Sanjay Tiku* and N. J. Marchand** *Department de Metallurgie et Genie des Materiaux, Ecole Polytechnique, University of Montreal, P. O. Box 6079 Station "Centre Ville", Montreal, Canada, H3C 3A7. **V. P. R & D, AMRA Technologies Inc., 4700 de la Savane, Montreal, Canada, H4P 1T7.
Keywords: APCD, Current Focussing, Crack, Aircraft structure, On-line Measurement
ABSTRACT
An advanced alternating current potential difference (ACPD) measurement technique has been developed to perform on-line measurement of fatigue crack initiation and propagation on the test specimens as well as on aircraft structures. To that effect, an advanced multiple frequency electronic system has been designed and developed. The main features and capabilities of this unit will be presented. The ACPD system also makes use of a new technology called current focusing. This technology allows current to be confined to a precise region of interest. The crack calibration measurements obtained will be shown. The new APCD sensors have been installed on three principal structural elements (PSEs) namely wing carry-through bulkheads of a F-18 aircraft for on-line measurement and crack detection during full scale testing. This project is being carried out under the "International Follow on Structural Test Program" (IFOSTP). The sensor installation procedure, data acquisition and results obtained so far during the full scale testing will be presented, thus assessing the true capabilities of the system.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.full paper not received Publisher:Ashgate Publishing Company
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