On-line and off-line wheel/rail contact algorithm in the analysis of multibody railroad vehicle systems

An on-line and off-line hybrid contact algorithm for modeling wheel/rail contact problems is developed based on the elastic contact formulation. In the hybrid algorithm developed in this investigation, the off-line tabular search is used for predicting the location of tread contact points, while the on-line iterative search is used for predicting flange contact points. By so doing, a computationally efficient procedure is achieved while keeping accurate predictions of contact points for severe contact scenarios such as sharp curve and turnout negotiations. The use of the proposed hybrid algorithm can eliminate the time-consuming on-line iterative search for the second points of contact. Since the location of the second point of contact is pre-computed by the contact geometry analysis, the occurrence of two-point contact can be predicted by using the look-up table at the one-point contact configuration. A flange climb simulation demonstrates 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.