Time Dependances of the Resistance Coefficients of Polymeric Materials

INEOS OPEN ◽  
2020 ◽  
Vol 3 ◽  
Author(s):  
A. V. Matseevich ◽  
◽  
A. A. Askadskii ◽  
Keyword(s):  
Time Dependence ◽  
Physical Mechanism ◽  
Polymeric Materials ◽  
Resistance Coefficient ◽  
Constant Stress ◽  
Time To Rupture ◽  
Structure Sensitive ◽  
Material Durability ◽  
Resistance Coefficients ◽  
Extremal Character

One of the possible approaches to the analysis of a physical mechanism of time dependence for the resistance coefficients of materials is suggested. The material durability at the constant stress is described using the Zhurkov and Gul' equations and the durability at the alternating stress—using the Bailey criterion. The low strains lead to structuring of a material that is reflected in a reduction of the structure-sensitive coefficient in these equations. This affords 20% increase in the durability. The dependence of the resistance coefficient assumes an extremal character; the maximum is observed at the time to rupture lg tr ≈ 2 (s).

Elasticity of Soft Polymers. Constant-Stress Elongation Tests

1952 ◽  
Vol 25 (1) ◽  
pp. 56-70
Author(s):  
C. A. Dahlquist ◽  
J. O. Hendricks ◽  
N. W. Taylor
Keyword(s):  
Time Dependence ◽  
Viscous Flow ◽  
Empirical Equation ◽  
Relaxation Times ◽  
Polymeric Materials ◽  
Constant Stress ◽  
Elastic Behavior ◽  
Total Deformation ◽  
Test Conditions ◽  
Elastic Processes

Abstract The elastic properties of polymeric materials which are too soft to test on conventional stress-strain machines can be obtained by elongation at constant stress. A simple apparatus has been developed for maintaining constant stress during elongation. Data illustrate the time dependence of the elastic behavior of polymeric materials and demonstrate the usefulness of the constant-stress method in the evaluation of this time dependence. The constant-stress method is useful in the evaluation of plasticizers for gum rubbers. Because of the difficulty of separating highly delayed elastic elongation from viscous flow, the method has not been found practical as a tool for measurement of viscosity in the solid state. However, under most test conditions, viscous flow has been a negligible fraction of the total deformation. Several terms for delayed elasticity are required to fit an empirical equation to the elongation-time curves, and it seems probable that these terms are only an approximation of a very large number of delayed elastic processes having different relaxation times.

An Experimental Study of the Viscous Resistance of a 0,564-CB Form

1979 ◽  
Vol 23 (02) ◽  
pp. 140-156
Author(s):  
P. N. Joubert ◽  
P. H. Hoffmann
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Skin Friction ◽  
Resistance Coefficient ◽  
Viscous Resistance ◽  
Local Skin ◽  
Friction Resistance ◽  
Local Skin Friction ◽  
The University ◽  
Resistance Coefficients

Wind tunnel tests were performed to determine the viscous resistance and its components for a 0.564-CB model from the BSRA Trawler Series. It was found that the sum of the pressure and skin friction resistance coefficients agreed well with the viscous resistance coefficient determined from drag balance tests. The range of Reynolds number examined was from 1.15 × 106 to 5.17 × 106. The results for the viscous resistance and its components were fitted using least-squares methods to various equations. The results were also compared with the results of previous tests done at the University of Melbourne on models of Lucy Ash-. ton and a 0.80-CB tanker. It was found that the skin friction and viscous resistance coefficients had curves of quite different position and slope. Local skin friction distribution showed noteworthy differences, especially at the stern, with high values at the keel and low values approaching the waterline.

Study on the Resistance Characteristics of Heat Metering System Based on Electric Valve

2014 ◽  
Vol 492 ◽  
pp. 507-510
Author(s):  
Dong Jun Gong ◽  
Yao Zhang ◽  
Xing Ru Li ◽  
Li De Fang ◽  
Zi Hui Wei ◽  
...  
Keyword(s):  
Pressure Difference ◽  
Theoretical Calculations ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Experiment System ◽  
Average Value ◽  
Parallel Pipeline ◽  
Heat Metering ◽  
The Relationship ◽  
Resistance Coefficients

Through theoretical calculations and derivation, the paper obtained the relationship between resistance coefficient and pressure difference, as well as flow rate. For the series pipeline, the flow in the series pipeline is the same, as a result, all the resistance in the series pipeline is the total resistance. For the parallel pipeline, the pressure difference is same, and the all the flow in parallel pipeline is the total flow. According to the real example, the paper identified the inlet pressure difference of the indoor system, the most unfavorable ring and the ratio frictional resistance. Based on the room heat load calculation, the paper determined the most unfavorable loop diameter of each pipe section. By calculating the resistance coefficients of the electric valve at opening, the resistance coefficients of the electric valve at closing were obtained. In the experiment system, the resistance coefficient average value when the electric valve is off was 101831.65, which is basically in line with the calculable value 10719.6, indicating that the existing parameters are much more reasonable.

scholarly journals Real Values of Local Resistance Coefficients during Water Flow through Welded Polypropylene T-Junctions

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 895
Author(s):  
Marek Kalenik ◽  
Marek Chalecki ◽  
Piotr Wichowski
Keyword(s):  
Water Flow ◽  
Resistance Coefficient ◽  
Water Supply Systems ◽  
Internal Diameter ◽  
Local Resistance ◽  
Water Flow Velocity ◽  
Local Resistance Coefficient ◽  
Flow Through ◽  
Supply Systems ◽  
Resistance Coefficients

The paper presents results of investigation of the local resistance coefficient ζ in welded polypropylene T-junctions with the internal diameter 13.2 mm. The investigations were performed on an independently constructed test rig. The scope of investigations encompassed the T-junctions, which were (1) properly warmed up and properly pressed, (2) poorly warmed up and poorly pressed, or (3) excessively warmed up and excessively pressed. The local resistance coefficients ζ determined by measurements according to the standard PN-EN 1267:2012(Designation of the Polish Standard) were compared to those determined with use of the nomograms recommended for designing water supply systems and installations. Real values of the coefficients ζ, obtained in measurements were significantly higher than those read from the nomograms. The local resistance coefficients ζ in welded polypropylene T-junctions depend on water flow velocity and the manufacturing precision of a T-junction joint.

Method of estimating the rolling resistance coefficient of vehicle tyre using the roller dynamometer

2020 ◽  
Vol 234 (13) ◽  
pp. 3194-3204
Author(s):  
Adrian Soica ◽  
Adrian Budala ◽  
Vlad Monescu ◽  
Slawomir Sommer ◽  
Wojciech Owczarzak
Keyword(s):  
Rolling Resistance ◽  
Resistance Coefficient ◽  
Test Method ◽  
Test Facility ◽  
Vehicle Speed ◽  
Chassis Dynamometer ◽  
The Past ◽  
Test Conditions ◽  
Resistance Coefficients ◽  
Roll Out

The tendency in the past few years has been to introduce tyres with lower rolling resistance coefficients to the market. This paper presents a mathematical method for determining the rolling resistance coefficients variation depending on the speed. The method uses power balance which results from automobile dynamics while rolling on chassis dynamometer. The rolling resistance coefficients of tyres obtained through ‘drum test method’, for which the rolling resistance coefficients variation is known in terms of vehicle speed, are considered as reference values, while than rolling resistance coefficients of tyres obtained through ‘MAHA roller dynamometer’ using the recorded lost drag power in the roll-out phase on the stand are considered as tested values. The rolling resistance coefficients variation could be determined up to the maximum permissible speed of the tyre, for all wheels trained on the stand and not just for one tyre, as determined in laboratory conditions. The test conditions are similar to those in real road conditions, where the temperature of the environment and wheels cannot be controlled. The values obtained by the authors’ proposed method were compared with the values obtained by the ‘drum test method’. The main contribution of the proposed method is to estimate the rolling resistance coefficients without using a very expensive test facility.

Mechanics of Herbert Pendulum Hardness Tester and its Application

2017 ◽  
Vol 741 ◽  
pp. 122-127 ◽  
Author(s):  
Radim Halama ◽  
Jiří Podešva ◽  
Ryosuke Suzuki ◽  
Masaaki Matsubara ◽  
Rostislav Čech
Keyword(s):  
Classical Mechanics ◽  
Rolling Resistance ◽  
Resistance Coefficient ◽  
Metallic Materials ◽  
Low Friction ◽  
Hardness Tester ◽  
Swing Angle ◽  
Simplified Solution ◽  
Resistance Coefficients ◽  
Insight Into

The knowledge of classical mechanics gives deeper insight into the Herbert hardness tester applicability for material testing. Elastic materials with low friction presence between contact surfaces are supposed to be investigated in this study. Firstly the dynamics approach is used to obtain simplified solution of swing angle. Then a new solution of the problem is gained by means of an energy approach. Slight decrease of the swing angle is predicted by the new solution as also shown in experiments. After comparison of both solutions a new formulae useful for evaluation of rolling resistance coefficient is applied for measurements performed on some metallic materials and artificial sapphire. Rolling resistance coefficients obtained by the way are always less than maximal estimated value.

scholarly journals Comparative modeling of hull form resistance for three ocean going vessels using methodical series

2015 ◽  
Vol 4 (4) ◽  
pp. 489 ◽  
Author(s):  
Nitonye Samson ◽  
Adumene Sidum
Keyword(s):  
Reynolds Number ◽  
Frictional Resistance ◽  
Comparative Modeling ◽  
Resistance Coefficient ◽  
Container Ship ◽  
Test Technique ◽  
Hull Form ◽  
Reynolds Number Increase ◽  
Friction Line ◽  
Resistance Coefficients

This paper presents a comparative estimation of the hull form resistance for Cargo ship, Ocean-going Tug and Container ship. The research study evaluates the influences of various ship hull parameters in relations to the vessel speeds and level of turbulence (Reynolds number). The modeling was done using MATLAB software and the model test technique based on the ITTC, ATTC, Granville and Hughes friction line application. The result shows that the hull form resistances follow the same trend in the ITTC, ATTC and Granville models, while the Hughes model gave a different trend with other techniques. It further revealed that as the speed increases by 10knots, the frictional resistance coefficients decrease by 11.86% for the ITTC & Granville models, and 12.03% for the Hughes model. For Ocean-going Tug and Container Ship, the frictional resistance coefficient decrease by 12.31% for the ITTC & Granville models, and 12.14% for the Hughes model. The Reynolds number increase by 62.52% for every 10knots increase in the speed of the Cargo ship and 62.23% for every 10knots increase in the speed of the Ocean going tug and Containership. At various experimental speeds, the results showed that for every 1 knots increase in the speed of the Containership, the effective power developed increases by 9.45%. This provides a technical and analytical guide on hull form resistance trend for engineers and ship operators.

A New Computational Model about Vehicle’s Sliding Resistance Coefficients

2011 ◽  
Vol 228-229 ◽  
pp. 60-65
Author(s):  
Hong Liang Lin ◽  
Qiang Yu ◽  
Xue Li Zhang
Keyword(s):  
Drag Coefficient ◽  
Dynamic Performance ◽  
Great Influence ◽  
Rolling Resistance ◽  
Resistance Coefficient ◽  
Calculation Model ◽  
Air Drag ◽  
Sliding Resistance ◽  
Rolling Resistance Coefficient ◽  
Resistance Coefficients

Vehicle’s sliding resistance mainly includes rolling resistance, air drag resistance and friction within the transmission, wheel bearings and other related components. Among those, rolling resistance and air drag always exist whenever vehicle is running, so they have great influence on vehicle’s dynamic performance and fuel economy. Therefore, it is important to determine vehicle’s rolling resistance coefficient and air drag coefficient quickly and accurately in order to operate vehicle properly and reduce the vehicle’s fuel consumption. Combining theoretical analysis with experimental verification, calculation model based on road coasting test was given by means of least squares principle. And through which vehicle rolling resistance coefficient and air drag coefficient were determined easily. Then by using the test data from some Minibus, the vehicle's rolling resistance coefficient and air drag coefficient are calculated according to established model. The computation result shows that rolling resistance coefficient is a linear function of the speed and the air drag coefficient is constant. Finally, the analysis shows that the calculation model is simple, precise and useful.

Rolling resistance, vertical load and optimal number of wheels in human-powered vehicle design

2016 ◽  
Vol 231 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Paolo Baldissera ◽  
Cristiana Delprete
Keyword(s):  
Aerodynamic Drag ◽  
Rolling Resistance ◽  
Resistance Coefficient ◽  
Optimal Number ◽  
Vehicle Design ◽  
Definition Of ◽  
Human Powered ◽  
The Relationship ◽  
Resistance Coefficients ◽  
Strict Definition

Even if it makes a smaller contribution than aerodynamic drag, rolling resistance plays a non-negligible role in the efficiency of human-powered vehicles, whether they are designed for daily commuting or to set speed records. The literature, experimental evidence and models show that the rolling resistance coefficient of cycling wheels strongly depends on the supported load, suggesting that the number of wheels and the load distribution could play a role in vehicle design and in road-test data analysis. Starting with an in-depth look at the relationship between a single wheel and overall vehicle rolling resistance coefficients, an analysis is proposed and discussed with the aim of minimizing the rolling resistance of a vehicle. Finally, a parametric surface response model for rolling resistance is obtained as a function of wheel size and the number of wheels. The overall analysis overturns the popular assumption according to which ‘the more wheels, the more rolling resistance’, at least according to a strict definition of the phenomenon.

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