Abstract
To predict the dynamics of a vehicle for handling and ride comfort, we need the accurate tire model since almost all forces and moments acting on the vehicle are generated at the tire contact patch and transmitted through the tire structure. The forces and the moments in the contact patch must be accurately computed. A three-dimensional semi-empirical transient tire model was previously developed in the Advanced Vehicle Dynamics Lab (AVDL) at Virginia Tech, and extended the capabilities of the steady-state tire model also developed earlier at AVDL. A three-dimensional semi-empirical stochastic transient tire model on hard flat and uneven surface is presented here. The tire structure is modeled by an elastic ring supported on a spring and damper system. The elastic ring represents the belt ring and the spring and damper system represents the sidewall and the tread element. The analysis of the deformation of the tire structure is performed on both flat and uneven surfaces to obtain the geometry of the contact patch and the normal pressure distribution. The forces and the moments are formulated using empirical data and based on theoretical mechanics. For a more realistic approach, selected tire parameters are considered uncertain and treated in a stochastic framework using a polynomial chaos theory. Illustrative simulations were performed for both handling and ride studies: a driving/braking maneuver, a lane changing maneuver, and tire rolling over an uneven surface. Both deterministic and stochastic simulation results are shown and compared with the steadystate tire model results and validated based on available data from the literatures.
Keywords: transient tire model, stochastic system