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Showing papers in "Vehicle System Dynamics in 1985"


Journal ArticleDOI
TL;DR: The state-of-the-art general purpose vehicle system dynamics software is reviewed in this article, where two representative programs, MEDYNA and NEWEUL, are described with respect to modeling options, computational methods, software engineering as well as interfaces to other software.
Abstract: SUMMARY This paper pursues two objectives: Firstly, to review the state-of-the-art of general purpose vehicle system dynamics software and secondly, to describe two representatives, the program MEDYNA and the program NEWEUL. The general modeling requirements for vehicle dynamics software, the multibody system approach and a comparative discussion of multibody software are given. The two programs NEWEUL and MEDYNA are described with respect to modeling options, computational methods, software engineering as well as their interfaces to other software. The applicability of these programs is demonstrated on two selected examples, one from road vehicle problems and the other from wheel/rail dynamics. It is concluded that general purpose software based on multibody formalisms will play the same role for mechanical systems, especially vehicle systems, as finite element methods play for elastic structures.

65 citations


Journal ArticleDOI
TL;DR: A review of the state of knowledge and understanding of the steering behavior of single-track vehicles can be found in this article, with the main accent on vehicle design, and vehicle design analysis and behaviour prediction.
Abstract: SUMMARY The paper is a review of the state of knowledge and understanding of the steering behaviour of single-track vehicles, with the main accent on vehicle design, and vehicle design analysis and behaviour prediction. The body of the paper consists of a chronological account of the steps which have been taken in establishing the current position. Scientific study of the motions of two-wheelers has been in progress for more than 100 years, but progress was slow and many conflicting conclusions were drawn until increasing understanding of tyre mechanics, systematic application of the laws of motion for systems of rigid bodies, digital computation and modern numerical methods, and improved mobile measurement, recording, and data processing capabilities allowed the pace to accelerate. The current position, which is that a good understanding of the relationship between design and performance has been achieved, but that by no means have all the problems of significance been solved, is described at the end of ...

59 citations


Journal ArticleDOI
TL;DR: In this paper, a spatial model of a medium-range passenger vehicle is augmented by a disturbance model (stochastic dual track excitation of the road surface with excitation delay time, if need be with irregularity sensors), a perception filter (weighting of human sensitivity to vibration) and a filter fo...
Abstract: SUMMARY In vehicles with traditional passive suspension, the spring and damping elements between car body and axles have a fixed characteristic. This means that when the suspension is adjusted, a compromise between comfort and safety has to be arrived at. With active suspension, on the other hand, both these criteria can be enhanced at the same time. Moreover, further improvements in driving behaviour can be made which are not possible with passive suspension. In this case, the time delay between front and rear axle excitation is represented by a fade approximation, which means that linear controller design methods in the state space (Riccati controller, Kalman filter) can be used to implement active vehicle suspension. A spatial model of a medium-range passenger vehicle is augmented by a disturbance model (stochastic dual track excitation of the road surface with excitation delay time, if need be with irregularity sensors), a perception filter (weighting of human sensitivity to vibration) and a filter fo...

40 citations


Journal ArticleDOI
TL;DR: In this article, a review of the state-of-the-art results in extending conventional analysis techniques to the treatment of highway trains is presented, that is, to heavy trucks with multiple articulation points and suspensions with multiple axles.
Abstract: SUMMARY This review of the state of the art emphasizes recent results that have been obtained in extending conventionalanalysis techniques to the treatment of “Highway Trains”, that is, to heavy trucks that have multiple articulation points and employ suspensions with multiple axles. Equations of motion applicable to the equilibrium turning performances of articulated vehicles are examined with respect to using analysis techniques involving steering gains, understeer gradients, effective wheel-bases, handling diagrams, and critical speeds. These examinations provide the basis for in sights into simplified approaches for understanding the steady turning mechanics of articulated, multi-axle vehicles riding on pneumatic tires.

36 citations


Journal ArticleDOI
TL;DR: In this paper, a general purpose program for the analysis and design of mechanical systems is presented, with a brief description of the underlying theory and of the system analysis features is given, and two representative examples in the program's main application area, vehicle dynamics, are presented in order to demonstrate its capabilities.
Abstract: SUMMARY A computer general purpose program for the analysis and design of mechanical systems is presented. A brief description of the underlying theory and of the system analysis features is given. Two representative examples in the program's main application area, vehicle dynamics, are presented in order to demonstrate its capabilities. First, the derailment behaviour of three connected freight cars is studied. As a second example, a motor car with different vehicle parameters running across road irregularities is analysed.

31 citations


Journal ArticleDOI
TL;DR: In this paper, a seven degree-of-freedom vehicle model incorporating a fully interconnected active suspension is developed, and the model is used to analyze the effect of coupling and absolute damping on sprung mass isolation, as well as tire normal load distribution.
Abstract: SUMMARY A seven degree-of-freedom vehicle model, incorporating a fully interconnected active suspension is developed. The model is used to analyze the effect of coupling and of absolute damping on sprung mass isolation, as well as tire normal load distribution. A parametric study shows that when absolute damping is used, decoupling the heave and pitch body modes both improves body isolation, and reduces fore-aft tire load transfer. However, absolute body roll damping, while improving body isolation, increases the effect of road disturbances on lateral load transfer distribution.

30 citations


Journal ArticleDOI
TL;DR: In this paper, the technical state-of-the-art of aerodynamics of ground transportation vehicles is reviewed and the interactions between vehicle system dynamics and aerodynamics are addressed and correlation of theoretical and experimental data show the present potential of vehicle aerodynamics and point to fields in which further research work is necessary.
Abstract: SUMMARY The technical state-of-the-art of aerodynamics of ground transportation vehicles is reviewed. Currently available theoretical calculation methods and experimental simulation techniques as well as typical results illustrating the impact of aerodynamics on vehicle performance and running characteristics are summarized and the interactions between vehicle system dynamics and aerodynamics are adressed. Correlation of theoretical and experimental data show the present potential of vehicle aerodynamics and point to fields in which further research work is necessary.

30 citations


Journal ArticleDOI
TL;DR: In this article, a wear algorithm was proposed to predict the shapes into which rail vehicle wheels and rails wear in tangent track use, and the results showed that the wheel profiles wear into shapes that are nearly identical for four different wear model formulations examined.
Abstract: SUMMARY The wear algorithm described In this paper has the capability to predict the shapes into which rail vehicle wheels and rails wear in tangent track use. Results of the algorithm applied to a freight car model show that the wheel profiles wear into shapes that are nearly identical for four different wear model formulations examined.

26 citations


Journal ArticleDOI
TL;DR: In this article, a method is presented for the digital simulation of multiple degrees-of-freedom lumped parameter vibrating systems with arbitrary constitutive elements in an inertial frame of reference.
Abstract: SUMMARY A method is presented for the digital simulation of multiple degrees-of-freedom lumped parameter vibrating systems with arbitrary constitutive elements in an inertial frame of reference. The geometry of the system is treated independently of the constitutive elements and as a result nonlinear (time domain) or linearised (frequency domain) calculations may be performed using a single input description. The method is used to simulate a 3-axle rigid heavy commercial vehicle for harsh vibrating conditions. Some of the assumptions to which the calculations are sensitive are examined. Agreement between the response of a 3-dimensional whole vehicle model and measurements on the test vehicle is satisfactory.

24 citations


Journal ArticleDOI
TL;DR: In this article, the bending vibrations of a wheel are calculated by means of a finite element model and the forced and self-sustained oscillations are determined using modal expansion techniques.
Abstract: SUMMARY In urban rapid transit systems the squealing noise of railway wheels during the passage through narrow curves is very troublesome to passengers and city dwellers. Frequency analyses of measured curving-noise levels show that the bending vibrations of the wheel disks excited by stick-slip motion between the wheel rim and the rail are the main sources of this sound radiation. To get insight into the dynamics of the noise generation it is necessary to understand the bending vibration behaviour of a wheel disk as well as the sound radiation mechanism and the generation of self-sustained oscillations in the contact area. The present paper deals with a theoretical model which comprises all three parts of the problem. In the first part the natural bending vibrations of the wheel are calculated by means of a finite element model. In the second part the forced and self-sustained oscillations are determined using modal expansion techniques. The third part deals with the calculation of the radiated sound pre...

23 citations


Journal ArticleDOI
TL;DR: The Daimler-Benz Driving Simulator as discussed by the authors is a simulator for driving simulators that is based on the VANET simulator and can be used to simulate real-time driving.
Abstract: (1985). The Daimler-Benz Driving Simulator. Vehicle System Dynamics: Vol. 14, No. 1-3, pp. 86-90.

Journal ArticleDOI
TL;DR: In this article, an analytical and numerical study of a multi-degree of freedom passenger car incorporating Passive, Active, and Semi-Active Suspension was performed, and the influence of active and semi-active damping on vehicle ride quality control was determined, and compared with the conventional passive suspension by means of a computer simulation.
Abstract: SUMMARY An analytical and numerical study of a multi-degree of freedom passenger car incorporating Passive, Active, and Semi-Active Suspension is performed. The model with data of a typical vehicle includes rigid body translational and rotational modes. This constitutes an extension of the state-of-the-art, since previous investigations of semi-active suspensions were restricted to heave and pitch mode control (exclusive of roll). The vibrations of the four-wheeled vehicle moving at constant forward speed are induced by random roughness of the left and right track. The influence of active and semi-active damping on vehicle ride quality control is determined, and compared with the conventional passive suspension by means of a computer simulation. Simulation results in the time and frequency domain show that the semi-active damper is superior than the conventional passive one, with performance approaching that of a fully active system. The penalty cost associated with these ride comfort improvements is an i...

Journal ArticleDOI
TL;DR: In this article, the authors examined the energy losses which derive from the vibratory phenomenon experienced by a motor vehicle when It traverses an irregular road surface and revealed that there are, at least, four "dynamic" energy-loss mechanisms contributing to vehicular rolling resistance.
Abstract: SUMMARY The energy losses which derive from the vibratory phenomenon experienced by a motor vehicle when It traverses an Irregular road surface have been examined. The study has revealed that there are, at least, four “dynamic” energy-loss mechanisms contributing to vehicular rolling resistance. Specifically, it was determined that the energy losses associated with the dynamic deflection of the tire and the stroking of the suspension damper are predicted reasonably well by a linear mass-spring-damper model of a motor vehicle traversing an uneven road surface at constant speed. The energy losses attributable to impacts between tire and road become significant only when the speed is very high or the road is very rough. Finally, measurements have shown that the angular accelerations associated with time-varying radial deflections of the tire will cause an energy loss when the shear forces required to accelerate or decelerate the wheel become larger than can be sustained by the frictional coupling prevailing ...

Journal ArticleDOI
TL;DR: In this paper, the authors describe four control configurations for an electromagnetic vertical active suspension fitted to a BR Mk III coach, two of the control systems were designed using classical frequency response techniques and two using linear optimal control theory.
Abstract: SUMMARY The paper describes four control configurations designed for an electromagnetic vertical active suspension fitted to a BR Mk III coach. Two of the control systems were designed using classical frequency response techniques and two using linear optimal control theory. Theoretically the performance of the optimal control systems compared favourably with that of the classical controllers and design of the regulator proved to be both rapid and straightforward. However, physical realisation of the optimal control system required a rationalisation of the vehicle model which drew heavily on experience gained in the design of classical control systems. During track testing, problems of interaction between vehicles were encountered, as a result the biggest improvements in ride were obtained with a simple “skyhook” damper which was less specific to the vehicle than the other configuration. However, with further development one of the optimal controllers will probably turn out to be the most effective as it ...

Journal ArticleDOI
TL;DR: In this article, the dynamic excess loads can be correctly described by the analysis of an integrated track-vehicle -drive system model, which is a relatively extended "track - vehicle" system.
Abstract: SUMMARY Traction vehicles moving along a track go through excited vertical and pitching vibrations due to the vertical unevennesses in the permanent way. These vibrations give rise to variations in the axle load, and dynamic loads in each element of the drive system are created by the variations in the creep- and axle load dependent tractive effort transmitted through wheel-rail contacts. Service life and reliability of the expensive traction vehicles are considerably influenced by the variation in the dynamic load conditions of the drive system. The dynamic excess loads can be correctly described by the analysis of an integrated “track - vehicle - drive system” model. This paper deals with the dynamic processes of the drive system which is a part of a relatively extended “track - vehicle” system. In the course of the analysis, linear and non-linear system models are used. Our numerical examinations, carried out so far, show that linear system models can yield acceptable results only in the case of relati...

Journal ArticleDOI
TL;DR: In this paper, a mathematical model of a vehicle has been used to describe the car braking process on an uneven rectilinear road, which is built in such a way to allow applying interchangeably one of the six models of the tire radial properties in it - five of the models have been taken from the literary sources.
Abstract: SUMMARY This paper presents the mathematical model of a vehicle. The model has been used to describe the car braking process on an uneven rectilinear road. The model is built in such a way to allow applying interchangeably one of the six models of the tire radial properties in it - five of the models have been taken from the literary sources. Irregularities of the road surface are the realization of the random process which is desoribed by the power spectral density. Three-parametric description of the tire tangential properties has been applied here.Results obtained from the comparison of the six models of the tire radial properties as well as exemplary results obtained from the simulation of the oar braking process on even and uneven road surfaces have all been presented in this paper. An attempt has been undertaken to evaluate the influence of the road unevenness upon the effectiveness of the oar braking process.

Journal ArticleDOI
TL;DR: In this paper, a theoretical analysis on vehicle cornering behavior in braking and acceleration is presented, with a focus on the impact of braking behavior on the acceleration of the vehicle on the vehicle.
Abstract: (1985). A Theoretical Analysis on Vehicle Cornering Behaviours in Braking and in Acceleration. Vehicle System Dynamics: Vol. 14, No. 1-3, pp. 140-143.

Journal ArticleDOI
TL;DR: The results of the disturbance input calculations indicated that under low lateral acceleration conditions, drivers of different commercial vehicle configurations should be capable of providing adequate control compensation to achieve more or less equal stability margins for most systems as discussed by the authors.
Abstract: SUMMARY Computer analysis of the closed-loop directional stability of four common commercial vehicle configurations was performed using 1) a disturbance input technique to study low lateral acceleration driving conditions, and 2) a lane-change maneuver for studying system response at elevated lateral acceleration conditions. The results of the disturbance input calculations indicated, that under low lateral acceleration conditions, drivers of different commercial vehicle configurations should be capable of providing adequate control compensation to achieve more or less equal stability margins for most systems. Evaluation of directional stability, based upon the transient lane-change maneuver, indicated systematic reduction in system damping for all vehicles with Increased levels of lateral acceleration. The 5-axle tractor-semitrailer system exhibited the greatest level of directional damping and rollover immunity during the lane-change maneuver. The truck full-trailer was the least damped system while als...


Journal ArticleDOI
TL;DR: In this paper, a technique of partitioning the data and drawing together consistent responses in order that high quality results can be produced is presented. But it has been found that non-stationary behaviour, particularly conicity changes, mean that the results obtained are virtually useless unless the railway vehicle on test has very special properties.
Abstract: SUMMARY The Random Decrement technique which takes a time history and develops from it a step response function was presented at a previous IAVSD Conference. In practice it has been found that non-stationary behaviour, particularly conicity changes, mean that the results obtained are virtually useless unless the railway vehicle on test has very special properties. To overcome this a technique of partitioning the data has been developed. The technique then draws together consistent responses in order that high quality results can be produced. In this way the measured kinematic behaviour of the railway vehicle with profiled wheels can be described in terms of frequency and damping. This enables comparison with theoretical predictions. The paper describes the theoretical method, the theoretical validation and experimental results which have been produced using this technique.

Journal ArticleDOI
TL;DR: In this article, an energy phase plane is presented to comprehensively represent the steering characteristics of motor vehicles for identifying, understanding and comparing the test results in the entire operating range (including the limit maneuvering properties) some important parameters(front and rear cornering stiffness, under/oversteer quantity, cornering energy level, etc.) as well as vehicle behaviors for the entire process of the maneuver ( including front and rear slip angle, instant center, spin and/or drift situation, into and/ or out of vortex situation, etc) are reflected in a single phase plan diagram.
Abstract: SUMMARY An “energy phase plane” method is presented to comprehensively represent the steering characteristics of motor vehicles for identifying, understanding and comparing the test results in the entire operating range (including the limit maneuvering properties) Some important parameters(. front and rear cornering stiffness, under/ oversteer quantity, cornering energy level, etc,) as well as vehicle behaviors for the entire process of the maneuver ( including front and rear slip angle, instant center, spin and/or drift situation, into and/or out of vortex situation, etc) are reflected in a single phase plan diagram.

Journal ArticleDOI
TL;DR: In this article, the effect of wheel and/or rail lubrication in reducing wheel/rail wear rates was evaluated by steady-state curving calculations of a freight car model with conventional and radial trucks.
Abstract: SUMMARY The effect of wheel and/or rail lubrication in reducing wheel/rail wear rates is evaluated by steady-state curving calculations of a freight car model with conventional and radial trucks. Numerical results indicate that for curves with radii less than 400m, rail lubrication is necesary and the wheel/rail wear rates may be reduced to 1/2.5 of that without lubrication.

Journal ArticleDOI
TL;DR: In this paper, the authors determined the Tangential Stresses and the Wear for the Wheel-Rail Rolling Contact Problem and showed that the wear of the wheel-rail rolling contact problem does not increase the risk of failure.
Abstract: (1985). Determination of the Tangential Stresses and the Wear for the Wheel-Rail Rolling Contact Problem. Vehicle System Dynamics: Vol. 14, No. 1-3, pp. 152-156.



Journal ArticleDOI
TL;DR: In this article, the dynamic behavior of the locomotive was analyzed by linear and nonlinear computations and compared numerical results to measurements with respect to stability and random response, using linearized laws of contact mechanics and of spring and damper characteristics.
Abstract: SUMMARY For high speed railway traffic the “ICE” train is being developed in the Federal Republic of Germany. The ICE consists of two Bo'Bo' power cars and up to three coaches in between. The innovative powered bogies with alternatively coupled traction motors were field tested on the dieselelectric locomotive DE 2500 UmAn up to 250 km/h. Extensive measurements of the vehicle's response, the rail inputs and the wheel and rail profiles were documented. Following the field tests we analysed the dynamic behaviour of the locomotive by linear and nonlinear computations and compared numerical results to measurements with respect to stability and random response. Linear analyses use linearized laws of contact mechanics and of spring and damper characteristics. Nonlinear methods of limit cycle calculation and statistical linearization perform the quasilinearization in the course of the numerical process. The agreement between field tests and computer-aided studies was satisfactory and allowed us to complete our d...

Journal ArticleDOI
TL;DR: In this article, the stability of the motions in the horizontal plane of most types of rail vehicles depends to a large extent on the nature of the structure connecting the wheelsets and the number of wheels.
Abstract: SUMMARY The stability of the motions in the horizontal plane of most types of rail vehicles depends to a large extent on the nature of the structure connecting the wheelsets. If the number of wheel...

Journal ArticleDOI
TL;DR: In this article, a theory of backward motion of multi-articulated vehicles was studied under geometrical motion, and verified by experiments, and conditions which design specifications had to satisfy were given from controllability, and control limits from the maximum steering angle.
Abstract: SUMMARY This study deals with the establishment of a theory of backward motion of multi-articulated vehicles and their control. First, a theory of backward motion of multi-articulated vehicles was studied under geometrical motion, and verified by experiments. Then, the conditions which design specifications had to satisfy were given from controllability, and control limits from the maximum steering angle. Using the optimal control theory, the maneuverability of multi-articulated vehicles was discussed, and the difficulty of backward maneuverability with an increase in the number of articulated vehicles was shown. On the basis of these study results, the effectiveness of an auxiliary operation system was suggested.

Journal ArticleDOI
TL;DR: In this paper, the results of a test program performed on a conventional three-piece freight car truck, utilizing the roll dynamics unit (RDU) at the Transportation Test Center (TTC) in Pueblo, Colorado, were compared with predictions from a mathematical model developed specifically for the purpose of predicting the steady state behavior of a vehicle running on rollers.
Abstract: SUMMARY This paper describes the results of a test program performed on a conventional three-piece freight car truck, utilizing the Roll Dynamics Unit (RDU) at the Transportation Test Center (TTC) in Pueblo, Colorado. The purpose of the test program was to determine the steady state behavior, in particular the train resistance or drag, that resulted from axle misalignments and simulated curves. The drag of each axle and the angles of attack with respect to the rollers were measured during the experiment. These results were compared with predictions from a mathematical model that had been developed specifically for the purpose of predicting the steady state behavior of a vehicle running on rollers. The predictions from this “roller model” were also compared with the results from a “curving model”, which is able to predict the steady state behavior of a vehicle running on track.