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碩士論文公告區 |
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| 年度： | 91 | |
| 姓名： | 張翔傑(Chieh-Hsiang Chang) | |
| 論文題目(中)： | 研究以敲擊回音之表面波位移推導轉換函數的可行性 | |
| 論文題目(英)： | Study the Feasibility of deriving the transfer function from the Rayleigh wave in the impact-echo displacement waveform | |
| 摘要(中)： | ||
| 本研究乃是以敲擊回音法之表面波位移推導轉換函數的可行性，由於敲擊回音法檢測時所得到之反應頻譜中，各尖峰之振幅會隨注入能量及接觸時間不同而有相當大之差異，所以實驗的結果需使用轉換函數才能做定量評估，但受限於儀器無法直接取得敲擊時鋼珠敲擊力量以及接觸地面時間，因此並不能得到真實轉換函數頻譜，僅能由敲擊時作用力和表面波振幅之理論關係而得近似轉換函數，其原係假設將時間領域所得之敲擊回音反應中的表面波位移波形除上修正係數（ ）後，使其最大振幅值在理論上與敲擊力成正比，將此修正後表面波來模擬敲擊時作用力與時間歷時。並由近似轉換函數去探討版厚振幅值與版厚關係，分下列兩方向加以討論： （一）由數值模擬混凝土版狀結構物推導版厚振幅值與版厚關係通式。 （二）實際檢測中版厚振幅值與通式值之差異 以數值模擬釐清混凝土版厚、敲擊接觸時間、混凝土波傳性質的改變對近似轉換函數的影響，以上述之變數製作模擬試體，並模擬敲擊回音試驗得其位移波形，進行轉換函數得其版厚振幅值，推導出版厚振幅值與版厚關係通式。在實驗部分當接收器到敲擊源距離與版厚比值為0.1及0.2 時，各種版厚數值與實驗所得之版厚振幅誤差僅在6﹪左右，表示由此通式評估版厚振幅有其可信度。 |
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| 摘要(英)： | ||
| This dissertation is a study for the feasibility of deriving the transfer function from the Rayleigh wave in the impact-echo displacement waveform. The peak amplitude of in impact-echo spectrum may be varied by the energy and the contact time produced by the impact force. The experimental result needs to be transformed into transfer function for quantitative evaluation. Because the contact time and amplitude of force can not be recorded by present instrumentation, the transfer function can not be calculated. We can only get the approximate transfer function from the simulated impact force derived by the Rayleigh wave. We first find the relation between maximum amplitude of R wave and of force. Then according to the established relation we can get the simulated impact force by dividing the R-wave by suitable coefficient. This study discusses the problem with two aspects. (1) Use finite-element models simulating the response of concrete plate to obtain the general formula that derived from amplitude of plate’s response and thickness of plate. (2) Study the difference between real experimental results and numerical results. Numerical models were established to study the effects of thickness of plate, contact time, and property of concrete to simulated transfer function. Use these results to derive a relation between amplitude of plate’s response and thickness of plate. In the experimental study, when the ratio between impactor-receiver distance and plate thickness is 0.1 and 0.2, the discrepancy between experimental and numerical result is 6％. The result shows the reliability of using the formula to predict the amplitude of the peak corresponding to plate-thickness in simulated transfer function. |
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| 檔案： | 沒有相關檔案 | |
| 相關連結： | http://ethesys.lib.cyut.edu.tw/ETD-db/ETD-search-c/view_etd?URN=etd-0821103-080020 | |