臺灣博碩士論文加值系統

敲擊回音法能有效檢測混凝土內部缺陷，該方法在結構表面敲擊以激發應力波，接著量取表面位移進行傅立葉轉換，再由頻譜之頻率尖峰值判讀缺陷位置。當以敲擊回音試驗偵測傾斜介面時，因試體表面與反射介面不平行，應力波在兩介面之間的來回反射並不像平行面一樣規則，因此頻譜的回音尖峰並不一定會對應到測點正下方之介面，且回音頻率尖峰不太明顯。若以影像法繪製頻譜影像時，會發現介面的傾角及位置都略有偏差。
本研究之目的在開發一有效之頻譜影像傾斜介面修正法，以修正來自傾斜介面上各點應力波回傳所造成的互相干擾。本研究所提出之頻譜移位影像法，與震測移位影像法類似，但處理之訊號並非時間域訊號，而是頻率域訊號。移位法利用橢圓疊加的原理，將所有測點的頻譜中各頻率的能量散布到整個半橢圓中，各像素得到來自所有測點的能量疊加。由於頻譜移位影像法中，頻率振幅對頻譜影像各像素均有相同比重貢獻，會導致非傾斜介面位置產生鬼影干擾。因此本文再利用權重分配法以增強傾斜介面反射能量並去除影像修正後產生的鬼影。此外，本文也對頻譜影像進行色階轉換以增強影像對比。藉由本文提出方法可使垂直斷面影像清楚顯示傾斜裂縫的形狀以及位置。
本研究先以有限元素法模擬六個不同斜率的傾斜裂縫，再以數值結果驗證本研究提出方法之可行性，由數值模擬結果可看出經由頻譜移位影像法後，能加強裂縫影像，修正傾斜裂縫位置，且能消除影像中的鬼影。本研究同時進行三組模型試驗，實驗結果顯示，頻譜移位影像法能有效應用於實驗訊號，且所顯現的影像是更為直觀的試體剖面圖，能準確地定出傾斜裂縫的位置與大小，在實際應用上應可大幅提升混凝土非破壞檢測之效能。

Impact echo method can effectively detect internal defects of concrete, this method is to impact the structure surface to stimulate the stress wave, and then to measure the surface displacement of the Fourier transform, and then interpreted by the peak value of the spectrum of frequencies of defect sites.
When using Impact echo method to detect tilt interface, the specimen surface and the reflection interface is not parallel, so force wave between the two interfaces coming back reflection is not like the rule between two parallel surfaces.
Therefore, spectrum echo peak is not necessarily correspond to the measuring point just below the interface, and the echo frequency peak is not too obvious.If you use the image method to draw a spectral tomography, you will find out the inclination and position of the interface have a slight deviation.
The purpose of this study is to develop an effective Spectral Tomography Tilt Interface Amendment Method to amend mutual interference cause by the stress wave returns from tilt interface . This paper presents a Spectral Migration Image Method, similar to the Earth’s Interior Migration Method, but the signal processing is not a time domain signal, but the frequency domain signal.
Migration uses the oval superposition principle, the energy of each frequency in the spectrum of all measured points spread to the entire semi-elliptical, each pixel from all points of the energy overlay.
As the Spectral Migration Image Method, frequency amplitude spectrum of each pixel of the image have the same proportion of the contribution will result in non-tilt interface location of the Interference signal. This article re-use of the method of weight distribution to enhance the tilt interface reflection energy and remove the image correction resulting from the Interference signal.
In addition, the gradation conversion of spectrum images to enhance image contrast. By this paper, the method can make the vertical cross-section image clearly shows the shape and position of the inclined cracks.
This study use the Finite Element Method to simulate six different slope of the inclined cracks, then use numerical results verify the feasibility of the proposed method.
From numerical simulation results, we can see that through the Spectrum Migration Amendment Method can fix tilt crack location, enhance the signal strength of the crack area and focus on the correct thickness of the defect, and eliminate Interference signal, solve the problem of error in judgment.
This study sets three model tests at the same, the experimental results can also be found that the amendment method proposed in this article can be effectively applied to the experimental signal, accurately identified the location and size of the inclined cracks.

口試委員會審定書 I
誌謝 II
中文摘要 III
英文摘要 V
第一章 前言 1
1-1 研究動機 1
1-2 文獻回顧 2
1-3 本文簡介 4
第二章 敲擊回音法之原理 6
2-1應力波傳行為 6
2-2敲擊回音法 8
2-3敲擊回音試驗參數 12
2-3-1 敲擊源 12
2-3-2 總取樣時間 16
2-3-3 取樣時距 17
2-4敲擊回音法算例 17
第三章 頻譜訊號之影像法 25
3-1頻率域垂直斷面掃描法 25
3-2垂直頻譜斷層掃描 27
3-3移位影像法 30
3-3-1權重分配法 33
3-4權重公式與色階公式修正 35
第四章 有限元素分析 47
4-1 有限元素法分析軟體介紹 48
4-2 有限元素分析步驟 49
4-2-1 元素型態及材料定義 50
4-2-2 建立幾何模型 51
4-2-3 劃分網格 51
4-2-4 負載與束制 53
4-2-5 求解 55
4-2-6 結果分析 57
4-3 數值算例結果與影像法分析 57
4-3-1 數值算例一 57
4-3-2 數值算例二 60
4-3-3 數值算例三 62
4-3-4 數值算例四 64
4-3-5 數值算例五 66
4-3-6 數值算例六 69
4-4 小結 72
第五章 模型試驗分析 98
5-1 實驗設備 98
5-2 實驗參數 99
5-3 模型試體 100
5-4 數值算例結果與影像法分析 102
5-4-1 模型試驗一 103
5-4-2 模型試驗二 105
5-4-3 模型試驗三 107
5-5 小結 109
第六章 結論與展望 125
參考文獻 128

1.Achenbach, J. D. (1973), Wave Propagation in Elastic Solids, North- Holland, Amsterdam, Chp. 7&9.
2.Bendat, J. S. & Piersol, A. G. (1986), Random Data：Analysis and Measurement Procedures, 2nd end. , New York, Wiley.
3.Cheng, C. and Sansalone, M. (1993),”The Impact-echo Response of Concrete Plates Containing Delaminations：Numerical, Experimental and Field Studies”, Material and Structures, Vol.26, pp274-285.
4.Cheng and Sansalone M. (1993),”Effect on Impact-Echo Signals Caused by Steel Reinforcing Bar and Voids around Bars”, ACI Materials Journal, Vol.93, No.5, pp421~434.
5.Schubert F, Wiggenhauser H, Lausch R. On the accuracy of thickness measurements in impact-echo testing of finite concrete specimens-numerical and experimental results. Ultrasonics 2004;42:897–901
6.Colla and Lausch(2003),”Influence of Source Frequency on Impact- echo Data Quality for Testing Concrete Structure”, NDT & E Inter- national, Vol. 36, pp203-213.
7.Ohtsu M, Watanabe T. Stack imaging of spectral amplitudes based on impact- echo for flaw detection. NDT E Int 2002;35(3):189–96.
8.Hu F.Q. (1996), ”On Absorbing Boundary Conditions for Linearized Euler Equations by a Perfectly Matched Layer”, J. Comput. Phys., V129, pp 201-219.
9.Liang and Su (2001), ”Detection of the Corrsion Damage of Rebar in Concrete Using Impact-Echo Method”, Cement and Concrete Research, Vol.31, pp1427~1436.
10.Lin, Y., Sansalone M. and Carino N. J. (1990),”Finite Element Studies of the Transient Response of Plates Containing Thin Layers and Voids”, J. Nondestructive Evaluation, Vol.9, No.1, pp27-47.
11.Lin, Y., Sansalone M. (1991),”Detecting Flaws in Concrete Beams and Columns Using the Impact-Echo Method”, Materials J. the American Concrete Institte.
12.Lin, Y., Sansalone M.(1992),”Transient Response of Thick and Square Bars Subjected to Transverse Elastic Impact”, J. Acoustical Society of America, Vol.91, No.2,Feb., pp885-893.
13.Lin Y. and Su W. C. (1996), ”Use of Stress Waves for Determining the Depth of Surface-Opening Crack in Concrete Structure”, ACI Materials Journal, Vol.93,No,5,pp494~505.
14.Lin Y. et al. (2003), A simple Device for Detecting Impact Time in Impact-Echo Testing of Concrete”, NDT & E, Vol.37, pp1~8.
15.Liu P. L., Tsai C.D. and Wu T.T. (1996), ”Imaging of Surfaces Breaking Concrete Cracks Using Transient Elastic Waves”, NDT & E International, Vol.29, No.5, pp323~331.
16.Liu P. L., Lee K. H., Wu T. T. and Kuo, M. K. (2001),”Scan of Surface–breaking Crack Using Transient Elastic Waves”, NDT & E International, Vol. 34, pp219~226.
17.Liu P. L. and Yiu C.Y.(2002),”Imaging Of Concrete Defects Using Elastic Wave Tests", Invited Paper, Proceedings, the 2002 Far-East Conference on Nondestructive Testing, Tokyo.
18.Liu G. R. and Jerry Q. (2003),”A Non-reflecting Boundary for Analyzing Wave Propagation Using the Finite Element Method”, Finite Elements in Analysis & Design, V39, pp403-417.
19.Sansalone, M and Carino, N. J. (1986),”Impact-Eeco:A Method for Flaw Detection in Concrete Using Transient Stress Waves”, NBSIr86-3452, National Bureau of Standard, Gaithersburg, Maryland, Sept., pp222.
20.Sansalone, M and Carino, N. J. (1990),”Finite Element Studies of the Impact-Echo Response of Layered Plates Containing Flaws”, Int’l Adv. In Nondestructive Testing, 15th ed., W.G. McGonnagle, ED., Gordon & Breach Science Publishers, N.Y., pp 313-336.
21.Smith W. D. (1974),”A Nonreflecting Plane Boundary for Wave Propagation Problems”, J. Comput. Phys., Vol.15, pp492-503.
22.Tong, Jian-Hua, Liao, Shu-Tao, and Lin, Chao-Ching (2007), “A New Elastic-Wave-Based Imaging Method for Scanning the Defects inside the Structure,” accepted for publication in IEEE Transactions on Ultrasonics, Ferrorelectrics, and Frequency Control.
23.Pei-Ling Liu, Po-Liang Yeh(2010), ”Vertical spectral tomography of concrete structures based on impact echo depth spectra” ,NDT&E International, Vol.43, pp45–53.
24.蔡崇道, 暫態彈性波在非破壞檢測之應用－層狀介質反算及混凝土裂縫偵測, 博士論文, 國立台灣大學應用力學研究所, 1997年.
25.葉柏涼, 敲擊回音法之時間－頻率域分析與影像法, 博士論文, 國立台灣大學應用力學研究所, 2006年.
26.邱進隆, 運用橢圓定理權重分配法修正暫態彈性波移位影像顯像法之研究, 國立中央大學, 2009年.