Contact Patch Comparison Between a Roller Rig and Tangent Track for a Single Wheelset

Abstract

This study compares contact patch size for a single wheelset when operated on a roller rig with what occurs on a tangent track, using SIMPACK, a multi-body dynamics software. The primary purpose of the study is to determine if one is able to use a roller rig to duplicate and evaluate the contact patch dynamics that occur on a tangent track. The ability to evaluate the contact patch dynamics on a roller rig provides the significant advantage of conducting tests in the controlled environment of laboratory, to more accurately measure the constants that are commonly needed for creepage models, such as Kalker’s. The wheelset is modeled as a 6 degrees of freedom (unconstrained) body for the tangent track study. The Wheelset is constrained longitudinally for the roller rig simulations. The wheel-rail interface is modeled using the options available in SIMPACK, which are based on Kalker’s empirical creepage model. The simulation data is exported into Matlab for further analysis of the contact patch size. The study suggests that it is possible to use a constant scaling factor for relating the contact patch size on a roller rig with a tangent track, using the constrained contact method. For the elastic contact method the contact patches cannot be related to each other through a constant. In that case, a formula is needed to relate the two contact patches.