Towards a Multi-Scale Understanding of Thermoacoustic Fatigue in Aerospace Materials and Structure

Abstract : This report describes research performed over the course of a four-year program funded by the European Office of the United States Air Force(EAORD) as a part of a long-term project to collect high quality data for the validation of computational mechanics models of thermoacousticloading. The focus is on the adaptation of stereoscopic (3D) Digital Image Correlation for use in combined thermal and high temperaturemeasurements. A system is described in which a pulsed laser of duration 4 nanoseconds is used to capture high-quality displacement and straindata from vibrating components (PLDIC). Based on this a novel method of capturing data from a component subjected to random excitationwas developed. A laser vibrometer was used along with a custom LabVIEW program to trigger the pulsed laser relative to points of maximumvelocity in the components vibration cycle. A dynamic calibration procedure was performed for both a conventional high-speed DIC systemand the Pulsed-Laser DIC system to assess the measurement uncertainty from the respective systems, which was found to be similar.