Dynamic Behavior of Rotor Bearing System

Rotating machinery is becoming faster and lightweight due to the advanced technologies made in engineering and materials sciences. It is required them to run for longer periods of time. The high speed rotor bearing system often shows unpredictable dynamic response due to manufacturing defects. As it is not possible to produce perfect surface even with the best available machine tools. The radial and axial clearance provided in the design of bearings to compensate for thermal expansion, can be a source of vibrations and introduce nonlinearity in the dynamic system. Using vibration analysis, the condition of a machine can be periodically monitored. The main objective of this paper is to study the vibration characteristics of rotor equipped with long journal bearings placed at both ends. Besides the non-linear forces of the lubricated pairs, a non-linear elastic, damped coupling was assumed between the bearings and the rotor pedestal. Rotating speed is used as the control parameter to observe various forms of vibrations.