NUMERICAL STUDY OF JOURNAL BEARINGS WITH ELECTRORHEOLOGICAL LUBRICANTS
电流变液滑动轴承的数值研究

Electrorheological fluid (ERF) journal bearings have a promising prospect in engineering application. Recently the experimental results by Nikolakopoulos show that the lubricating properties of ERF journal bearings can be controlled to satisfy different work conditions by adjusting the strength of applied electric field. Now the theoretical research of ERF journal bearings is in its infant stage. Tichy has presented a theoretical method of Bingham fluid journal bearings, which can be used to predict the pressure distribution in the bearing clearance and the positions of yield surfaces as well. At the end of his paper, he points out that his method can be extended to the study of ERF journal bearings.ERF is a kind of Bingham-like fluids. The differences between ERF and common Bingham plastic model are that the yield stress of ERF can be changed with applied electric field. In the present paper, when we extend Tichy's method to study ERF journal bearings, a non-physical phenomenon is obtained that the positions of yield surfaces are fixed while the applied electric field varies. On the other hand, Tichy's method may only fit the case of journal bearings with infinite width. In order to study the performance of ERF journal bearings with finite width theoretically and numerically, a generalized Reynolds equation is derived based on a Bingham-like model and the concept of apparent viscosity, and a method of iterative relaxation is used to solve the generalized Reynolds equation. A series of numerical results about pressure distribution and positions of yield surfaces is obtained. The rule of changes of yield surface position with applied electric fields is obtained for the first time. Our conclusions are that: the pressure distribution and the position of yield surface in the clearance of journal bearings can be controlled by applied electric field; it is one of the important mechanical mechanism of the performance improvements of ERF journal bearings that the movements of yield surface with the changes of applied electric field; at large shear rates, the apparent viscosity of electrorheological lubricants varies little with applied electric field, so this mechanism is more important in these cases and must be considered in the design of ERF journal bearings.