Showing papers in "Vehicle System Dynamics in 1979"
TL;DR: In this paper, the authors describe the theory of frictional rolling contact as far as it is significant for the wheel-rail system and give a present day account of the simplified theory and the exact linear and non-linear theory.
Abstract: SUMMARY This paper describes the theory of frictional rolling contact as far as it is significant for the wheel-rail system. It is divided into two parts. The first part, mostly non-mathematical, contains a historical survey from the times of Carter and Fromm (1926) to the present day, in which all aspects of rolling contact theory are discussed. Included are a quantitative account of the results of Hertz theory (Section 3), and a table of the creepage and spin coefficients. The second part gives a present day account of the simplified theory (Section 4), and of the exact linear and non-linear theory (Section 5). The paper closes with some recommendations for future research, of which the most pressing is a thorough investigation of the accuracy of simplified theory.
228 citations
TL;DR: In this paper, four basic tire models suitable for dynamic vehicle simulation are formulated and compared through a six-degree-of-freedom nonlinear simulation of a cargo truck crossing rough ground.
Abstract: SUMMARY Four basic tire models suitable for dynamic vehicle simulation are formulated. The models are compared through a six-degree-of-freedom nonlinear simulation of a cargo truck crossing rough ground. Guidelines are developed for the selection of an optimum tire model for a given dynamic vehicle simulation.
123 citations
TL;DR: In this article, a 5-DOF plane vehicle model is studied and a computer program has been developed for optimization of two or more of the system parameters to make a vehicle response (or a weighted sum of responses) a minimum.
Abstract: SUMMARY A 5-DOF plane vehicle model is studied. A randomly profiled road is assumed to impart normally distributed stationary vertical random displacements to the front and rear wheels. Several vehicle performance criteria based on response mean square spectral densities are discussed. It is emphasized that these performance criteria contain more information than do the simple response standard deviations. A computer program has been developed for optimization of two or more of the system parameters to make a vehicle response (or a weighted sum of responses) a minimum. Constraints on parameters and responses can be introduced. Ride comfort, road holding, energy absorption, fatigue failure and first-passage failure are studied. Numerical examples are given.
23 citations
TL;DR: A review of the available literature describing the methods of modelling the vibrational response of articulated vehicles to the road inputs at the tire contact points is presented in this article, where the authors discuss the mathematical techniques that have been put forward for obtaining road input characteristics, for modelling the vehicles in a range of degrees of freedom, and for performing the analysis necessary to obtain the vibration response.
Abstract: SUMMARY This paper presents a review of the available literature describing the methods of modelling the vibrational response of articulated vehicles to the road inputs at the tire contact points. It states and discusses the mathematical techniques that have been put forward for obtaining road input characteristics, for modelling the vehicles in a range of degrees of freedom, and for performing the analysis necessary to obtain the vibrational response. Finally the indices that have been proposed for ride comfort and ride safety are given and the manner in which various researchers relate these to the vibrational characteristics of the vehicles is described.
23 citations
17 citations
15 citations
TL;DR: In this article, the wheel profile of a rail vehicle is optimized to improve the performance of the rail vehicle by optimizing the wheel profiles to improve its dynamic performance, and the wheel diameter is increased.
Abstract: (1979). Optimizing the Wheel Profile to Improve Rail Vehicle Dynamic Performance. Vehicle System Dynamics: Vol. 8, No. 2-3, pp. 116-122.
14 citations
TL;DR: In this article, a semi-trailer vehicle with an automatic steering system is described, and the authors discuss the stability and followability of the vehicle with the assistance of the steering system.
Abstract: (1979). On the Stability and Followability of the Semi-Trailer Vehicle with an Automatic Steering System. Vehicle System Dynamics: Vol. 8, No. 2-3, pp. 206-211.
10 citations
TL;DR: In this paper, the spatial kinematic constraints of arbitrary wheel and rail profiles are analyzed by solving a system of nonlinear equations for longitudinal and lateral creepages and spin, and the external loads exerted on the wheelset are expanded.
Abstract: The spatial kinematic constraints of arbitrary wheel and rail profiles are analysed by solving a system of nonlinear equations. The nonlinear equations for longitudinal and lateral creepages and spin are derived. The nonlinear equations of motion of a restrained wheelset on straight and curved track are set up and reduced. The external loads exerted on the wheelset are expanded. Nonlinear creep loads are evaluated, using different methods of saturation.
7 citations
TL;DR: In this paper, the authors used a Galerkin method to compute the limit cycle of a wheeled vehicle using a single-axis accelerometer and gyroscope, and showed that the result was correct.
Abstract: (1979). Computation of Limit Cycles of a Wheelset Using a Galerkin Method. Vehicle System Dynamics: Vol. 8, No. 2-3, pp. 168-171.
7 citations
TL;DR: In this paper, it is shown that for railway vehicles with coned wheels mounted on solid axles there is a conflict between stability of lateral deviations from the motion along the track and ability to steer round curves.
Abstract: SUMMARY For railway vehicles having coned wheels mounted on solid axles there is, in general, a conflict between stability of lateral deviations from the motion along the track and ability to steer round curves. However, certain configurations of three-axle vehicle can satisfy the requirement of perfect curving and for certain values of the system parameters are dynamically stable. In the case where three wheelsets have semi-rigid articulation and either the distribution of conicity amongst the wheelsets or the position of the articulation joint are varied, it is shown that both flutter and divergence instabilities can occur at low speeds, in contrast to the more common dynamic instabilities of other forms of railway vehicle which are driven by the inertia forces.
TL;DR: In this article, an analytical expression for the low speed transfer function of a railway vehicle is derived, from which conclusions can be drawn regarding the effect of the elastic connections between wheelsets on dynamic behaviour.
Abstract: SUMMARY An important function of a bogie of a railway vehicle (or of the running gear of guided vehicles in general) is to guide or steer the vehicle along the course of the track while isolating the vehicle and its payload as well as possible from unintended but inevitable imperfections in the position of the track. Against this background, an analytical expression is derived for the low speed transfer function of a bogie, from which conclusions can be drawn regarding the effect of the elastic connections between wheelsets on dynamic behaviour. At higher speeds inertia effects of the unsprung masses have a negative effect on dynamic behaviour, the magnitude of this effect being different for different types of elastic connections. This is also reflected in the critical speed and the interaction between body and bogie. With respect to the wear of wheels and rails on curved track, the range of radii of curves which can be traversed without flange contact and, for smaller radii, the rate of increase of flan...
TL;DR: In this paper, Coupling and order-reduction of combined linear state-space and multi body systems with application to the Dynamics of a Wheel-Rail Vehicle is discussed. But this work is limited to the case of a wheel-rail vehicle.
Abstract: (1979). Coupling and Order-Reduction of Combined Linear State-Space and Multi body Systems with Application to the Dynamics of a Wheel-Rail Vehicle. Vehicle System Dynamics: Vol. 8, No. 2-3, pp. 184-190.
TL;DR: A model of driver behavior is described which is based on a current theory of neurophysiological processes occurring in the cerebellum and learns to control the vehicle through experience, provides discontinuous ramp steer inputs to the vehicle, accepts discontinuous input data, and is applicable to all control situations.
Abstract: SUMMARY A model of driver behavior is described which is based on a current theory of neurophysiological processes occurring in the cerebellum. The model learns to control the vehicle through experience, provides discontinuous ramp steer inputs to the vehicle, accepts discontinuous input data, and is applicable to all control situations. The model is implemented on a simple simulation model of a car and learning is accomplished by the use of an explicit driver model which drives the vehicle along a specified trajectory.
TL;DR: In this article, the authors provide a conceptual framework for assessing the results, by drawing on analytical and experimental work concerned with manual control in closed-loop tracking systems, and show that a fixed-control driver strategy is required where precise path control is necessary.
Abstract: SUMMARY Compared with the fixed-control case, relatively few studies of the effects on handling quality of the nature of the free-control response of an automobile to steering torque inputs have been reported. Prior to reviewing these studies, an attempt is made in this paper to provide a conceptual framework for assessing the results, by drawing on analytical and experimental work concerned with manual control in closed-loop tracking systems. Application of these ideas to the automobile shows that a fixed-control driver strategy is required where precise path control is necessary. Less demanding situations would allow a free-control driving mode. Steering task performance is found to be relatively insensitive to free-control vehicle responses. However, drivers exhibit clear preferences for certain ranges of steering torque gradient, and for rapid responses of steering wheel angle to torque inputs. Vehicle handling variables interact strongly in their effect on driver opinion. For example, the optimum ste...
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