Blade Modal Parameter Identification Based on Fiber Strain Sensing and Fitting Circle Method

The dynamic response characteristics of civil aircraft are closely related to aerodynamic load, rotor speed, flight attit ude and other parameters under specific flight conditions. Ther efore, real-time identification of rotor blade dynamic modal pa rameters is of great significance for evaluating flight conditions and ensuring. flight safety. Therefore, this paper proposes a ne w method of rotor blade modal parameter identification based on fiber optic strain sensing and fitting circle method. The fiber Bragg grating (FBG) sensor is used to collect the blade vibratio n strain signal in real time, and the fitting circle method is combined to identify the modal parameters. The system frequency response error function matrix based on the strain response ch aracteristics is derived, and the fitting circle model including th e correlation coefficient of blade frequency response function is constructed. By solving the best fitting circle parameters, the i dentification of structural modal parameters is realized. On thi s basis, a composite blade modal parameter identification syste m based on quasi-distributed fiber strain sensing is constructed, and the vibration responses of 10 FBG sensors on the blade are collected under different working conditions. The natural freq uency and damping ratio of the blade are identified by the expe rimental method, and the corresponding modal pattern is recon structed. The research results break through the limitations of the normal-scale state parameter identification method, such as weak anti-noise interference, low resolution, false mode and di fficulty in order determination, which is helpful to improve the modal parameter identification accuracy and reduce the influe nce of noise.