Wheel Center Research Articles

Increase of informativity of two-frequency method of defectometry at ultrasonic control of details and units of railway rolling stock

When forecasting the technical state of the parts and units of railway rolling stock in operation, an important task is to determine the shape of the discontinuity in ultrasonic non-destructive testing in order to predict its behavior in further operation (this is especially important if the discontinuity in the results of such control is acceptable). Author proposed a solution for the improvement of the two-frequency defectometry method. A mathematical apparatus was developed and a method for determining the coefficient of the discontinuity shape was elaborate on its basis. The method makes it possible to determine the shape of both a point and an extended discontinuity. The software product NDTRT-07.03.01.18 was developed to automate calculations in determining the shape of discontinuity by a two-frequency method. The article gives a description of the experimental studies carried out to evaluate the reliability of the proposed method. This method can be used in determining the shape of the discontinuity in the details of the rolling stock, in which the defect can have a different shape, for example: cast wheel centers; various shaped castings used in the manufacture of rolling stock units (brackets for locomotive bogies, cast sidewalls for cars), as well as in parts manufactured by the method of plastic deformation, including wheel treads, axles, all-rolled wheels, rolled wheel centers, etc. In these details discontinuities are predominantly planar in nature, but voluminous discontinuities are also encountered - non-deformable nonmetallic inclusions, therefore the developed method can be applied to such objects of rolling stock railways.

NURBS toolpath planning for glass sharp corner edge grinding

In this paper, a transition toolpath planning algorithm is proposed to achieve sharp corner edge grinding in personalized glass products manufacturing. The developed algorithm is based on a segmented conic NURBS curve with parameterized knot and weight sequences. First, the requirements for glass sharp corner grinding are given, and a transition velocity constraint is derived based on a grinding forces model. Moreover, considering the grinding depth and velocity control around the tips, a segmented NURBS transition toolpath is created to connect the broken wheel center trajectory. Afterwards, the application methods for the proposed NURBS curve in different commercial CNC systems are summarized and presented. An experimental study was carried out to validate the proposed method.

A probabilistic estimate of the vertical dynamic forces acting on the track, in the model of a three-layer beam under the influence of a four-axle freight car

The article contains a method for determining the ma-the permanent way as deflections, angles of section rotation, bending trix of mutual spectral densities of vertical dynamic forces acting on a moments, transverse forces, stresses of its three-layer structures. railway track, depending on its spectrum of irregularities. It will allow to Mathematical model of track oscillations is used for calculations make a more accurate calculation of the mean values and mean-square as a construction containing three infinitely long beams, the lower deviations of vertical dynamic forces, as well as such characteristics of of which lies on the modified Winkler base. Authors present formulas for finding amplitude-frequency characteristics connecting vertical deflections of structural layers and vertical dynamic load acting on a track. A method is described for finding a matrix of mutual spectral densities of vertical dynamic forces acting on a track having real deviations from its position in the profile, with the passage through it of a four-axle freight car. Considered example finds the amplitude-frequency characteristic that connects the vector of dynamic forces in the contacts of wheels and rails with the vector of vertical displacements of wheel centers for the model of a four-axle car. Concluding authors give the results of calculations of the amplitude-frequency characteristic of the elements of the matrix of mutual spectral densities of vertical dynamic forces acting on the track. The received statistical estimations can be used at calculations of service life of ballastless track constructions and loading on roadbed.

MODELS OF ROBOT’S WHEEL-MOVER BEHAVIOR ON FERROMAGNETIC SURFACES

The mobile robots which can move on complicated working surfaces play a significant role in the automation of various technological processes, in particular, ship repair, fire fighting, inspection of welding quality, rescue operations, etc. This work is a continuation of the authors’ investigation of the mobile robot’s moving on inclined and vertical ferromagnetic surfaces based on a magnetically operated wheel-mover. Special attention is paid to constructing magnetically operated wheel-mover with twelve legs and modeling of the robot’s wheel-mover behavior in different working modes including investigations of the wheel-mover center trajectory, behavior of control signals, etc. Geometrical dependences between a number of wheel-mover legs and deviation of the wheel center path from horizontal line are described. In the present article the modeling results for movement of the wheel-mover on both plain and non-plain surfaces are discussed. For this purpose, the mathematical model of the wheel-mover was created and analyzed and the results were verified using a simulation approach.

Distribution of Mechanical Stresses in a Tire Subjected to Pressing on the Wheel Center of an Electric Locomotive

We analyze the main types of defects appearing near the sites of concentration of mechanical stresses in the material of tires of the wheels of electric locomotives. We study the distribution of stresses near the areas of potential appearance of fatigue defects in the tire in the course of its setting on the wheel center by the finite element method and discuss the obtained results.

Wear life characterization of the grinding wheel for electrolytic in-process dressing (ELID) grinding of ball bearing raceways: a new perspective based on a moving normal distribution curve of the grit state variation

Many advantages make electrolytic in-process dressing (ELID) grinding desirable for cutting hard and brittle material with high surface requirements. The self-electrolytic in-process dressing property in ELID grinding is also largely responsible for the shorter wear life and lower forming accuracy of the grinding wheel. In ELID grinding, except for traditional mechanical wear, the electrolytic oxidation wear also adds more uncertainties to the wear velocity of the grinding wheel. To date, few investigations focused on the grinding wheel wear life characterization in ELID cut-in grinding of ball bearing raceway. In this study, the wear life characterization of the grinding wheel during ELID grinding was quantitatively simulated by a moving normal distribution curve of the grit state variation. As all types of cutting grits wear out, so did the normal distribution curve, showing movement towards the grinding wheel center. With the normal distribution curve moving towards the grinding wheel center, a local acceleration and local deceleration in moving velocities occurred. It is the diversity of the moving speed of the normal distribution curve that provides a quantitative description to understand the wear life characterization of the ELID grinding wheel. Some experimental results can easily explain this new proposed perspective. This new perspective can also be extended to predict the forming accuracy and surface topography of the bearing raceway during ELID grinding.

Estimation of tyre forces using smart tyre sensors and artificial intelligence

In-tyre strain measurements from a smart tyre sensor system are analysed using two artificial neural network types, in order to estimate tyre forces. A tyre finite element model is used to calculate in-tyre strain (inputs) and tyre forces developed at the wheel centre (outputs) for use in the neural networks. Neural networks are trained on pure slip conditions and tested on combined slip events with the goal of accurately predicting tyre longitudinal and lateral forces and the aligning moment. The large mapping function is fitted using multilayer perceptron and radial basis function networks. Results from the best radial basis function network design are excellent, with training times under one minute, testing times of milli-seconds and calculated tyre forces within 1%. The conclusion is that radial basis function networks can be used effectively for real time analysis of strain sensor measurements in a smart tyre sensor system.

Контроль натяга бандажа на ободе колесного центра у сформированных колесных пар электровозов

Контроль натяга бандажа на ободе колесного центра у сформированных колесных пар электровозов

Estimation of tyre forces using smart tyre sensors and artificial intelligence

In-tyre strain measurements from a smart tyre sensor system are analysed using two artificial neural network types, in order to estimate tyre forces. A tyre finite element model is used to calculate in-tyre strain (inputs) and tyre forces developed at the wheel centre (outputs) for use in the neural networks. Neural networks are trained on pure slip conditions and tested on combined slip events with the goal of accurately predicting tyre longitudinal and lateral forces and the aligning moment. The large mapping function is fitted using multilayer perceptron and radial basis function networks. Results from the best radial basis function network design are excellent, with training times under one minute, testing times of milli-seconds and calculated tyre forces within 1%. The conclusion is that radial basis function networks can be used effectively for real time analysis of strain sensor measurements in a smart tyre sensor system.

Dynamic characteristics of a planetary gear system based on contact status of the tooth surface

Studies on the planetary gear have attracted considerable attention because of its advantages, such as compactness, large torque-to-weight ratio, vibrations, and high efficiency, which have resulted in its wide applications in industry, wind turbine, national defense, and aerospace fields. We have established a novel dynamic model of the planetary gear transmission by using Newton’s theory, in which some key factors such as time-variant meshing stiffness, phase relationships, and tooth contact characteristics are considered. The influences of gear axial tipping, operating conditions, and the meshing phase on the contact characteristics and the dynamic characteristics were researched systematically. It was found that the contact area of the tooth surface was moved due to the axial gear tipping, which obviously affected the meshing stiffness. With the increase in the inclination angle of the sun gear, the meshing stiffness decreases, which produces an evident influence on the high natural frequency in the planetary transmission system. In terms of the dynamic characteristics of the system, the component of rotating frequency appeared in the dynamic meshing force of the sun gear and the planetary gear. Moreover, the floating track of the center wheel varied significantly and exhibited an oval distribution as the inclination angle of the sun gear changed. When the inclination angle of the sun gear increased, the rotating frequency component increased significantly, but the other meshing frequency components remained unchanged; meanwhile, the deformation of the floating track also increased. If the inclination angle of the sun gear changes, the vibration state of the system and the collision impact could become more serious, and the lifetime of the planetary transmission system will reduce. Furthermore, when the load was increased, we found that the gear-tooth contact zone transformed from line contact to surface contact, the meshing stiffness increased, the effect of high natural frequency on the planetary transmission system became more evident, but its low-order natural frequency remained stable. With regard to the dynamic characteristics of the system, the components of the major frequency at the external gearing remained unchanged, but the rotation frequency of the sun gear and the meshing frequency amplitude increased linearly with the increase in load. In conclusion, the variation in the meshing stiffness of the planetary gear system had minor impact on the low-order natural frequency, but had a significant impact on the high natural frequency of the planetary transmission system due to the phase variation of the gear.

Systematization and comparative scheme analysis of mechanisms of planetary rotary hydraulic machines

The systematization of planetary rotary hydraulic machines (PRHM) with floating rollers is presented in the article. This systematization is carried out according to such structural features as: the number of waves that have central tooth gears with internal and external teeth, the character of the leading link motion; selection of a supporting (fixed) link; selection of the link containing the channels. The systematization allows us to list all essentially different schemes of PRHM and conduct their comparative analysis. The comparison is based on such technical parameters as: symmetry of schemes; absence of dead spots; PRHM performance, pulsation of instantaneous performance; channel cross-sectional area. The comparison showed that based on a set of indicators, the schemes with the numbers of central wheel waves 2×4; 4×6; 6×8 are preferred, in which the rotor performs a purely rotary motion.

Velocity control algorithm in glass polishing based on the cubic NURBS curve

To limit velocity fluctuations and to achieve a controllable jerk value in a glass polishing process, a new velocity control algorithm is proposed based on nonuniform rational B-splines (NURBS). The key of this algorithm is replacing the traditional linear acceleration–deceleration with flexible NURBS acceleration–deceleration. Based on the linear acceleration–deceleration algorithm, the control points of the NURBS curve are confirmed, and the final velocity of the polishing wheel center is solved using the Preston equation. With jerk continuity and limitations of the servo system, nonlinear equations are constructed, and the weighting factors corresponding to the control points are obtained. Cubic velocity control equations can be derived from the obtained feature parameters, which include the final velocity, control points, weighting factors and knot vectors. Based on the proposed NURBS acceleration–deceleration algorithm, a fourth-order Runge–Kutta formula was used to obtain the initial points, and the Milne–Hamming equation was used to predict and correct the next point. The predictor-corrector interpolation algorithm for parametric trajectory was implemented during the polishing process. The experimental results indicate that the proposed approach guarantees limited fluctuations of the relative velocity at contact points and ensure smoother velocity changes at dangerous points.

Soil hydrophysical degradation associated with forest operations

ABSTRACTSkid trails in the Hyrcanian forest of northern Iran are important for moving wood to log landings; however, they can cause soil compaction and alter water infiltration. This research therefore presents an analysis of the impact of ground-based skidding on soil hydrophysical properties in Kuhmiyan forest located in the Hyrcanian forest. Soil infiltration, bulk density, and soil resistance to penetration have been studied at three different depths of soil along the skid trails. Three sampling locations were considered: wheel ruts, center of skid trails, and undisturbed forest (control). The results showed that the total infiltration rate, and also the instantaneous infiltration rate, were significantly higher in the control treatment. The results also showed an increase of 57% and 31% for the soil bulk density at wheel ruts and centers of skid trails compared to the control. Furthermore, there was a significant difference between soil resistance in the control and the other two treatments, with wheel ruts having the highest resistance. According to the results, there was a strong negative correlation between infiltration and soil resistance (r = –0.94), and between infiltration and bulk density (r = –0.93). Using a protective layer of slash and logging debris and residual on skid trails can be highly recommended to moderate soil compaction and mitigate the destructive impact of logging equipment.

The control of blades orientation to air flow in wind energetic device

New wind energetic devices with controlled orientation of flat blades to air flow are developed. The proposed device consists of main central wheel and several flat blades hinged to the wheel with the ability to change the orientation of their working surfaces relative to the direction of incoming wind flow. Experimental analysis of blade’s interaction with air flow is performed. Aerodynamic coefficients for blade’s drag and lifting forces are determined experimentally in wind tunnel ARMFIELD. Optimization of system parameters is made using programs Excel and MathCad. To increase the efficiency of energy transformation, it is proposed to change by special law an angular position of flat blade during rotation of the central wheel. For this purpose axles of blades are kinematically connected with the central wheel. It is shown that optimal angular rotation frequency ratio between central wheel and blade is equal to 2. Serviceability and main advantages of the proposed method are confirmed by experiments with physical model of airflow device.

Sharp corner transitional trajectory planning based on arc splines in glass edge grinding

The sharp corners on final contours in flat glass grinding can cause broken wheel center trajectories. A corner transitional trajectory planning algorithm based on arc splines is proposed in this paper to control the wheel center trajectory G1 continuity and the grinding depth at a corner. The radii of arc splines are derived first to meet design requirements based on the geometrical features of a sharp corner. A three-phase feedrate planning scheme is introduced to generate the arc splines. Corner classification and treatment are presented to make the proposed algorithm flexible, and steps for algorithm application are summarized. Experimental results demonstrate that the proposed algorithm can achieve satisfactory shape accuracy at corners without any breakage, rounding, or flattening.

Attitude Control Equation of the Two-wheeled Self-balancing Electric Vehicle

In order to get control of motion characteristics of the two-wheeled self-balancing vehicle, based on the dynamic modeling and the correction of ADAMS simulation, a mathematical model of body posture of body angle and wheel driving torque which contains a correction factor was build. The simulation results of the model show that the horizontal velocity of the center of gravity of the swing rob and the wheel center were almost coincides entirely with each other both on model calculation and ADAMS simulation, so the body of the vehicle could keep relatively static on horizontal direction under the control of this model. The position changing value of swinging rob was always less than 1mm, Thus it proved that the modified equation was proper and could be used to control the motion of the two-wheeled self-balancing electronic vehicle.

Research on squeal noise of tread brake system in rail freight vehicle

Brake squeal is a result of a unstable flutter from brake system, it results to the noise pollution in railway side and excessive wear of wheel tread. A finite element model of brake system for rail freight vehicle is set up, the contact and friction between the brake shoe and wheel tread is considered, the complex modals of brake system are calculated, the possibility of happening chatter and squeal noise are analyzed. The results show that the pressure angle or the brake force direction have a important influence on the unstable chatter and squeal noise, the more greater the pressure angle deviates from the wheel center, the more greater the possibility of happening chatter and squeal noise is, and the possibility of happening chatter and squeal noise is also increased along with the addition of friction factor.

A new methodology to calculate the equivalent stiffness matrix of the suspension structure with flexible linkages

The purpose of this work is to present a methodology for calculating the equivalent stiffness matrix of the wheel center of the vehicle suspension. For a suspension, the stiffness matrix of the wheel center, which is effected by the bushings and flexible linkages, control the suspension’s elasto-kinematic ( e–k) specification. The equivalent stiffness matrix of the wheel center is formulated by using the stiffness of the bushings and linkages. And the models of series and parallel springs are used to calculate this equivalent stiffness matrix based on the number of the bushings and linkages. An example is presented to illustrate how to use the proposed methodology to derive the equivalent stiffness matrix of a suspension system with three bushings and flexible linkages. The results show that the equivalent stiffness of the wheel center will decrease if the linkage stiffness is considered. This methodology can be used in all kinds of suspension structure. It can also be used to optimize and design the suspension system.

A Multiple Data Fusion Approach to Wheel Slip Control for Decentralized Electric Vehicles

Currently, active safety control methods for cars, i.e., the antilock braking system (ABS), the traction control system (TCS), and electronic stability control (ESC), govern the wheel slip control based on the wheel slip ratio, which relies on the information from non-driven wheels. However, these methods are not applicable in the cases without non-driven wheels, e.g., a four-wheel decentralized electric vehicle. Therefore, this paper proposes a new wheel slip control approach based on a novel data fusion method to ensure good traction performance in any driving condition. Firstly, with the proposed data fusion algorithm, the acceleration estimator makes use of the data measured by the sensor installed near the vehicle center of mass (CM) to calculate the reference acceleration of each wheel center. Then, the wheel slip is constrained by controlling the acceleration deviation between the actual wheel and the reference wheel center. By comparison with non-control and model following control (MFC) cases in double lane change tests, the simulation results demonstrate that the proposed control method has significant anti-slip effectiveness and stabilizing control performance.

A Computational Study on the Moment Coefficient Cm of Formula One Exposed Dry and Wet-Condition Wheels

A model of Formula One racing car rotating dry wheel in contact with the ground is studied using a computational approach as a validation case. This validation case focuses on the computed surface pressure around the wheel's center line. This computed result is compared to an experimental one obtained from the available literature work and it showed good agreement. Another case study is considered with replacing the dry wheel model with another wetcondition wheel model. The wet-condition wheel's work is mainly concentrated on the developed aerodynamic forces especially the wheel moment values. This moment is translated to an expression of resistive torque developed by the air stream on the wheel and computed in each case study. In addition, general schematic pictures of the flow behavior around the wet wheel are presented.