A field balancing method of a flexible rotors based on modal analysis and fourier transformation

A field balancing method of a flexible rotor was presented to suppress vibration due to imbalance. In this method, a rotor system dynamic model was established with FE theory, and its differential equation of motion was expanded according to its modal shapes. By using FFT and IFFT transformation, the unbalanced load spectrum in frequency domain was acquired, and then the rotor imbalance was eventually identified. Simulation and experimental results showed that this method can identify the rotor imbalance accurately, it only needs to collect data of vibration response below critical speed without trial weights. After adding counterweights, the imbalance vibration for each mode of the rotor can be effectively suppressed.