小波分析方法應用於樑與平板的破損偵測之研究

A Study of Structural Damage Detection in Plates and Beams by Wavelets Transforms

近年來，小波轉換已廣泛應用在各種複雜的影像處理、雜訊濾除與訊號分析，本研究將利用小波轉換方法在非破壞檢測上。當結構有破損時，其振動模態經小波轉換後可以在破損處發現明顯的變化，進而預測其缺陷存在的位置。本研究將探討含缺陷之懸臂樑與兩邊固定之平板的破損偵測分析。研究中將以一維離散小波轉換與二維離散小波轉換為基礎來檢測含多重缺陷之樑與板，並經田數值模擬分析以及實驗共同進行並比較其結果。測試結果顯示，離散小波分析方法可以有效的找出結構中多個缺陷位置，並可應用在其他之複雜結構上。 Recently, wavelet transform has been snidely used in various image processing, noise filtering and signal processing. In this study, a method for Non-Destructive Testing (NDT) in beams and plates based on wavelet analysis is being investigated. It is believed that the presence of cracks on structures members may change the modal properties, and those can be detected by wavelet transform. Furthermore, the damage locations can be found. In this study, a doable-cracked beam and a plate with multiple cracks are analyzed by means of discrete wavelet transform. One-dimensional and two-dimensional discrete wavelet transforms are employed to detect the cracks on the beans and the plate, respectively. The results obtained from the experiments will be compared with those obtained from the numerical modeling analysis. The proposed wavelet analysis can effectively identify the damage locations and may be applied to other complex structures.