Flow and load characteristics in a coaxial microbearing of finite length

An analytical solution of the velocity field in a microbearing of finite length is derived based on a slip-flow model. Flow characteristics, such as velocity and friction torque for different slip coefficients are investigated in detail. The results show that the flow and load characteristics inside the microbearing depend on not only the magnitude of the slip coefficient but also the boundary conditions at both ends of the microbearing. It is found that when the slip coefficient decreases from 0.4 to 0.01, the friction torque exerted on the rotating shaft increases, and the effect of bearing ends becomes larger and larger. At = 0.01, the torque near the ends of the bearing rises to four times that in the middle of the rotating shaft. As the slip coefficient continues to decrease from 0.01, the friction torque in the middle of the shaft remains unchanged, while the distribution characteristic of the torque near the shaft ends approaches that in a macrobearing.