Dynamic analysis of viscoelastic rotor-bearing systems with fractional material damping

In rotordynamics, there is a broad range of applications for different types of rotors. Starting from slender rotors for applications in the medical industry to non-slender rotors in the energy industries. These industries require optimised rotors. The optimisation process increases the importance of understanding the vibrations occurring in the system and investigating the effects of new materials. In order to adequately address the complexity of the requirements, reduce computational costs, and enhance the safety of product design, it is necessary to employ an appropriate modelling approach and utilise efficient numerical simulation techniques. Consequently, a modelling approach has been developed to describe a viscoelastic rotor-bearing system valid for a wide frequency range. In order to represent all rotordynamic effects, including the destabilisation of a rotor, the internal damping is represented by fractional time derivatives. The rotor is modelled using Timoshenko beam theory and supported on anisotropic bearings, with an arbitrary unbalance. In this paper, an efficient and precise simulation of the rotor-bearing system is achieved using the Numerical Assembly Technique, which is described as a semi-analytical approach. Finally, a comparison is made between the applied fractional material damping model and a classical material model, and the influence of the fractional parameter is discussed.