Modeling of Bearing Dynamics Using Combined EFEM-DEM Method

In this work, a new modeling technique was developed to investigate the effects of rotor and support flexibilities on the performance of bearing system. The dynamics of the ball bearings were simulated using an existing dynamic bearing model, which was developed using the discrete element method (DEM). The explicit finite element method (EFEM) was used to model the flexibilities of various structures, such as the rotor and bearing housing. The capability of the EFEM model was also extended to include the modeling of different materials, such as elastomers. Constitutive relationship for the elastomer is based on the Arruda-Boyce model combined with a generalized Maxwell-element model to capture both hyperelastic and viscoelastic behaviors of the material. In order to combine the dynamic bearing model with finite element rotor and support system, new contact algorithms were developed for the interactions between the components in the system. The Total Lagrangian formulation approach was applied to decrease the computational effort needed for modeling the combined EFEM-DEM system. The combined model has investigated and shown that deformations of rotor and housing have significantly changed the motions of bearing elements. And the behaviors of bearing, rotor and housing are interdependent on each other It has also been shown that choosing a proper bushing is an efficient way to reduce vibrations and increase bearing stability.