Title: Quantitative Comparison of Close-Proximity and Large-Standoff Thermography for Nondestructive Inspection of Carbon Epoxy Composites

Authors: Maria F. Beemer and Steven M. Shepard

DOI: 10.33599/nasampe/c.19.0674

Abstract: As a result of the integration of carbon fiber / epoxy matrix materials into aerospace and particularly space vehicles, there has been considerable emphasis on the ability of Nondestructive Testing (NDT) methods to adapt to inspection of large areas, where established NDT methods, in which an apparatus must be scanned over the surface of a large part manually or using gantries, robots or creepers, are often too slow or expensive be practical. In recent years, flash thermography (FT) has gained wide acceptance as a primary method for Nondestructive Testing (NDT) of polymer composite structures, with a key advantage being its ability to inspect what has been considered to be a large area (~1 sq. ft.) when compared to point scan methods (e.g. ultrasound). However, in the context of large aerospace structures on the scale of hundreds or even thousands of square feet, the concept of large-area inspection must be reconsidered.

A recently introduced approach, Large-Standoff, Large-Area Thermography (LASLAT), projects a longer excitation pulse from a halogen lamp over a larger working distance (10 - 15 ft). The LASLAT field of view is larger (~20” x 15”) than that of FT, but with the added advantage that the field of view can be scanned over a larger inspection area using only pan and tilt degrees of freedom, eliminating the need for a gantry or robot when inspecting large structures and significantly reducing inspection time.

In this study, we compare flaw detection performance of FT and LASLAT approaches on a carbon epoxy sample that represent common delamination and evaluate depth range using a flat-bottom hole target. Metrics for comparison include signal-to-noise and inspection time.

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Conference: CAMX 2019

Publication Date: 2019/09/23

SKU: TP19-0674

Pages: 12

Price: $24.00