Multivariable hybrid models for rotor-bearing systems

In this paper the flexural vibration of rotors, mounted on fluid film beari ngs, is considered. The rotor is described by a series of distributed and l umped elements. Frequency-dependent, transfer matrix methods are used to de termine the characteristic determinant of the system. Direct search optimiz ation techniques are employed enabling the whirl frequency and system stabi lity to be determined and compared with results obtained from lumped modell ing. Thereafter the dynamic stiffness matrix for the system is defined, fro m which the multivariable frequency response matrix for system can be estab lished. Frequency domain identification techniques are employed enabling th e multi-input, multi-output transfer function matrix of the system, to be d etermined. It is shown that by this method an accurate low order model can be achieved, for feedback control analysis and design. (C) 2000 Academic Pr ess.