Lubricated Friction of Rubber. II. Interaction of Rubber and Sliding Surfaces

1968 ◽  
Vol 41 (4) ◽  
pp. 843-853
Author(s):  
E. P. Percarpio ◽  
E. M. Bevilacqua
Keyword(s):  
Vehicle Control ◽  
Skid Resistance ◽  
Force Coefficient ◽  
Test Vehicle ◽  
Test Conditions ◽  
Actual Use ◽  
Patterned Tire ◽  
Rational Program ◽  
Accident Statistics ◽  
Side Force Coefficient

Abstract Skid resistance of tires on wet pavements in an important component of tire safety; it is important to evaluate it precisely under conditions which are pertinent to actual use. The closest approximations to practical conditions are provided by measures of side force coefficient or by locked wheel sliding, both of which are related to problems of vehicle control. However, both of these require that a test vehicle be provided with four identical tires, that a surface large enough to test on be available, and that all test conditions including the nature of the surface be reproducible. For any rational program of research, costs of comparing materials of tire and of road would mount astronomically unless a controlled laboratory test were available which is well correlated with field experience, so that many variables can be studied conveniently in the laboratory. Such a test is available in the applications of the Portable Skid Resistance Tester. Results with this apparatus have been shown to correlate well with those from tests of vehicles on roads over a range of road properties, correlations apparently being with properties of a patterned tire. The results have been further shown to be well correlated with accident statistics. This report will show that correlations with tests on vehicles are valid over a wide variation in rubber properties as well.

The Permanence Properties of Flexible Urethan Foams

1964 ◽  
Vol 37 (1) ◽  
pp. 38-75 ◽  
Author(s):  
Samuel Steingiser ◽  
W. C. Darr ◽  
J. H. Saunders
Keyword(s):  
Aging Process ◽  
Accelerated Testing ◽  
Time Axis ◽  
Considerable Time ◽  
Experimental Systems ◽  
Test Conditions ◽  
Actual Use ◽  
The Common ◽  
Permanence Properties ◽  
End Use

Abstract The acceptance of urethan foam as a commercial product has hinged to an important extent on its permanence as a foam under all conditions of actual end use. Customer experience with commercial flexible urethan foams has confirmed the satisfactory service life of these materials. However, in the development of this industry, it was necessary to be able to predict the performance of experimental systems which later were to become fully commercial. Most often, this prediction had to be made very early, long before the materials were allowed to be put into end service. The common way to do this is by accelerated testing, wherein the time axis is condensed by stepping up the aging process well beyond any normal conditions. Considerable time and expense are saved in this kind of test; however, there is always the question that such an accelerated step-up of test conditions is not representative of actual use, and/or causes reactions in the sample which do not occur in normal use. It is important that these questionable features be reconciled before the intercomparability of accelerated and shelf-life testing is accepted.

Numerical Simulation Analysis of Car Overtaking on SST Turbulence Model

2014 ◽  
Vol 628 ◽  
pp. 270-274
Author(s):  
Yi Bin He ◽  
Qi Zhi Shen
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiment ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Force Coefficient ◽  
Side Force ◽  
Sst Turbulence Model ◽  
Side Force Coefficient

Thebased SST (shear strain transport) turbulence model combines the advantages of and turbulence models and performs well in numerical experiment. In the paper, the SST turbulence model is applied to model vehicle overtaking process with numerical simulation technology. The change graph of drag coefficient and side force coefficient are gained. Analysis of the phenomena is presented at the end.

scholarly journals Influence of Rectangular Strips’ Size on Aerodynamic Performance of a High-Speed Train Subjected to Crosswind

2021 ◽  
Author(s):  
Mengying Wang ◽  
Zhenxu Sun ◽  
Shengjun Ju ◽  
Guowei Yang
Keyword(s):  
High Speed ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Orthogonal Experimental Design ◽  
High Speed Train ◽  
Force Coefficient ◽  
Roll Moment ◽  
Side Force ◽  
Moment Coefficient ◽  
Side Force Coefficient

Abstract Conventional studies usually assume that the train surface is smooth, so as to simplify the numerical calculation. In fact, the surface of the train is irregular, which will change the flow characteristics in the boundary layer and further affect the aerodynamic performance of a train. In this work, roughness is applied to the roof of a 1:25 scaled train model in the form of longitudinal strips. Firstly, the improved delayed detached eddy simulation (IDDES) method is adopted to simulate the aerodynamic performance of the train model with both smooth and rough surface, which are subjected to crosswind. Results show that the side force coefficient and the roll moment coefficient subjected to rough model decreased by 3.71% and 10.56% compared with the smooth model. Then, the width, height and length of the strips are selected as variables to design different numerical simulation schemes based on the orthogonal experimental design method. Through variance analysis, it can be found that four design parameters have no significant effect on the side force coefficient. Meanwhile, for the roll moment coefficient, the length of the strips in the straight region of the train has a significant effect and the width of the strips has a highly significant effect on it. These conclusions can provide a theoretical basis to improve the aerodynamic performance of the high-speed train subjected to crosswind.

EFFECT OF SILICA LOADING AND COUPLING AGENT ON WEAR AND FATIGUE PROPERTIES OF A TREAD COMPOUND

2018 ◽  
Vol 92 (2) ◽  
pp. 326-349 ◽  
Author(s):  
Harini Sridharan ◽  
Abhilash Guha ◽  
Sanjay Bhattacharyya ◽  
Anil K. Bhowmick ◽  
R. Mukhopadhyay
Keyword(s):  
Crack Growth ◽  
Coupling Agent ◽  
Abrasion Resistance ◽  
Rubber Matrix ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Force Coefficient ◽  
Side Force ◽  
Tan Δ ◽  
Side Force Coefficient

ABSTRACT The effects of highly dispersible silica and the nature of silane in a tire tread cap compound were studied with particular reference to dynamic mechanical properties, abrasion resistance, side force coefficient, and fatigue crack growth (FCG) properties. The rubber matrix chosen was a blend of solution grade styrene butadiene rubber and polybutadiene rubber. Six different loadings of silica were used. Bistriethoxysilylpropyltetrasulfide (S) was taken as the coupling agent. In addition, the potential of two new generation silanes, 3-octanoylthio-1-propyltriethoxysilane (N) and 3-mercaptopropyl-di [tridecan-1-oxy-13-penta ethyleneoxideethoxysilane] (V) was also explored at 70 phr silica loading. Optimum properties were obtained at 50 phr loading of silica (S50). The tensile moduli for the compounds increased sharply with silica loading. Higher values of tan δ, indicating higher hysteresis, were obtained in compounds containing higher filler dosage. However, enhanced abrasion resistance and side force coefficient were observed at higher loadings of silica due to an increased reinforcement phenomenon. The crack growth exponent (β) was lowest for S50. Among the silanes tested, V showed a 22% drop in tan δ at 70 °C, 11% drop in abrasion loss, and an increase in FCG rate. N exhibited a lower FCG rate as compared with the silane S.

Friction on Wet Surfaces of Tire-Tread-Type Vulcanizates

1964 ◽  
Vol 37 (4) ◽  
pp. 878-893 ◽  
Author(s):  
Barbara E. Sabey ◽  
G. N. Lupton
Keyword(s):  
Skid Resistance ◽  
Correct Interpretation ◽  
Temperature Range ◽  
The Road ◽  
Test Conditions ◽  
Maximum Value ◽  
Rubber Compounds ◽  
Materials Used ◽  
Increasing Temperature ◽  
Styrene Butadiene

Abstract A laboratory investigation has been made into the variation with temperature of the hardness and resilience of a wide variety of rubber compounds of the tire tread type. The effect of hardness and resilience on the fractional properties of the compounds under wet conditions has also been studied. In the first series of tests the resilience and hardness of 25 compounds were measured over a temperature range 0° to 80° C. All were vulcanized tire tread type compounds, and the basic materials used comprised 14 natural rubbers, 7 styrene/butadiene (SBR) rubbers, 2 butyl, 1 polybutadiene, and 1 ethylene/propylene. The tests showed a marked increase in resilience with increasing temperature for all compounds except the polybutadiene; the hardness of all compounds changed very little with temperature, only a slight decrease being observed over the whole temperature rise. Nine compounds of representative resilience and hardness were selected for a second series of tests in which friction was measured over a temperature range 1° to 40° C on seven surfaces representing roads of different textures. For eight of the compounds, friction values decreased with increase in temperature; for the other compound the friction increased to a maximum value at 30° C. These changes in friction cannot be explained by changes in hardness of the compounds, but they are in accordance with resilience changes, taking into account the different test conditions obtaining in the friction and resilience tests. The friction tests also showed that with the portable skid-resistance tester used to measure friction the sharpness of the projections in the road surface is more important than their size in determining the friction values under wet conditions, even when rubber compounds of low resilience are used. The implications of the findings and their application to the study of friction between tire and road are discussed. In particular, they have a bearing on the correct interpretation of resilience measurements of tire tread materials in relation to friction values under wet conditions.

Influence of ATF Dynamics and Controls on Jet Engine Performance

2007 ◽  
Author(s):  
J. Bierkamp ◽  
S. Ko¨cke ◽  
S. Staudacher ◽  
Roland Fiola
Keyword(s):  
Dynamic Behaviour ◽  
Engine Performance ◽  
Vehicle Control ◽  
Medium Size ◽  
Aircraft Engines ◽  
Ambient Conditions ◽  
Test Vehicle ◽  
Turbofan Engine ◽  
Jet Engine ◽  
Performance Capability

Current and future requirements in the verification and validation of the performance of modern aircraft engines lead to continuously increasing requirements on the transient performance capability and flexibility of Altitude Test Facilities (ATF). These requirements have been investigated via numerical simulations of a medium size turbofan and a modern core engine. The simulations using the turbofan engine, document a significant influence of the boundary conditions supplied by the ATF on the dynamic behaviour of bypass engines. Variations in engine acceleration times and compressor stability have been identified. This leads to stability requirements for entry conditions at Fan face and ambient conditions at the nozzle exit. The especially demanding operability tests with core engines, challenge ATF systems due to the additional need to simulate the behaviour of low pressure components. It turns out that the interaction between test vehicle and ATF, in both cases, requires special attention and great care in the design of the ATF control system. Therefore a closed loop simulation model including, ATF, ATF controls system, test vehicle and vehicle control has been developed in order to assess and evaluate the integrated ATF - test vehicle behaviour in advance of the test. The integration of the test vehicle and vehicle control into the modular simulation tool is described. The standardized interface allows integrating different vehicle types without a lot of effort. The application of the simulation in a core engine ATF test is described as an example. The observed vehicle - ATF interaction with and without control is discussed.

Development and Performance of the Portable Skid Resistance Tester

1965 ◽  
Vol 38 (4) ◽  
pp. 840-862 ◽  
Author(s):  
C. G. Giles ◽  
B. E. Sabey ◽  
K. H. F. Cardew
Keyword(s):  
Field Trials ◽  
Test Surface ◽  
Skid Resistance ◽  
Textured Surfaces ◽  
Basic Principles ◽  
The Road ◽  
Factors Influencing ◽  
On The Road ◽  
And Performance ◽  
Patterned Tire

Abstract The portable skid-resistance tester can carry out a wide variety of measurements on the road and in the laboratory. This paper outlines the basic principles underlying the design of the tester and describes the laboratory and field trials conducted during the development of the instrument. The factors influencing its performance are emphasized. In its performance, the instrument behaves as a patterned tire skidding at 30 mph. It is particularly well suited for testing rough-textured surfaces, and readings are independent of gradient, camber, or crossfall on the test surface.

Side Force Coefficient Evaluation of a Commercial Bus with Vortex Generators

2019 ◽  
Author(s):  
Daniel Garcia Ribeiro ◽  
Juan Flores Mezarina ◽  
Pedro David Bravo-Mosquera ◽  
Hernán Cerón-Muñoz ◽  
John Jairo Vaca-Rios
Keyword(s):  
Vortex Generators ◽  
Force Coefficient ◽  
Side Force ◽  
Side Force Coefficient
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