An in-situ self-calibration method for non-contact full-field strain measurement

Abstract

Abstract Online calibration is important for strain measurement especially for non-contact full-field strain measurement. A self-calibration method based on modal expansion and strain–displacement relationships is developed for full-field strain measurement. The proposed method has the capability to calibrate the in–situ measured data with ground truths continuously without shutting down the test equipment. To validate the methodology for strain calibration, a simulated beam, and a cantilever beam under sinusoidal and random excitations are investigated. The post-calibrated strain of the simulated beam is better agreement with ground truths, and the TRAC e at three points are greater than 99%. The post-calibrated strain the by videometric method, is consistent with measured data using strain gauges. And the accuracy of post-calibrated strain under sinusoidal or random excitation, is higher than that of the pre-calibrated strain. The results of experiments indicate that the proposed method is effective for calibrating strain obtained by visual measurement methods.