Dynamics of an AMB-rotor with time varying stiffness and mixed excitations

A rotor- active magnetic bearing (AMB) system with a periodically time-varying stiffness subjected to multi- external, -parametric and -tuned excitations is studied and solved. The method of multiple scales is applied to analyze the response of the two modes of the system near the simultaneous sub-harmonic, super-harmonic and combined resonance case. The stability of the steady state solution near this resonance case is determined and studied applying Lyapunov's first method. Also, the system exhibits many typical nonlinear behaviors including multi-valued solutions, jump phenomenon, softening nonlinearities. The effects of the different parameters on the steady state solutions are investigated and discussed. Simulation results are achieved using MATLAB 7.0 program.