Traditional multibody dynamic (MBD) tire models concentrate on the tire patch force development and the tire in‐plane characteristics. The tire lateral dynamics and nonlinear effects caused by the tire compliances during rough terrain driving and severe maneuvers are mostly neglected in vehicle analytical simulations. The tire finite element models, though capable of dealing with these phenomena, are basically not designed for quick vehicle dynamic evaluations. A simple three‐dimensional (3‐D) MBD tire model for full vehicle performance and maneuvering simulations over various road surfaces is therefore desirable for the ever expanding analysis capabilities and the improved accuracy of the computer‐aided vehicle design analysis.
In this paper a tire modeling concept to extend the in‐plane dynamic tire model to full 3‐D tire dynamics is proposed. Essentially, this tire model divides the traditional tire/wheel system model into three elements: two rigid bodies representing the wheel mass/inertia and the tire tread mass/inertia, and a spring/damper representing the sidewall visco‐elasticity. Thus, 6 degrees‐of‐freedom (DOFs) are added for each tire over traditional tire models. Using any existing tire patch force calculation model, this proposed model can be used to simulate full 3‐D dynamic responses of a vehicle.
To implement this model, techniques to extract the nonlinear spring rates of the sidewalls and to enhance the tire patch force calculations over uneven terrains are explained in this paper. Results of the vehicle simulation using this tire model were compared with measured field data. They showed that this tire modeling concept yields a practical representation for tire 3‐D nonlinear dynamic characteristics.