Identification of dynamic coefficients of the journal bearing considering velocity slip of cavitation zone in the rotating spindle unit

Abstract

A rotating spindle unit, supported by the journal bearings, is developed to improve the cavitation erosion resistance of the journal bearing as well as the spindle dynamic performance. The turbulent lubrication model considering velocity slip in cavitation zone is derived, and the static and dynamic parameters of the journal bearing are obtained. An identification algorithm is further derivated to identify simultaneously the 16 dynamic coefficients of the two journal bearings in the spindle unit. The available experimental results reveal that the journal bearing coefficients are well predicted and estimated by the present model, and the estimated bearing parameters by regularization solution are in good agreement with the assumed values, while it has opposite effect by directed solution for discrete ill-posed problems. It is concluded that the identification accuracy of bearing parameters is governed by the displacement error, and the percentage deviation of dynamic coefficients decreases with the decrease of the displacement error.