導波檢測系統之開發與驗證

近年來由於全球面臨能源短缺及環境污染等問題，綠能產業已成為各地致力發展的新趨勢，而基於台灣西部海域極佳的海上風場，離岸風機的發展也漸漸地受到重視。但風機之基樁位處複雜的海洋環境中，容易受到潮汐或地震等外力作用而影響其包覆之穩定度。因此本文研究將基樁簡化為單一鋼管模型，設計一套用於包覆程度檢測的導波量測系統，由於其量測依據為特定模態之回波衰減量，因此導波模態的激發與回波辨識是本文的重點。系統內包含自製之發射電路及壓電陶瓷陣列，回波訊號的辨識則使用時頻轉換，將其結果與PCdisp繪出之頻散曲線圖做對照，即從時間和頻率上比較實際量測訊號與理論值之相關性。分析結果則顯示出在不同環境下，此系統激發與加強之模態均與理論值相符合，能夠將其進一步的應用於振幅衰減的檢測上。

關鍵字

導波法；離岸風機基樁；頻散曲線圖； PCdisp

並列摘要

Due to the shortage of global energy and the Environmental pollution issues, the industry of green energy has become a new trend of development in recent years. Based on the great wind field in offshore western Taiwan, the development of offshore wind turbines were taken more seriously. But the foundation of the pile in the complex marine environment, affected by the external forces like tide or earthquake easily and make it unstable. As a result, this paper uses a single steel pipe as the model and designs a guided-wave measurement system for the detection of the pile. The detection is based on the specific mode of the echo attenuation, so the excitation of the mode and the identification of the echo signal is the focus in this paper. This system includes self-made transmmitting circuit and piezoelectric ceramic array. The echo signal is identified by time-frequency conversion and compared with the dispersion curve plotted by PCdisp, which means to compare the correlation between the actual measurement signal and the theoretical value. The results of the analysis shows that the modes be excited and enhanced in this system are in agreement with the theoretical values in different environments, which means it can be applied to the detection of the amplitude attenuation.

並列關鍵字

Guided wave method ； Offshore wind turbine ； Foundation piles ； dispersion curve ； PCdisp

參考文獻

[1] J. A. McFadden, "Radial Vibrations of Thick‐Walled Hollow Cylinders," The Journal of the Acoustical Society of America, vol. 26, no. 5, pp. 714-715, 1954.

[2] P. M. Naghdi and R. M. Cooper, "Propagation of Elastic Waves in Cylindrical Shells, Including the Effects of Transverse Shear and Rotatory Inertia," The Journal of the Acoustical Society of America, vol. 28, no. 1, pp. 56-63, 1956.

[3] D. C. Gazis, "Three‐Dimensional Investigation of the Propagation of Waves in Hollow Circular Cylinders. I. Analytical Foundation," The Journal of the Acoustical Society of America, vol. 31, no. 5, pp. 568-573, 1959.

[4] A. H. Fitch, "Observation of Elastic‐Pulse Propagation in Axially Symmetric and Nonaxially Symmetric Longitudinal Modes of Hollow Cylinders," The Journal of the Acoustical Society of America, vol. 35, no. 5, pp. 706-708, 1963.

[5] A. E. Armenakas, D. C. Gazis, and G. Herrmann, Free vibrations of circular cylindrical shells. Pergamon Press, 1969.

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導波檢測系統之開發與驗證

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