Wheel Size Research Articles

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

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

Imprinting high-gradient topographical structures onto optical surfaces using magnetorheological finishing: manufacturing corrective optical elements for high-power laser applications.

Corrective optical elements form an important part of high-precision optical systems. We have developed a method to manufacture high-gradient corrective optical elements for high-power laser systems using deterministic magnetorheological finishing (MRF) imprinting technology. Several process factors need to be considered for polishing ultraprecise topographical structures onto optical surfaces using MRF. They include proper selection of MRF removal function and wheel sizes, detailed MRF tool and interferometry alignment, and optimized MRF polishing schedules. Dependable interferometry also is a key factor in high-gradient component manufacture. A wavefront attenuating cell, which enables reliable measurement of gradients beyond what is attainable using conventional interferometry, is discussed. The results of MRF imprinting a 23 μm deep structure containing gradients over 1.6 μm / mm onto a fused-silica window are presented as an example of the technique's capabilities. This high-gradient element serves as a thermal correction plate in the high-repetition-rate advanced petawatt laser system currently being built at Lawrence Livermore National Laboratory.

The Effect of the Quenching Method on the Deformations Size of Gear Wheels after Vacuum Carburizing

Abstract This paper presents a comparison of the deformations and residual stresses in gear wheels after vacuum carburizing process with quenching in high-pressure nitrogen and oil. The comparison was made on a medium-sized gear wheels, made of AMS6265 (AISI 9310) steel. This steel is applied in the aerospace industry for gears. The study has provided grounds for an assessment of the effect of the method of quenching on the size of deformations. Compared to oil quenching, high-pressure gas quenching following vacuum carburizing resulted in more uniform and smaller deformations.

Impact of Wheel Size (26 vs 29 inch) on Energy Expenditure during Mountain Bike Trail Riding

Impact of Wheel Size (26 vs 29 inch) on Energy Expenditure during Mountain Bike Trail Riding

Influence of Grinding Wheel Dressing on the Roughness of Final Surface and Cutting Force during GGG60 Grinding

Dressing of grinding wheel is important value, which can influence final surface. Therefore, it is necessary to address this issue some attention. Dressing is used for sharpening of clogged and blunted grinding wheel and adjustement of their geometric shape. The article deals with one of the experiments that are carried out in this area at FPTM JEPU in Ústí nad Labem. Experiments refer specifically to impact assessment of dressing size on the final selected values of surface integrity. Within the article, the assessment covered the surface roughness Ra, Rz and Rt. At the same time were also scanned using a dynamometer Kistler components of the cutting forces and even here it was possible to observe the influence of the dressing size of the grinding wheel on these values.

The effect of caster wheel diameter and mass distribution on drag forces in manual wheelchairs.

This study proposes a way to reduce energy losses in the form of rolling resistance friction during manual wheelchair propulsion by increasing the size of the front caster wheels and adjusting the weight distribution. Drag tests were conducted using a treadmill and a force transducer. Three different casters diameter (4 in., 5 in., and 6 in.) and six different mass distribution combinations (based on percentage of total weight on the caster wheels) were studied. A two-way analysis of variance test was performed to compare caster size and weight distribution contribution with drag force of an ultralight wheelchair. The 4 in. caster contributed significantly more drag, but only when weight was 40% or greater over the casters. Weight distribution contributed more to drag regardless of the casters used.

Improvement of Surface Roughness with Micro-Axial Vibration of Spindle by Pressure Pulsation of Grinding Fluid Supplied through inside of Wheel

In grinding, the moving trajectories of abrasive grains are almost straight to the motion of the rotation and feed of the grinding wheel, so that grinding marks are formed continuously. As a result, surface roughness is dependent on grain size and organization of the grinding wheel. If the trajectory of the abrasive grain is wavy, the peak lines of the grinding marks will be partially removed by following the abrasive grain. This improves surface roughness. The objective of this study is to develop a mechanism to give axial vibration to the grinding wheel by the pulsation of the plunger pump, and thus to improve the surface roughness of the machined surface.

ELID Fine Grinding of Sapphire Rollers with Emphasis on Roughness and Material Removal Rate

The demand for sapphire (α-Al2O3) has significantly increased due to its reliable properties. Sapphire is known for its high hardness and high brittleness. Sapphire has excellent properties such as optic, mechanical and physical properties, which can be maintained even if machined in high temperatures. Due to these properties, sapphire has been used in many different applications such as aerospace, optics, and electronics as well as other industries. Machining of Sapphire is challenging due to its high hardness and brittleness. Fine grinding can be preferable over conventional grinding when machining ceramics because of the ability to provide a flat surface. However, the manufacturing cost for such materials is very high because of high tool wear and longtime machining. In addition, most of the grinding process is followed by a lapping process. Elimination of lapping process can be accomplished using many techniques, one of which is the use of electrolytic in process dressing (ELID). Therefore, the use of fine ELID grinding will reduce the machining time which in turn reduces the manufacturing cost. Part of the solution also investigates the influence of different variables on the workpiece surface finish. This paper presents the influence of four parameters with three level each: different pressures, different eccentricities, different spindle speeds, and different wheel speed ratios. A full factorial design, for both roughness (Ra) and material removal rate (MRR) conducted to present mathematical models which predict future results. The kinematics of the process will be investigated based on the effect of different eccentricity. The mesh size of the diamond grinding wheel used in this experiment is #400.

A Novel Online Detection System for Wheelset Size in Railway Transportation

The online detection of wheelset size has important implications for ensuring the safety of railway operation and decreasing the maintenance costs. Based on laser displacement sensors (LDS), a novel online detection system of the wheel size is proposed using only six two-dimensional LDS and two one-dimensional LDS. The calculation principles of tread profile and wheel diameter are given, as well as the calibration method. Errors induced by wheel-rail vibration, misalignment, sensor noise, S-shape running, and wheelset differential are also analyzed. After system implementation, field experiments were performed using both standard wheel and several real trains. It turns out that the detection uncertainty of flange width and height is 0.1 mm and wheel diameter 0.3 mm, which can meet the requirements of maintenance.

Online detection system for wheel-set size of rail vehicle based on 2D laser displacement sensors

The real-time detection of wheel-set size, the most significant technical parameter during vehicle operation, has important implications for ensuring the safety of wheel running. Based on laser ranging, an online detection system of the wheel size installed below the track is developed. Eight two-dimensional (2D) laser displacement sensors are applied to detect the wheel-set size including wheel flange and tread profile. A digital I/O card is utilized to generate synchronous signals which guarantee simultaneous working of all sensors. Least square based curve fitting and pick-up algorithm of tread feature-points are used to process the measured data and calculate the flange width, flange height and wheel diameter. The experimental results show that the online detection system of wheel-set size can realize the non-contact, dynamic and real-time measurement of wheel-set parameters. When train running speed is under 5km/h and sampling frequency is 30Hz, the detection accuracy of flange width and height is ±0.2mm and the detection accuracy of wheel diameter is ±0.5mm, which can meet the requirements of maintenance operation.

Improvement of Surface Roughness with Micro-Axial Vibration of Spindle by Pressure Pulsation of Grinding Fluid Supplied through inside of Wheel

In grinding, the moving trajectories of abrasive grains are almost straight to the motion of the rotation and feed of the grinding wheel, so that grinding marks are formed continuously. As a result, surface roughness is dependent on grain size and organization of the grinding wheel. If the trajectory of the abrasive grain is wavy, the peak lines of the grinding marks will be partially removed by following the abrasive grain. This improves surface roughness. The objective of this study is to develop a mechanism to give axial vibration to the grinding wheel by the pulsation of the plunger pump, and thus to improve the surface roughness of the machined surface.

Attitude control system design using a flywheel suspended by two gimbals

This work presents the attitude control system design procedures for a three axis stabilized satellite in geostationary orbit, which contains a flywheel suspended by two gimbals. The use of a flywheel with two DOFs is an interesting option because with only one device it's possible to control the torques about vehicle's three axes; through the wheel speed control and gyrotorquing phenomenon with two DOFs. If the wheel size and speed are determined properly it's possible to cancel cyclic torques using gas jets only periodically to cancel secular disturbance torques. The system, based on a flywheel, takes only one pitch/roll (earth) sensor to maintain precise attitude, unlike mass expulsion based control systems, which uses propellants continuously, beyond roll, pitch and yaw sensors. It is considered the satellite is in nominal orbit and, therefore, that the attitude's acquisition phase has already elapsed. Control laws and system parameters are determined in order to cancel the solar pressure radiation disturbance torque and the torque due to misalignment of the thrusters. Stability is analyzed and step and cyclic responses are obtained.

Evaluation of Vehicular Discomfort Measures Produced by Speed Bumps Using Numerical Simulation

In the design of automotive components the use of numerical simulations has contributed to reducing the design time, decreasing the prototypes costs and increasing reliability of the final product. However is necessary a investigation on human body vertical vibrations transmitted by different types of vehicle for the purpose of recognition the danger and guiding to eliminate of risks of discomfort theirs. This study, the object is to compare the discomfort levels of occupants when different vehicles (car, bike and bus) move over a speed bump. The results show that wheelbase, wheel size and vehicle weight can lead to different vehicular discomfort results. Results of the study demonstrated that heavy vehicles occupants (bus or truck) are subject to discomfort greater than occupants of light vehicles (cars and motorcycles) ones.

초음파 센서를 이용한 모션 인식 차량 통합 제어 장치의 제작 및 실험

Worldwide, studies on intelligent vehicles for the convenience of drivers have been actively conducted as the number of cars has increased. However, vehicle convenience enabled by buttons lowers the concentration on driving and hence poses as a huge threat to the safety of the driver. The use of one of the convenient features, impaired driving auxiliary equipment, is limited because of its complex usage, and this device also hinders the front view of the driver. This paper proposes a vehicle-control device for controlling the convenient features as well as changes in speed and direction using gestures and motions of the driver. This device consists of an ultrasonic sensor for recognizing movement, an arduino for accepting signal control functions and servo and DC motors apply to various vehicle parts. Firstly, the vehicle-control device was designed using a 3D CAD program known as Solid-works based on the size of the steering wheel. Then, through simulations, a suitable length for minimizing the absorbent between ultrasonic sensors was confirmed using a program known as COMSOL Multiphysics. Finally, simulation results were verified through experiments, and the optimal size of the device was identified through the number of errors.

Online monitoring of precision optics grinding using acoustic emission based on support vector machine

This paper aims to accomplish online monitoring of precision optics grinding with processing condition factors based on theoretical analysis and through grinding experiments. The model for monitoring surface quality of optical elements online (OSQMM) which contains identification model (IM) and interpolation·factor-support vector regression (i•f-SVR) is proposed. IM is applied to analyze and determine which kind of processing condition factors and which kind of its feature parameters are the best one to be used for online monitoring. i•f-SVR which contains the effect factor (fe) and interpolation function (I) to overcome the drawbacks of existing SVR models is applied to predict the monitoring thresholds. The grinding experiments were designed and performed. The influences of technological parameters (e.g., grain size of the grinding wheel, grinding depth, speed of the grinding wheel, speed of the worktable, and materials of workpiece) and processing condition factors (e.g., acoustic emission, grinding force, and vibration) on the surface quality were investigated and analyzed by IM. i•f-SVR was trained and established by the data which were gained through the experiments. After that, the other grinding experiments were performed to apply and verify OSQMM. The results were that the accuracy of alarm for roughness was 85.19 % and the accuracy of alarm for surface shape peak–valley value was 75.93 %. The results show that this method can be effectively applied to monitor the precision optics grinding process online.

Evaluation of the Power Generation Capacity of Hydrokinetic Generator Device Using Computational Analysis and Hydrodynamic Similitude

This paper presents a similitude and computational analysis of the performance of a scaled-down model of a paddle wheel style hydrokinetic generator device used for generating power from the flow of a river. The paddle wheel dimensions used in this work are one-thirtieth scale of the full-size paddle wheel. The reason for simulating the scaled-down model was to prepare for the testing of a scaled-down physical prototype. Computational Fluid Dynamics using ANSYS Fluent 14.0 software was used for the computational analysis. The scaled-down dimensions were used in the simulations to predict the power that can be generated from the scaled size model of the paddle wheel, having carried out similitude analysis between the scaled down size and its full-size. The dimensionless parameters employed in achieving similitude are the Strouhal number, power coefficient, and pressure coefficient. The power estimation of the full-size was predicted from the scaled size of the paddle wheel based on the similitude analysis.

Development of a Tactile Wheel for a Small Robot Using an Infrared Proximity Sensor

Tactile sensors are very important components in robots, not only in robot hands but also in mobile robots since the robot is always in contact with the terrain. This study describes a new tactile wheel for a small robot, which detects a wheel-terrain contact point by an infrared proximity sensor. In spite of the small wheel size, this tactile wheel is high-resolution because the contact point angle is measured by a potentiometer installed on the outside of the wheel. We plan to use this tactile wheel for self-localization of a mobile robot on an uneven terrain.

The effect of wheel diameter on vertical and horizontal mountain bike position

Background: Mountain bike wheel dimensions have evolved to larger diameters in recent years. While numerous claims can be found for performance advantages of larger diameter wheels, systematic comparisons of mechanical characteristics are not available.Purpose: Compare the change in velocity and the variability of vertical position between 26 and 29 inch diameter mountain bike wheels while rolling across a straight 10 m long bumpy track over a range of velocities. Methods: Horizontal and vertical bike position data were collected across a straight wooden track (10 m) with an assortment of 21 randomly spaced wooden bumps ranging in size from 1.75 to 7.5 cm. Position data were recorded at 200 Hz using a 10 camera Vicon System with a reflective marker attached to the stem. Two front wheels (Stan's NoTubes ZTR Crest, Maxxis Ardent tire, 26 psi inflation, tubeless) were matched in all characteristics except diameter and mass. Mass differed by about 100 g (7%). A carbon, hardtail frame (Niner Air 9) was used throughout with 29 inch rear wheel; 26 and 29 inch front wheels were exchanged between conditions. Rigid (White Brothers Rocksolid) and suspension (Rockshox Reba) front forks were tested with each wheel condition. For each wheel/fork combination 10 trials were ridden with increasing speeds that ranged from 3 to 8 m/s. Conditions were randomized with the rider (male, 30 yrs) riding passively without lifting or pedaling during each trial. Analysis of covariance was used to compare conditions with speed as the covariate. Linear regression was used to assess the relationship of the change in velocity to incoming velocity and the variability of vertical position to incoming velocity.Results: There was no significant difference for all wheel/fork conditions with the change in velocity (suspension; p = 0.4523, rigid; p = 0.4164). The variability of vertical position with a rigid fork and 29 inch wheel was significantly greater (p = 0.0004) than with the 26 inch wheel. With the suspension fork, there was a small but significant difference (p = 0.0006) with the 29 inch wheel over the 26 inch wheel.Discussion: Wheel diameter had no significant influence on the change in velocity of the bike. However, for both fork conditions, the variability of vertical position was significant between the 29 and 26 inch wheels. The larger wheel experienced a greater vertical motion due to the mechanics of the wheel. The larger diameter of the 29 inch wheel translated to more contact time with each bump causing more vertical motion. This difference was seen in both fork conditions, albeit much smaller with the suspension fork. For each wheel/fork condition, the change in velocity decreased as the incoming velocity increase. For both wheel diameters with the suspension fork, the vertical motion decreased as incoming velocity increased, whereas with the rigid fork, vertical motion increased with an increase in incoming velocity. Conclusion: Wheel diameter has a significant influence on the vertical motion of a mountain bike; however, changes of velocity were not affected by wheel size. Wheel diameter on a mountain bike with a rigid front fork has a significant influence on vertical motion while a bike travels along a bumpy track. The larger wheel diameter produced greater vertical motion.

Pneumatic power plant as an alternative source of ecologically clean domestic energy

The solution of the problem of unstable parameters of the output voltage of wind power plants because of the inconstancy of wind flow, limiting the scope of their application based on the transition to the development of pneumatic power plant, containing energy accumulators in the form of high-pressure compressed air tanks in its structure is considered in the paper. Concrete design of low-capacity pneumatic power plant is proposed. The issue of calculating and selecting the sizes of energy accumulators in the form of high-pressure tanks, taking into account certain intervals of the wind flow is studied. Duration of continuous operation of the electrical load with power of up to 1 kW at various energy accumulator capacities is determined. The choice of power of the load consumed from the condition of its uninterruptible power supply with the presence of constraints on the sizes of the energy accumulators, their charging rate, installed capacity of the power generator, type size of the wind wheel, as well as constancy of the wind flow strength and speed are shown.

An experimental study on grinding parameters for manufacturing PCD micro-milling tool

Micromachining has become a necessary manufacturing process. Micro-milling tool and its evolution play a vital role in the development of micromachining. This study optimizes the grinding process of polycrystalline diamond (PCD) compact for manufacturing PCD micro-tool. The optimization is conducted by using four parameters, i.e., grain size of PCD compact, grain size of abrasive wheel, grinding speed, and feed rate designed by the Taguchi orthogonal array. The study then evaluates two grinding characteristics, i.e., grinding forces and cutting edge radius of the PCD compact. The results of ANOVA show that the most influential parameter on grinding PCD compact is the grain size of the PCD compact, followed by the grain size of the abrasive wheel, feed rate, and grinding speed. As an example, a quadrilateral PCD micro-milling tool with a cutting edge diameter of 80 μm is fabricated by using the optimized parameters.