Investigations on the force generation and deformation of agricultural tyres with a Single Wheel Tester

摘要

With the Single Wheel Tester of the University of Hohenheim the generation of horizontal forces depending on slip and slip angle can be determined. In this investigation the lateral forces have been examined. The course of the lateral forces versusthe slip angle can be approximated by an exponential function. Especially for vehicle dynamics, when only small slip angles are regarded, the cornering stiffness is often used due to its linearized lateral force - slip angle ratio. However, results of measurements with non-steady-state slip angle show a delay in force generation, which is not expressed in the cornering stiffness. The Maxwell-model for the dynamic lateral forces shows a good accordance with the measured data. With a laser measuring device the internal contour of the tyre in the tread and in the sidewall can be determined. Thereby the shape of the contact area can be calculated for the rolling tyre. First results show that the tyre contour is not only deformed in the contact area but also displaced upwards outside the contact area. Additionally there is a predeformation, which is not taken into account by existing tyre models for the contact area calculation.