Increase Of Rolling Resistance Research Articles

Evaluation of road roughness and its influence on operating parameters in open-pit mines

Hauling ore and waste rock is a major cost factor in open-pit mines, encompassing both road maintenance and off-road truck operation. Road maintenance costs are directly influenced by traffic volume and the size of trucks using the roads. Off-road truck operating costs are impacted by various factors, including those affecting their movement, such as the direct interaction between tires and the road surface. Tire-road interaction significantly affects rolling resistance. Rougher surfaces with deeper grooves caused by track sinks lead to higher rolling resistance. This study employed laser profiling to characterize the surface roughness of five mine haul roads in two large Brazilian iron ore mines. This study evaluated the impact of these road irregularities on various operating parameters for 240-ton off-highway trucks, including rolling resistance, average travel speed, travel time, productivity, and unit transport cost. The results indicate that a 10 cm increase in road surface roughness can lead to a significant increase in rolling resistance (up to 5%), a substantial decrease in average speed (25%), a notable increase in travel time (26%), a decrease in productivity (19%), and a corresponding increase in unit transport cost (21%).

The impact of wheelchairs driving support systems on the rolling resistance coefficient

The 21stcentury is characterized by an increase in the obesity of society, including people with disabilities. The increase in the weight of people in wheelchairs requires them to have more power to drive these types of vehicles. Diseases and a varied level of disability or infirmity may lead to the inability to overcome the resistance of a vehicle driven by muscle power, such as a wheelchair. The solution to this problem are systems supporting the motion of this type of vehicles among which we can distinguish electric-manual hybrid drives that add energy to the drive system and systems that reduce the amount of force necessary for the movement of the cart lowering at the same time of its moving speed. Systems and mechanisms that have been developed for this purpose contain an increased number of cooperating elements than in a classic wheelchair, leading to an increase in rolling resistance. The article presents the methodology and test results of rolling resistance coefficients of wheelchairs with innovative systems supporting their propulsion showing that the tested auxiliary drives generate an increase in rolling resistance of vehicles for the disabled from 30 % to 75 %.

Potential of three-dimensional footprint mold in investigating the effect of tractor tire contact volume changes on rolling resistance

In the present study a method is developed to estimate the three-dimensional (3D) footprint of pneumatic agricultural tires based on molding the tire footprint by liquid plaster and converting these molds to three-dimensional models using a 3D scanner. A Goodyear 12.4–28, 6 ply tractor drive tire was operated on a clay loam soil in a soil bin under three vertical loads, using three inflation pressures and three soil moisture contents at a constant forward speed of 0.45 ms-1. The results showed the rut depth and contact volume increased by increasing the vertical load and inflation pressure and soil moisture content. Contact volume was increased by increasing the vertical load, inflation pressure, and soil moisture content. A multiple regression model was presented with a coefficient of determination (R2) of 0.88 to predict the contact volume based on vertical load, inflation pressure, and soil moisture content. Finally, a univariate regression model was presented to predict the rolling resistance based on the contact volume with a relatively high R2 of 0.93. It was also found that in deformable surfaces, vertical penetration and soil contact volume are the main reasons for the increase in rolling resistance.

Influence of standing position on mechanical and energy costs in uphill cycling

This study was designed to examine the influence of standing position (vs. seated) during uphill cycling on both mechanical cost (MC) and energy cost (EC) in elite cyclists. For the study, thirteen elite cyclists (VO2max: 71.4 ± 8.0 ml·min−1·kg−1) performed, in a randomised order, three sets of exercises. Each set comprised 2 min of exercise, alternating every 30 s between seated and standing postures, using different slopes and intensity levels on a motorised treadmill. MC was calculated from the measurement of power output and speed, whereas EC was calculated from the measurement of oxygen consumption and speed. MC was significantly higher (+4.3%, p < 0.001) in standing position compared to seated position when all slopes and intensities were considered. However, EC was not significantly affected by the change in position. The standing position also induced a significant increase in rolling resistance power (p < 0.001), rolling resistance coefficient (p < 0.001) and lateral sways (p < 0.001). The significant increase in MC observed in standing position was due to a higher rolling resistance induced by bicycle sways and a shift forward of the centre of mass compared to seated position. This result should lead bicycle tire manufacturers to reduce the increase in rolling resistance between the two positions. Considering the relationship observed between the MC and bicycle sways, cyclists would be well advised to decrease the bicycle sways in order to reduce the MC of locomotion.

Effect of High Aspect Ratio Fillers on the Performance of Styrene-Butadiene Rubber

ABSTRACTAmong the many material performance properties of vulcanized elastomers for tire tread application, rolling resistance and wet traction are particularly important since both greatly impact fuel efficiency and traction of a vehicle. Rolling resistance and wet traction are generally negatively correlated, i.e., with the increase in rolling resistance of a tire, its wet traction decreases. Silica nanofillers are often used for achieving the desired balance of wet traction and rolling resistance. However, the high cost of silica limits its wide spread application. In this research we studied the effects of using fillers with different aspect ratios (calculated by dividing the long dimension of a filler by its short dimension) on the performance of vulcanized styrene butadiene rubber (SBR), a common rubber for tire tread application. Three high aspect ratio fillers were used: aragonite calcium carbonate, wollastonite and carbon nanofiber. For comparison purpose, spherical silica filler was also included. We found that the high aspect ratio fillers were efficient in improving the wet traction and rolling resistance as well as enhancing the mechanical energy dissipation of SBR. Among the three high aspect ratio fillers studied, wollastonite provided the best wet traction and rolling resistance balance due to its high aspect ratio and compatibility with the base rubber. The effects of fillers induced crosslinking on the dynamic performance were also discussed.

Influence of Road Wetness on Tire-Pavement Rolling Resistance

Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually performed for dry road conditions. Based on the fact that roads are wet during a considerable time over the year and as part of the projects MIRIAM, ROLRES and ROSANNE, the TUG (Technical University of Gdansk) in Poland and VTI (Swedish National Road and Transport Research Institute) in Sweden carried out trailer rolling resistance measurements on wet road surfaces to investigate water film influence on rolling resistance on different pavements. A specially-designed trailer to measure rolling resistance has been used. The test sections were both rural roads and an abandoned airfield equipped with water film sensors mounted in the pavement. Results indicate strong influence of test speed and water film depth, as well as influence of surface texture. The increase of rolling resistance on wet surfaces is caused by both hydrodynamic phenomena and cooling effect of water that decreases tire temperature thus increasing rolling resistance.

Tyre/road interaction model for the prediction of road texture influence on rolling resistance

A novel modelling approach to predict the influence of road texture on the rolling resistance of car tyres is presented where the large static tyre deformations and the small texture induced tyre vibrations are treated separately. The energy dissipation due to the large continuous cyclic deformation of the tyre cross section for a treadless tyre subject to nominal load on a smooth road is determined in a non-linear steady-state rolling analysis on an FEM tyre model. The additional energy dissipation resulting from the con tact forces and tyre vibrations due to the combined effect of the tread profile and the road texture, are determined based on a modal representation of the deformed tyre. The predicted rolling resistance coefficients are compared to experimental data. Although an offset in the absolute rolling resistance levels can be observed, the model predicts the correct trend regarding the increase of rolling resistance with increasing texture depth.

Artificial Neural Network estimation of wheel rolling resistance in clay loam soil

Despite of complex and nonlinear relationships imparting soil–wheel interactions, however, logical, non-randomized, and manifold relations tackle to express and model the interactions which are valid for variety of conditions and are likely to be established whereas mathematical equations are restricted to present. A 3-10-1 feed-forward Artificial Neural Network (ANN) with back propagation (BP) learning algorithm was utilized to estimate the rolling resistance of wheel as affected by velocity, tire inflation pressure, and normal load acting on wheel inside the soil bin facility creating controlled condition for test run. The model represented mean squared error MSE of 0.0257 and predicted relative error values with less than 10% and high coefficient of determination (R2) equal to 0.9322 utilizing experimental output data obtained from single-wheel tester of soil bin facility. These rewarding outcomes signify the fitting exploit of ANN for prediction of rolling resistance as a practical model with high accuracy in clay loam soil. Derived data revealed rolling resistance is less affected by applicable velocities of tractors in farmlands nevertheless is much influenced by inflation pressure and vertical load. An approximate constant relationship existed between velocity and rolling resistance implying that rolling resistance is not function of velocity chiefly in lower ones. Increase of inflation pressure results in decrease of rolling resistance while increase of vertical load brings about increase of rolling resistance which was measured to be function of vertical load by polynomial with order of two model validated by conventional models such as Wismer and Luth model.

Investigating the effect of velocity, inflation pressure, and vertical load on rolling resistance of a radial ply tire

A single-wheel tester facility at Department of Agricultural Machinery of Urmia University was utilized to investigate the effect of velocity, tire inflation pressure, and vertical load on rolling resistance of wheel. A Good year 9.5L-14, 6 radial ply tire was used as the tester wheel on clay-loam soil and was installed on a carriage traversing the length of soil bin. Three inflation pressures of 100, 200, and 300kPa as well as three levels of velocity (i.e. 0.7, 1.4, and 2m/s) and five levels of vertical load applied on wheel (i.e. 1, 2, 3, 4, and 5kN) were examined. Covariance analysis (ANCOVA) of resulted data revealed that rolling resistance is less effected by applicable velocities of tractors in farmlands but is much influenced by inflation pressure and vertical load. An approximate constant relationship existed between velocity and rolling resistance indicating that rolling resistance is not a function of velocity particularly in lower ones. Moreover, it was observed that increase of inflation pressure results in decrease of rolling resistance. Additionally, increase of vertical load brings about increase of rolling resistance which was estimated to have polynomial relation with order of two. A model comprising tested variables was developed with relative high accuracy.

Assessing Range and Performance of Electric Vehicles in Nordic Driving Conditions – Project ”RekkEVidde”

Until battery technology makes a leap, shortage of range is by far the greatest flaw in electric vehicle technology that is otherwise very effective and promising. However, energy use is also highly dependent on duty cycles, driving conditions and traffic situation. Furthermore, cabin heating in an EV will not be supported by energy losses as in an ICE-car. Therefore, actual range can differ substantially in real-life situations, and can be much shorter than the official figures given by the manufacturers. Project RekkEVidde is aiming at drafting a testing scheme to address EV driving in Nordic conditions, and produce realistic range estimates for the consumers to help them understand and make better use of this raising technology. Initial laboratory testing was imposed on a Citroën C-Zero EV using multiple different driving cycles and testing also at -20 °C, not just the normal ambient. First review of the results in this paper shows that the energy consumption was raised on average some 30 % at low ambient, resulting to a 15 to 30 % shorter range. This was due to only increasing the air drag component according to increase in air density, but further on-road testing will also give us more information on increase of rolling resistance because of snow and ice packed on road surface. Furthermore, use of cabin heating was not included in these numbers. Should it be turned on, the range will be further shortened as much as 50 % in slow-speed urban driving.

Esso Energy Award Lecture, 1984 - A new tyre polymer improving fuel economy and safety

A new philosophy, relating to both rolling resistance (fuel consumption) and wet grip (safety), has been developed, based on measurements of the dynamic properties of tread compounds in the laboratory under conditions approaching those existing at the tyre-road surface interface under both rolling and wet sliding conditions. The generally accepted wet grip theories used throughout the tyre industry lead to the conclusion that when wet grip is improved, there is an increase in rolling resistance. The new philosophy enabled a tailor-made polymer to be developed that broke away from convention and gave a reduced rolling resistance while improving wet grip. Extensive laboratory and vehicle testing was performed on tyres made with the new polymer, to verify the new hypothesis and to ensure that the polymer was a commercial proposition before it was officially announced and introduced into commercial tyres during late 1981.