Search Results

Tyre behavior plays an important role in vehicle dynamics simulation. The Magic Formula Tyre Model is a semi-empirical tyre model which describes tyre behavior quite accurately in the handling simulation. The Magic Formula Tyre Model needs a set of parameters to describe the tyre properties; the determination of these parameters is nontrivial task due to its nonlinear nature and the presence of a large number of coefficients. In this paper, the homotopy algorithm is applied to the parameter identification of Magic Formula tyre model. A morphing parameter is introduced to correct the optimization process; as a result, the solution is directed converging to the global optimal solution, avoiding the local convergence. The method uses different continuation methods to globally optimize the parameters, which ensures that the prediction of the Magic Formula model can be very close to the test data at all stages of the optimization process.

In this paper, based on our previously preliminary out-of-plane tire model, a complete out-of-plane flexible tire model is further developed by considering the variation of dimension and parameter values among different slices of the tire model. This tire model is validated via various MSC ADAMS® FTire virtual cleat tests. Especially, the cleat tests with non-zero tire camber angles and non-symmetric cleat shapes, which can better capture the out-of-plane tire properties, are included. By comparing the predicted results of the proposed tire model with FTire for various cleat tests, it shows that the complete out-of-plane flexible ring tire model is better at fully representing the actual tire properties for some complicated cleat testing scenarios.

A tire may be one of the most critical and complex components in vehicle dynamics and road loads analyses because it serves as the only interface between the road surface and the vehicle. Extensive research and development activities about vehicle dynamics and tire models have been published in the past decades, but it is still not clear about the applications and parameter identification associated with all of these tire models. In this literature review study, various published tire models used for vehicle dynamics and road loads analyses are compared in terms of their modeling approaches, applications and parameters identification process and methodologies. It is hoped that the summary of this literature review work can help clarify and guide the future research and development direction about tire modeling.

An outrigger is the device that is mounted on a test vehicle to protect it and/or its driver during handling test maneuvers, such as double lane change, constant radius cornering, J-turn, etc. The design of the outrigger is challenged by the constraints associated with its size, installation flexibility, strength, weight, and moment of inertia for a minimum or negligible impact on the test vehicle dynamics. To achieve an appropriate design of an outrigger for a specific vehicle, it is essential to determine the appropriate dynamic loads that the outrigger needs to support after its geometry and installation scheme have been determined. In this study, a flexible representation of an outrigger is mounted on a military vehicle that is simulated on a NATO double lane change maneuver at the given forward speeds.

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-vehicle system model is established with ADAMS/CAR. A double lane change maneuver path boundary is setup based on NATO AVTP 03-160W requirement. Multiple choices of driver preview path are derived from optimization of the closed-loop driver-vehicle-road system, where the objective is to successfully pass the double lane change maneuver at a given forward speed without violating the boundary. With the multiple choices of preview path, the vehicle dynamic responses, such as tire patch load, vehicle lateral acceleration, yaw velocity, steering wheel angle and roll angle, will vary associated with each driver's preview path. The relationship between the path clearance and vehicle dynamic responses as well as the forward speeds is further investigated. Finally a methodology to predict the maximum forward speed to successfully pass double lane change is proposed.

A truck-trailer combination is modeled using ADAMS/Car from MSC Software for handling and ride comfort performance simulations. The handling events include a double lane change and lateral roll stability. The ride comfort performance events include several sized half-rounds and various RMS courses. The variables for handling performance evaluation include lateral acceleration, roll angles and tire patch normal loads. The variables for ride performance evaluation are absorbed power and peak acceleration. This study considers the trailer spring stiffness, anti-roll bar and jounce bumper gap as the design variables. Through DOE simulations, we derived the response surface models of various performance variables so that we could consider the performance sensitivities to the design variables.