Speaker
Description
Hydrodynamic journal bearings are essential machine parts that are used in particular for applications with high rotational speeds. Their precise simulation requires the consideration of thermomechanical interactions between solids and fluid. During operation, the shear-stresses in the fluid with lubricant film heights in the range of 5 to 100 µm, lead to significant friction losses acting as a considerable heat source. This heating not only causes a non-linear change in the fluid viscosity, but also influences the temperature. This results in a deformation of the adjacent solid bodies, which naturally influences the pressure in the fluid film due to the thermomechanical coupling.
These coupling effects dynamically change the geometry of the lubricating film and significantly influence the load carrying capacity and dynamic properties (stiffness and damping) of the bearing.
Against this background, the present contribution investigates the thermomechanical interactions within a cylindrical radial journal bearing consisting of shaft and bearing shell including suitable boundary conditions. For this purpose, a temperature model for the solids is developed and implemented to solve the heat conduction equation and is coupled with a mechanical model. To achieve a high numerical efficiency, the p-finite element method is utilized and studied concerning its numerical behavior. The fluid temperature is described by the energy equation, which is approximated using the finite volume method.
After validating the model, it is applied to the thermomechanical analysis of a bearing to gain a deeper understanding of the coupling effects as well as their impact on the bearing’s performance including numerical effort and solution quality.
