Dynamic and stability analysis of rotor-shaft systems with viscoelastically supported bearings

This research investigates the dynamic analysis of a single-rotor shaft system with elastic bearings at the ends mounted on viscoelastic suspensions. Timoshenko shaft model is utilized to incorporate the flexibility of the shaft; the rotor is considered to be rigid and located at the mid-span of the shaft. The viscoelastic supports of the linear bearings are modeled using Kelvin-Voigt model. Equations of motion are derived for the system, and both free and forced vibration analysis are performed. Comparisons of the natural frequencies are made between the Jeffcott model and the Timoshenko model. The effects of stiffness and loss coefficients of the viscoelastic supports on the complex natural frequencies are investigated. Stability analysis is performed utilizing the Routh Hurwitz criterion for polynomials with complex coefficients and the variational analysis. Experimental investigations were carried out for the system and compared to the predicted theoretical results. Theoretical results show that optimum values of the viscoelastic stiffness and loss coefficient can be achieved for a specific rotating shaft system to reduce vibrations and increase the operating regions.