Location

La Jolla, CA

Start Date

1980 12:00 AM

Description

Detection of fatigue cracks at the fastener holes in the lower portion of the C5A wing lap joint is complicated by lack of a direct line of access, and by the presence of fasteners and sealant material. Furthermore, any successful detection procedure must take into account the wide variation in the geometrical features of the joint. In this work, periodic permanent magnet EMATs (electromagnetic-acoustic transducers) have been employed to excite the n=o horizontally polarized shear mode of the skin at 200 kHz and 250 kHz. These modes are partially transmitted into the overlap region joined by the fastener. Spectral analysis of suitably time gated and apodized portions of the reflected waveform have allowed simulated cracks growing out of fastener holes to be detected, and preliminary sizing algorithms have been developed.

Book Title

Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE

Chapter

13. New Technology Applications

Pages

568-571

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Inspection of the Lower Half of Wing Lap Joints with EMATs

La Jolla, CA

Detection of fatigue cracks at the fastener holes in the lower portion of the C5A wing lap joint is complicated by lack of a direct line of access, and by the presence of fasteners and sealant material. Furthermore, any successful detection procedure must take into account the wide variation in the geometrical features of the joint. In this work, periodic permanent magnet EMATs (electromagnetic-acoustic transducers) have been employed to excite the n=o horizontally polarized shear mode of the skin at 200 kHz and 250 kHz. These modes are partially transmitted into the overlap region joined by the fastener. Spectral analysis of suitably time gated and apodized portions of the reflected waveform have allowed simulated cracks growing out of fastener holes to be detected, and preliminary sizing algorithms have been developed.