Measurement of deformation and strain field of cantilever beam under forced vibration

Based on digital image correlation and binocular stereo vision, a method is proposed for measuring full field deformation and strain of cantilever beam under forced vibration. First, in the actual measurement, the traditional correlation function with linear model may not be reliable to describe the deformation and light intensity change of subset. Therefore, the radial basis function is introduced into the correlation function to specify the weight of each pixel in the subset, which improves the reliability of the correlation matching. Second, the rigid motion of the excitation source is monitored by sticking a marker at the fixed end. By measuring the position of the marker in the process of vibration, the motion direction of the excitation source can be obtained and then define the new Z-axis along the motion direction. After transformation of the coordinate system, the pure deformation at any position of the beam surface is equal to the displacement at that point minus the displacement of the excitation source. Finally, the deformation and maximum principal strain field of cantilever beam under sinusoidal excitation at different frequencies is compared and analyzed. The method can provide a reference for the deformation measurement under forced vibration.