Deflection measurements of laminated thin plates using Electronic speckle Pattern interferometry

Abstract

An adaptive Electronic speckle Pattern Interferometry (ESPI) system has been developed to measure out-of-plane de formation of laminates subjected to quasi-static loads. The systeir was installed and setup for calibration with aluminum specimens mounted to an optical breadboard. Several parameters of the test fixture and system's geometry needed to be adjusted before usable fringe patterns were obtained, and the system's resolution and range were determined. The ESPI system was then reconfigured for use with composite specimens subjected to quasi-static loading. Results of fringe patterns, calibration curves and deformation patterns are presented for Al and graphitelepoxy specimens. The ESPI resolution was estimated at 25 μm per fringe for the Al surface, and 11 μm per fringe for the composite laminate. From the results, it can be concluded that the usable deflection range is limited at high systeir resolutions.