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Nonlinear vibration analysis of rotors supported by ball bearings

Bahan, Doğancan
Performance of ball bearing-rotor systems is highly dependent on and often limited by characteristics of ball bearings. Ball bearings are nonlinear by their nature and this nonlinearity must be investigated rigorously to correctly predict vibration response of the system. The steady-state periodic response of rotor systems with nonlinear ball bearings is investigated. The rotor is modeled with the Finite Element Method. Nonlinear model for the bearings considers finite number of balls, bearing clearance and contact between balls and races. The nonlinear differential equation of motion is converted to a nonlinear algebraic equation set by Harmonic Balance Method. Receptance Method is applied to decrease the number of nonlinear equations to be solved. Newton’s Method with arc-length continuation is used to solve the resulting equation set. Case studies are performed to investigate bearing vibrations such as varying compliance resonance, response to unbalance and interaction of flexible rotor-bearing vibrations.