| While the handling characteristics of road vehicles have been studied extensively in recent years, the handling behaviour of off-road vehicles on deformable terrain has not yet been given sufficient attention. With the increasing use of multiaxle, all-wheel-drive vehicles in cross-country transport, in resource industry and in military operations, there is a need for the development of a realistic simulation model for the handling behaviour of off-road vehicles. This would provide practicing engineers with an analytical framework for the further improvements of the handling of these vehicles.; The forces and moments that control the motion of a ground vehicle, hence its handling, are generated by tire-ground interaction. This research investigated the longitudinal and lateral forces developed by a tire on deformable terrain. A new off-road tire test facility at the Transport Technology Research Laboratory, Carleton University has been designed and constructed. Experiments have been performed to study the general relations between the longitudinal and lateral forces and the longitudinal slip-slip angle for an off-road tire. Tire forces have been measured on a deformable soil under various normal loads and inflation pressures. Furthermore, based on the shear stress-shear displacement relations of soil, a new off-road tire model for predicting the longitudinal and lateral forces under combined longitudinal slip and slip angle has been developed.; The tire model with the data obtained using the tire test facility has been integrated into an off-road vehicle handling simulation model. The handling model has been developed based on the computer code AUTOSIM. It takes into account non-linear characteristics of the steering and suspension systems of the vehicle. To demonstrate the utility of the model, the steady-state handling characteristics of a six-wheel-drive, front-wheel steering vehicle on paved road and on deformable terrain, as well as its behaviour in a lane-change manoeuvre have been evaluated and presented as examples. Furthermore, an animation program for displaying the lane-change response of the vehicle is included. |
