Stability analysis and optimization of a hybrid rotating machinery support combining journal bearings with viscoelastic supports

Abstract

Hybrid oil-bearing-viscoelastic-support systems are promising mechanical devices aiming to provide stability and vibration control in rotating systems. This paper proposes a mathematical model that combines analytical calculation of oil-film coefficients, fractional derivative approach for the viscoelastic materials dynamics and generalized equivalent parameters for dynamically modelling multi-DOF supports as stiffness coefficients. This general model accounts double frequency dependence of the hybrid system, i.e., spin speed and external excitation frequency, and temperature dependence of the viscoelastic material. The generalized equivalent parameter approach is fundamental for determining natural frequencies and ordaining the eigenvalues and eigenvectors of a rotating system that combines viscous and viscoelastic behaviors. The simulations show that viscoelastic supports improve the rotating system stability when compared to the system using oil bearings. Furthermore, the optimization can be applied to the hybrid system, improving the vibration suppression characteristics of the device.