Modeling Tribological Impact on Overall System Dynamics

Abstract

While the support bearings are key elements of rotating machinery systems, the overall system performance and design depend on a close integration of several disciplines. For prescribed life and operating environment the applied static loads and speeds on each of the system component may be generally determined by an equilibrium analysis. Conventional rotor dynamics models may be used to model overall system dynamics, rotor response and dynamic loads imposed on the support bearings. As a function of these applied conditions bearing response and dynamic performance is determined by integration of the equations of motion of each bearing element; in the case of rolling bearings, the available bearing dynamics models, such as ADORE (Advanced Dynamics Of Rolling Elements) provide integration of the classical differential equations of motion to model real-time performance of the bearing. With prescribed bearing geometry and applied operating conditions, it is well established that lubricant properties and mechanics play a major role in determining the stability of bearing elements and overall system performance. The rolling-sliding interactions in the concentrated contacts between the bearing elements produce heat, which travels through the bearing and the overall system. This affects temperature of the bearing elements, which in turn changes the bearing geometry and material behavior including the lubricant. Thus overall system design and performance simulation requires a close iteration between the various models at varying levels of sophistication.