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Minimising opposing forces is a matter of interest to most cyclists. These forces arise from passage through air ('drag') and interaction with the road surface ('resistance'). Recent work recognises that resistance forces arise not only from the deformation of the tyre ('rolling resistance') but also from irregularities in the road surface ('roughness resistance'), which lead to power dissipation in the body of the rider through vibration. The latter effect may also have an adverse impact on human health. In this work we offer a quantitative theory of roughness resistance and vibration that links these effects to a surface characterisation in terms of the International Roughness Index (IRI). We show that the roughness resistance and the Vibration Dose Value (or VDV, the usual vibration dosage metric) can be expressed in terms of elementary formulae. The roughness resistance depends only on the vertical stiffness of the bicycle and the roughness index. Surprisingly, other apparently relevant parameters, such as physiological characteristics of the bicycle rider and other features of the bicycle, do not enter. For roads of moderate roughness, roughness resistance is larger than rolling resistance. For very rough roads, roughness resistance is larger than aerodynamic drag. So only on roads of high quality (in most jurisdictions, accounting for less than 10% of the total) can roughness resistance be ignored. Roughness resistance can be mitigated by reducing the vertical stiffness of the bicycle. In common with other recent reports, we find that almost any cycling activity will breach public health guidelines relating to Vibration Dose Value. [ABSTRACT FROM AUTHOR]

Abstract\nIMPLICATIONS FOR REHABILITATIONThe gross mechanical efficiency of the manual wheelchair propulsion movement is particularly low compared to other movements. The energy losses in the manual wheelchair propulsion movement are partly due to energy losses associated with the wheelchair, and especially to the rolling resistance of the wheels. The distribution of mass between the front rear wheels and the caster wheels has a significant impact on the rolling resistance. The study of the caster wheels cannot therefore be neglected due to their involvement in rolling resistance. Thus, this study aimed to evaluate the power dissipated due to rolling resistance by different caster wheels, at different speeds and under different loadings on various terrains. Four caster wheels of different shapes, diameters, and materials were tested on two surfaces representative of indoor sports surfaces at four different speeds and under four loadings. The results showed a minimal dissipated power of 0.4±0.2W for the skate caster, on the parquet, at 0.5 m/s and under a loading of 50 N. The maximal mean power dissipated was 43.3±27.6W still for the skate caster, but on the Taraflex, at 1.5 m/s and under loading of 200 N. The power dissipated on the parquet was lower than the one on the Taraflex. The Spherical and Omniwheel caster wheels dissipated less power than the two other casters. This study showed that caster wheels cannot be neglected in the assessment of gross mechanical efficiency, particularly in light of the power dissipated by athletes during propulsion.Highlights the importance of choosing the right front casters depending on the conditions of use of the manual wheelchair.First study to evaluate power dissipation due to rolling resistance in front casters during wheelchair propulsion.Shows that a Taraflex type floor is not suitable for wheelchair sports performance and injury prevention purposes and lower musculoskeletal constraints with equivalent performance.Highlights the importance of choosing the right front casters depending on the conditions of use of the manual wheelchair.First study to evaluate power dissipation due to rolling resistance in front casters during wheelchair propulsion.Shows that a Taraflex type floor is not suitable for wheelchair sports performance and injury prevention purposes and lower musculoskeletal constraints with equivalent performance. [ABSTRACT FROM AUTHOR]

Cellulose fibers were modified via aqueous silane‐graphene oxide (GO) coordination by flash drying and extrusion dispersion process. The adsorption of GO reduced the polarity of the cellulose fiber surface and attenuated the agglomeration effect between the cellulose fibers, thus facilitating the dispersion of fibers in the rubber matrix. Adding aqueous 3‐aminopropylsilane oligomer (8150) incorporated active sites on the surface of cellulose fibers, thereby improving the interfacial binding properties of cellulose nano fibers (CNFs) and natural rubber (NR). After blending the modified CNFs with NR latex, high‐temperature flocculation was performed using an atomised flash device. Finally, CNF/NR was pre‐dispersed through a twin‐screw extruder, after which a CNF/NR masterbatch with excellent performance was prepared. Experimental results revealed that composites prepared using GO‐8150 via the flash drying‐twin‐screw dispersion process exhibited excellent dispersion characteristics, processing properties, mechanical properties, rolling resistance, wear resistance, and heat generation properties. Compared with traditional dry mixing, the composites prepared by flash drying‐twin‐screw dispersion process showed a 16.95% increase in tensile strength, 16.07% increase in 300% constant elongation, 19.01% reduction in abrasion consumption, 42.26% reduction in rolling resistance, and a reduction in the Payne effect. This study offers an efficient and environmentally friendly method for the high‐value utilization of natural fibers and the preparation of NR composites with excellent properties, while providing a green and nonpolluting modification process with no acidic liquid discharge. Highlights: GO‐8150 reduces the polarity of the fibers and promotes dispersion.The flash extrusion dispersion process achieves green flocculation.42% lower rolling resistance for rubber composites. [ABSTRACT FROM AUTHOR]

The rolling resistance of car tires is one of the most important parameters characterizing tires today. This resistance has a very significant contribution to the energy consumption of wheeled vehicles. The climate crisis has forced tire and car manufacturers to place great emphasis on the environmental impact of their products. Paradoxically, the development of electric vehicles has led to an even greater importance of rolling resistance, because in electric vehicles, a large part of the influence of grade resistance and inertial resistance has been eliminated due to re-generative braking, which resulted in rolling resistance and air resistance remain as the most important factors. What is more, electric and hybrid vehicles are usually heavier, so the rolling resistance is increased accordingly. To optimize tires for rolling resistance, representative test methods must exist. Unfortunately, the current standards for measuring rolling resistance assume that tests are carried out in conditions that are far from real road conditions. This article compares the results of rolling resistance tests conducted in road conditions with the results of laboratory tests conducted on roadwheel facilities. The overview of results shows that the results of tests conducted in accordance with ISO and SAE standards on steel drums are very poorly correlated with more objective results of road tests. Significant differences occur both in the Coefficients of Rolling Resistance (CRR) and in the tire ranking. Only covering the drums with replicas of road surfaces leads to a significant improvement in the results obtained. For investigations of rolling resistance in non-steady-state conditions, the flat track testing machine (TTF), equipped with asphalt cassettes, is shown to provide measurement data in agreement with the road test data. [ABSTRACT FROM AUTHOR]

In this study, the surface of pyrolysis carbon black (CBp) is modified by integrating the ball milling process with plasma treatment. High‐energy mechanical ball milling enabled more uniform contact and sufficient reaction temperature for the silane coupling agent and CBp. In addition, the impact of plasma activated the ash and surface deposits of CBp, reducing its inertness. Herein, the filler dispersion grade, Payne effect, vulcanization characteristics, and mechanical and dynamic mechanical properties are investigated by considering modified CBp/natural rubber (NR) composites. The ball milling plasma process can reduce the polarity of CBp. Compared with untreated CBp/NR composites, the plasma‐treated SCA‐CBp/NR composites exhibited increased CBp dispersion grades, higher processing safety, better processing fluidity, and improved mechanical properties. The reduced Payne effect ensured more filler‐rubber network structure, resulting in a reduction in rolling resistance. Highlights: The coupling agent and CBp are treated by low‐temperature plasma and ball milling. The process promotes the formation of the filler‐rubber network. The dispersion grade of composites increased by 26.29%. The tensile strength increased by 5.57%, and the rolling resistance decreased by 19.44%. [ABSTRACT FROM AUTHOR]

Silica/solution-polymerized butadiene-styrene rubber (SSBR)/natural rubber (NR) compo-sites were prepared by mechanical mixing method with silane coupling agent, bis[3-(triethoxysilyl)propyl]tetrasulfide (Si 69) and 3-mercaptopropyl-ethyoxyl-di(tridecyl-pentamethoxy)-silane (Si 747), as modifier and the effect of types and addtion amounts of silane coupling agent on the microstructure, curing characteristics, processing performance, physical and mechanical performance, dynamic mechanical properties, tire performance, and the relationship between structure and performance of the composite. The results showed that compared with the composite just only modified by Si 69, the incorporation of Si 747 resulted in the scorch time and optimum curing time of the composite shorten signi-ficantly, and the curing rate improved gradually with the increase in the addition amount of Si 747; the synergistic modification of Si 69 and Si 747 made the physical and mechanical properties, tensile strength, resilience and modulus at 300% of the composite all reduced; when the addition amount of Si 747 increased, the apparent activation energy which was used to characterize the temperature dependence of storage modulus of the composite reduced gradually; the dispersion of silica in the composite improved significantly after the addition of Si 747; the loss factor (tan δ) of the composite modified by Si 747 alone at 0 ℃ increased significantly and tan δ at 60 ℃ decreased significantly; the rolling resistance of the tire improved gradually with the increase in the addition amount of Si 747.

The aim of the research was to design and build a research stand that can be used to compare different types of tire tread profiles of the Mars rover (made using 3D printing) and to select the one that meets the criterion of the lowest power consumption of the drive motor, which corresponds to the minimum rolling resistance in paved area. As part of the task, a research stand was designed and built, consisting of two drive units of the tested drive system: one as a driving unit, the other as a driven unit, generating resistance when rolling one tire after another. During the tests, the following parameters were measured: the amplitude of the supply current, the rotational speed, information about which was obtained from the motor controller and the encoder located in the BLDC motor, and their variability over time. Additionally, the amplitude of the force pressing the wheel against the supporting surface, which generated tire deflection, was also measured. A relationship was demonstrated between the type of tire tread used, the force pressing the tires against the supporting surface and the rolling resistance forces of the Mars rover tires. The tire with the lowest rolling resistance under given operating conditions was selected.

In order to determine the relationships between the soil stiffness constants of cohesive modulus of deformation, friction modulus of deformation and soil constant value and the rolling resistance, a series of tests was conducted using two types of loam and clay loam soil textures at four moisture contents of 10, 20, 30 and 40% and five loading speeds of 1, 2, 3, 4 and 5 mm s–1. The results showed that all of the independent factors had a significant effect on the soil stiffness constants, so with increases in moisture content and loading speed, the soil stiffness constants of cohesive modulus of deformation, friction modulus of deformation and soil constant value varied significantly. The highest cohesive modulus of deformation and friction modulus of deformation values were obtained at a moisture content of 10% and loading speed of 5 mm s–1 in a clay loam soil. All parameters were significant in calculating the rolling resistance using Bekkers’ relationship. With increases in soil moisture content, the rolling resistance increased, while increasing the loading speed reduced the rolling resistance significantly. In general, the highest rolling resistance value of 16 887.1 N was obtained at a moisture content value of 40% and a loading speed of 1 mm s–1 in loam soil. [ABSTRACT FROM AUTHOR]

To characterize the relationship among rolling resistance (RR), preferred speed, and propulsion mechanics. N = 11 non-disabled individuals (mean (SD)); Age 24 years (2), BMI 23.8 kg/m2 (4.3) completed a submaximal graded wheelchair exercise test (GXTsubmax, fixed speed, terminated at Rating of Perceived Effort (RPE)=8 (0-10 scale)) and a single-blind, within-subject repeated measures wheelchair propulsion experiment (RME). RR at RPE = 10 (estimated maximum workload, Maxestimated) was estimated from the GXTsubmax RPE-RR relationship. RME consisted of N = 19 1-minute trials (self-selected speed) each followed by 2-minutes rest. The trials included N = 16 unique RR between 25-100% of Maxestimated. Averages of all pushes in N = 16 unique 1-minute trials were computed for average RR (N), speed (m/s), peak force (Fpeak (N)), force rate of rise (Fror (N/s)), push frequency (PF (pushes/min)), and push length (PL (deg)). Repeated measures correlation assessed relationships among outcome variables (α = 0.05). RR was associated with decreased speed (r=–0.81, p < 0.001), increased Fpeak (r = 0.92), Fror (r = 0.26), and PL (r = 0.32) (all p > 0.001), and unrelated to PF (r = 0.02, p = 0.848). Increased speed was associated with increased Fror (r = 0.23, p = 0.003) and PF (r = 0.27, p < 0.001) and decreased Fpeak (r=–0.66, p < 0.001) and PL (r=-0.25, p < 0.001). Increasing RR increases Fpeak despite reducing self-selected speed. RR and speed were strongly and moderately related to Fpeak, respectively, but weakly related to other propulsion mechanics. These results suggest that reducing user-system RR may confer dual benefits of improved mobility and decreased upper extremity loading. Further testing among wheelchair users is required. Clinical trial registration number: NCT04987177 To our knowledge, this is the first study to directly characterize the dose-response relationship between rolling resistance and manual wheelchair propulsion biomechanics. By characterizing the relationship between rolling resistance and propulsion mechanics, more objective and accurate clinical interventions can be assessed/implemented. Our results suggest that reducing the user-wheelchair system rolling resistance should decrease peak forces, which is favorable, as increased peak forces have been linked to upper extremity pain and pathology. Our findings of weak relationships between rolling resistance and push length, push frequency, and force rate of rise, suggest that reductions in rolling resistance may not be the optimal method for "improving" these variables. Propulsion training has been shown to achieve long-term favorable changes in these variables, so an area for future work can be to evaluate if reducing rolling resistance or propulsion training is more effective at "improving" these variables. The strong relationship we observed between rolling resistance and self-selected speed, suggests that user-wheelchair system rolling resistance reductions might encourage increased mobility in the home and community, theoretically improving participation and thus quality of life. [ABSTRACT FROM AUTHOR]

In this research, field experiments were carried out in two types of soil (sandy clay loam and clay) to model the traction performance of the tractor considering drawbar power, rolling resistance, and traction efficiency, using deep learning and convolutional neural network while having some parameters such as soil type and conditions, tool parameters, and operation parameters. The tests were conducted within each soil texture as factorial tests based on the randomized complete block design (RCBD) in triplicates. The tests were done in various moisture levels (8-17% for dry soils and 18-40% for moist soils), tractor forward speed (1.2, 1.6, 1.8, and 2.2 km h-1), working depth (30 and 50 cm), the number of passes (2 and 6 times), and tyre inflation pressure (20 and 25 psi). The cone index, dynamic load, draft force, and moisture content were measured in each test. The networks designed to model the drawbar power, rolling resistance, and traction efficiency were of convolutional neural network type. Various algorithms, such as Sgdm, Adam, and Rmsprop, were utilized to train the network. The results showed that the neural network developed by Sgdm algorithm outperformed the others. Therefore, this algorithm was utilized for the modelling process. Statistical criteria such as R² and MSE were also employed to evaluate the performance of the network. The 8-499-499-1 architecture showed the best performance for the drawbar power with R²=0.9953 and MSE=0.0016. Concerning the rolling resistance, the best performance was observed in 8-301-305-1 architecture with R²=0.9903 and MSE=0.0039. The best performance for the traction efficiency was obtained by 8-371-371-1 architecture with R²=0.9888 and MSE=0.003. The results showed that these networks can model parameters by removing convolution layers and reducing dimensions. [ABSTRACT FROM AUTHOR]

Acid coagulation is the most traditional latex coagulation technology, but this coagulation process leads to delayed vulcanization, corrosiveness, and environmental pollution. Different coagulation processes significantly impact the raw rubber network structure, leading to differences in the properties of both raw rubber and rubber vulcanizates. Raw rubber was prepared by three acid‐free coagulation processes: freeze, microwave, and flash drying. The network density, molecular chain flexibility, molecular weight, processing fluidity, and plasticity retention of the raw rubber were characterized, and the vulcanization characteristics, viscoelasticity, mechanical properties, and dynamic mechanical properties of the cured rubber composites were investigated. Raw rubbers prepared by microwave drying and flash drying had higher crosslink density, more flexible molecular chains, larger molecular weight, and wider molecular weight distribution, thereby increasing the crosslink density of rubber vulcanizates. The crosslink density of the raw rubber prepared by microwave drying versus the acid coagulated raw rubber increased by 51% to 105.71 mol/m3, the tensile strength increased by 16% to reach 28.12 MPa, and the elastic modulus and rolling resistance under dynamic stress increased. This paper provides a new idea for analyzing the relationship between the raw rubber network structure and the properties of vulcanized rubber. Highlights: Acid‐free raw rubbers are prepared by freeze, microwave, and flash drying.Coagulation processes significantly impact the raw rubber network structures.Effects of raw rubber network structures on properties are investigated.Crosslink density, plasticity retention, and tensile strength are improved. [ABSTRACT FROM AUTHOR]

Manufacturers of electric cars provide their vehicles with many technical data that are important for the user. This includes information on dimensions, mass, performance, consumption, battery capacity, range, payload, etc. However, some interesting parameters are usually withheld from the end user. These parameters include, for example, the loss in the energy flow from the battery to the driving wheels or the rolling resistance of the vehicle. However, since these loss parameters have a significant influence on the vehicle's consumption, it is of interest to know them. This article presents a method for determining these two parameters. The basis for this are simple driving tests that can be carried out by anyone on public roads. [ABSTRACT FROM AUTHOR]

A nylon-like polyester tire cord, which combined the characteristics of nylon and polyester tire cords, was designed as the carcass reinforcement material used to meet the increasing demands of the tire industry for performance and impact on the environment. Tires' carcass construction plays a crucial role in affecting handling performance and ride comfort. Small changes in the carcass component can lead to significant improvements in the total tire/vehicle performance. This study evaluated the performance of nylon-like polyester and nylon 6 motorcycle tires. The results showed that the nylon-like polyester tire passed all indoor tests, and post-cure inflation (PCI) could be eliminated, resulting in energy and cost savings. The rolling resistance coefficient of the nylon-like polyester tire was reduced by 6.8% compared to that of the nylon 6 control tire, which could save fuel and have a positive impact on the environment. Nylon-like polyester tire cord extracted from the experimental tire possessed a higher modulus compared to that of nylon 6 tire cord, which could lead to better handling and ride comfort performance. Morphological pictures showed that both nylon-like polyester and nylon 6 cords extracted from tires had a good rubber coverage and comparable adhesion properties. [ABSTRACT FROM AUTHOR]

The preparation of four types of epoxidized iron‐based comb butadiene‐isoprene rubber (EBIR) with different epoxidation degrees (4.7%, 6.4%, 10.2%, and 12.3%) was investigated for the first time in this study. The modification involved the use of hydrogen peroxide and formic acid as raw materials for the epoxidation process. Following this, silica/EBIR composites were prepared by mixing EBIR with silica nanoparticles, without the use of a silane coupling agent (SCA). The objective was to investigate the influence of the epoxidation degree on the structure and properties of the resulting silica/EBIR nanocomposites. The results indicated that the introduction of epoxy groups had a positive effect on the interfacial interaction between the rubber and filler, leading to improved dispersion of the silica nanoparticles in the rubber matrix. Consequently, the tensile properties, wet skid resistance, and abrasion resistance of the silica/EBIR composites were found to be superior to those of the un‐epoxidized silica/BIR composites. Furthermore, comparing the silica/EBIR‐12.3 nanocomposites with silica/BIR‐Si69 nanocomposites, it was revealed that silica/EBIR‐12.3 showed a 69.4% enhancement in wet skid resistance and an 8.0% reduction in rolling resistance. These findings demonstrate the potential of silica/EBIR composites for high‐performance tire tread rubber applications, offering environmental benefits and improved properties. [ABSTRACT FROM AUTHOR]

This research investigates the utilization of a hybrid nanofiller comprising graphene oxide (GO) and amine‐modified nano silica in natural rubber matrix via the latex stage coagulation method. The resulting novel composite materials were characterized comprehensively for their static and dynamic mechanical properties. The hybrid nanofiller exhibited excellent dispersion within the rubber latex, facilitating the formation of a well‐interconnected network structure. The formed network resulted in remarkable improvements in tensile strength, elongation at break, and modulus of the composites. Dynamic mechanical analysis revealed that the hybrid filler (GO/nano‐silica hybrid (GO/NS)) could effectively reinforce the rubber matrix by constraining the mobility of rubber chains, leading to increased stiffness and mechanical strength. In fact, the confinement effect of the nanofillers has been carefully evaluated from dynamic mechanical spectroscopy. The increased glass transition temperature of the rubber nanocomposites specifies the restricted segmental mobility of the rubber chains. Moreover, the hybrid composites displayed significantly low rolling resistance, particularly GO/NS 2 (31% reduction), indicating their potential application as tire treads for fuel‐efficient and green tire manufacturing. The mechanical and rolling resistance properties achieved in these composites can be attributed to the efficient dispersion of the GO/nano‐silica hybrid(GO/NS) nanofiller and the resulting network formation within the rubber matrix. Findings emphasized the composites' viability as sustainable and eco‐friendly tire materials, potential for enhanced fuel efficiency, and reduced environmental footprint in tire manufacturing technology. Highlights: The hybrid nanofiller (GO/nano silica hybrid) exhibited excellent dispersion within the rubber latex, leading to the formation of a well‐interconnected network structure.The resulting network structure significantly improved the tensile strength, elongation at break, and modulus of the composite materials.Dynamic mechanical analysis demonstrated that the hybrid filler effectively reinforced the rubber matrix, increasing stiffness and mechanical strength by constraining the mobility of rubber chains.Our hybrid composites displayed a remarkable reduction in rolling resistance, particularly GO/NS2, with a 31% reduction, indicating their potential application as tire treads for fuel‐efficient and green tire manufacturing.The study emphasized the composites viability as sustainable and eco‐friendly tire materials, offering potential benefits for enhanced fuel efficiency and reduced environmental footprint in tire manufacturing technology. [ABSTRACT FROM AUTHOR]

The aim of the research was to design and build a research stand that can be used to compare different types of tire tread profiles of the Mars rover (made using 3D printing) and to select the one that meets the criterion of the lowest power consumption of the drive motor, which corresponds to the minimum rolling resistance in paved area. As part of the task, a research stand was designed and built, consisting of two drive units of the tested drive system: one as a driving unit, the other as a driven unit, generating resistance when rolling one tire after another. During the tests, the following parameters were measured: the amplitude of the supply current, the rotational speed, information about which was obtained from the motor controller and the encoder located in the BLDC (brushless direct-current) motor, and their variability over time. Additionally, the amplitude of the force pressing the wheel against the supporting surface, which generated tire deflection, was also measured. A relationship was demonstrated between the type of tire tread used, the force pressing the tires against the supporting surface and the rolling resistance forces of the Mars rover tires. The tire with the lowest rolling resistance under given operating conditions was selected. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper focuses on the modeling and analysis of a four-groove passenger car tire, size 235/55R19, using finite element analysis. The Mooney–Rivlin material model is employed to define the hyperelastic behavior of the tire rubber compounds for all solid elements. The tire rim is modeled as a rigid body using aluminum alloy material, and the beads are modeled as beam elements using steel material. The tire model is validated in both static and dynamic domains through several simulations and is compared to published measured data. The tire is validated using footprint and vertical stiffness tests in the static domain. In the static footprint test, a steady-state vertical load is applied, and the tire–road contact area is computed. In the vertical stiffness test, a ramp vertical load is applied, and the tire’s vertical displacement is measured to calculate the tire’s vertical stiffness. In the dynamic domain, the tire is validated using drum-cleat and cornering tests. In the drum-cleat test, a drum with a 2.5 m diameter and a cleat with a 15 mm radius is used to excite the tire structure and obtain the frequency of the vertical and longitudinal first modes of vibration, that is, by applying the fast Fourier transformation (FFT) of the vertical and longitudinal reaction forces at the tire center. In addition to this test, the tire model is pre-steered on a flat surface with a two-degree slip angle and subjected to a steady state linear speed of 10 km/h to predict the cornering force and compute the cornering stiffness. In addition, the effect of tire longitudinal speed on the rolling resistance coefficient is then predicted at zero slip angle using the ISO 28580 rolling resistance test. The findings of this research work provide insights into passenger car tire–road interaction analysis and will be further used to perform tire rubber compound material model sensitivity analysis.

Background: Rolling resistance and aerodynamic losses cause a significant part of a truck's energy consumption. Therefore there is an interest from both vehicle manufacturers and regulators to measure these losses to understand, quantify and reduce the energy consumption of vehicles. On-road measurements are particularly interesting because it enables testing in various ambient conditions and road surfaces with vehicles in service. Objective: Common driving loss measurement devices require unique instrumented measurement wheels, which hinders effective measurements of multiple tyre sets or measurements of vehicles in service. For this purpose, the objective is to develop a novel load-sensing device for measuring braking or driving torque. Methods: The strength of the measurement device is calculated using finite element methods, and the output signal is simulated using virtual strain gauge simulations. In addition to the signal simulation, the device is calibrated using a torsional test rig. Results: The simulation results confirm that the device fulfils the strength requirements and is able to resolve low torque levels. The output signal is simulated for the novel cascaded multi-Wheatstone bridge using the strains extracted from the finite element analysis. The simulations and measurements show that the measurement signal is linear and not sensitive to other load directions. The device is tested on a truck, and the effort of mounting the device is comparable to a regular tyre change. Conclusions: A novel driving loss measurement device design is presented with an innovative positioning of strain gauges decoupling the parasitic loads from the driving loss measurements. The design allows on-road testing using conventional wheels without requiring special measurement wheels or instrumentation of drive shafts, enabling more affordable and accurate measurements. [ABSTRACT FROM AUTHOR]

Accurate assessment of rolling resistance is important for wheelchair propulsion analyses. However, the commonly used drag and deceleration tests are reported to underestimate rolling resistance up to 6% due to the (neglected) influence of trunk motion. The first aim of this study was to investigate the accuracy of using trunk and wheelchair kinematics to predict the intra-cyclical load distribution, more particularly front wheel loading, during hand-rim wheelchair propulsion. Secondly, the study compared the accuracy of rolling resistance determined from the predicted load distribution with the accuracy of drag test-based rolling resistance. Twenty-five able-bodied participants performed hand-rim wheelchair propulsion on a large motor-driven treadmill. During the treadmill sessions, front wheel load was assessed with load pins to determine the load distribution between the front and rear wheels. Accordingly, a machine learning model was trained to predict front wheel load from kinematic data. Based on two inertial sensors (attached to the trunk and wheelchair) and the machine learning model, front wheel load was predicted with a mean absolute error (MAE) of 3.8% (or 1.8 kg). Rolling resistance determined from the predicted load distribution (MAE: 0.9%, mean error (ME): 0.1%) was more accurate than drag test-based rolling resistance (MAE: 2.5%, ME: −1.3%). [ABSTRACT FROM AUTHOR]

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In Discrete Element Method (DEM), the stiffness of particles is often reduced artificially for calculation speed-up. It is known that the attraction force and rolling resistance should be scaled to counter-balance the excessive energy dissipation caused by prolonged contact duration with reduced stiffness. The present study theoretically derives the scaling laws from dimensionless equations of motion in a generic form, which are for both particle translation and rotation and with multi-body interactions. It is verified that the proposed scaling laws keep the same particle motion in the dimensionless time and space during the contact of more than two particles. It is also demonstrated that the behaviour of the original (stiff) particles in Couette flow can be replicated well in various conditions in general. Some deviation to the original system could be observed in certain conditions, which is likely related to the reduction of contact frequency. • Artificially reduced stiffness is used in DEM for simulation speed-up. • Generic scaling laws of attraction forces and rolling resistances are theoretically derived. • Multi-body interactions are considered in the derivation. • The scaling laws maintain the same particle behaviour in dimensionless time and space. • The effectiveness and limitations of the scaling laws are discussed. [ABSTRACT FROM AUTHOR]

This paper focuses on the modeling and analysis of a four-groove passenger car tire, size 235/55R19, using finite element analysis. The Mooney–Rivlin material model is employed to define the hyperelastic behavior of the tire rubber compounds for all solid elements. The tire rim is modeled as a rigid body using aluminum alloy material, and the beads are modeled as beam elements using steel material. The tire model is validated in both static and dynamic domains through several simulations and is compared to published measured data. The tire is validated using footprint and vertical stiffness tests in the static domain. In the static footprint test, a steady-state vertical load is applied, and the tire–road contact area is computed. In the vertical stiffness test, a ramp vertical load is applied, and the tire's vertical displacement is measured to calculate the tire's vertical stiffness. In the dynamic domain, the tire is validated using drum-cleat and cornering tests. In the drum-cleat test, a drum with a 2.5 m diameter and a cleat with a 15 mm radius is used to excite the tire structure and obtain the frequency of the vertical and longitudinal first modes of vibration, that is, by applying the fast Fourier transformation (FFT) of the vertical and longitudinal reaction forces at the tire center. In addition to this test, the tire model is pre-steered on a flat surface with a two-degree slip angle and subjected to a steady state linear speed of 10 km/h to predict the cornering force and compute the cornering stiffness. In addition, the effect of tire longitudinal speed on the rolling resistance coefficient is then predicted at zero slip angle using the ISO 28580 rolling resistance test. The findings of this research work provide insights into passenger car tire–road interaction analysis and will be further used to perform tire rubber compound material model sensitivity analysis. [ABSTRACT FROM AUTHOR]

This paper supports the implementation of a braking efficiency estimator of urban vehicle on rural roads, based on analytical and numerical approach. A statistical study is defined by the Association Road Managers and Partners (AGEPAR) estimates the rate of unpaved roads in Africa around 72%, which approximately 90% of passengers and goods transport that generally doesn’t respect loading standards. This is a major reason for increase traffic accidents in these countries. Hence the need to define vehicle speed limitations that takes in vehicle parameters and irregularities road. This can be done by defining a predicting model of dynamic behaviour for small vehicles, which constitute the majority of African vehicle fleet. To achieve this, we numerically solve the longitudinal dynamic equations of a vehicle body combine with front and rear axles on a road which has irregularities, opposed to existing models and Field data that are defined on surface roads which have little or no irregularities. The input parameters of the model are the initial vehicle speed, the road profile, inclination angle of road, peak wheel cylinder, wheelbase, centre of gravity height, rising time, brake pads contact area, final drive gear ratio, gearbox gear ratio, moment of inertia of engine, slip ratio, vehicle weight, moment of inertia at on axle and dynamic tyre radius which are assumed similarly and the braking system which is a disc braking system. The suspension is assumed identical and rigid since our study focuses on longitudinal and not vertical dynamics. The results produced by our modelling on paved and unpaved roads are compared with those obtained experimentally by J. R. Choa and the unpaved road data we obtained. The relative differences in braking times are respectively 6.5% and 3.1%. For the stopping distance, these relative differences are 11.5% and 11.9%.

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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The influence of fumed nano-SiO2 on the performance of a typical tire tread compound, fabricated by mechanical mixing process, was investigated in the present research. The tire tread compound contained styrene-butadiene rubber (SBR)/ cis -butadiene rubber (BR) blend reinforced with a well-developed commercial highly dispersive silica filler at 70 phr loading. Nano-SiO2 with higher specific surface area, e.g., ∼240 m2/g, was substituted partially with silica particle at three different concentrations of 5, 10, 15 phr. Improvement in various aspects of the control sample including crosslink density calculated based on the swelling test and tube theory, bound rubber content, and physico-mechanical properties was observed for nano-SiO2 loading below 10 phr due to its effective role in refinement of filler dispersion state and enhancement of rubber-filler interactions. However, most of the properties were sacrificed at 15 phr nano-SiO2 loading even with respect to the control sample which emphasized the effectiveness of nano-SiO2 within an optimum loading. Moreover, nano-SiO2 at optimum loading exhibited great improvement in initial decomposition temperature about 50°C, considerable improvement in rolling resistance (more than 8%) and enhancement in wear resistance which could be crucial for tire tread manufacturers. [ABSTRACT FROM AUTHOR]

Carbon black is a very important reinforcing agent for rubber, which can significantly improve rubber modulus, strength, and abrasion performance. However, there are defects such as large hysteresis loss, dynamic energy loss, and high heat build‐up by using carbon black to reinforce rubber. In this paper, a new silane coupling agent named M1 was prepared and introduced as the coupling agent of carbon black, and M1 modified carbon black was prepared. The Fourier transform infrared spectroscopy, thermogravimetric analysis, and X‐ray photoelectron spectrometer results demonstrated the successful modification and revealed the interaction mechanism between M1 and carbon black. The results showed that strong interfacial bonding can be generated between M1 and carbon black through physical and chemical interactions, thereby promoting the dispersion of carbon black in the rubber matrix. Then, carbon black/rubber nanocomposites were prepared with different amount of M1. Because M1 could improve the dispersion of carbon black in the rubber matrix, the carbon black/rubber nanocomposites with M1 have lower network and loss factor, lower rolling resistance, and higher abrasion resistance, which is ideal to manufacture green bus and truck tires for energy‐saving, environment‐friendly, and low‐carbon society. [ABSTRACT FROM AUTHOR]

This study was designed to investigate the effect of wheel and tire selections on the propulsion characteristics of a high-strength lightweight manual wheelchair using robotic wheelchair propulsion. Four configurations were compared with differing combinations of drive wheel tires and casters, with the baseline reflecting the manufacturer configuration of a solid mag drive wheel and 8"×1" caster. The robotic wheelchair tester propelled the chair using pre-generated straight and curvilinear manoeuvres using repeatable and reliable cyclic torque profiles. Additionally, energy loss of the components was measured using coast-down deceleration tests to approximate the system-level rolling resistance of each configuration. Results indicate a significant decrease in propulsion cost, increased distance travelled and increased manoeuvrability across all configurations, with upgraded casters and tires. These results indicated that with better casters and drive wheel tires, the performance of high strength lightweight wheelchairs can be improved and better meet the mobility needs of users. Wheel and tire selection can have a demonstrable impact on the propulsion efficiency of manual wheelchairs Coast-down test protocols can be used as a simple and cost-effective means of assessing representative energy losses across various surfaces Wheelchair configurations can be optimized with proper knowledge of the main energetic loss contributions and the environments and contexts of use [ABSTRACT FROM AUTHOR]

The structure and properties of high modulus natural rubber (NR) / cis-1,4-polybutadiene rubber (BR) blends reinforced with carbon black and modified with trans-1,4-poly(butadiene-co-isoprene) rubber (TBIR) and low Mooney viscosity trans-1,4-poly(butadiene-co-isoprene) rubber (LTBIR) were investigated. The results showed that both of the TBIR and LTBIR could significantly improve the compatibility between NR and BR. Compared with NR/BR vulcanizates, the mechanical properties and resilience of high modulus NR/BR vulcanizates modified with TBIR and LTBIR with reducing 4 phr (mass) carbon black were improved, wear volume reduced by 13%, compression heat generation reduced by 10%, rolling resistance reduced by 20%, first-grade flex fatigue life improved by about 1.6 times, and sixth-grade flex fatigue life improved by about 1.1 times.

Manufacturers of electric cars provide their vehicles with many technical data that are important for the user. This includes information on dimensions, mass, performance, consumption, battery capacity, range, payload, etc. However, some interesting parameters are usually withheld from the end user. These parameters include, for example, the loss in the energy flow from the battery to the driving wheels or the rolling resistance of the vehicle. However, since these loss parameters have a significant influence on the vehicle’s consumption, it is of interest to know them. This article presents a method for determining these two parameters. The basis for this are simple driving tests that can be carried out by anyone on public roads.

A nylon-like polyester tire cord, which combined the characteristics of nylon and polyester tire cords, was designed as the carcass reinforcement material used to meet the increasing demands of the tire industry for performance and impact on the environment. Tires’ carcass construction plays a crucial role in affecting handling performance and ride comfort. Small changes in the carcass component can lead to significant improvements in the total tire/vehicle performance. This study evaluated the performance of nylon-like polyester and nylon 6 motorcycle tires. The results showed that the nylon-like polyester tire passed all indoor tests, and post-cure inflation (PCI) could be eliminated, resulting in energy and cost savings. The rolling resistance coefficient of the nylon-like polyester tire was reduced by 6.8% compared to that of the nylon 6 control tire, which could save fuel and have a positive impact on the environment. Nylon-like polyester tire cord extracted from the experimental tire possessed a higher modulus compared to that of nylon 6 tire cord, which could lead to better handling and ride comfort performance. Morphological pictures showed that both nylon-like polyester and nylon 6 cords extracted from tires had a good rubber coverage and comparable adhesion properties.

In recent years, the research on airless tire (Non-pneumatic tire, NPT) for passenger cars has received extensive attention. The background to this is the development of autonomous driving technology. Autonomous driving of Level 4 and above is un-manned driving, so it is more important to reduce the frequency of maintenance due to accidental failures, and punctureless airless tires are expected as tires for autonomous driving vehicles. Rolling resistance of tires is a highly important property for tire development. The reduction of rolling resistance of tires has become more significant in the tire industry, because it has close relation to the fuel consumption efficiency. As for conventional pneumatic tire, the rolling resistance is mainly generated by energy loss of tire components during tire deformation and it is well known that to reduce the rolling resistance, tanδ of rubber should be decreased. The purpose of this study is to clarify the contributing factors of airless tires to rolling resistance. As a result of measuring the tire force generated by a rolling experiment using a scale model airless tire, it was confirmed that the wheel load fluctuated impulsively. Therefore, we observed the tire deformation during rolling with a high-speed video camera and clarified the mechanism of tire force generation.

An experimental investigation was conducted in this study to assess the effect of the front toe angle and tire pressure on the fuel efficiency of light-duty vehicles. According to the investigations, increasing the toe angle results in an increase in rolling resistance, which has an impact on the fuel efficiency of the vehicle. It was observed that due to misalignment of the front toe-in angle (0.00° to 5.06°) and front toe-out angle (0.00° to −5.06°), the car had traveled approximately 7.38 km and 7.63 km less for the same amount of fuel. The rate of increase in fuel consumption was found to be about 74 % and 79.31 %, respectively. Also, it was shown that under steady-state conditions, the rolling resistance varies nonlinearly with tire inflation pressure while the fuel consumption varies nearly linearly. As the tire pressure lowered (under-inflation, 22 psi), it was observed that the vehicle's rolling resistance rose at a rate of nearly 85.10 % and fuel consumption increased at a rate of nearly 40.29 %. In contrast, the rolling resistance and fuel consumption were considerably reduced as the tire pressure increased from 33 psi to 42 psi (over-inflation). Finally, a regression model was proposed using test data. Such a model would be useful to explain the relationship between the related factors and determine the rate of fuel consumption. [ABSTRACT FROM AUTHOR]

Rolling resistance (RR) is key research content for developing low-carbon energy-saving tires, and the resultant change in the tire temperature field exerts a crucial impact on tire performance. Currently, there is no accurate and systematic analysis method for solving the steady-state temperature field (SSTF) and RR of tires with complex patterns and non-pneumatic tires (NPTs), which are characterized by discontinuous structure in the circumferential direction. A solution strategy that entails SSTF and RR based on explicit transient rolling analysis and thermal-mechanical coupling is proposed and its accuracy is verified using the SSTF test pertaining to the low-speed and low-load capacity non-pneumatic tire (LSL-tire), which exhibits a 7.56% and 6.94% average temperature deviation for the outer surface center of the tread and for the outer surface center of spokes, respectively. Uniaxial tensile mechanical property tests and dynamic mechanical analysis (DMA) of the utilized rubber and polyurethane (PU) materials were conducted, and their specific heat capacity, thermal conductivity, and density were tested. Based on three-dimensional nonlinear finite element simulation and considering the characteristics pertaining to the loss factor of viscoelastic materials changing with temperature, the SSTF and RR of the LSL-tire under different loads and velocities were analyzed. The results indicate that the influence of load and speed on the SSTF of LSL-tire is quite significant, whereas the influence of speed on the RR is not apparent. For all conditions, the highest steady-state temperature points of the tread are located in its center, and in the spokes they are located in the joint between spokes and the outer ring; the spokes contribute the most to the RR, followed by the tread. [ABSTRACT FROM AUTHOR]

The dispersion of fillers，physical and mechanical properties and dynamic mechanical properties of vulcanizates were investigated using two grades of solution polymerized styrene butadiene rubber (SSBR) FX 5021 and FX 3211 as matrix materials and silica as reinforcing fillers. The results showed that the silica in FX 5021 compound had better dispersion, and the curing rate of FX 5021 compound was slower. FX 5021 vulcanizate had higher tensile strength and modulus, while FX 3211 vulcanizate had higher tear strength, resilience and abrasion resistance. FX 5021 vulcanizate had higher wet skid resistance and rolling resistance.

In this paper, an accelerant with vulcanization‐promoting and silanization‐promoting effects, 1,3‐diphenylguanidine (DPG), is loaded on green filler silica by high‐energy ball milling technology. Meanwhile, DPG breaks the ionization equilibrium of latex and realizes the self‐flocculation. The DPG‐induced self‐flocculation technology promotes the dispersion of silica and the silanization reaction, forming more complete filler‐rubber network and three‐dimensional crosslinking network. X‐ray diffraction, Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis results show that the ball milling technology makes DPG strongly adsorbed on the surface of silica, and the loading rate is 14.4%. Compared with dry mixing, the ball milling‐self‐flocculation technology increase the silanization index, tensile strength and aging coefficient by 8%, 31%, and 19%, respectively. The curing rate is improved, and the rolling resistance is the lowest. This research provides a green flocculation technology of the raw materials in formula without other flocculants and acidic wastewater discharge, avoiding the serious dust pollution and high energy consumption in the dry mixing process, as well as the poor aging resistance of rubber in the acid flocculation process of latex. [ABSTRACT FROM AUTHOR]