Finite element study of pressure distribution under tyre during low speed for explaining rolling resistance

Abstract

Road transports are necessary as they are very flexible, and are essential for the logistics of today, though this requires sustainable solutions for environmentally stable transportation. Trucks are immense machines that are heavily affected by resistance, in both air and rolling resistance. In this report, the main focus will be to gain a better understanding of how the pressure distribution under a tyre influences the rolling resistance. In order to achieve a clearer perception of this phenomena, a 2D finite element model was defined. Two separate concepts were constructed, a more advanced model in ANSYS and a more simplified, yet more controllable, model in MATLAB. A hypothesis was formulated, wherein it is described that the pressure distribution is thought to be offset in the rolling direction. This would be the driving mechanism in creating rolling resistance, and the FE-models were made in order to try and capture this behaviour. The models were created with two layers, one for the sidewall and one for the belt. The boundary conditions were different between the models, in ANSYS the force was prescribed while in MATLAB, the deformation was prescribed. The simulations do show an offset for the pressure distribution beneath the tyre, which was thought to be the case. Though the simulation show that the offset would be in the other direction, something that was hard to explain. The two different model do however show a similar pattern, which was encouraging, though no unambiguous tendency was found. A varying vertical load, and the effects of that variation would be a desired factor to test, though since the project was short on time, this was not examined. Finally, there is more work to do in order to better understand the subject, which could be made by testing the model further or by developing a more complex model in either 2D or 3D.