An Enhanced Greenwood-Williamson Contact Model for the Evaluation of Local Tire/Road Contact Area

Contact modeling plays a crucial role in tire road interaction, impacting several fields, including vehicle dynamics, road safety, and transportation efficiency. As the tire is in contact with the road, the real contact area is smaller than the nominal area due to the indentation of the rubber over the road profile, influenced by the distribution of road texture. This paper introduces a novel approach to contact modeling, focusing on the evaluation of the ratio between the real contact area and the nominal one (AcA0), considering the Greenwood-Williamson formulation. This ratio is fundamental for characterizing the tire-road contact behavior, as it depends on tire viscoelastic properties, road roughness characterization and tire operating conditions. The paper presents some simulations conducted in MATLAB to assess the AcA0 ratio for various road specimens. These simulations were conducted considering a specific compound, while varying parameters such as contact pressure and compound temperature, with a fixed sliding velocity. This research, thus, enhances the understanding of how the road texture, combined with the tire properties and operating conditions, affects tire indentation over the road profile which is strictly related to the perceived friction values.