MBS/FEM Co‐Simulation Approach for Lubrication Problems

Abstract

Hydrodynamic bearings are used in many technical systems, e.g., in combustion engines, in gear boxes or in rotor systems. To model such bearings, different methods are available. Often, reduced bearing models are applied which can be incorporated into the multibody systems by analytical formulas or pre‐computed look‐up tables [1]. Such approaches are very time‐efficient but suffer from limited physical correctness. In order to improve the physical bearing model, the fluid flow and temperature field in the bearing gap have to be computed with partial differential equations which have to be solved simultaneously with the multibody system. These equations are nonlinear and have to be discretized with finite elements, for instance. In the current work, we consider a fully coupled simulation of a multibody rotor system with a finite element model for the hydrodynamic bearings. A co‐simulation interface between two commercial simulation tools is presented. For the synchronization of the solvers, three numerical coupling approaches (an explicit, an implicit and a semi‐implicit approach) are analyzed and compared. For the examined rotor/bearing system, it is shown that semi‐implicit coupling techniques may remarkably stabilize the solver coupling compared to well‐established explicit co‐simulation techniques [2]. Furthermore, a reduction method is introduced and applied in connection with the semi‐implicit coupling approach which can significantly decrease the computation time compared with the classical full‐implicit coupling approach [3]. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)