A method for contact analysis of revolute joints with noncircular clearance in a planar multibody system

Journal bearings are generally used to comprise a revolute joint in mechanical systems. Noncircularity and clearance in journal bearing are obvious due to a long time of nonuniform wear. In this regard, a method of analyzing the contact in revolute joints with noncircular clearances in a multibody system is proposed. The revolute joint with noncircular clearance is assumed to be constituted by an elliptic bore and a pin. The method described is not representative of an elliptic bore journal bearing in a detailed manner. This method involves discretizing the geometric profile of the bushing of the revolute joint. By analyzing the relative separations between the discrete points and the geometric center of the pin, the contact area between the bushing and the pin can be judged and the maximum contact depth obtained. Compared with traditional methods, the proposed method has the advantage that it can be used to analyze noncircular contact problems in revolute joints with a clearance. A slider-crank mechanism is used as an example to compare the effects of the geometrical properties of circular and noncircular (elliptical) revolute joints with clearance on the dynamic response of the mechanisms. The results show that clearance joints with noncircular geometry predominantly affect the dynamic stability of a high-speed mechanism. Moreover, the efficiency of the contact analysis and model solving precision are strongly dependent on the number of discrete points in the geometric profile of the joint elements. The size of the joint clearance has a small effect on the solving efficiency of the model.