臺灣博碩士論文加值系統

在石化業及高科技產業中，油品、化學原料及其製品大多是利用管線來進行輸送，因此這類工廠中常存在眾多的管線分布在各個區域。然而這類的液體或氣體大多屬於可燃性、易燃性或者具有直接傷害性的材料。因此為避免管線因為腐蝕、撞擊…等因素造成破管而導致洩漏的情形發生，必須進行定期的維護與檢測管線厚度。導波法作為工業上常見的非破壞檢測方法，能夠對長距離且大範圍管線的健康狀況進行有效的分析與判斷。隨著全球原物料價格逐漸上漲且工安意外頻傳，越來越多人願意使用導波法對管線進行健康監測以避免因為管線安全而造成更重大損失。
管線遭受不同的外力時會產生不同的凹陷情形，本文將凹陷情形分為：（一）管壁減薄（表面凹陷，具有明顯截面積變化）；（二）凹痕（管壁內外同時凹陷，無明顯截面積變化）兩種。透過模擬T(0,1)導波經過不同軸向、周向及深度尺寸管壁減薄的影響，進一步探討較為複雜的內外同時凹陷之凹痕。通過模擬結果得知，T(0,1)對於凹陷的周向及深度改變量有較好的靈敏度，其反射係數會隨著周長與深度的增加而上升；軸向改變量則會受到波形建設性與破壞性干涉的影響，造成疊加或相抵銷的現象，在軸長L=λ⁄4時，具有最大的反射係數，並且由波傳動畫圖可以得知，隨著軸長的增加導波經過管壁減薄與凹痕時會產生明顯的散射，進而導致反射訊號振幅下降。由於凹痕並無明顯截面積改變量來作為判斷凹痕嚴重程度的依據，本文根據凹痕周向改變範圍計算圓周變形率來與模擬結果進行比對。結果顯示，凹痕的反射係數會隨著圓周變形率的增加而上升。此外，為獲得更好的軸向檢測靈敏度，本研究使用L(0,2)對不同軸長的凹陷進行模擬分析。根據T(0,1)及L(0,2)對相同軸長凹陷的模擬結果得知，L(0,2)對於軸向的凹陷具有較佳的靈敏度，然而L(0,2)在6吋碳鋼管上必須在70 kHz以上激振才會是非頻散模態，故低頻的T(0,1)適合用來量測軸向範圍較大的凹陷，而L(0,2)相對而言較適合用來量測軸向範圍較小的凹陷。本研究之結果可提供實務檢測者瞭解所能量測的凹陷尺寸，及選用不同模態探頭與頻率在判別凹陷嚴重程度之參考依據。

In petrochemical refineries and various high-tech industries, oil products, chemical gases, raw materials, and products are mainly transported by pipelines. Many pipelines can often be seen in various areas in such factories. Some types of liquids or gases are mostly flammable or directly harmful materials. Therefore, to avoid leakage of the pipeline due to corrosion, impact... and other factors, the pipeline must be regularly maintained and inspected. As a common non-destructive detection method in the industry, the guided wave method can effectively analyze and judge the health of long-distance and large-scale pipelines. With the gradual increase in the global raw material prices and the frequent occurrence of industrial safety accidents, more and more people are willing to use the guided wave method to monitor the health of pipelines to avoid more significant losses caused by pipeline safety.
When the pipeline is subjected to different external forces, different depression situations will occur. This thesis divides the depression situations into (1) pipe wall thinning (surface depression, with obvious cross-sectional area changes); (2) dent (both internal and external simultaneously dent, no obvious cross-sectional area change) two kinds. By simulating the influence of T(0,1) guided waves through different axial, circumferential, and depth dimensions of the pipe wall thinning, the more complicated dents that simultaneously dent both inside and outside are further explored. According to the simulation results, T(0,1) has better sensitivity to the circumferential and depth changes of the depression, and its reflection coefficient will increase with the increase of the circumference and depth; the axial change will be affected by the waveform. The influence of constructive and destructive interference causes the phenomenon of superposition or offset. When the shaft length L=λ⁄4, it has the largest reflection coefficient, and it can be known from the wave transmission drawing that as the shaft length increases, the waves pass through the pipe wall thinning and dents will produce obvious scattering, wherefore it causes the amplitude of reflected signal decrease. Since there is no obvious change in the cross-sectional area of the dent as a basis for judging the severity of the dent, this paper calculates the circumferential deformation rate according to the circumferential change range of the dent to compare with the simulation results. The results show that the reflection coefficient of the dent will increase with the increase of the circumferential deformation rate. In addition, to obtain better axial detection sensitivity, this study uses L(0,2) to simulate and analyze depressions with different axial lengths. According to the simulation results of T(0,1) and L(0,2) for the same axial length depression, L(0,2) has better sensitivity to axial depression. However, when using L(0,2) to detect the 6-inch carbon steel pipe, the frequency must be excited above 70 kHz to obtain the non-dispersive mode. Therefore, the low-frequency T(0,1) is more suitable for measuring the depression with a large axial range, while the L(0,2) is more sensitive with a small axial range depression, relatively. The results of this study can provide practical inspectors to understand the size of the depression measured and to select different modal probes and frequencies as a reference for judging the severity of the depression.

論文審定書 i
誌謝 ii
中文摘要 iii
英文摘要 iv
目錄 vi
圖目錄 viii
表目錄 xi
第一章 緒論 1
1.1前言 1
1.2研究動機與目的 4
1.3文獻回顧 5
1.4研究方法 7
1.5論文結構 8
第二章 基本理論 12
2.1導波基本模態 12
2.1.1扭矩模態 12
2.1.2縱向模態 13
2.1.3撓曲模態 13
2.2導波頻散行為 14
2.3波形結構 15
第三章 模擬設定與實驗架構 23
3.1有限元素法模擬分析 23
3.1.1凹痕建立與網格劃分 24
3.1.2圓管施加負載與導波激發 25
3.1.3訊號擷取 26
3.2實驗設置與架構 27
3.2.1儀器介紹 27
3.2.2直管上之實驗訊號 28
3.2.3管線設置 30
第四章 實驗與模擬結果討論 41
4.1不同凹陷對於導波模態之影響 41
4.1.1 不同周向長度之管線減薄對於扭矩模態的影響 42
4.1.2不同軸向長度之凹痕對於扭矩模態的影響 43
4.1.3不同程度的減薄對於扭矩模態的影響 45
4.1.4二維傅立葉轉換 45
4.2不同減薄尺寸對於縱向模態的影響 46
4.2.1不同軸向長度之減薄對於縱向模態的影響 46
4.2.2不同程度管壁之減薄對於縱向模態的影響 47
4.2.3不同軸長之管壁減薄對於T(0,1)與L(0,2)的影響 48
4.3凹痕對於扭矩模態的影響 49
4.4凹痕導波實驗量測結果討論 52
4.5實驗結果與模擬結果討論 54
第五章 結論與未來展望 86
5.1結論 86
5.2未來展望 87
參考文獻 88
附錄A：圓管導波基本理論 93




圖目錄
圖1.1 傳統接觸式超音波檢測圓管示意圖與實際操作圖 9
圖1.2 環狀陣列探頭 10
圖1.3 導波檢測示意圖(a)儀器架設與檢測示意圖，(b)檢測訊號示意圖 10
圖1.4 凹痕管 11
圖1.5 管線設施分類 11
圖2.1 模態表示法 17
圖2.2 圓管上模態波傳情形。(a)扭矩模態，(b)縱向模態與(c)撓曲模態 17
圖2.3 使用6英寸碳鋼管之相位速度頻散曲線 18
圖2.4 於6英寸管中不同頻率L(0,2)模態傳遞1.5公尺之時域訊號(a)70 kHz、5 Cycles之波傳訊號，(b) 20 kHz、5 Cycles之波傳訊號 18
圖2.5 使用6英寸碳鋼管之群波速度頻散曲線 19
圖2.6 使用6英寸碳鋼材質管線的頻散曲線(a)相位速度頻散曲線，(b)群波速度頻散曲線 20
圖2.7 缺陷引發波式轉換示意圖(a)A模態傳經缺陷，(b)發生波式轉換產生新的B與C等模態 21
圖2.8 T(0,1)扭矩模態之波形結構 21
圖2.9 L(0,2)縱向模態之波形結構 22
圖3.1 Solid 45元素節點與自由度 33
圖3.2 Solid 186元素節點與自由度 33
圖3.3 凹痕定義 34
圖3.4 凹痕凹陷情形。圖(a)表面凹陷圖、(b)內外同時凹陷 34
圖3.5 凹痕設置示意圖 34
圖3.6 管線網格劃分示意圖。圓周網格劃分60段，軸向網格 35
圖3.7 管線負載設置 35
圖3.8 使用22.5 kHz作為單頻調製之基底訊號時，在5cycle下加權後的時域與頻域圖 36
圖3.9 使用22.5kHz激振管線圓周周向負載波傳情形（T(0,1)模態） 37
圖3.10 使用80 kHz激振管線圓周軸向負載波傳情形 37
圖3.11 入射波與銲道回波時域訊號圖 38
圖3.12 GUL導波檢測儀器 38
圖3.13 3英寸碳鋼管頻散曲線 39
圖3.14 Wave Pro G4軟體檢測結果圖 39
圖3.15 紅黑比與缺陷嚴重程度示意圖 40
圖3.16 實驗設置圖 40
圖4.1 模擬T(0,1)經過相同尺寸（周長λ、軸長λ⁄4）但不同凹陷形式管線之時域訊號圖 60
圖4.2 不同凹陷形式橫截面 60
圖4.3 模擬T(0,1)經過固定深度0.25t與軸長λ⁄4時不同周長之管壁減薄直管時域訊號圖 61
圖4.4 模擬T(0,1)經過固定深度0.5t與軸長λ⁄4時不同周長之管壁減薄直管時域訊號圖 62
圖4.5 模擬T(0,1)經過固定深度0.75t與軸長λ⁄4時不同周長之管線外表面凹痕時域訊號圖 63
圖4.6 模擬T(0,1)於三種深度下不同周長之管壁減薄直管反射係數 64
圖4.7 模擬T(0,1) 於三種深度下不同周長之管壁減薄直管紅黑比 64
圖4.8 相同深度下不同周長之管壁減薄情形 64
圖4.9 相同周長下不同深度之管壁減薄情形 65
圖4.10 軸向長度與反射係數關係圖 65
圖4.11 模擬T(0,1)於深度0.25t與周長λ⁄2時不同軸長之管壁減薄直管時域訊號 66
圖4.12 模擬T(0,1)於深度0.5t與周長λ⁄2時不同軸長之管壁減薄直管時域訊號 66
圖4.13 模擬T(0,1)於深度0.75t與周長λ⁄2時不同軸長之管壁減薄直管時域訊號 67
圖4.14 模擬T(0,1) 於三種深度下不同軸長之管壁減薄直管反射係數 68
圖4.15 模擬T(0,1) 於三種深度下不同軸長之管壁減薄直管紅黑比 68
圖4.16 不同缺陷深度對於反射係數之影響 69
圖4.17 六英寸碳鋼管頻散曲線。縱軸為波數、橫軸為頻率 69
圖4.18 軸長0.25λ、周長0.5λ與深度0.5t之管壁減薄直管分析結果 70
圖4.19 軸長0.5λ、周長0.5λ與深度0.5t之管壁減薄直管分析結果 71
圖4.20 軸長0.25λ、周長0.25λ與深度0.5t之管壁減薄直管分析結果 72
圖4.21 軸長0.25λ、周長0.5λ與深度0.75t之管壁減薄直管分析結果 73
圖4.22 使用扭矩模態於直管上傳遞之時域訊號圖 74
圖4.23 使用縱向模態於直管上傳遞之時域訊號圖 74
圖4.24 使用L(0,2)於固定周長但不同軸長之凹痕時域訊號圖 75
圖4.25 不同模態於固定周長但不同軸長之凹陷（管壁減薄）反射係數圖 76
圖4.26 不同深度之凹痕（軸長=λ⁄4、周長=λ⁄2） 76
圖4.27 使用T(0,1)於不同周向長度之凹痕截面向量 77
圖4.28 不同軸長與周長之內外管表面同時凹陷凹痕反射係數圖 78
圖4.29 不同軸長的內外管表面同時凹陷之凹痕波傳圖 78
圖4.30 不同類型之凹陷波傳圖 79
圖4.31 不同周長之凹痕其管線周向剖面相似度與反射係數關係圖 79
圖4.32 不同軸長的內外管表面同時凹陷之凹痕對於T(0,1)與L(0,2)影響 80
圖4.33 凹痕管1 80
圖4.34 凹痕管2 80
圖4.35 使用導波檢測凹痕管 81
圖4.36 凹痕管線實際量測情形 81
圖4.37 使用導波檢測凹痕管1之實驗結果 81
圖4.38 頻率區間1之實驗結果 82
圖4.39 頻率區間2.2之實驗結果 82
圖4.40 凹痕管1之實際凹陷情形 83
圖4.41 使用導波檢測凹痕管2之實驗結果 83
圖4.42 頻率區間1之實驗結果 84
圖4.43 頻率區間2.2之實驗結果 84
圖4.44 凹痕管2之實際凹陷情形 84
圖4.45 相同尺寸凹痕實驗與模擬之反射係數圖 85
圖4.46 相同尺寸凹痕實驗與模擬之紅黑比 85

表目錄
表3.1 導波於6英寸碳鋼管（Schedule 40）各頻率區間與頻率對照表 32
表4.1 凹痕周向尺寸 57
表4.2 不同深度與周長之凹痕反射係數值 57
表4.3 不同深度與周長之凹痕紅黑比 57
表4.4 不同深度與軸長之凹痕反射係數值 58
表4.5 不同深度與軸長之凹痕紅黑比 58
表4.6 不同圓周截面之相似度 58
表4.7 實驗量測凹痕管1之特徵訊號 59
表4.8 實驗量測凹痕管2之特徵訊號 59

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