A HYDRODYNAMIC JOURNAL BEARING TEST RIG WITH DYNAMIC MEASUREMENT CAPABILITIES

A bearing test rig was developed to characterized the static and dynamic properties of hydrodynamic journal bearings. Static measurement capabilities include operating eccentricity, pressure and thermal boundary conditions, and continuous circumferential pressure and film thickness profiles at multiple axial planes. Dynamic stiffness and damping coefficient measurements are achieved using steady state harmonic excitations generated by a two-axis shaker system. All essential data for a complete understanding of one particular bearing can be collected simultaneously. To ensure high quality results, the rig was designed to minimize the influence of measurement uncertainties on the derived dynamic coefficients. Complete details are described. The rig is configured to test bearings with 70 mm bore diameters at speeds up to 2500 rpm and loads up to 6000 N. The data reduction technique is presented along with typical results at one steady operating position for a three-lobe bearing which demonstrate the reproducibility and dependability of the data. For the reported data, dynamic stiffness and damping values for three independent sets of data are within 13 percent at worst and usually within 3 percent. Typical uncertainties are less than 10 percent for stiffness and less than 30 percent for damping.