Estimation of the damping matrix in rotating machinery for the calculation of the stability threshold speed

Rotor internal damping is recognized as one of the main causes for instabilities in rotating systems. In a linear speed dependent model, the stability threshold speed can be calculated numerically. However, this threshold depends highly on the modeling choice and mainly on the relation between rotating and nonrotating damping. In this paper, the importance of a well-founded knowledge of the system parameters is highlighted and a method is proposed to estimate the damping of a rotating system not only influenced by the gyroscopic effect but also by rotating damping. With this method, it is possible to reconstruct the physical damping matrix and distinguish between rotating and nonrotating damping. Moreover, the gyroscopic effect can be identified. After a description of the method, a numerical validation is performed