Showing papers in "Vehicle System Dynamics in 1982"
TL;DR: An algorithm “Fastsim” for the simplified theory of rolling contact is described which is 15-25 times as fast as the existing programs Simrol (Kalker), and 3 times asfast as Rolcon (Knothe).
Abstract: SUMMARY An algorithm “Fastsim” for the simplified theory of rolling contact is described which is 15-25 times as fast as the existing programs Simrol (Kalker), and 3 times as fast as Rolcon (Knothe). The relative total force computed with Fastsim differs at most 0.2 from that calculated with Simrol, Simcona (Goree & Law), Rolcon, and the “exact” program Duvorol (Kalker). Descriptions and lists of an Algol 60, and HP 67 program version are available upon request: the Fortran IV version is given in the paper.
821 citations
TL;DR: In this paper, a simple vehicle model incorporating passive, active, and semi-active suspensions is presented, and the expected response of a vehicle with an active and/or semiactive suspension, subject to non-ideal feedback information is presented.
Abstract: SUMMARY A simple vehicle model is presented incorporating passive, active, and semi-active suspensions. When the desired feedback variables are ideally available, the system response is well understood and excellent sprung mass isolation results. More often than not, the measured variables must be signal processed in some manner prior to their use in some control algorithm. This paper presents the expected response of a simple vehicle with an active and/or semi-active suspension, subject to non-ideal feedback information.
79 citations
TL;DR: In this paper, a model of a vehicle traversing a roadway is presented, which includes both the heave and pitch motions of the vehicle, and control strategies for the totally active case and vehicle isolation is demonstrated.
Abstract: SUMMARY A model is presented which includes both the heave and pitch motions of a vehicle traversing a roadway. Provision is made for testing totally passive, totally active, and semi-active secondary suspensions. Control strategies are developed for the totally active case and vehicle isolation is demonstrated. These active controllers are then modified to be semi-active, i.e., no power is provided from the controller to the vehicle. The semi-active isolation is shown to be comparable to the totally active system and much superior to the passive suspension.
56 citations
TL;DR: In this paper, a review of theoretical and experimental works relative to the handling performance of commercial vehicle combinations is presented, taking into account the following features: directional performance, roll dynamics, braking performance and combined braking and directional performance.
Abstract: SUMMARY This paper presents a review of theoretical and experimental works relative to the handling performance of commercial vehicle combinations. A commercial vehicle combination (road train) is defined as a tractor unit and an arbitrary number of trailers. The review contains literature corresponding the most widely used types of trains: tractor-semitrailer, truck-trailer and tractor-semitrailer-semitrailer (doubles). The vehicle dynamic performance has been investigated taking into consideration the following features: directional performance, roll dynamics, braking performance and combined braking and directional performance. With the aim of evaluating the present state of research activities in the field of lateral dynamics of articulated commercial vehicles, the author has compiled some 250 references.
42 citations
TL;DR: In this paper, a general theory is developed for the two-axle vehicle in which there is a lack of symmetry, fore-and-aft, both of the interwheelset structure and of the equivalent conicities of the wheelsets.
Abstract: SUMMARY For railway vehicles having coned wheels mounted on solid axles, there is a conflict between the stability of lateral deviations from the motion along the track and the ability to steer round curves. A general theory is developed for the two-axle vehicle in which there is a lack of symmetry, fore-and-aft, both of the interwheelset structure and of the equivalent conicities of the wheelsets. It is shown that whilst parameters can be selected which provide static and dynamic stability and perfect steering for both directions of motion, there is a lightly damped mode of oscillation for any practical configuration and the significance of this is discussed.
20 citations
TL;DR: In this article, the lateral compliance of the tires was included via a simplified version of the stretched-string model, and a comparison between calculations and test results indicated that lateral compliance was an important influence on the transient response of these vehicles.
Abstract: SUMMARY This paper presents a study of the directional dynamics of large industrial tractors. These vehicles have special properties which make their dynamics interesting, including soft rear tires, large yaw moments of inertia and low or negative understeer gradients. A linear yaw plane model was used for the analysis. The lateral compliance of the tires was included via a simplified version of the stretched-string model. Measurements were performed in support of the modeling effort, including inertial parameters, understeer gradient and transient response. A comparison between calculations and test results indicated that lateral compliance was an important influence on the transient response of these vehicles.
19 citations
TL;DR: In this article, a quasistatic theory of wheelset forces for an important practical case of the wheelset rolling when one of wheels touches the rail in two contact zones is presented.
Abstract: SUMMARY This paper describes a quasistatic theory of wheelset forces for an important practical case of the wheelset rolling when one of the wheels touches the rail in two contact zones. One of these zones lies on the tread and the other on the wheel flange. For such contact the specific problem of finding the distribution of forces between the tread and flange arises. The simultaneous frictional rolling contact problems for both contact zones have been described with Kalker×apos;s non-linear theory and wheelset equilibrium equations. The numerical results presented are for an individual wheelset on straight track, the distribution of forces being described for a wide range of loading conditions. The influence of steering on the distribution of forces has also been presented. This theory can be easily extended for quasistatic curving of railway vehicles and may assist wear studies for vehicles with worn wheels.
16 citations
TL;DR: In this paper, the effect of ground slope, axle load, ground speed, tyres and ground surface on yaw rate response to steer input was evaluated for agricultural tractors with steer input.
Abstract: SUMMARY Agricultural tractors are relatively slow moving vehicles but a good steer response under all working conditions is generally required. This paper evaluates the effect of ground slope, axle load, ground speed, tyres and ground surface on yaw rate response to steer input.
12 citations
TL;DR: In this paper, the basic relation for the specification of undesirable vibrations of a vehicle caused by random unevenness of the pavement is derived, and proposals for the classification of random pavement unevenness, based on the categorization of global dynamic properties of the relevant vehicles, may be derived.
Abstract: In this paper the basic relation for the specification of undesirable vibrations of a vehicle caused by random unevenness of the pavement is derived. This relation has a global character, and is very simply to be physically interpreted. All its parameters may be easily identified from suitably organized experiments. Thus, its use in current operating conditions is possible without additional requirements concerning staff qualification. From this basic relation, proposals for the classification of random pavement unevenness, based on the categorization of global dynamic properties of the relevant vehicles, may be derived. Combining the physical point of view with some economic considerations, the minimization of undesirable vibrations may be attempted when improving, in a balanced proportion, both the quality of vehicles in terms of their dynamic transfer functions and the level of the pavement surface imperfections.
10 citations
TL;DR: In this paper, a railway wagon carrying liquid cargo on a railway track is investigated and the dynamic behavior of the sloshing liquid-mass is considered through its mechanical model, and two vehicle-liquid system models are considered to determine the dynamic response of the system moving with constant acceleration.
Abstract: The dynamic response of a railway wagon carrying liquid cargo on a railway track is investigated. The dynamic behaviour of the sloshing liquid-mass is considered through its mechanical model. Two vehicle-liquid system models are considered to determine the dynamic response of the system moving with constant acceleration. The first model (S1) is assumed to respond under the heave mode and is subjected to single base point excitation. The second model (S2) responds under both the heave and the pitch degrees of freedom and is subjected to two-point base excitation. Two vehicle models, N1 and N2, with an equivalent solidified mass of the liquid and corresponding to models S1 and S2 are also considered to compare the vehicle response with and without the effect of the liquid sloshing. The equations of motion for the vehicle-liquid cargo system models (S1 and S2) are nonlinear and coupled. The equations of motion for the vehicle carrying equivalent solid cargo (models N1 and N2) are linear. The track unevenness is assumed to be a homogeneous random process. The vehicle is assumed to move over the track with constant acceleration and is therefore subjected to nonstationary base exitation. The equations of motion are solved numerically using the simulated track unevenness. It is found that the sloshing of liquid reduces the vehicle response whenever the natural frequencies of the vehicle and the sloshing liquid are far apart. The opposite is found to be true whenever the two natural frequencies are close to each other. Further it is found that the model S1 overestimates the heave response and underestimates the free surface response as compared to the model S2. It is concluded that the model S1 is inadequate to take into account the effect of the sloshing of liquid on the vehicle dynamics.
9 citations
TL;DR: In this paper, the authors presented a linear differential equation for the radial and circumferential displacement of all points on the ring, and the distribution of pressure over the region of contact.
Abstract: SUMMARY The belted radial passenger car tire is idealized as a prestressed circular ring connected to a hub through a distribution of linear springs modeling the sidewall. A second distribution of such springs exterior to the ring represents the tread rubber. The tire is supposed to be at rest, loaded at its hub, and pressed onto a flat, rigid, frictiontess roadway. In this situation the linear differential equations of the model are solved using a singular perturbation technique. Given the load at the hub, the solutions furnish the length of tread in contact with the road, the radial and circumferential displacement of all points on the ring, and the distribution of pressure over the region of contact.
TL;DR: In this paper, the dominant vertical motions of a simple vehicle traveling on a flexible periodic guideway are investigated, and a state equation with periodic coefficients and periodically jumping states is presented.
Abstract: SUMMARY The dominant vertical motions of a simple vehicle traveling on a flexible periodic guideway is investigated. The mathematical model leads to a state equation with periodic coefficients and periodically jumping states. The aim of the paper is the dynamic analysis of the vehicle-guideway system with respect to stability, guideway deflections and vehicle accelerations. As alternative to the common simulation technique, the analytical solution based on Floquet theory is applied. Both methods are implemented in a computer program and used to perform a detailed parameter study which shows the dependence of the dynamical system behavior on the nondimensional system parameters.
TL;DR: In this article, a theory has been developed for the prediction of necessary conditions for selfexciting vibrations of a tire, which is based on the assumption that the tire has the ability to transmit energy from external environment to vehicle.
Abstract: SUMMARY In this paper a mechanical work of external forces and torques, acting on the tire has been considered. A theory has been developed for the prediction of necessary conditions for selfexciting vibrations. The theory establishes, that the mechanical work of external forces and torques must be positive, or, what is equivalent, that the tire has to transmit energy from external environment to vehicle. The work of forces and torques has been considered as a convolution of functions, which next has been submitted to Laplace transformation. The condition of selfexcitation of vibrations, obtained from above in the frequency domain, establishes, that the imaginary part of all eigenvalues of frequency response matrix must be negative. As an example, the ranges of selfexcited vibrations of the tire have been calculated. The tire has been treated as a stretched circular string. Four different models have been considered. Three of them have been massles (kinematic), namely Pacejka's model, Von Schlippe's model...
TL;DR: In this article, the steady state turning of single track vehicles on a horizontal, even road is investigated, supposing the air to be at rest, taking into account wind drag and gyroscopic effects generated by wheels and other vehicle components.
Abstract: SUMMARY Detailed Investigations of the Steady State Turning of Single Track Vehicles In the paper the steady state turning of single track vehicles on a horizontal, even road is investigated, supposing the air to be at rest. The vehicle model used has six degrees of freedom: rolling, yawing, pitching and bouncing of the vehicle, rotation of the front wheel system (steering) relatively to the main frame and distortion of the rear wheel system due to limited stiffness of its linkage, and also takes into account wind drag and gyroscopic effects generated by wheels and other vehicle components. A special importance is given to the geometry of the vehicle The results show a comparison of two types of motorcycles with different geometries and tires. To characterize the vehicle behaviour the roll, side slip and steering angle as functions of the normal acceleration are used. A more detailed study in respect to the steering torque is added.
TL;DR: In this paper, a mathematical model for the representation of longitudinal oscillations which can occur in car/trailer systems in braking, when the trailer brakes are applied through compression of the towing hitch, is described.
Abstract: SUMMARY A mathematical model for the representation of longitudinal oscillations which can occur in car/trailer systems in braking, when the trailer brakes are applied through compression of the towing hitch, is described. The model is used to show how the trailer braking system parameters affect the steady deceleration performance of the vehicle combination, and the stability, in the linear system sense, of the steady motions. The sensitivity of the stability to other system design parameters is also examined. Digital simulation of the motions occurring in response to a step input of car braking torque is reported, with the results confirming the predictions of the linear stability analysis, and also showing the influence of backlash in the trailer brake actuating mechanism. The system is shown to be capable of self-excitation in a “shunting” mode, in which the car and trailer motions are in antiphase, with the stability/damping property critically dependent on drawbar damping, and only weakly dependent ...
TL;DR: In this article, the authors derived the dimension theorem for linear mappings of a railway vehicle with any arbitrary number of wheelsets, body parts, and connecting elements for the case of a two-axled vehicle.
Abstract: SUMMARY Paper deals with the linear behaviour of a railway vehicle with any arbitrary number of wheelsets, body parts and connecting elements. A vehicle which has both perfect curving properties and asymptotical stability at vanishing speed, has to satisfy a twofold condition, indicated by Wickens in 1978. In the present paper this condition is derived in reliance upon the dimension theorem for linear mappings. How the investigation can be executed in practice, is shown for the case of a two-axled vehicle. At last the behaviour in a transition curve is discussed.
Journal Article•
TL;DR: In this article, the authors describe shopping behaviour and retail trade in the city centre before metro opened and provide a preliminary analysis of the impact on these that metro has already made, and an assessment of the future course and direction of this impact.
Abstract: The opening and operation of the Tyne and Wear Metro system is likely to produce substantial changes in travel behaviour and activity levels within the conurbation. The central area of Newcastle - the focus of the system - may be expected to experience the impact of these changes as much as any other part of the county. This report describes shopping behaviour and retail trade in the city centre before metro opened and provides a preliminary analysis of the impact on these that metro has already made, and an assessment of the future course and direction of this impact. The research is based on a series of observational and questionnaire surveys of pedestrian flows, commercial land use, retail trade levels, and shopping and travel behaviour. Because of the complexity of the subject, conclusions are drawn from a synthesis of the findings of these different data collection exercises rather than from the results of any single one. (A)
TL;DR: In this article, the simulation model which was used was very realistic especially because it was a perfect imitation of the anti-skid control-cycles in connection with the exact description of the mechanics and of the dynamic of pressure of the brake system.
Abstract: SUMMARY Wheel locking is an important reason why instabilities such as jackknifing and trailer swing occur with tractor-semitrailers on wet slippery roads. The theoretical connections were explained in Vehicle System Dynamics 7 (1978) 4, pp. 183-201, on the basis of the results of a computing model. Anti-skid systems (official abbr. in Germany: ABV) promise to solve this problem once and for all. For this reason the examination was extended. That is the topic of this paper The simulation model which was used was very realistic especially because it was a perfect imitation of the anti-skid control-cycles in connection with the exact description of the mechanics and of the dynamic of pressure of the brake system. The vehicle handling during braking in a turn with different anti-skid systems (individual, select-low, diagonal) and their compatibility were shown. The systems differ, sometimes to a great extent, in the way they react.
TL;DR: In this paper, the motion of a train wheelset is investigated using Hopf bifurcation theory, which takes full account of the nonlinear effects of the flange-rail contact forces which are incorporated in the model; the numerical solution is obtained over a wide range of forward speeds by transforming the bifurlcation problem into a regular nonlinear boundary value problem, which is solved by standard methods.
Abstract: SUMMARY The motion of a train wheelset is investigated using Hopf bifurcation theory. The method takes full account of the nonlinear effects of the flange-rail contact forces which are incorporated in the model; The numerical solution is obtained over a wide range of forward speeds by transforming the bifurcation problem into a regular nonlinear boundary value problem, which is solved by standard methods. This solution is shown to be orbitally, asymptotically stable. The algorithm supplies complete information on the lateral and yaw motions and on the period of oscillation, even for very high forward speeds.
Journal Article•
TL;DR: The simulation model which was used was very realistic especially because it was a perfect imitation of the anti-skid control-cycles in connection with the exact description of the mechanics and of the dynamic of pressure of the brake system.
Abstract: Wheel locking is an important reason why instabilities such as jackknifing and trailer swing occur with tractor-semitrailers on wet slippery roads. The theoretical connections were explained in Vehicle System Dynamics 7 (1978) 4, pp. 183-201, on the basis of the results of a computing model. Anti-skid systems (official abbr. in Germany: ABV) promise to solve this problem once and for all. For this reason the examination was extended. That is the topic of this paper. The simulation model which was used was very realistic especially because it was a perfect imitation of the anti-skid control-cycles in connection with the exact description of the mechanics and of the dynamic of pressure of the brake system. The vehicle handling during braking in a turn with different anti-skid systems (individual, select-low, diagonal) and their compatibility were shown. The systems differ, sometimes to a great extent, in the way they react.
TL;DR: Applications of the obtained results in vehicle vibrational analysis when the vehicle is considered as one-input, two-input or multiinput system are shown.
Abstract: Basic relation between input spectral density matrix and output spectral density matrix of a linear stochastically excited dynamic system is indicated. General conclusions regarding the output processes spectral densities, coherences and phase angles in respect to the input processes stochastic properties are drawn. The possibility of the determination of the system's transfer functions when input and output spectral density matrices are known is discussed. Applications of the obtained results in vehicle vibrational analysis when the vehicle is considered as one-input, two-input or multi-input system are shown. (Author/TRRL)