Investigation on the effects of the ball diameter difference in the sound radiation of full ceramic bearings

This paper takes the ball diameter difference into consideration in the nonlinear dynamic model of the full ceramic bearing. The interactions between the elements of the bearing are derived based on the dynamic theory of the rolling bearing. The sound radiation is obtained using the sub-source decomposition method, and a verification experiment is carried out on the motorized spindle test rig to assess the precision of the model. The rotation speed, axial preload and radial loads are selected as influence factors, and parametric investigations are conducted to study the impact of the factors on the interactions between the elements. The circumferential distributions of the sound radiation are investigated, and parameters including sound pressure level and peak directivity angle are taken as evaluation indexes. Results show that the ball diameter difference has significant impact on the sound radiation of full ceramic bearings, and the impact grows with rotation speed. The sound directivity is closely related to the forces acting on the inner ring, and is affected by the axial and radial loads in different ways. This study provides information for the bearing acoustic characteristics, and is relevant for the design and operation of ceramic bearings.