Dynamic measurement of aeroengine blade deformation based on stroboscopic stereo digital image correlation

Aircraft engine blades are subjected to fluctuating loads during high-speed operation, which can lead to fatigue fractures, posing a significant threat to flight safety. Stereo digital image correlation (stereo-DIC) technology offers significant advantages in full-field three-dimensional deformation measurement. We present an effective method for measuring the motion and deformation of rotating aircraft engine blades based on 3D-DIC. A stroboscopic stereo-DIC system is established to capture clear speckle images of blades under high-speed rotation. To calibrate the stereo vision system for measuring large-curvature blades, a calibration algorithm based on the separation of intrinsic and extrinsic parameters is proposed. A blade positioning method based on fingerprint mapping is also introduced, enabling the identification of the physical numbering of the current blade. To address the largeangle rotation DIC matching problem, a method utilizing speeded-up robust features and motion statistics is proposed to obtain initial subpixel DIC matches for large-rotation blades. We present measurement results of the dynamic displacement field of aircraft engine blades and provides a detailed discussion. Experimental results demonstrate the feasibility and accuracy of the proposed stereo-DIC system and methodology. This method can be applied for noncontact health monitoring of aircraft engine blades.