Abstract

In this investigation, the on-line and off-line hybrid contact algorithm for modeling wheel/rail contact problems is developed based on the elastic contact formulation. In the tabular contact search used in existing specialized railroad vehicle dynamics codes, contact points are predicted using an assumption of rigid contacts. For this reason, the contact points can be different from those predicted by the on-line based contact search used in elastic contact formulation. The difference in the contact point becomes significant when flange contacts that have large contact angles are considered. In the hybrid algorithm developed in this investigation, the off-line search that can be effectively used for the tread contact is switched to the on-line search when the contact point is jumped to the flange region. By so doing, a computationally efficient procedure is achieved while keeping accurate predictions of contact points on the wheel flange. Furthermore, the use of the proposed hybrid algorithm can eliminate the use of time-consuming on-line search procedures for the second points of contact as well. Since the location of second points of contact is pre-computed in the contact geometry analysis, the occurrence of two-point contact can be predicted using the look-up table in a straightforward manner. It is demonstrated by several numerical examples that the proposed hybrid contact search algorithm can be effectively used for modeling wheel/rail contacts in the analysis of general multibody railroad vehicle systems.