超音波檢測表面裂縫深度之研究

The Measurement of Crack Depth by Ultrasonics

林盛棟(Sheng-Tung Lin)

指導教授 ： 何旭川

元智大學/工程學院/機械工程學系/碩士(1999年)

摘要

超音波檢測可檢測結構內部和表面缺陷如裂縫、空孔等，為應用最廣的非破壞檢測方法，然在實驗室欲以人工方法製成真實裂縫不僅過程複雜困難失敗率亦相當高。本文以線割放電加工方法製成有限寬度的人工溝槽取代真實裂縫，探討不同方法裂縫深度量測的優劣。實驗方法為將不同深度的試塊，以不同頻率及入射角量測裂縫深度，比較這些參數對量測裂縫深度的影響及準確度，最後就各種量測方法的準確度及限制做綜合比較與評估。實驗結果可做為有效量測結構裂縫深度的參考，同時亦可在無法製作真實裂縫以人工溝槽取代時，提供比較類比的參考數據。

關鍵字

超音波檢測 ； 非破壞檢測 ； 人工溝槽 ； 裂縫 ； 入射角 ； 頻率

並列摘要

The capability of detecting defects inside the structures and on the surface such as cracks and voids, make the ultrasonics become the most common use of non-destructive examination technique. It is always difficulty to fabricate a real crack in the laboratory. Present investigation uses a finite width of artificial slot made by electrical discharge machining, to simulate the real crack. Five different methods of measuring the depth of surface crack are presented. The effects of frequency and incident angle on the measurement accuracy for these five methods are evaluated. Comparisons are made among those methods to examine their advantages and disadvantages. The results can provide useful information to determine the best way of detecting defects.

並列關鍵字

ultrasonics ； non-destructive examination ； slot ； crack ； incident angle ； frequency

參考文獻

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7. Hudgell, R. J. and Lumb, R. F. “Non-Destructive Measurement of Depth of Surface-Breaking Cracks Using Ultrasonic Rayleigh Waves.”Brit. J. NDT (1974), pp.144-149.

8. Domarkas, V. ; Khuri Yakub, B. T. and Kino, G. S. “Length and DepthResonances of Surface Cracks and Their Use for Crack Size Estimation.”Appl. Phys. Lett., Vol. 33(7), 1978, pp.557-559

9.Simpson Jr, W. A. “Time-Frequency-Domain Formulation of UltrasonicFrequency Analysis.” J. Acoust. Soc. Am., Vol. 56(6), 1974, pp.1776-1781.