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Proceedings Paper

Ultrasonic inspection technique for composite doubler/aluminum skin bond integrity for aircraft
Author(s): John H. Gieske; Dennis P. Roach; Phillip D. Walkington
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Paper Abstract

As part of the FAA's National Aging Aircraft Research Program to foster new technologies for civil aircraft maintenance and repair, use of bonded composite doublers on metal aircraft structures has been advanced. Research and validation of such doubler applications on U.S. certified commercial aircraft has begun. A specific composite application to assess the capabilities of composite doublers was chosen on a L-1011 aircraft for reinforcement of the corner of a cargo door frame where a boron-epoxy repair patch of up to 72 plies was installed. A primary inspection requirement for these doublers is the identification of disbonds between the composite laminate and the aluminum parent material. This paper describes the development of an ultrasonic pulse-echo technique using a modified immersion focus transducer where a robust signal amplitude signature of the composite/aluminum interface is obtained to characterize the condition of the bond. Example waveforms and C-scan images are shown to illustrate the ultrasonic response for various transducer configurations using a boron-epoxy/aluminum skin calibration test sample where disbonds and delaminations were built-in. The modified focus transducer is compatible with portable ultrasonic scanning systems that utilize the weeper or dripless bubbler technologies when an ultrasonic inspection of the boron-epoxy composite doublers installed on aircraft is implemented.

Paper Details

Date Published: 31 March 1998
PDF: 8 pages
Proc. SPIE 3396, Nondestructive Evaluation of Materials and Composites II, (31 March 1998); doi: 10.1117/12.301516
Show Author Affiliations
John H. Gieske, Sandia National Labs. (United States)
Dennis P. Roach, Sandia National Labs. (United States)
Phillip D. Walkington, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 3396:
Nondestructive Evaluation of Materials and Composites II
Steven R. Doctor; Carol A. Nove; George Y. Baaklini, Editor(s)

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