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In this study, a three-axle vehicle model established with ADAMS/Car is first correlated with field test data from quasi-static tilt table and highly dynamic NATO double lane change maneuver tests, respectively. It is then applied to predict the vehicle static rollover threshold (SRT) and dynamic rollover threshold (DRT). With the optimization approach proposed in this study it is possible to efficiently tune the anti-roll bar stiffness at each axle, to either maximize SRT or DRT, or balance both. The sensitivity results derived from the optimization iteration process can be applied to effectively size the three anti-roll bars that balance the static and dynamic roll stability performances. The proposed method can be potentially applied to include other parameters to address the roll stability issues and beyond.

In this study, a closed-loop driver-truck-trailer system model is established with ADAMS/Car. A double lane change maneuver (DLCM) path boundary is set up based on the NATO AVTP 03-160W requirement. The best driver preview path at a given speed to pass the DLCM is derived from optimization of the closed-loop driver-vehicle-road system, where the objective is to successfully pass the DLCM at the given forward speed. This must be done without violating the maneuver boundary, lifting any tires off the ground, as well as staying within the Driver's steering effort limit. Depending upon the Driver's control strategy, which is reflected by the formulation of the optimal objective, the dynamic responses of the truck-trailer combination will vary. Two extreme conditions are discussed in this study: full and no consideration of trailer, respectively, when negotiating the DLCM.

Dynamic interactions of urban buses with urban roads are investigated in view of the vibration environment for the driver and dynamic tire forces transmitted to the roads. The static and dynamic properties of suspension component and tires are characterized in the laboratory over a wide range of operating conditions. The measured data is used to derive nonlinear models of the suspension component, and a tire model as a function of the normal load and inflation pressure. The component models are integrated to study the vertical and roll dynamics of front and rear axles of the conventional and modern low floor designs of urban buses. The resulting nonlinear vehicle models are thoroughly validated using the fieldmeasured data on the ride vibration and tire force response of the buses.