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標題: | 光學干涉術對於平板之動態分析的應用 The Application of the Optical Interferometer for Dynamical Analysis on Plates |
作者: | Shu-Hua Chang 張淑華 |
指導教授: | 陳 國 在(Kuo-Tsai Chen) |
關鍵字: | 矩形平板,四邊固定,橫向剪切干涉術, rectangular plate,fix end,lateral shearing interferometer, |
出版年 : | 2007 |
學位: | 博士 |
摘要: | 光學量測方法最大的優點在於其為非接觸式及具高解析度的特色,因此在測量上是非常重要的技術,其中光學的干涉術最具代表性。干涉術的架構大體可分為二種,即共光路與非共光路,非共光路架構,其參考光和物光沿不同的光路傳播,因此易受環境條件影響精確性,而共光路架構則參考光與物光沿相同光路傳播,此方法可克服實驗環境問題。共光路架構最典型的架構為橫向切剪干涉術,此種干涉架構對於環境條件較不敏感,無需侷限於精密之光學實驗室內進行。對於偵測振動物體之表面變形狀態,合併相移法則可做為振動物體之動態分析。
在本論文中,應用橫向剪切干涉術找出振動平板之最大振幅精確的位置,並於其上施加質量載重或內部支承,使得共振模態改變,進而降低平板的聲輻射,本文中包含了平板的理論分析,探討振動的響應,光學部分則說明橫向剪切干涉術的原理,並以實驗印證此系統對於降低聲音輻射之影響。 針對鏡面鋼板及霧面鋼板實驗,結果顯示在較低的模態中,如(1,1)及(1,2)模態,輔以橫向剪切干涉術可大幅消除主要貢獻的聲輻射,特別是鏡面平板之(1,1)模態,附加質量載重聲輻射衰減量達32.2dB。 Because of its non-contact and high-resolution characteristics, optical measurement has been one of the most important techniques of measurements. The interferometry structure has two types including a common path and a non-common path. In the architecture of non-common path, the reference beam and object beam spread in different optical paths. Therefore, the precise of measurement is easily influenced by the environment condition. However, both beams in the common path structure deliver in the same optical path. This way can get over the environmental factors in laboratory. The lateral shearing interferometer is the typical common path interferometry. This structure is not so sensitive to the external condition, which enables itself not to be limited in the optical laboratory in experiments. One of the most interesting and useful applications of lateral shearographic interferometry is the detection and measurement of the vibration objects deformation. The lateral shearing interferometers combined with phase shifting for vibration analysis of plates can be presented perfectly. The one which should be mentioned is methods of measuring vibration. We adopt the time average and stroboscopic techniques. This study attempts to discuss the lateral shearing interferometer approach in order to find out the location of maximum amplitude. And applying added mass loading and inner support methods can change the resonant modal and meanwhile reduce the acoustic radiation from square plates. The study includes the dynamical analysis of uniform plates, the theoretical consideration on vibration analysis and lateral shearing interferometer, and the laboratory demonstration on the acoustic-radiation reduction of plates by using lateral shearing interferometer approach. Results of dynamical analysis on different plates obviously reveal lower modes such as (1, 1) and (1, 2) modes must respond to the most acoustic radiation from plates. This experiment proves that much more reduction of acoustic radiation from plates over greater frequency range can be reached when using a lateral shearing interferometer. The corresponding experimental results clearly show that the greater effectiveness on (1, 1) mode by 32.2dB reduction for glass polish finish plate refashioned by using mass loading. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/27551 |
全文授權: | 有償授權 |
顯示於系所單位: | 工程科學及海洋工程學系 |
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