Multi-objective optimisation of support characteristics of rotor bearing systems

Rotors today are made highly flexible with ever increasing demand for higher speeds, and it is important to predict the rotor dynamic behaviour accurately. Supports play an important role and influence the magnitude of vibration in response to external forces. In the present study, frequency dependent polymeric support characteristics have been found by using a multi objective optimisation scheme for minimising the unbalanced response and maximising the stability limit speed. This is an improvement over the previous papers where a simple equally weighted sum of two objective functions was used. A novel hybrid of particle swarm optimisation (PSO) and augmented Lagrangian has been used here to find the global minima. Using appropriate constraints, the slope of the support characteristics versus frequency is restricted to realistic values. Rotor systems with rolling element bearings and plain cylindrical journal bearings are studied using this approach and higher stability limits are obtained.