FEM simulation and transmission experiments on patterned metallurgy miniature journal bearings operating at extra-high-rotational speeds

This study investigates the performance of powder metallurgy journal bearings with non-pattern and herringbone surface patterns. Transmission performance experiments were conducted at various rotational speeds, ranging from 1,000 to 38,000 rpm, to measure bearing radial vibration, friction torque, and temperature rise. A theoretical analysis was also performed to develop a finite element model incorporating the porosity effect of micro-hydrodynamic journal bearings by the use of COMSOL 6.1 software. It examined the operating conditions of different bearings at various rotational speeds, and revealed their difference in transmission performances. Theoretical analysis and experimental results indicate that herringbone-grooved bearings generate high-pressure peaks at the groove tips due to the pumping effect. The patterned surfaces cause increased friction and temperature rise between the fluid and the solid, and induce cavitation in the non-patterned regions, leading to a slight increase in vibration. However, the design reduces the contact area between the fluid and solid, and the elevated temperature decreases fluid viscosity, which helps reduce friction. Experiments also show that the frictional torque is lower at all rotational speeds, demonstrating potential for high-speed applications.