Abstract: The identification effects of different modal parameters (displacement mode, rotation mode, and curvature mode) of the beam structure on structural damage during crack initiation are studied in this paper. Firstly, the displacement mode, the rotation mode and the curvature mode of the two-span simply supported beam are calculated using the vibration response. Secondly, combining the multi-resolution and singularity analysis characteristics of continuous wavelet transform, the wavelet transform coefficients of three modal parameters are calculated to identify the singularity of structural modal parameters. Thirdly, the recognition effects of each method on structural damage are compared by adding different degrees of random noise to the simulation data. The results show that the damage identification methods based on three different modal parameters can locate small-scale structural damage, but the anti-noise performance of each method is different, the anti-noise performance of the rotation mode is the best, the displacement mode is second and the curvature mode is poor. Finally, the experimental data is used to verify the recognition effect of each damage identification method based on different modal parameters on the actual structural damage. The experimental results show that the damage recognition effect of the rotation mode parameters is better, while the displacement mode and the curvature mode parameters are similar, but the curvature mode method is more likely to be interfered at the smaller damage. These analysis results provide a reference for the selection of different damage identification parameters according to the environment and response characteristics in engineering practice.
