Bearing simulation gets real

The Beast preprocessor displays a model of a deep-groove ball bearing (SKF Type 6309) used for the simulations. Simulation of a deep-groove ball bearing running at 600 rpm under a 1-kN radial load. Ball azimuth zero is at the bearing top (12 o'clock). A 0.5 ball azimuth represents the 6 o'clock position. The instrumented cage for testing ball-cage forces with a calibration ball in the cage pocket sans the outer ring. Axial cuts in the cage bar boost strain-gage signals and help to mechanically isolate one pocket from another. A comparison of plots from experiments and simulations show good agreement. Note that test signals changing sign in the misaligned case are an instrumentation artifact and do not reflect real forces. The pressure distribution of all balls on an inner ring segment at an arbitrary point for the misaligned test case is represented as a parametric surface. The circumferential direction is from bottom left to top right. The test cage with a steel rim affixed to the backbone. The rim provides a "readable" surface for the proximity sensors. Simulating bearing dynamics is highly specialized and beyond the capabilities of most off-the-shelf analysis packages. That is why bearing maker SKF developed its own Bearing Simulation Tool (Beast) for internal use. Beast's multibody scheme models the dynamic behavior of all bearing components under load — balls, rollers, inner and outer rings, and cages. The model includes forces on the cage, its motion, as well as skew and tilt of rollers, and ball skidding. Earlier rolling bearing simulation codes either ignored cages or described them with simplified 2D models. Beast, in contrast, uses a 3D model for the task. Engineers specify all boundary conditions, applied loads, and parts geometry, especially important metrics for modeling cages. To verify the simulation's accuracy, SKF engineers ran tests on