Rolling resistance at non-steady-state conditions - investigating the effect of tyre temperature
Time: Mon 2024-06-10 10.00
Location: Kollegiesalen, Brinellv. 6
Language: English
Subject area: Vehicle and Maritime Engineering
Doctoral student: Lisa Ydrefors , Fordonsdynamik, VinnExcellence Center for ECO2 Vehicle design, The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden
Opponent: Professor Igo Besselink, Eindhoven University of Technology
Supervisor: Annika Stensson Trigell, Teknisk mekanik, VinnExcellence Center for ECO2 Vehicle design; Jenny Jerrelind, Fordonsdynamik, VinnExcellence Center for ECO2 Vehicle design; Mattias Hjort, VinnExcellence Center for ECO2 Vehicle design, The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden; Sogol Kharrazi, VinnExcellence Center for ECO2 Vehicle design, The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden
Abstract
Road transport accounts for nearly a fifth of the global greenhouse gas emissions. Despite significant reductions, achieved by e.g. the introduction of electric vehicles, more can be done. One way is to reduce the rolling resistance, which is one of the resistive forces acting on a moving vehicle.
The overall goal of this work is to fill part of the knowledge gap regarding tyre rolling resistance to support the development of more energy efficient vehicles. Focus is on the influence of the operating conditions, with emphasis on tyre temperature and non-steady-state measurements. Today, rolling resistance of new tyres is rated to guide consumers to choose an energy-efficient tyre. However, this rating is based on standardised steady-state drum measurements at 25°C which often results in the measured rolling resistance being evaluated at higher operating temperature than during normal driving. To account for the drum’s curvature, Clark’s formula is used to convert the drum measurement to represent the tyre’s rolling resistance on a flat surface.
In this work, a new method for non-steady-state rolling resistance measurements on a flat surface has been developed and used to show that rolling resistance has a large and non-linear dependence on tyre temperature. This influence varied across the tested tyres, which indicates that the rolling resistance rating could be affected by the measurement temperature. It was shown that the influence of the tyre temperature on rolling resistance was more profound on a drum compared to a flat track. Therefore, it would be beneficial to include a temperature dependency in Clark’s formula to increase its accuracy.
Furthermore, a rolling resistance model has been developed to describe the relationship between tyre deformation and rolling resistance. The model is parametrised with measurement data and simple enough to be used in complete vehicle dynamic simulations.
Overall, this work has contributed with an increase of knowledge about rolling resistance and how it is influenced by tyre temperature, through the development and use of a new measurement method. The results can be used to improve range estimations and to develop more energy-efficient vehicles at realistic operating conditions.