Showing papers in "Vehicle System Dynamics in 1974"
TL;DR: In this paper, the authors used more realistic linear models taking into account the unsprung mass, and the gain in comfort obtained by lowering the natural frequency of the sprung mass is calculated for various two-and three-mass models along with other characteristics such as the dynamic tyre load, spring and damper forces and relative motion of the masses.
Abstract: SUMMARY In a previous paper, [3] the random vibrations of simple linear models of automobile suspension were solved with respect to seat elasticity and human sensitivity to vibrations. The present study uses more realistic linear models taking into account the unsprung mass. Two configurations of masses are investigated: a two-mass system consisting of a sprung mass and an unsprung mass, and a three-mass system having an additional mass which acts as a vibration absorber. The gain in comfort obtained by lowering the natural frequency of the sprung mass is calculated for various two-mass and three-mass models along with other characteristics such as the dynamic tyre load, spring and damper forces and relative motion of the masses.
25 citations
TL;DR: In this article, the sensitivity coefficient and the sensitivity equation are introduced as the most fundamental elements in sensitivity analysis for vehicle dynamics, and the complex sensitivity coefficient is introduced in the generalized form using matrices.
Abstract: The sensitivity coefficient and the sensitivity equation are introduced as the most fundamental elements in sensitivity analysis for vehicle dynamics. Next the complex sensitivity coefficient and the complex sensitivity equation are introduced in the generalized form using matrices. Some examples of application of sensitivity analysis are shown using a simple model of steering system and the test method on the handling performances in the Specification of Experimental Safety Vehicle (ESV) of Japan. /DOT/
10 citations
TL;DR: In this paper, a model consisting of a chain of material points and springs is proposed to investigate the longitudinal motion of a long train on which tractive or braking forces apply, which can be investigated by means of difference equation methods and of Laplace transformations.
Abstract: SUMMARY The dynamical behaviour of the longitudinal motion of a long train on which tractive or braking forces apply, often is investigated by representing the train by a model consisting of a continuous bar in which longitudinal vibrations can occur In the present publication a model consisting of a chain of material points and springs is proposed It can be investigated by means of difference equation methods and of Laplace transformations In certain respects the discrepancies of the results with those obtained for a continuous model, are considerable and it may be concluded that a more complete investigation of the discrete model is necessary
4 citations
TL;DR: In this article, a nonlinear digital computer model was developed on which the theoretical system analysis is based, taking account of the nonunear tire properties and the friction couple of the fifth wheel.
Abstract: SUMMARY In this paper some results of theoretical and experimental investigations on the dynamic directional properties of heavy tractor-semitrailer vehicles are presented. A nonlinear digital computer model was developed on which the theoretical system analysis is based. This model takes account of the nonUnear tire properties and the friction couple of the fifth wheel. A combination of numerical computation methods (Runge-Kutta and Newton-Raphson techniques) is used for the digital computer simulation. Full scale road tests with articulated vehicles of 38 ton total weight were conducted for experimental validation of the used theoretical model. As input signals to the vehicle, predetermined steering wheel angle functions were used. The system output signals corresponding to these input functions were measured and stored. A comparison of the obtained theoretical and experimental results shows a very good qualitative agreement and hence leads to the conclusion that the developed theoretical model can give...
3 citations
TL;DR: In this article, the authors present analytical techniques for evaluating the dynamic riding behavior of a vehicle and apply them to a fairly sophisticated model of a bus, where a three-dimensional structure, elastic frame and non-linear shock-absorbers have been considered.
Abstract: The purpose of this paper is to present analytical techniques for evaluating the dynamic riding behavior of a vehicle. These techniques have been applied to a fairly sophisticated model of a bus, where a three-dimensional structure, elastic frame and non-linear shock-absorbers have been considered.
3 citations
TL;DR: A simple “one-wheel-model” for the vehicle and a suitable performance index for the optimization problem are derived and the results show that the performance nearly matches the predicted value.
Abstract: SUMMARY The problem of minimizing the stopping distance of a vehicle along a given trajectory is considered. A simple “one-wheel-model” for the vehicle and a suitable performance index for the optimization problem are derived. A simplified problem is considered first from which an analytical solution for the optimal trajectory is obtained. The suboptimal open loop control inputs are then approximately computed via a search algorithm. The results show that the performance nearly matches the predicted value.
2 citations
TL;DR: In this article, the controllability of a tractor-semitrailer vehicle during straight-line braking is investigated and the question whether the system is always controllable is answered in the negative for locked up wheels at the tractor front axle.
Abstract: SUMMARY (Title: On Controllability of a Tractor-Semitrailer Truck During Braking) The concept of controllability coming from linear system theory is applied to the motion of a tractor-semitrailer vehicle during straight-line braking. Some states of braking with locked up wheels at different axles are considered. The question whether the system is always controllable must be answered in the negative for locked up wheels at the tractors front axle. In other cases controllability in its mathematical meaning which, however, does not always appear to be fully adequate for practical problems, is possible.
2 citations
TL;DR: In this paper, the important interaction between vehicle and track can be taken into account by the riding quality for a certain vehicle on every particular piece of track, determined by the acceleration transmitted to the payload, weighted according to comfort standards, and the relative displacements between wheel and rail.
Abstract: SUMMARY The so-called critical speed of a linearized railway vehicle is shown to be no useful measure for the stability of the system in practice. The important interaction between vehicle and track can be taken into account by the riding quality for a certain vehicle on every particular piece of track. The riding quality is determined by the accelerations transmitted to the payload, weighted according to comfort standards, and the relative displacements between wheel and rail. From the riding quality demands both for vehicle design and for maintenance of the track can be derived.
2 citations
1 citations
TL;DR: In this article, the authors investigated the dynamic characteristics of a full sized passenger automobile of the 5000-6000 lb weight class relative to Vehicle Handling, Performance and Ride Quality, and the overall geometry of the vehicle was considered as being fixed for all weight modifications.
Abstract: SUMMARY This investigation discusses the dynamic characteristics of a full sized passenger automobile of the 5000-6000 lb weight class relative to Vehicle Handling, Performance and Ride Quality. Weight and moment of inertia parameters are introduced to modify weights and mass moment of inertia judicially and the dynamic behavior is investigated on the basis of the above mentioned criteria. Finally weight reductions at discrete locations along the vehicle length axis are contemplated and the dynamic behavior is determined relative to the above criteria. The overall geometry of the vehicle is considered as being fixed for all weight modifications.
1 citations
TL;DR: In this article, the lower elastic vibrations of a motorcar body are calculated using the displacement method. But it must be pointed out that the model structure has to be constructed considering requirements made upon the results.
Abstract: SUMMARY (Title: Investigations into the vibrations of an automobile body) The numerical treatment of the lower elastic vibrations of a motorcar body is presented. The displacement method has been found to be an effective technique for this calculation. When idealising the structure it is tried to show the lower boundary for the subdivision of the structure, with which satisfying results can be obtained. The presented results show, that the calculation of the vibration characteristics of a car body is possible with relatively simple model structures. But it must be pointed out that the model structure has to be constructed considering requirements made upon the results. For the calculation of the four lower vibration modes the car body is idealised with beam and triangular elements. By this method the stiffness and mass matrices arc derived. The distributed mass is simply condensed to mass points in the nodes of the structure. Together with the stiffness matrix the mass matrix is reduced to a practical siz...