Introducing the Modified Tire Power Loss and Resistant Force Regarding Longitudinal Slip

Investigation of vehicle resistant forces and power losses is of crucial importance owing to current state of energy consumption in transport sector. Meanwhile, considerable portion of resistant forces in a ground vehicle is traced back to tires. Pneumatic tires are known to be a source of energy dissipation as a consequence of their viscoelastic nature. The current study aims to provide a modification to tire resistance by considering the power loss in a tire due to longitudinal slip. The modified tire resistance is comprised of rolling resistance and a newly introduced resistance caused by tire slip, called slip resistance. The physical model is chosen for parameters sensitivity study since the tractive force is described in this model via tangible physical parameters, e.g. tire tangential stiffness, coefficient of friction, and contact patch length. Hence, the tire physical model is capable to investigate the influence of different parameters such as coefficient of friction, normal load, and inflation pressure on dependency of tractive force upon longitudinal slip. The results show that tractive force is a determining factor in the modified tire resistance. In addition, it is seen that behavior of the modified tire resistance undergoes qualitative changes so that for a specified tractive force, it might be a strictly decreasing function of the mentioned parameters. But as the tractive force gradually increases, it might be changed to a non-monotonic function and after that to a strictly increasing function of the above parameters. Furthermore, the results are validated by measuring the vehicle constant-speed fuel consumption experimentally.