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Wyszukujesz frazę "road adhesion" wg kryterium: Wszystkie pola


Wyświetlanie 1-3 z 3
Tytuł:
Modulation effect of vibration frequency of an unsprung heavy machine under the variable road adhesion conditions
Autorzy:
Chwastek, S.
Powiązania:
https://bibliotekanauki.pl/articles/244951.pdf
Data publikacji:
2013
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
mobile heavy machines
unsprung vehicles
galloping effect
adhesion factor
slipping action
frequency modulation of vibration
Opis:
Mobile heavy machines as unsprung vehicles exhibit low dissipation ability, hence the ride even at low speeds may give rise to intensive vibration. Particularly dangerous situations occur when the road wheels break away from the road surface due to the ’galloping’ effect, being the result of excited vertical and angular vibration of the machine frame in the vertical plane of symmetry. That implies a major restriction on the ride velocity, which negatively impacts on the machine performance. Vibrations thus produced are mostly in the low-frequency range and hence energy dissipation in tyres will reduce the vibration intensity in a minor degree only. The motion of tired wheels will always involve some slipping. While investigating the feasibility of increasing the efficiency of the vibration reduction systems, one ought to take into account the variable adhesion of road wheels due to different dynamic loading acting on the vehicle axles during the ride. Observations of unsprung machines during the ride suggest the occurrence of self-excited vibration. Mobile machines constitute dynamic systems, which can be governed by nonlinear, sometimes non-stationary differential equations of motion. Their stability also depends on intensity of external vibrations. This study investigates the motion of unsprung mobile machines, taking into account the dynamic processes in the driving system under the conditions of the variable adhesion of road wheels. The model of interaction between a tired wheel and the terrain takes into account the relationship between the road wheel adhesion factor and the slipping action. Mathcad supported by Matlab-Simulink and in the frequency domain – simulations in the time domain. The purpose of the simulation procedure was to find the causes of the vibration modulation frequency and determine the conditions triggering the occurrence of self-excited vibrations. Simulations are supported by the analysis of motion stability.
Źródło:
Journal of KONES; 2013, 20, 4; 55-62
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of adhesion characteristics of different tyre types in different weather conditions
Autorzy:
Pokorski, J.
Reński, A.
Sar, H.
Powiązania:
https://bibliotekanauki.pl/articles/246790.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
tyre-to-road adhesion
skid resistance tester
traffic safety
accident reconstruction
Opis:
Tyre-to-road adhesion has a great influence on transmitting forces between wheels and road surface and in the consequence on the safety of automobile motion. It plays significant role in vehicle motion modelling, especially for the needs of traffic accidents reconstruction and the development of active safety systems in automobiles. Simultaneously, the knowledge about tyre-to-road adhesion is limited, especially in case of the differences between anti-slip properties of summer and winter tyres. In the paper, method of the measurement of tyre-to-road adhesion coefficient is presented. The measurement system SRT-4 consists of special dynamometer trailer, towing vehicle and test-measuring equipment. It was designed for the needs of road engineering and further developed in the Institute of Vehicles of Warsaw University of Technology. It enables to obtain adhesion characteristics, i.e. graph of adhesion coefficient as a function of wheel slip ratio. In the article, examples of tyre-toroad adhesion characteristics and velocity characteristics of peak adhesion coefficient for different types of tyres (summer, winter) in different weather conditions are presented. Differences in characteristics courses caused by tyre type and weather conditions are discussed. For instance, in case of winter tyres it was noticed that their peak value of adhesion coefficient was reached for higher values of slip ratio than it was observed for summer tyres.
Źródło:
Journal of KONES; 2012, 19, 3; 363-369
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of vehicle stability on road curves in winter conditions
Autorzy:
Kemzuraite, K.
Pukalskas, S.
Bureika, G.
Powiązania:
https://bibliotekanauki.pl/articles/247233.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
vehicle stability
vehicle dynamics
road curve
road surface adhesion coefficient
lateral acceleration
road traffic safety
Opis:
The paper reveals peculiarities of a vehicle movement/operation on road curves when the road surface is slippery and/or snowy, with asphalt ruts. The survey of scientific works related to the lateral acceleration and movement dynamics of a vehicle is presented. Field experiments with different vehicles were carried out in winter conditions. The acceleration value and stability parameters depending on the speed of a vehicle and adhesion coefficient on road curves are analysed. Dependence of the vehicle lateral acceleration on road curves with various adhesion surfaces are given in graphical charts. Recommendations how to improve road safety by limitation of the speed in winter conditions are formulated. Finally, basic conclusions are given. Handling the vehicle on the road with the compressed snow surface (on the curve of the radius of 120 m) is much more dangerous when the adhesion coefficient of the wheels and the road is low if compared to handling the vehicle along the dry ruts at the same speed. When the vehicle moves along the curve of 120 m radius at a speed of 70 km/h, and the road surface is snowy, the lateral acceleration of 3.1 m/s2 is reached. The paper indicates that lateral acceleration of 3.1 m/s2 can be reached while moving along the snowy road with dry ruts at a speed higher in 27% (90 km/h). For improving the vehicle safety, it is recommended to have road signs on sharp turns/curves (R less than 120 m) to decrease the vehicle speed in 20 km/h.
Źródło:
Journal of KONES; 2011, 18, 4; 191-197
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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