An optical technique for detecting fatigue cracks in aerospacestructures

摘要

The development of a field-deployable non-intrusive optical-basedcrack-detection and measurement system based ontemperature-sensitive-paint (TSP) technology is described. The TSPdeveloped is based on a platinum porphyrin immobilized in asol-gel-derived thin film. For this test, the TSP is deposited on top ofan aluminum plate that is then subjected to dynamic fatigue through theuse of an electrodynamic shaker. Detection of cracks in the aluminum isaccomplished by monitoring the changes in the surface temperature of theplate as it was excited at its resonant frequency. Visualization andmeasurement of the cracks is easily accomplished in near real time usingthis method. Finally, this method is compared with conventionalthermography, and the results indicate that for aluminum, thesurface-temperature change was below the resolution of conventionalinstrumentation