A new tyre model for the simulation of road/rail vehicles when operating on rails

This paper builds on earlier work that describes the design, build, and commissioning of a purpose-built tyre test rig that was used to investigate specialised tyres designed for Road-Rail Vehicles (RRVs), which operate on both roads and railway tracks. When on tracks, they can be used for various purposes including shunting heavily loaded wagons. That is the focus in this paper. A new empirical tyre model is proposed for simulating RRVs operating on rails. While many tyre models exist in the automotive sector, none have been adapted to simulate RRV performance on rails. The tyre model presented here is intended to be efficient, producing optimal design information with a minimum set of parameters and hence a manageable test process to generate the data to parameterise it. As the model is intended for shunting operations the focus is on modelling the tractive performance as a function of longitudinal slip. The full formulation of the QUALITYRAIL (QUAdratic to LInear TYre to RAIL) tyre model is presented. The results from a tyre test programme were used to generate a data set that allowed the formulation of a model representing variations in speed, load, and wet or dry conditions. A further set of physical testing was carried out in the wet and dry at different loads and speeds to validate the new tyre model. The data points for these tests were independent of the original test programme to ensure a rigorous approach for the validation. The results of this study demonstrate that the novel tyre model can efficiently and accurately represent the tractive performance of a pneumatic tyre acting on rails at various speeds and loads in both wet and dry conditions, with potential to contribute through simulation to improve the design and performance of future RRVs.