rotor expansion
2.Based on the assumption of periodic rubbing force in rotor system, the rubbing forces onto each node of rotor system are estimated by modal expansion technique and the sub-harmonic decomposition of residual matrix between faulty and faulty-free vibration signals of rotor system through FFT (fast Fourier transformation).
4.In the process of system dynamic trajectory simulation and integration of sensitivity dynamic equations,Taylor series expansion technique is used to calculate the high order derivatives of rotor angles,speed and sensitivity variables with respect to time. Therefore,bigger simulation time step can be employed,which can improve computation speed while keeping normal calculating precision.
