臺灣博碩士論文加值系統

近年來，世界各國都發生過結構物因老化等因素造成崩塌或損毀的災害事件，為了能提早預防這些災害的發生，對於結構物之健康檢測和評估是相當受到重視的議題。本論文首先利用ARX模型與特徵正交分解的方法在時間域上進行系統參數識別，以結構系統的輸入與輸出歷時求得水泥砂漿柱試體的自然頻率與模態振形。再來，透過有限元素軟體Nastran來進行數值模擬，計算結構的特徵(自然頻率、模態)。再與ARX模型和特徵正交分解法系統識別之結果作比較，來驗證ARX模型和特徵正交分解法的正確性和可行性。
為了建立良好的損傷指標進行結構物健康監測，將數值模擬方式獲得的結構模態振形為基礎，以中央差分法方式得到模態形狀曲率，及以梁之應變能公式推導出模態應變能，利用此兩種損傷指標方法來尋找結構系統的損傷位置，並應用於實際案例中。在試驗中，試體僅利用四個加速度計來收集資料，導致模態資料數據不完全，雖然透過曲線擬合的方式求得更完整的模態資訊，但還不足以模擬一真實結構模態特性，導致識別結構損傷的結果發生錯誤。

For decades, the damage or collapse of structures due to structural deterioration has occurred in countries around the world. In order to prevent the occurrence of the disaster, structure health monitoring and diagnosis become an essential issue. In this paper, first, autoregressive with exogenous input (ARX) model and the proper orthogonal decomposition (POD) method in time domain are used to identify system parameters of a small-scaled column specimen such as natural frequencies and modal shapes based on measured time-history response of the column. Then, numerical results through finite element simulation by the software “Nastran” are obtained to compare with the result of system identification by the ARX model and POD method. These comparisons can validate the correctness of system identification.
Furthermore, for structure health diagnosis, model shapes, modal shape curvatures, and modal strain energy indices are utilized as indices to detect damage. First, mode shapes are generated by numerical simulation. Then, modal shape curvatures are obtained by the central difference method. Finally, modal strain energy indices can be derived according to the formula of strain energy of beams and calculated by numerical integration. The numerical results show that modal shape curvatures and modal strain energy indices are sensitive to damage location and can identify damage location accurately. Next, these two damage indices are applied to real experimental data. However, the results of detecting damage location are not satisfied. Because the only four accelerometers in testing are used to collect acceleration response, mode shape data from system identification is incomplete. Although more mode shape data may be generated by applying curve fitting to the identified four mode shape data, the calculation of modal strain energy indices based on the augmented mode shape data is still not accurate.

中文摘要 i
英文摘要 ii
誌　謝 iv
目　錄 v
表目錄 viii
圖目錄 ix
第一章 緒論 1
1.1 研究動機與目的 1
1.2 研究內容 2
1.3 文獻回顧 4
1.3.1 系統識別 4
1.3.2 結構損傷檢測 5
第二章 系統識別理論 7
2.1 系統識別理論介紹 7
2.2 ARX模型 7
2.2.1 單輸入單輸出（SISO）ARX模型 7
2.2.2 多輸入多輸出（MIMO）ARX模型 11
2.3 特徵正交分解 13
第三章 實際試驗與數值模擬 17
3.1 試驗設備 17
3.1.1 硬體部分 17
3.1.2 軟體部分 19
3.2 試驗模型 26
3.3 試驗規劃與內容 27
3.3.1 衝擊力 27
3.3.2 地震力 28
3.3.3 試驗內容 28
3.4 結構系統識別 31
3.4.1 訊號分析與前處理 32
3.4.2 識別分析結果與討論 32
3.5 有限元素模擬與分析 37
3.5.1 有限元素軟體介紹 37
3.5.2 建模流程和分析結果 37
3.6 系統識別結果和有限元素分析結果之比較 42
第四章 結構健康檢測 51
4.1 損傷檢測指標 51
4.2 利用模態振形來辨別結構損傷位置 51
4.3 利用模態形狀曲率來辨別結構損傷位置 57
4.4 利用模態應變能來辨別結構損傷位置 61
4.5 實際試驗分析 67
4.5.1 模態振形擬合 67
4.5.2 實例探討 69
第五章 結論與建議 77
參考文獻 79

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