Showing papers in "Vehicle System Dynamics in 1972"
TL;DR: In this article, the theory of liquid motion with a free surface is presented for containers of various geometries, and forces and moments of the liquid exerted upon the vehicle are presented and a simple mechanical model is presented.
Abstract: SUMMARY The unrestrained free surface of a liquid has an alarming propensity to undergo large excursions for even very small motions of the container. This fact may endanger the stability, as well as the riding and maneuvering quality of the vehicle considerably. It is particularly true for fuel- or cargo tanks of automotive vehicles, railroad tank cars, for fuel tanks of large ships and tankers, for which violent sea conditions at times result in fairly large amplitudes of pitching, heaving and rolling, as well as for airplanes and spacevehicles flying through atmospheric disturbances. The response of liquids contained in cargo- or fuel tanks is therefore of quite some concern, especially in those cases where the sloshing liquid masses occupy a large amount of the total mass of the vehicle. For this reason the theory of liquid motion with a free surface is presented for containers of various geometries. Forces and moments of the liquid exerted upon the vehicle are presented and a simple mechanical model ...
37 citations
TL;DR: In this paper, a theory was developed for the analysis and prediction of the dynamic frequency response of lateral force and moment acting upon a pneumatic tire when the wheel is moved laterally and swivelled about the vertical axis.
Abstract: SUMMARY A theory has been developed for the analysis and prediction of the dynamic frequency response of lateral force and moment acting upon a pneumatic tire when the wheel is moved laterally and swivelled about the vertical axis. The theory establishes the force and moment response of a tire model which consists of a stretched circular string with mass, elastically supported to the wheel-center-plane. The analysis is confined to small deviations from rectilinear motion such that it is permissible to assume that sliding does not occur in the contact area. In this manner, the equations are kept linear. The theory which gives an exact analysis of the dynamic response of the model adopted shows satisfactory qualitative agreement with experiments. The change in the moment response due to tire inertia reduces the tendency to shimmy at higher frequencies and higher speeds. The lateral force response, however, changes in an unfavorable fashion which, for castered wheels, may result in a decrease of the effectiv...
36 citations
TL;DR: In this article, the changes of vibration comfort and stability of vehicles as effected by the value of frictional force generated in laminated springs are discussed and the probability of departure of the tyres from the ground is described.
Abstract: SUMMARY The changes of vibration comfort and stability of vehicles as effected by the value of frictional force generated in laminated springs are discussed and the probability of departure of the tyres from the ground is described. A partly automated analogue computer simulation being equivalent to a great number of highway experiments was applied in the study. The computer model was excited by several stochastic roadprofile - analogue signals generated by filters from the wide-band random signal of a digital noise generator.
14 citations
TL;DR: In this article, the effects of two proposed fifth wheel design changes on the jackknifing behavior of a vehicle in a turning, braking maneuver are studied, and the results demonstrate that the tendency of the vehicle to jackknife can be reduced with a geometric modification of the fifth wheel.
Abstract: SUMMARY The nonlinear equations of motion are derived for a tractor-semitrailer truck where both the itractor and the semitrailer yaw, pitch, roll, and translate. Special emphasis is placed on the constraints imposed by the fifth wheel on the vehicle motion. In particular, the effects of two proposed fifth wheel design changes on the jackknifing behavior of a vehicle in a turning, braking maneuver are studied. The results demonstrate that the tendency of the vehicle to jackknife can be reduced with a geometric modification of the fifth wheel.
11 citations
TL;DR: In this article, the stability changes considerably at large absolute values of the tangential acceleration and may lead to a considerable further decrease of the maximum possible speed of travel, which lies partly under the boundary due to friction limitations.
Abstract: SUMMARY (Title: On the Stability of Turns of a Motor Vehicle with and without Tangential Acceleration) As can be shown in the treatment of the steady-state turn, the conditions for stability of a possible turning motion give rise to a limitation of the speed of travel which lies partly under the boundary due to friction limitations. In particular, at transient turns (braking or accelerating in a turn) the stability changes considerably at large absolute values of the tangential acceleration and may lead to a considerable further decrease of the maximum possible speed of travel.
3 citations
TL;DR: In this paper, the authors have developed vehicular traffic dynamics for automated vehicle systems using calculus of variations and optimal control theory, and the relationship between the traffic dynamics developed in this paper and traffic dynamics which have been used extensively before for non-automated systems is shown.
Abstract: SUMMARY Automation of vehicular traffic in different forms has been considered by many people. It offers many advantages. Vehicular traffic dynamics for automated vehicle systems are developed here using calculus of variations and optimal control theory. Using such an optimization approach, the relationship of the traffic dynamics developed here and the traffic dynamics which have been used extensively before for non-automated systems is also shown. Such an approach considers multiple objective functions for the system.
2 citations
TL;DR: In this paper, a mathematical model of the trailer is presented, which includes roll, pitch, and vertical motion, and the skid resistance calculated by using this model gives an excellent check on the standard ASTM skid number formula.
Abstract: SUMMARY The towed trailer method for skid resistance measurements is a practical one for characterizing the friction characteristics of highway pavements, and has been standardized by the ASTM 11). Numerous papers have been published about the improvement of equipment and field-testing techniques but little has been done toward a theoretical explanation. This paper presents a mathematical model of the trailer which includes roll, pitch, and vertical motion. The skid resistance calculated by using this model gives an excellent check on the standard ASTM skid number formula. The response time and damping effect after locking one test wheel can be clearly seen in this model. Possible effects of the dimensions of trailer, stiffness of suspension system, tire pressure, etc. to skid resistance can also be examined.
1 citations
1 citations
TL;DR: The influence of vehicle handling on the possible avoidance of accident situations is discussed in this paper, where it is shown that accident reconstruction at present does not provide the necessary information to relate the cause of accidents to the lack of road worthiness of vehicles.
Abstract: SUMMARY The influence of vehicle handling on the possible avoidance of accident situations is discussed. lit is shown that accident reconstruction at present does not provide the necessary information to relate the cause of accidents to the lack of road worthiness of vehicles. It follows that the vehicle behavior in proximity of its performance limit must be determined in order to infer its accident avoidance potential. The paper presents a review of the state-of-the-art of vehicle modeling, simulation of vehicle maneuvers and full scale testing. The application of the direct method of the stability theory is suggested as a possible means of obtaining performance limit envelopes which are necessary for establishing standards of the performance of vehicles.
TL;DR: In this article, a primitive levered vehicle, with limited modes of operation, is discussed, and the problems include the development of an adequate lever system, an actuation system, and a control system which regulates the foot placement and the motion pattern of each lever.
Abstract: SUMMARY The primitive levered vehicle, with limited modes of operation, is discussed. It is pointed out that stable modes of operation, which are developed from a knowledge of the requirements of levered locomotion in machines, must be a reality before the successful operation of such a machine is achieved. The problems include the development of an adequate lever system, an actuation system, and a control system which regulates the foot placement and the motion pattern of each lever. If the machine is to be useful it must be capable of maneuvering, of adjustment to terrain irregularities and of recovery from gross motion disturbances. Levered vehicles are classified into automatic and operator monitored machines, the latter being those with complete operator control of all lever motions. The problems include lever design, the foot locus, actuation systems, and lever arrangements. Some design considerations are also considered with respect to two specific types of lever arrangements. A design approach uti...