Vehicle Dynamics Modeling of Commercial Vehicle Steer Axle Tire Disablements at Highway Speeds 2023-01-0665

There have been many studies regarding the stability of vehicles following a sudden air loss event in a tire. Previous works have included literature reviews, full-scale vehicle testing, and computer modeling analyses. Some works have validated physics-based computer vehicle simulation models for passenger vehicles and other works have validated models for heavy commercial vehicles. This work describes a study wherein a validated vehicle dynamics computer model has been applied to extrapolate results to higher event speeds that are consistent with travel speeds on contemporary North American highways. This work applies previously validated vehicle dynamics models to study the stability of a five-axle commercial tractor-semitrailer vehicle following a sudden air loss event for a steer axle tire. Further, the work endeavors to understand the analytical tire model for tires that experience a sudden air loss. The studies discussed include executing physics-based vehicle dynamics models at speeds ranging from 88.5 kilometers per hour (55 miles per hour) up to 125.5 kilometers per hour (78 miles per hour), at various vehicle loading conditions and differing levels of velocity-dependent rolling resistance. The effects of speed and payload on vehicle response are analyzed and discussed.

For all the simulations in this study, a left steer axle tire sudden deflation was modeled. The results of the work revealed that after a modeled sudden air loss event, a manageable steering wheel angle would have to be input into the tractor steering system to arrest the initial yaw to the left caused by unbalanced longitudinal forces on the steer axle. The resultant initial corrective steer angle was found to be consistent with testing results and was in the range of 36 to 59 degrees steering wheel angle (SWA). As control of the tractor-semitrailer is maintained, the steering wheel angle required to hold the vehicle in a lane, steady-state, was found to be in the range of 24 to 38 degrees SWA.