Location

La Jolla, CA

Start Date

1-1-1998 12:00 AM

Description

Thermal wave imaging has been shown to have the quantitative capability for measuring aircraft skin corrosion thinning. [1] For single fuselage skin, the technique is sensitive to less than 1% material loss, and can make rapid (a few seconds) measurements which compare well with direct micrometer readings. The method uses pulse heating of the aircraft by means of photographic flashlamps which are enclosed in a metal shroud to trap and funnel the light uniformly onto the surface during the 5msec duration of the pulse. An infrared (IR) focal plane array camera, aimed and focused at the surface through an opening in the rear of the hand-held shroud, monitors the rapid cooling of that surface following the pulse. Metal doublers, bonded to the inside surface of the fuselage, cause the outside surface just above them to cool more rapidly, whereas regions which are thinned because of internal surface corrosion cool less rapidly. By appropriate selection of the gate time(s) for monitoring the cooling, these features show up as distinct dark (light) features in the resulting thermal wave images. The system we have developed at Wayne State University has the electronics and computer mounted on a two-wheeled cart, and the imaging head (shroud/lamps/camera) remotely located and connected to the cart by a long (50-ft) umbilical cable (shown in the photo from the FAA’s Airworthiness Assurance Validation Center (AANC) hangar in Albuquerque, NM).

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

17A

Chapter

Chapter 1: Standard Techniques

Section

Thermal Wave Imaging

Pages

449-452

DOI

10.1007/978-1-4615-5339-7_57

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

NDE of Corrosion and Disbonding on Aircraft Using Thermal Wave Imaging

La Jolla, CA

Thermal wave imaging has been shown to have the quantitative capability for measuring aircraft skin corrosion thinning. [1] For single fuselage skin, the technique is sensitive to less than 1% material loss, and can make rapid (a few seconds) measurements which compare well with direct micrometer readings. The method uses pulse heating of the aircraft by means of photographic flashlamps which are enclosed in a metal shroud to trap and funnel the light uniformly onto the surface during the 5msec duration of the pulse. An infrared (IR) focal plane array camera, aimed and focused at the surface through an opening in the rear of the hand-held shroud, monitors the rapid cooling of that surface following the pulse. Metal doublers, bonded to the inside surface of the fuselage, cause the outside surface just above them to cool more rapidly, whereas regions which are thinned because of internal surface corrosion cool less rapidly. By appropriate selection of the gate time(s) for monitoring the cooling, these features show up as distinct dark (light) features in the resulting thermal wave images. The system we have developed at Wayne State University has the electronics and computer mounted on a two-wheeled cart, and the imaging head (shroud/lamps/camera) remotely located and connected to the cart by a long (50-ft) umbilical cable (shown in the photo from the FAA’s Airworthiness Assurance Validation Center (AANC) hangar in Albuquerque, NM).