Vehicle Dynamics Studies Research Articles

Heavy duty vehicle rollover detection and active roll control

This paper presents the results of a comprehensive study on heavy-duty vehicle (HDV) roll stability improvement technology. The proposed rollover threat warning system uses the real-time dynamic model-based time-to-rollover (TTR) metric as a basis for online rollover detections. Its feasibility for implementation in a HDV rollover threat detection system is demonstrated through vehicle dynamic simulation studies. The research on the development of a rollover threat detection system is further enhanced in combination with an active roll control system using active suspension mechanism to improve heavy-duty trucks’ roll stability both in the static cornering and in emergency maneuvers. It has been demonstrated that the roll stability of typical heavy-duty trucks has been largely improved by the proposed active safety monitoring and control system.

Vehicle dynamics of a high-speed passenger car due to aerodynamics inside tunnels

High train speeds inside narrow double-track tunnels using light car bodies can reduce the ride comfort of trains as a consequence of the unsteadiness of the aerodynamics. This fact was substantiated in Japan with the introduction of the series 300 Shinkansen trains more than a decade ago, where the train speed is very high also in relatively narrow tunnels on the Sanyo line. The current work considers the resulting effects of vehicle dynamics and ride comfort with multi-body dynamics using a model of the end car of the German high-speed train ICE 2. The present efforts are different from traditional vehicle dynamic studies, where disturbances are introduced through the track only. Here disturbances are also applied to the car body, which conventional suspension systems are not designed to cope with. Vehicle dynamic implications of unsteady aerodynamic loads from a previous study are examined. These loads were obtained with large eddy simulations based on the geometry of the ICE 2 and Shinkansen 300 trains. A sensitivity study of some relevant vehicle parameters is carried out with frequency response analysis (FRA) and time domain simulations. A comparison of these two approaches shows that results which are obtained with the much swifter FRA technique are accurate also for sizable unsteady aerodynamic loads. FRA is, therefore, shown to be a useful tool to predict ride comfort in the current context. The car body mass is found to be a key parameter for car body vibrations, where loads are applied directly to the car body. For the current vehicle model, a mass reduction of the car body is predicted to be most momentous in the vicinity of 2 Hz.

Vehicle dynamics with LMS Virtual.Lab Motion

LMS Virtual.Lab Motion is a complete and integrated solution to simulate realistic motion and loads of mechanical systems. It permits engineers to quickly analyse and optimize the real-world behavior of the mechanical design, before committing to expensive physical prototype testing. LMS Virtual.Lab Vehicle Motion simulates all types of vehicle ride and handling behavior from passenger cars and motor sport vehicles to multi-axle vehicles like trucks and buses. Through the multi-attribute nature of the LMS Virtual.Lab Solution, different vehicle performances can be balanced and optimized. This allows performing studies for example to improve the road noise while keeping the handling performance untouched. For handling analyses, LMS Virtual.Lab Motion Vehicle includes the possibility to quickly run standardized events. The industry driver ‘IPG-DRIVER’ is integrated in LMS Virtual.Lab Motion, which allows to simulate all the actions a human driver performs while driving a vehicle. The main tire models integrated in LMS Virtual.Lab Motion are the TNO Delft tire models (MF-Tyre and MF–SWIFT) and CDTire. Other tire models can be integrated using the Standard Tire Interface. The interface with Matlab/Simulink and LMS Imagine.Lab Amesim allows the integration of detailed models of electronic as well as hydraulic control systems in order to perform combined simulations to analyze for example the effect of active safety systems on the vehicle dynamics. As such, LMS Virtual.Lab Motion Vehicle provides a complete package to efficiently perform vehicle dynamics studies.

Scaled vehicle tire characteristics: dimensionless analysis

This article demonstrates the use of dimensional analysis for scaled vehicle tires. The motivation for this approach is the understanding of realistic nonlinear tire behavior in scaled vehicle control studies. By examining the behavior of vehicle tires within a dimensionless framework, several key tire parameters are developed that allow for an appropriate relationship between full-sized tires and scaled tires. Introducing these scalings into vehicle dynamics studies allows for the development of scaled vehicles that have a high degree of dynamic similitude with full-sized vehicles, but are safer and more economical testbeds on which to develop experimental control strategies. Experimental data are used to compare the nonlinear characteristics for sets of scaled and full-sized tires. Finally, design of a scaled vehicle based on tire characteristics is demonstrated.

A new shock absorber model for use in vehicle dynamics studies

The design of modern railway shock absorbers can be separated into several aspects. The most important of which are geometry, functionality, durability and strength. The functional aspect stands fo...

DETERMINATION OF MAGIC TYRE MODEL PARAMETERS

Abstract Tyre behaviour plays an important role in vehicle dynamics studies. The Magic Formula Tyre Model is a semi-empirical tyre model which can describe tyre behaviour quite accurately. A set of Magic Formula parameters constitutes the basis of the model. The determination of these parameters out of tyre measurement data produced by the Delft tyre measurement trailer is dealt with in this paper. Problems that may occur during the "fitting process' are indicated as well. The comparison between the latest version and the 'Monte Carlo version' of the tyre model shows that the latest version results in better fitting results especially for camber influences and (even more important) in an improvement on the fitting process.

Transient Finite Element Analysis of Tire Dynamic Behavior

Abstract Dynamic behavior of a pneumatic tire is simulated by use of an explicit finite element (FE) code. Different parts of the tire and their corresponding material properties are taken into account in the FE model because they play a significant role in tire dynamics. The work presented in this study discusses simulation of cornering behavior, braking behavior, and combined cornering-cum-braking behavior. The effects of camber angle and grooved tread on tire cornering behavior are discussed. ABAQUS/Explicit, a general non-linear FE code, was used for these simulations. To predict the Magic Formula characteristics over a complete range, various simulations are performed at different normal loads and operating conditions. Predicted Magic Formula curves from the simulation results for various dynamic conditions closely follow the experimental data curves. Even though these simulations demand huge computational resources, the predicted Magic Formula curves can be directly used as input in the complete study of vehicle dynamics. Thus, this proposed approach minimizes the costly experiments needed to determine the Magic Formula characteristics and thereby forms a viable tool in the design and the development of tires.

Shear Force and Moment Descriptions by Normalisation of Parameters and the “Magic Formula”

Summary Previous work by Radt on the use of normalised parameters to bring economy to the task of measuring, describing and computing tyre shear forces and parallel works of Pacejka on the ‘similarity method’ are reviewed, extended and applied. Similarity ideas are used in association with the ‘Magic Formula’. Some published tyre force and moment results are divided into basic and nonbasic sets. The basic set contains a notional minimum amount of information from which the full spectrum of results can be obtained by applying similarity ideas. Calculations are carried out to show how the nonbasic results can be reconstructed from the basic set. Advantages are obtained by using a novel nonlinear transformation of the longitudinal and sideslip variables. The results are shown to be qualitatively excellent and quantitatively quite good. Of course, the accuracy is not as high as with a full Magic Formula treatment but the economy is remarkable. The process is captured in a MATLAB algorithm, included as an appendix. It is thought that this provides a useful facility for enabling vehicle dynamics studies of a more generic flavour, in which circumstances conspire to make high precision of tyre force descriptions inappropriate or impossible.

Heavy Truck Handling Performance Analysis in Vehicle Test and Computer Simulation

Abstract The dynamic stability of heavy trucks, as spinout, jackknifing, and rollover, is highly dependent on vehicle configuration, driving maneuver, and the force and moment characteristics of tires. Increasing safety requirements on the handling performance of heavy trucks demand tools that allow a tire design engineer to predict tire influences on the tire/vehicle system dynamic behavior. The computer simulation of handling performance of vehicles offers possibilities of evaluating influences of tire design changes on handling properties in any developing stage of new tire lines. Thus, modern simulation techniques may contribute to the building and testing of tires in an early design stage. This paper presents results from a recent program of tire/vehicle system research, applying tire/vehicle testing and simulation techniques to a 40 ton truck-semitrailer combination. The goal of this work is to visualize the possibilities of state-of-the-art simulation technologies on the tire design process. Tire force and moment characteristics can be calculated from the tire layout by an advanced tire model. The tire model for this type of calculation is a multibody system. Calculated and measured dynamic tire characteristics are used for the full vehicle handling simulation in ADAMS. Extensive tire characteristic testing on the road and test stand was done to improve and validate the tire model. Vehicle handling tests as steady state circular and lateral transient response tests were done for the empty and laden vehicle with different tires to prove the vehicle model. With the use of the simulation of the tire and vehicle behavior, the tire design engineer will be able to judge tire characteristics of different variants in an early design stage. Vehicle dynamic simulation studies up to instability as spinout, jackknifing, and rollover can be performed using modern CAE methods without harming man and environment, but subjective and objective tire evaluation still remains necessary for approving and validating the predicted results.

DETERMINATION OF MAGIC TYRE MODEL PARAMETERS

Abstract Tyre behaviour plays an important role in vehicle dynamics studies. The Magic Formula Tyre Model is a semi-empirical tyre model which can describe tyre behaviour quite accurately. A set of Magic Formula parameters constitutes the basis of the model. The determination of these parameters out of tyre measurement data produced by the Delft tyre measurement trailer is dealt with in this paper. Problems that may occur during the process' are indicated as well. The comparison between the latest version and the 'Monte Carlo version' of the tyre model shows that the latest version results in better fitting results especially for camber influences and (even more important) in an improvement on the fitting process.

A LASER-BASED HIGHWAY-SPEED ROAD PROFILE MEASURING SYSTEM

A large proportion of road roughness measuring equipment used throughout the world today is based on transducers which sense the relative movement between the vehicle body and its rear axle. Although these systems are reliable, simple to use, and have the capacity for the measurements to be performed over a range of travel speeds, the resulting roughness statistic is influenced by the ride characteristics of the host vehicle. In most cases the data are of limited use in the detailed study of vehicle dynamics. Other problems are calibration of the roughness vehicle, comparison between similar and dissimilar systems, and stability of the measures over time. To circumvent these problems, road profile based reference systems are gaining popularity with a resulting increase in useful data for vehicle dynamicists. To meet this need, the Australian Road Research Board (ARRB) has developed a highway speed, road profile measuring system to collect profile data on Australian roads. This device and the signal processing are described in this paper and some results are presented.

Non-linearities in Road Vehicle Dynamics

SUMMARY In the study of lateral vehicle dynamics with the objective to enhance stability and handling qualities, non-linear aspects may have to be included to cover also larger lateral accelerations and amplitudes. The paper treats whole vehicle motions and relative motions of vehicle subsystems. In particular, single car stability, also in the large, is discussed as well as the shimmy phenomenon and the car-trailer instability.

Nonlinear Wheelset Forces in Flange Contact—Part 2: Measurements Using Dynamically Scaled Models

This paper presents new experimental methods for the study of rail vehicle dynamics through the use of scaled models on tangent track, and the application of these techniques to the measurement of nonlinear wheelset force/displacement relations in steady-state. These relations are important to the analysis of wheelset response to track inputs, curving performance of trucks, and wheelclimb derailment. A one-fifth scale model instrumented wheelset with new wheel profiles is used, with similitude scaling of the contact forces achieved through use of a polycarbonate resin for the contact surfaces. Data are presented for wheelset lateral force and yaw moment for the nonlinear range of wheelset lateral displacements and yaw angles, including flange contact. The measured data validate the analytical model presented in Part 1 of this paper, based on nonlinear wheel/rail contact geometry, creep forces with adhesion limits, and wheelset kinematics. A criterion for wheelclimb derailment is presented and verified experimentally.

Free-Fail Vehicle Dynamics Observation and Prediction

During the past five years, the U.S. Naval Ordnance Laboratory, the Royal Aircraft Establishment, and the Australian Weapons Research Establishment have been engaged in a joint study of free-fall vehicle dynamics. The goal of this program was to obtain highly detailed wind-tunnel measurements on research shapes and then use these data to carry out computer simulations of vehicle trajectories. These simulations were compared with actual measurements obtained from a full-scale instrumented store in free flight. The program was also concerned with a wind-tunnel and free-flight investigation of novel stabilizers (tails) designed to eliminate various types of dynamic instabilities.

General Aspects of the Lateral Dynamics of Railway Vehicles

Recent developments in research into the lateral dynamics of railway vehicles are reviewed with particular reference to dynamic stability, dynamic response, and curving. Two engineering aspects of this work are stressed—namely, the advantages of applying linear theory to a comprehensive study of vehicle dynamics, and the choice of basic assumptions required to make such studies realistic for design purposes.