Ultrasonic inspection technique for composite doubler/aluminum skin bond integrity for aircraft
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 US 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 comer 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.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 634095
- Report Number(s):
- SAND-98-0311C; CONF-980334-; ON: DE98003147; CNN: Contract DTFA-03-91-A-0018; TRN: AHC2DT01%%106
- Resource Relation:
- Conference: SPIE non-destructive evaluation techniques for aging infrastructure and manufacturing, San Antonio, TX (United States), 31 Mar - 2 Apr 1998; Other Information: PBD: Feb 1998
- Country of Publication:
- United States
- Language:
- English
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