Actions for Opitimization of a Multifrequency Eddy-Current Test System Concerning the Defect Detection Sensibility

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Opitimization of a Multifrequency Eddy-Current Test System Concerning the Defect Detection Sensibility / R. Becker, K. Betzold

Conference Author
Eddy-Current Characterization of Materials and Structures (1979 : Gaithersburg, Md.)
Physical Description
1 online resource (16 pages) : illustrations, figures, tables
Additional Creators
Becker, R., Betzold, K., American Society for Testing and Materials, and ASTM International
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Summary
A multifrequency algorithm is applied to suppress signals caused by disturbing parameters. This procedure (based on the projection principle in a multidimensional vector space) and the electronics employed in prototype form are described. The prototype operates with up to four frequencies in a wide range (500 Hz to 1 MHz). The frequencies are continuously tunable and are fed into the coil one after the other by high-speed multiplexing. The multifrequency approach yields a read-out value affected only by defects. The defect signals then can be assessed by means of reference defects of known depths giving equivalent indication peaks. The elimination of the disturbing signals chiefly increases defect detection sensitivity. In general, however, the suppression is not total, and, additionally, the original defect signals are reduced to a greater or lesser degree by the application of the projection principle. The testing frequencies used have a strong influence on the projection losses and therefore on the defect detection sensitivity. A computer program system that allows the reaction of the impedance of the coil to be calculated as a function of the electric, magnetic, and geometrical properties of the specimens and the dimensions of the coil itself is used to determine an optimum frequency combination for the given test situation. This procedure is applied to the testing of heat-exchanger tubes, claddings, and welded joints. The results obtained with the optimized test system are presented.
Dates of Publication and/or Sequential Designation
Volume 1981, Issue 722 (January 1981)
Subject(s)
Other Subject(s)
ISBN
9780803147928 (e-ISBN)
9780803107526
0803107528
Digital File Characteristics
text file PDF
Bibliography Note
Includes bibliographical references 8.
Other Forms
Also available online via the World Wide Web. Tables of contents and abstracts freely available; full-text articles available by subscription.
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Also available in PDF edition.
Reproduction Note
Electronic reproduction. W. Conshohocken, Pa. : ASTM International, 1981. Mode of access: World Wide Web. System requirements: Web browser. Access may be restricted to users at subscribing institutions.
Technical Details
Mode of access: World Wide Web.
Source of Acquisition
ASTM International PDF Purchase price USD25.
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