Key Engineering Materials Vol. 642

Abstract: A new kind of smart hydrodynamic journal bearings with giant magnetostrictive actuators (GMA) is introduced. The static and dynamic displacement outputs of the designed GMA are up to tens of microns, about the same order of magnitude as the conventional journal bearing clearance. Vibration suppression of the new smart journal bearing is theoretically evaluated using a simple Jeffcott rotor-bearing system. Kinematic equations are set up including the magneto-mechanical coupling model for GMA. The bearing oil film force under large vibration is calculated using a fast and efficient non-stationary oil film database technique. The unbalance vibration orbit of the rotor center is simulated. A simple synchronous proportional control method for GMA with different control phases and gains is investigated. The suppress effect of unbalance vibration and improvement of oil whip unstable speed is evaluated. The simulation proves that the new journal bearing has better stability, and that rotor vibration can be actively suppressed.

Abstract: For the need of high speed and load capacity of precision industry, a bearing used in a high speed spindle is studied. The hydrodynamic bearing composed a hydrodynamic bearing made of porous material and several hydrostatic chambers with an external oil system. The hydrodynamic bearing is pressurized with oil chamber and supports the spindle shaft both at rest and at rotation state. Because of the external pressure and the property of porous material, the load capacity of hydraulic bearing can be promoted without decreasing precision. To consider the relationship of parameters, we applied the Reynolds equation and Darcy’s law to describe the flow of the oil film between bearing and spindle shaft.

Abstract: An elastic contact solution considering the effect of free surface and code are developed using Hetenyi’s approach and semi-analytical method. Discrete convolution-fast Fourier transform (DC-FFT) is used to calculate elastic deformation. The modified conjugate gradient method is applied to solve surface contact pressure. By comparing with other literatures’ results, the program made by authors is proved valid.