Dynamics of multi-disk shafting supported on journal bearing

For permanent magnet disc motor-impeller shafting, the dynamic model was established to calculate principle modes and nonlinear dynamic responses. The influences of eccentric magnitude, dynamic viscosity, bearing clearance on nonlinear dynamics were discussed. The results show the shafting have conical mode, translational mode, the first and second bending mode. Two critical speeds were corresponding to conical and translational modes. The shafting has period N and quasi-periodicity characteristics by effect of nonlinear oil film force. When other basic parameters were unchanged, the increasing eccentric magnitude made compressor vibration be larger firstly and then smaller. The larger oil viscosity and smaller bearing clearance increase the stability of motion. The conclusions of the paper provide a theoretical reference for dynamic design and fault diagnosis of the shafting.