Modelling of multi-bearing rotor systems for vibration analysis and control law synthesis

Abstract

A complete mathematical model for a multi-bearing rotor system incorporating a newly developed active journal bearing has been presented. Both a non-linear model and a general linearization method have been developed. The system configuration parameters (the relative positions of the bearings) were expressed explicitly in the equations of motion. Therefore it makes it convenient to carry out dynamic analysis of the rotor system in either the rotating speed domain or the system configuration parameter domain. The Guyan matrix condensation technique has been adopted to reduce the number of equations in the equations of motion. The developed mathematical model has been used in predicting the critical speeds, thresholds of instability and unbalance response of a multi-bearing rotor system.