8. New Technology Roots
A brief summary of newly developed techniques for ultrasonic inspection of small diameter tubes using EMAT's is given. The technique employs a periodic-permanent magnetic torsion wave transducer which fits inside and can be quickly translated through the tube. Both dominant and higher order ultrasonic modes traveling longitudinally along the tube can be individually excited by varying the transducer design parameters. Experimental results are presented which define transduction efficiencies in aluminum, Inconel, and steel and the sensitivities of the various wave types to different defects. The ability of these techniques to detect flaws in difficult regions such as U-bends and dents is reported.
Vasile, C. F., "Steam Generator Tube Inspections with EMAT's" (1978). Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE, September 1976–June 1977. 57.