Estimating Rolling Element Bearing Stiffness Under Different Operational Conditions Through Modal Analysis

This paper presents a novel test rig, developed to analyse the behaviour of rolling element bearings subjected to highly varying loads. The design is optimised to measure the bearing behaviour, free from dynamics of the surrounding structure. In the current study, the test rig is used to evaluate the stiffness of a deep groove ball bearing under different operational conditions. The bearing behaviour is measured using the modal analysis technique. Then, an analytical model of the test structure is fitted on the data to estimate the bearing stiffness. The stiffness estimation is validated using a dummy bearing with a known stiffness. Finally, the stiffness of a mounted ball bearing is estimated. The paper evaluates the effect of a radial static load on the bearing stiffness. Stationary and operational conditions are compared as well. A clear difference between the stiffness of a rotating and non-rotating bearing is observed.