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Detection of Kissing Bonds with Laser Speckle Imaging

BRIDGET TANNIAN, JASON CLINE, GRAY RILEY, JEFFREY CHAMBERS, STEVEN ADLER-GOLDEN, BENJAMIN ST. PETER

Abstract


Composite materials are widely used in aircraft to reduce manufacturing costs, improve structural performance, and boost fuel efficiency. However, safety concerns arise because of the susceptibility of these composites to inadequate adhesive bond quality, including so-called “kissing bonds” which may occur because of initial fabrication or service-related issues. Such weakened bonds may have occurred due to contamination at the bondline surface or in the adhesive, imperfect adhesive thermal cure, or inadequate mixing of adhesive constituents. Because of the widespread and rapidly growing use of composite materials in military aircraft, there is a need for an easily used detection approach to routinely monitor the health of composite materials, both in the factory and in deployed aircraft. To address this need, we have developed a new optical/acoustic approach to test bond quality in composite materials. Lamb wave vibrations are induced in the sample with a high frequency transducer and are visualized using motion-contrast laser speckle imaging with a fast-framing commercial camera. In measurements conducted on test panel sandwiches prepared from SGP370-8H 8552 fiber/epoxy plates and epoxy adhesive, the processed video imagery reveals information on the presence and location of bond flaws in the adhesive layer.

Keywords


Non-destructive testing, condition-based maintenance, kissing bonds


DOI
10.12783/asc2017/15357

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