Multibody Dynamics Approach to the Modeling of Friction Wedge Elements for Freight Train Suspensions. I: Theory

Abstract

This paper presents a theoretical application of multibody dynamics with unilateral contact to model the friction wedge interaction with the bolster and the side frame. The objective of the proposed approach is to produce a stand-alone model that can better characterize the interaction between the bolster, the wedge, and the side frame. The new model allows the wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and the side frame), pitch (rotation about the lateral axis), and yaw (rotation about the vertical axis). The new model also allows for toe variation. The stand-alone model shows the capability of capturing the dynamics of the wedge which was unnoticed in previous models. The inclusion of unilateral contact conditions is integral in quantifying the behavior during lift-off and the stick-slip phenomena. The resulting friction wedge model is a three-dimensional, dynamic, stand-alone model of a bolster–friction wedge–side frame assembly.