Wheel Size Research Articles

Effect of wheel size and tread braking on subsurface crack initiation in heavy haul car wheels

Subsurface cracks initiating from internal defects are one of the main rolling contact fatigue damages that occur in heavy haul car wheels. Finite element analyses of the wheels are performed to assess the effects of the wheel size and tread braking on the subsurface crack initiations. Critical defect sizes for the subsurface crack initiations are calculated from the results of finite element analyses and fatigue tests of the wheel steel based on the multiaxial fatigue evaluation model. The critical defect sizes of 38 and 36 inch wheels are almost equivalent in service conditions in accordance with the AAR (the Association of American Railroads) standard. On the other hand, the 33-inch wheel has a larger critical defect size than the 38 and the 36-inch wheels. The 33-inch wheel has smaller stresses at the subsurface because it has a smaller wheel load than the other wheels. Stop braking with normal brake energy has fewer effects on the critical defect size. Therefore, the tread braking in this study is considered to have no negative effect on subsurface crack initiations.

Reliable and Accurate Wheel Size Measurement under Highly Reflective Conditions.

Structured-light vision sensor, as an important tool for obtaining 3D data, is widely used in fields of online high-precision measurement. However, the captured stripe images can show high-dynamic characteristics of low signal-to-noise ratio and uneven brightness due to the complexity of the onsite environment. These conditions seriously affect measurement reliability and accuracy. In this study, a wheel size measurement framework based on a structured-light vision sensor, which has high precision and reliability and is suitable for highly reflective conditions, is proposed. Initially, the quality evaluation criterion of stripe images is established, and the entire stripe is distinguished into high- and low-quality segments. In addition, the multi-scale Retinex theory is adopted to enhance stripe brightness, which improves the reliability of subsequent stripe center extraction. Experiments verify that this approach can remarkably improve measurement reliability and accuracy and has important practical value.

Theoretical analysis of electric vehicle energy consumption according to different driving cycles

The paper presents a theoretical analysis of energy consumption according to selected driving cycles. The aim of the study was to analyse the impact of various acceleration and speed values on the energy consumption of an electric vehicle. The object of the study was the Nissan Leaf vehicle, equipped with a synchronous AC electric motor. The research methodology involved creating a mathematical model based on the technical and operational parameters of the vehicle. The characteristics of the torque of the electric motor of the test object were used, the basic and additional resistance values were determined using the vehicle’s technical parameters such as: complete vehicle kerb weight plus the mass of passengers and cargo, useful battery capacity, width and height, type of a drive system used, wheel sizes. Finally, the energy consumption for each driving cycle was determined. According to the NEDC cycle, it amounted to a maximum of 15.6 kWh/100 km and was by 4 percent higher than the producer stated.

Unsteady pressure analysis of the near wall flow downstream of the front wheel of a passenger car under yaw conditions

The flow around passenger cars is complex and is characterized by many different structures and interactions. The occurring flow phenomena around a car determine crucial vehicle properties such as the driving stability, the noise level, the aerodynamic performance and the vehicle contamination. Therefore, it is of high importance to increase the understanding of the developing flow phenomena. Generic models are widely used to investigate flow structures and their interactions, but cannot serve to derive a general flow field for detailed full-scale vehicle models. A particularly complex area is the flow around the wheels and its interaction with the vehicle geometry. Studies on wheel-wheelhouse flow focus mainly on the geometrical influence of the wheel size, rim and tyre on the aerodynamic drag and the flow field close to the wheel. The present work investigates the flow behind the front wheel arch of a full-scale passenger car. Time resolved surface pressure measurements were taken to study the near wall flow under different yaw conditions. Based on the data obtained, flow structures are identified and their propagation speed is calculated. Further, characteristic frequencies observed are discussed. It is found that coherent structures are present behind the front wheel arch, one above the wheel centre height and one below it. These remain even under large yaw angles, no matter if the vehicle is yawed to lee- or windward. The investigation further shows that two characteristic frequencies can be found, St=0.03 and St=0.2, whereby the latter is caused by the wheel rotation. The same frequencies also occur under yaw conditions, but yawing the measurement area to leeward results in less pronounced frequency peaks.

Initial Design Characteristics, Testing and Performance Optimisation for a Lunar Exploration Micro-Rover Prototype

In the field of space and planetary missions, the use of robotic systems for exploration tasks has become quite common. The recent emergence of private ventures will increase the number of missions in the upcoming years, but the budget for each one of them will have to be considerably lower than that of government-based projects. With celestial bodies the size of the moon, sending a single rover has become inefficient for full-surface exploration, mapping and resource prospecting. To achieve these objectives, two main fields require further research. First, reducing single rover’s cost by making them smaller and simplifying their onboard equipment. Second, collaboration strategies for large groups of rovers should be devised to enable faster surface exploration. We are currently working on a 1-kg, three-wheeled rover prototype called Koguma. This platform is, first and foremost, to demonstrate the potential of deploying small rovers for planetary exploration. The simple design and low manufacturing cost associated with it will enable the integration of a larger number of prototypes, opening up more possibilities of field testing the collaboration software. The main concern surrounding this category of rovers is to determine the limits of their motion performances. To qualify for planetary missions, traversal capability over loose soils of varying steepness has to be assessed. In this paper, we present the design characteristics of this initial prototype. Inherited from previous generations of two- and three-wheeled rovers, we start by explaining the main motivations towards this model. From mass budget to dimensions, materials and system architecture, we will explain the ideas and reasoning behind our choices. We will then present the results surrounding initial performance tests on the Koguma platform. We conducted slope-climbing experiments using an orientation controllable sandbox. Mobility performance is assessed by evaluating the relationship between wheel key parameters and capabilities. These parameters are radius, width, and grouser size of the front wheels. Through this, we propose the first approach of design recommendations for the development of light, three-wheeled rovers.

歯科用合金の複合研削に関する研究 : (第3報) 研削面性状に及ぼす砥石の粒度, 研削荷重, 電流密度の影響

歯科用合金の複合研削に関する研究 : (第3報) 研削面性状に及ぼす砥石の粒度, 研削荷重, 電流密度の影響

Impact of Multiaxial Propulsion System of Machine-and-Tractor Units on Soil Density

Use of the powerful tractors as a part of the machine-and-tractor units (MTU) is limited to high impact of their propellers (deformers) on the soil. The increase in tractor weigh and the multiple MTU passes result in overconsolidation of the soil. As a result, physical and mechanical soil properties are modified. The modified quality of soil structure is difficult to be restored entirely. As a result the intensive tilled soil degrades with time and all that creates the ecosystem disbalance of cultivated land. The power method based on regularities of absorption of energy by various soil layers was applied to calculate indicators of soil consolidation. The energy method based on the regularities of the energy absorption by different soil layers was applied to calculate the soil consolidation rate. The conducted researches show that at a pressure of 150 kPa and humidity of 19.2 percent the soddy podzolic loam sand soil density increased from 970 to 1260 kg per cubic metre. The increase in number of the drive system axles can reduce the consolidation of the topsoil as well as lower layer.The intensity of decrease of soil panning considerably decreases when quantity of axes is over four. If the pressure upon the high workhardening soil is constant (the sizes of wheels increase at reduction of axes quantity) then the reducing of the dip of the wheel track can be obtained by increasing the number of the drive system axles. On the low work-hardening soil the effect of reduction of depth is not so much. Increasing the number of axles and the size of wheels for low work-hardening moisty soils is equally effective for reducing the dip of the wheel track. For the overmoist soils it will be better to increase the sizes of a basic surface of running system. If the number of axes is more than four then the decrease of high work-hardening soils consolidation will be less intensive.

Systematic design and development of a flexible wheel for low mass lunar rover

Low mass compact rovers provide cost effective means to explore extra-terrestrial terrains. Use of flexible wheels in such applications where the wheel size is restricted, improves traction at reduced slip and sinkage. Design of a flexible wheel for a given mission is a challenging task requiring consideration of stiffness of rim and spokes, stress induced in the wheel, chassis movement during wheel rotation and the operating mode of the wheel. Also, accurate mathematical models are required to save design and development time and reduce the number of prototypes for selection. It is observed that most of the research papers deal with performance testing of flexible wheels and information on analytical formulation is scarce. Therefore, in the present work, a methodology has been formulated to systematically design a flexible wheel for a low mass lunar rover. The prototype performance is tested and compared with analytical estimates and reasons for difference are investigated. Paper contains details of design criteria, mathematical modelling, realisation of wheel prototype, test fixture and analysis test comparison. Authors believe that this work provides a useful aid to the designer to systematically design flexible wheels for low mass lunar rovers.

Traction performance of different size of cage wheel for power tiller

The selection of cage wheel is of primary importance in tillage operations for the optimization of traction performance. Selection of proper cage wheel helps in limiting slip and fuel consumption which involves energy loss and it also minimize time required for soil tillage. The present study aim to investigate the tractive and drawbar performance of different diameter of cage wheels. Three cage wheels of diameter 68 cm, 73 cm, and 78 cm with 30° lug angles were tested in four different water levels of 5 cm, 10 cm, 15 cm and 20 cm in wet land field conditions. Results shows that cage wheel of 73 cm diameter gave better performance in terms of higher tractive efficiency with less power consumption, than other cage wheels. Reducing the diameter of cage wheel increases the draft and sinkage and blocking of soil on lug surface. The maximum tractive efficiency was found in the range of 73–78% at 789 N to 1224 N draft and drawbar power was in the range of 505 W to 565 W.

Impact of Wheel Size on Energy Expenditure during Mountain Bike Trail Riding

This study examined the energy expenditure during mountain bike trail rides on a 26-inch wheel (26er) compared to a 29-inch wheel (29er). Thirteen experienced bikers (four women, nine men, age=33.0±10.1 yrs), completed similar 6.7km trail rides on a 26er and 29er. GPS was used to measure distance and speed during each ride. Energy expenditure was determined by measuring oxygen consumption. Compared to the 26er, the 29er rides took less total time (24.2±3.2 vs. 25.5±3.5 minutes, p=0.015), hence faster speeds (4.7±0.6 vs. 4.4±0.6 m•s-1, p=0.022), lower average heart rates (155.0±19.2 vs. 162.2±16.8 bpm, p=0.047), and lower total calories (263.3±34.3 vs. 290.7± 36.9 kcals, p=0.001). Work rates represented by the rate of oxygen consumption (ml O2•min-1, p=0.65) were not different. At similar work rates, riders apparently gained a mechanical advantage on the 29ers allowing for 5% lower riding times and heart-rates, 6.8% faster speeds, and a 9.4% reduction in the total caloric expenditure for a standardized trail ride.

Hydrodynamic design of an enclosed Horizontal BioReactor (HBR) for algae cultivation

Modeling and optimization of key design parameters of bioreactors are critical for development of economically and technically viable algae technologies. The objective of this study is to use computational fluid dynamics (CFD) modeling to design a novel enclosed Horizontal BioReactor (HBR) equipped with a paddle wheel that incurs low capital and operating costs like raceway ponds, but achieves high productivities like enclosed photobioreactors. For the HBR the aspect ratio (length-to-width), paddle wheel diameter and positioning, culture depth, and baffle spacing can be manipulated to achieve adequate flow of the culture that minimizes the formation of low-velocity areas, below 20cm/s, termed “dead zones”. The CFD procedure focused on minimizing dead volume and power consumption. A small-scale HBR (3m2 of surface area) was used for development and validation of the hydrodynamic model, whose parameters were calculated using experimental data. The model was then applied to a pilot-scale HBR (40m2) that is operated outdoors. Placing the paddle wheel at either end of the reactor or incorporating baffles minimized the dead volume. The same effect was also achieved by increasing the size of the paddle wheel or the number of paddle wheels or the depth of the culture. On the other hand, increasing the reactor's aspect ratio resulted in more dead volume, although it decreased power consumption. These findings will be incorporated into the design of large-scale HBRs (200m2) for commercial deployment.

Design and analysis of outer rotor in-wheel motor for micro-electric vehicle

In order to improve the working performance and service life of the in-wheel motor for micro-electric vehicle, the outer rotor in-wheel motor of micro-electric vehicle is designed and the model is analyzed, which are based on the theory of electromagnetic field and working principle of the motor. Besides, the size of the micro-electric vehicle wheel is optimized and designed, and the length of the internal and external diameters of inner stator and outer rotor of the outer rotor in-wheel motor are designed and calculated. According to the air-gap selection principles, the parameter of air gap is designed and determined. Some important parameters are derived and calculated, such as the pole-arc coefficient, air-gap magnetic flux density, gap coefficient, and the coefficient of air-gap flux waveforms. The finite element model outer rotor of in-wheel motor is established by Ansoft Maxwell software, and the finite element mesh subdivision is carried on. Magnetic flux densities, magnetic field strength, and magnetic line of force are analyzed by dynamic simulation, and the starting characteristics and the change of torque curve are studied and analyzed. The final simulation analysis results are in good agreement with the design calculation results, which indicate that design scheme of outer rotor in-wheel motor is useful that can meet the performance requirements of outer rotor in-wheel motor for micro-electric vehicle.

Numerical generation of grinding wheel surfaces based on time series method

Surface integrity has a significant influence on the functional behavior of engineering components. An effective grinding wheel topography model is the foundation to realize the controllable design and manufacturing of grinding workpiece surface integrity. In this study, a moving average model (MA) based on time series method was proposed to generate the grinding wheel surface topography. 3D grinding wheel topographies were measured by an LSM 700 laser scanning confocal microscope (CLSM). The Johnson transformation system was applied to generate the non-Gaussian sequence with predetermined statistical parameters. To address the convergence and memory requirement problems, the non-linear conjugate gradient method (NCGM) with an exact line search by the secant method was employed to solve the system of nonlinear equations. The results showed a good agreement between the measured and the generated surfaces in terms of the autocorrelation function (ACF) and statistical parameters was achieved. It is worth noting that the computing time of the model developed in this study is only determined by the autocorrelation lengths which are almost independent of the size of the grinding wheel. This technique could be more efficient when applied to grinding wheels with large size. Therefore, this method may serve as an effective way to solve the grinding wheel topography reconstruction problem.

Modeling and Simulation of Two Wheelchair Accessories for Pushing Doors

ABSTRACTIndependent mobility is vital to individuals of all ages, and wheelchairs have proven to be great personal mobility devices. The tasks of opening and navigating through a door are trivial for healthy people, while the same tasks could be difficult for some wheelchair users. A wide range of intelligent wheelchair controllers and systems, robotic arms, or manipulator attachments integrated with wheelchairs have been developed for various applications, including manipulating door knobs. Unfortunately, the intelligent wheelchairs and robotic attachments are not widely available as commercial products. Therefore, the current manuscript presents the modeling and simulation of a novel but simple technology in the form of a passive wheelchair accessory (straight, arm-like with a single wheel, and arc-shaped with multiple wheels) for pushing doors open from a wheelchair. From the simulations using different wheel shapes and sizes, it was found that the arc-shaped accessory could push open the doors faster and with almost half the required force as compared to the arm-like accessory. Also, smaller spherical wheels were found to be best in terms of reaction forces on the wheels. Prototypes based on the arc-shaped accessory design will be manufactured and evaluated for pushing doors open and dodging or gliding other obstacles.

An approach on wheel position and orientation calculation for helical broaching tool sharpening

Helical chip gullets play a crucial role in the performance of broaching tool. Well-sharpened helical rake flanks, which require accuracy of rake angle, smoothness of rake flank, and the safety of operators, are significantly to maintain its broaching performance. In this study, a wheel orientation and position calculating approach was developed to the resharpen of helical rake flank by a ring-like grind wheel. With modeling the process requirements of helical rake flank sharpening as the constraints like single side contacting and desired rotation direction of grinding wheel, the enveloping theory-based contact curve identification helped the wheel orientation calculation approximate to a nonlinear searching problem for easily addressing by Newton-Raphson method. Then, the analyses of contact curves with different wheel orientations and a ground helical rake flank proofed the sharpening process requirement was satisfied, and the examined results of rake angle for both ground rake flank and simulated bars verified the accuracy of the presented approach. At last, optimal grinding wheel setup that has taken larger wheel size and practicable orientation was suggested based on the relationship analysis among wheel radiuses and orientations.

INVESTIGATION OF STRENGTH PROPERTIES OF IMPELLERS MADE OF COMPOSITE MATERIAL FOR DIESEL ENGINES

The purpose of the paper is to perform a comparative analysis of the strength properties of impellers made of a composite material with strength properties of impellers made of aluminum alloy. The main method of this study is the finite element method. Pre-and post-processor Femap was used to prepare the model and process the research results. The calculations were performed using a linear solver NX Nastran. Calculations are carried out for two wheel sizes (two diameters) and two calculated cases (for maximum working angular velocity and for destructive velocity). During research stress-deformed states of impellers were obtained. Stress distribution is qualitatively identical in all design options. Redistribution of stresses in impellers due to different materials stiffness is absent. Strength factor as a result of replacement of materials for the 1st and 2nd sizes fell by 7.8 and 5 %, respectively (absolute values - 1.06 and 1.16 respectively). Stress-deformed states obtained during strength calculation can be used for the subsequent manufacture of an impeller made of an anisotropic material. The calculation of frequencies and forms of free oscillations showed a decrease in the frequencies of free vibrations of impellers made of composite material, but it should be noted that even the «lowest» frequencies have approximately twice the maximum frequencies of the working range of the turbocharger. The results of the analysis show the promise of replacing materials in order to improve reliability. Strength calculation showed the need for additional experimental studies of impellers made of composite materials.

Design of a transformable mobile robot for enhancing mobility

This article proposes a design of a transformable mobile robot as a new concept of hybrid-type mobile robot in order to enhance mobility. Mobility considered in this work is based on stability, energy efficiency, and the capability to overcome obstacles. The proposed transformable mobile robot can change its bogie link lengths and wheel size. The relationships between mobility and the link length and the wheel size are studied. Its stability, energy efficiency, and the capability to overcome obstacles are compared through the simulations of three famous conventional passive bogie-type robots (Rocker-Bogie, RCL-E, and CRAB types) and the proposed robot. The simulation and experimental results show that the suggested transformable robot is superior to the conventional-type robots in terms of mobility enhancement.

An Analytical Method for Prediction of Material Deformation Behavior in Grinding Using Single Grit Analogy

FEM simulation and single grit experimental techniques are available to get an insight into the chip formation mechanism in grinding operations. However, those are case specific. In the present work, an analytical method has been developed by considering specific energy criteria and Johnson's indentation theory to predict the modes of chip formation. The force acting on an abrasive grit at every instance in a trajectory path has been calculated by considering grit size, wheel size, kinematic conditions and work material properties. Yield coefficient and non-dimensional strain at the grit-work interaction have been computed to identify mainly the ploughing to cutting transition phase.

Research on product value of wheel diameter and rotational speed — A new design parameter for micro radial turbines

The physical realizability is the primarily consideration in micro radial turbine design. The determination of realizability mainly depends on the physical size (wheel diameter) and operation condition (rotational speed). In the past design, the product value of wheel diameter (D) and rotational speed (N) was taken as design result, but this value would lead repeating works because it may not appropriate for the realizability of micro radial turbine. This paper takes DN value as a design parameter to help the micro radial turbine design directly. The analysis of matching relationship between stage velocity ratio and degree of reaction was studied firstly. The influence of matching effects was investigated secondly. Then the DN value was presented and the theoretical research for optimal value selection was conducted thirdly. Compared with the other design parameters, the DN value can reflect the effect of efficiency, wheel size, rotational speed and design working condition directly and the effect of wheel material, structure style, shafting and bearings type directly. So the DN value is a highly concentrated and useful parameter for micro radial turbines. Some aerodynamic and structure parameters of micro radial turbine will be facilitated and designed by using the method of this paper.

The effect of mountain bike wheel size on cross-country performance

ABSTRACTThe purpose of this study was to determine the influence of different wheel size diameters on indicators of cross-country mountain bike time trial performance. Nine competitive male mountain bikers (age 34.7 ± 10.7 years; stature 177.7 ± 5.6 cm; body mass 73.2 ± 8.6 kg) performed 1 lap of a 3.48 km mountain bike (MTB) course as fast as possible on 26″, 27.5″ and 29″ wheeled MTB. Time (s), mean power (W), cadence (revs · min−1) and velocity (km · h−1) were recorded for the whole lap and during ascent and descent sections. One-way repeated measure ANOVA was used to determine significant differences. Results revealed no significant main effects for any variables by wheel size during all trials, with the exception of cadence during the descent (F(2, 16) = 8.96; P = .002; P2 = .53). Post hoc comparisons revealed differences lay between the 26″ and 29″ wheels (P = .02). The findings indicate that wheel size does not significantly influence performance during cross-country when ridden by trained mountain bikers, and that wheel choice is likely due to personal choice or sponsorship commitments.