請用此 Handle URI 來引用此文件: http://hdl.handle.net/11455/47796
標題: 數位光彈法相位展開法整合研究
Phase Unwrapping Work in Digital Photoelasticity
作者: 黃敏睿
關鍵字: 機械工程類
技術發展
摘要: 本計畫旨在針對數位光彈相關技術作一整合性的分析與探討,擬結合時間域及空間域二種相位展開技術,進行光彈主應力角與主應力差等相位資訊的展開,所發展技術並擬應用於靜態與動態的光彈實驗判讀上。光彈乃一全場的量測技術,可同時提供受測體上每一點的主應力角與主應力差資訊,可結合多場相移影像的擷取的方式,再經由反正切函數計算出主應力角與主應力差相位圖,若更結合使用高記憶容量及高運算速度的電腦資料處理能量及彩色、高解析數位相機,數位光彈的應用技術變得極為多樣,處理的能力上也大大地提昇。然而,相位圖的相位展開上面臨了主應力角與主應力差間交互作用所造成相位模糊的問題,目前文獻已提出處理模糊區域的方法有負載步階法、多波長法、影像處理判斷方式等時間域及空間域相位展開方式,本計畫中擬針對這些方法進行比較研究與探討,以提出更簡單有效的方式,擬利用力學特性逕行主應力角的正確相位展開,再以此正確主應力角資訊結合具自我修正能力的主應力差反正切計算公式,求得無模糊區域的相位圖,來進行主應力差資料的還原。最後進行光彈實驗來驗證所提方法的正確性與有效性,並以可瞬時同時取得多場光彈條紋影像的光學架構來進行動態光彈相移影像的擷取,相關光學系統校正調整及多場影像間的相關性處理,計畫中一併探討。
Photoelastic stress analysis is a full-field optical technique for experimental stress analysis whose automation has received considerable research attention over the last two decades. Use of phase shifting has revolutionized the acquisition of photoelastic data. In addition, the availability of powerful computers with large memory capacity and colour, high resolution, cameras has made the digital photoelasticity technique with wide variety. However, since digital photoelasticity provides information on principal stress difference (isochomatic) and the orientation of principal stress direction (isoclinic) at every pixel in the stressed domain, a peculiar problem - isoclinic-isochromatic interaction is induced and leads to the so-called ambiguous zone in phase map. Therefore, one critical aspect which still deserves attention in phase shifting photoelasticity is phase unwrapping. To obtain the phase distribution by phase unwrapping, the phase map should be free of ambiguous zones. Various methodologies have been proposed to solve the ambiguity problems of photoelastic phase maps including load stepping, image processing skills, and different wavelengths etc. For obtaining isoclinic and isochromatic parameters many techniques are available. Among these techniques, the six-step phase shifting technique based on a circular polariscope arrangement is widely accepted and used for its simplicity and accuracy. Plane polariscope, however, is the simplest setup for isoclinic and isochromatic parameters extraction. Elliptical polariscope is used for the minimization of the dispersion of the wave plate under illumination of different wavelengths. The intercomparison between them, including easiness of individual setup, factors that affect quality of map, and noise reduction of calculated phase map, will be analyzed in details in the work. The sequential collection of the phase stepping photoelasticity grams has limited the application to only static analysis. Thus, the work herein will capture in real-time all the information needed to produce full-field maps of isochomatic fringe order and isoclinic angle and deal with the optical alignment of four phase shifted beams and the calibration of simultaneous grabbed images for the correct determination of photoelasticity parameters.
URI: http://hdl.handle.net/11455/47796
其他識別: NSC98-2221-E005-009
文章連結: http://grbsearch.stpi.narl.org.tw/GRB/result.jsp?id=1879010&plan_no=NSC98-2221-E005-009&plan_year=98&projkey=PB9807-1503&target=plan&highStr=*&check=0&pnchDesc=%E6%95%B8%E4%BD%8D%E5%85%89%E5%BD%88%E6%B3%95%E7%9B%B8%E4%BD%8D%E5%B1%95%E9%96%8B%E6%B3%95%E6%95%B4%E5%90%88%E7%A0%94%E7%A9%B6
顯示於類別:機械工程學系所

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