LAUSR

Abstract To ensure a widespread industrial application of Gas Foil Bearing (GFB) technology a robust prediction method for the stable operating regime has to be available. To predict the onset speed of instability (OSI) of GFBs either a time consuming transient time integration has to be performed or a faster frequency domain approach based on a perturbation method is used. Recent studies reported that the OSIs calculated with these two methods show significant discrepancies although the models are equivalent and the same boundary conditions are applied. This finding is further investigated in this work and it is confirmed that the discrepancy between both methods increases with the level of foil deformation. However a new formulation for the dynamic compliance coefficient is derived which significantly reduces these discrepancies. Different bearing designs and boundary conditions are investigated. Possible explanations for the remaining discrepancies are discussed. A new technique to calculate the OSIs in the frequency domain is developed.