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박상기(S. K. Park),이영호(Y. H. Lee) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
A method to test thin-walled tubes with diameter of a few centimeters by guided ultrasonic waves is reported, The principle is the application of two types of axially symmetric ultrasonic tube modes and "longitudinal" modes with particle displacement coupled in axial and radial directions for transverse failures and torsional modes, oscillating in the circumferential direction only, for longitudinal failures. Both types of modes propagate along the tube in the axial direction. A pulse-echo technique, therefore, is possible. The pulses are excited and received at one end of the tube by contactless electro-dynamic transducers. As soon as the tubes is put into a transducer coil at one end, testing of the whole tube can be accomplished in a few milliseconds. Transportation or rotation of the tubes is not necessary during the test.