Damage Identification Of Cantilever Panel Based On Limit Cycle Flutter Response

Based on the limit cycle flutter response of the cantilever panel under the single side wind of the subsonic wind tunnel,the experimental methods for damage identification of structural flaws were explored.Damage identification and damage location of subsonic cantilever panel structure in aeroelastic system were studied.The following theoretical and experimental studies were carried out.(1)A two-dimensional cantilever panel experiment was designed to be subjected to the single side subsonic flow.It was proved that the dynamic characteristics such as natural frequency,flutter frequency and flutter critical velocity were not sensitive to the damage identification of the cantilever panel.The natural frequencies,flutter frequencies and flutter critical velocities of two dimensional intact and damaged panels were theoretically analyzed.The aeroelastic response characteristics of cantilever panel were obtained by laser vibration measurement and strain measurement.The natural frequency,flutter critical velocity,flutter frequency and the laws of vibration amplitude changed with the flow of the damaged and intact panels were compared,and the relationship between these characteristics and the damage was studied.(2)Under the condition of the limit cycle flutter,the displacement mode of cantilever panel got from the experiment was not sensitive to the damage identification.By comparing the displacement mode of the intact panel with the damaged panel,it was found that the damage has no obvious effect on the displacement mode,and was not suitable for damage identification.The strain of the cantilever panel under the limit cycle flutter condition was obtained by the strain electric measurement,and the strain mode was obtained.It was found that it can be used as the damage identification characteristic of the panel.The local strain frequency at the damage location was related to the damage.It was found that the amplitude of the vibration frequency was the largest at the cantilever panel damage location,the farther away from the damage location,the smaller the amplitude.(3)Through optical DIC technology,the full field strain of cantilever panel under the condition of limit cycle flutter was measured with non-contact method.Using the VIC-3D software to calculate the strain correlation,the full field strain cloud images of the panel under aerodynamic load were obtained.By comparing the full field strain cloud images of the intact and the damaged panel,the damage identification and the damage position can be clearly found.At the same time,the fast Fourier transform of the full field strain of the cantilever panel was carried out,and amplitude frequency curves of multiple points were selected.It was found that there was the same relationship between the local strain frequency and the damage.It was verified the feasibility of DIC technology in the damage detection of panel structure in aeroelastic system.