增加一倍，損失因子值約減少(1.9~8.4)%﹔而損失因子量測值受試片面積之影響較小，當試片剖面積減少(75) %，損失因子值減少(0.16~1.31)%。 本論文最後應用四端參數法進行黏彈性材料隔振器之串、並聯應用，並以ANSYS軟體探討其隔振行為分析，同時進行實驗量測比較，結果顯示十分吻合。|
Vibration Isolation Analysis and Application of Viscoelastic Materials Wei-Hong Lin Abstract Viscelastic material possesses viscosity and elasticity simultaneously. When this kind material subjected dynamic stress, the vibration energy can be absorbed by its elasticity and dissipated by its viscosity. Thus viscoelastic material is good for a vibration isolation material. Its vibration isolation property can be characterized by the loss factor of the material as an isolation index. While loss factor is defined by the ratio of the imaginary part and real part of the complex modulus, which is the ratio of dynamic stress and dynamic strain of the viscoelastic material. The main purpose of this paper is to establish the measurement method of the loss factor of a viscoelastic material. By the developed method, the loss factors of eight specimens of different viscoelastic materials have been measured. It shows the values of loss factor are ranged in 0.0362~0.0925. Using the measured loss factor of a specific viscoelastic material as input data, the mobility function of a simple structure, which has used the viscoelastic material for vibration isolation, has been analyzed by utlizing FEM software ANSYS. Comparisons of the driving point mobility and the transfer mobility with the experimental measurement show good coincidence. In developing the measurement method of loss factor, Nielsen’s theory has been applied to delete the frequency dependence effect of loss factor. Thus the developed method can attain the loss factor value pertaining to pure material. Also, the sensitivity analysis of the parameters, such as the cross-sectional area size of test specimen and the applied dynamic load amplitude, to the loss factor value has been discussed. It concluded that the applied load amplitude is more sensitive to the loss factor value, while the area size is less sensitive. When the load amplitude is doubled, the loss factors decreased by an amount between (1.9~8.4)% . When the cross-section area is reduced to (75)% , the loss factor changed by (0.16~1.31)%. Finally, the method of four-pole-parameter has been used to discuss the vibration isolation behavior of the viscoelastic isolators arranged in series and in parallel. Also, an application example of vibration isolation has provided to illustrate the coincidence of the analysis results by ANSYS and that by measurement.
|Appears in Collections:||[系統工程暨造船學系] 博碩士論文|
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