Based on the liquid suspension three-degree-of-freedom motor, the three-degree-of-freedom dynamic model of spherical bearing is established. The spatial distribution of the radial electromagnetic force is calculated. The results show that the second harmonic has the greatest influence on the motor vibration. At the same time, considering the roughness of rotor surface, the pressure distribution and film thickness distribution of oil film are calculated by the finite difference method. Through the finite element method, the force of the stator spherical shell and the rotor is analyzed when the rotor slips. Moreover, the oil film modal is calculated and it is found that the forward precession is stronger when the oil film whirls. Finally, the experimental platform is built. The vibration amplitude of the spherical bearing under the condition of normal operation and oil whirl was measured. By comparing the relationship between vibration amplitude and vibration frequency, it is found that oil whirl causes negative vibration growth of spherical bearing, which leads to dry friction between rotor and stator. It provides a good theoretical basis for the practical application and further optimization design of spherical bearing.
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