Digital Image Edge Detection Method in the Application of the Beam Displacement Measurement and Damage Detection

The images of the simply supported beam in different deformation state captured by digital camera are processed. The polynomial function is used to fit the grey level near the edge of the beam in image. The edge is located by calculating the derivative of the fitting grey level. The identified edges in different deformation states are compared to measure the displacements along the edge of the beam. The second order derivative of the measured deflection curve is calculated to obtain the strain of the beam. The abnormal change in the strain data series is used to identify the damage of the beam. It can be shown in the model test results that the image method used here are useful in structure measurement and damage detection.