Wheel Set Research Articles

High-speed train wheel set bearing fault diagnosis and prognostics: Research on acoustic emission detection mechanism

Acoustic emission (AE) technology is suitable for the condition monitoring and fault diagnosis of high-speed train wheel set bearings (HSTWSB) owing to its high frequency and high sensitivity. However, there has been no research on the mechanism of the relationship between HSTWSB state and AE signal. Therefore, this study explores the AE detection mechanism of HSTWSB state. First, based on the structure and load characteristics of HSTWSB, combined with the Hertz contact theory, a force analysis of the whole, local, and single roller is performed. Second, based on the assumption of random distribution of asperities, a contact model of the rough surface of the bearing is established, and the elastic deformation analysis of the asperities under load is performed based on the theory of elasticity. The corresponding relationship between the asperity deformation energy and root mean square (RMS) of the AE signal is obtained. Meanwhile, considering the influence of elastohydrodynamic lubrication (EHL) and signal attenuation on the deformation energy, an AE mathematical model of the HSTWSB is established. Accordingly, based on the characteristics of HSTWSB with different damage types, the influences of the load, deformation, speed, and defect morphology on the AE signals are thoroughly analyzed, and the improved models corresponding to different damage types are established, which extends the AE model to greater freedom. Finally, taking different damage types of the outer ring fault bearings as examples, the correctness of the proposed models is verified by comparing the theoretically calculated and experimental results. The proposed models can provide theoretical support for the application of AE to bearing condition monitoring.

Metro Wheel Set Size Measurement Method Based on CDD Image Recognition

In the process of train operation, the contact friction between wheel and track will change the size of wheel set. In order to ensure the safe operation of train, it is of great significance to detect the change of wheel set size timely and accurately. On the basis of summarizing the research at home and abroad, the online dynamic detection technology of wheel set size is studied. Firstly, the overall architecture of the wheel set size online detection system is studied, the working principle of each detection module is explained, and the installation parameters of the laser displacement sensor are designed. Secondly, the machine learning algorithm of online dynamic detection technology of wheel set size is studied. The passing wheel sets are photographed by CCD camera, and then the three-dimensional model is reconstructed by point cloud data, and then the parameters of each part are measured and calculated according to the model. The wheel set size can be obtained.

Analysis of dynamic instability of the wheel set of a railway vehicle using the method of generalized hill determinants

The article considers the tasks associate with the study of dynamic processes of interaction between rolling stock and railways. Studies of the interaction of a wheel with a rail, fitting the vehicle into curves when modeling critical and emergency situations do not allow oversimplification of basic differential equations. And they should be based on exact nonlinear equations that take into account the entire set of geometric and kinematic relationships without simplification. An objective assessment dynamic characteristic of the vehicle can only be obtained by simultaneously taking into account both its vertical and horizontal irregularities. In order to determine boundaries of parametric resonance, article proposes method of generalized Hill’s determinants, the application of which is possible without taking into account small parameters.

Design and Optimization Formula SAE Drivetrain Components

Abstract: The overall objective of this paper is to refine the drivetrain system design, selection of suitable materials and analysis techniques for FSAE vehicles. The main objective of this work is to optimize the hub and Upright for 10-inch rim, in terms of reducing the overall weight of the system, additional accessories for variable camber and appropriate selection of bearings. To achieve this, the safety deformation factor, the fatigue resistance of the system and the fit of the entire wheel set were taken into account. Software used in design and validation are Solidworks, Ansys Keywords: FSAE, Wheel Hub, Upright, Shims, Brackets

Relevance of Complementary and Alternative Medical Interventions in Prevention of Mucormycosis in Post-Covid-19 Patients

Every day our bodies are exposed to several pathogens. In this invisible battle, a complex set of wheels comes into play, made up of millions of cells of different types and with different functions, responsible for ensuring the defence of the organism and maintaining the health of the body. It is the immune system that is responsible for this defence. The Covid-19 pandemic brought new problems, including pathogens that can take advantage of patients' weakness and worsen health conditions. Patients' after Covid-19 are facing a new threat, an infection caused by a fungus - mucormycosis. The main risk factors are taking corticosteroids and diabetes mellitus. The conventional medicine used in this type of treatment usually causes many adverse effects and there may be non-adherence. Alternatively, alternative medicine can be considered a useful approach and help improve wellness and even prevent complications of mucor infection. Complementary and alternative medicine treats emotional traits and mainly influences the patient's beliefs, thoughts, well-being, and mood and improves the immune system. Complementary and alternative medicine helps improve quality of life and can help patients reduce psychological distress. The present article discusses some key aspects of the role of alternative medicine and how complementary treatment can be considered in preventing complications of mucormycosis in post-Covid 19 patients.

High-speed train wheel set bearing fault diagnosis and prognostics: Fingerprint feature recognition method based on acoustic emission

Acoustic emission (AE) technology is suitable for the condition monitoring and fault diagnosis of high-speed train wheel set bearings owing to its high frequency and high sensitivity [1]. However, current AE diagnosis methods cannot consider both real-time characteristic and fault periodicity. To overcome these shortcomings, a fingerprint feature recognition method is proposed in this paper. First, the concept of dynamic threshold is proposed to ensure that the typical burst or hit-based AE signal can be accurately extracted under different speeds, loads, and damaged bearing states. Based on the dynamic threshold, a specific feature, namely the fingerprint feature, is defined to provide an instant visual pattern of the bearing fault. Second, a clustering significance index (CSI) is constructed, which can not only guide the intelligent selection of the dynamic threshold, but also help to realize the quantitative evaluation of the bearing damage state. Furthermore, this study combines hit statistics with the fault frequency to form a fault hit statistical spectrum. On this basis, a fault hit significance index (FHSI) is established for the quantitative judgment of the bearing damage state. Finally, the validity of the proposed methods was verified by testing under complex test conditions close to the actual line of a high-speed train, providing a valuable reference for the online monitoring of the bearing state under actual industrial conditions.

START: A Satellite Three Axis Rotation Testbed.

The main goal of this paper is to illustrate the development of a satellite attitude simulator testbed for on-ground experimentation of attitude, determination, and control methodologies. This setup aims to be a low-cost alternative to testbeds based on air-bearing couplings. Our system is mainly composed of a suspended base, a single-board processor, a set of reaction wheels, and a battery. The suspension system entails a set of thin high-tensile strength wires converging on a single wire, which is in turn connected to the base. This configuration allows a three degrees-of-freedom rotation range and minimal resistive torque in all the rotations axis. The adjustability of the hanging point at the base, and a set of sliding masses, allow us to achieve a quite accurate superposition of rotation point and center of mass for a quasi-neutral equilibrium. The testbed is completed by a PC workstation, to generate and stream the desired angular rates of the wheels, and a motion capture system for attitude determination.

Анализ организационно-структурных преобразований вагоноремонтных предприятий

The article provides a retrospective analysis of organizational and structural transformations in the railway car industry, the formation of a car repair complex as an independent sphere of industrial production. The article analyzes new approaches in the activities of large railcar repair companies, which account for up to 80% of planned types of freight car repairs. There is a concentration of repair production, the construction of organizational structures according to the principles of divisional management in machine-building holdings, the creation of new production facilities for the overhaul of wagon wheel sets, as well as for ongoing uncoupling repairs. The proposals of the Union of railcar repair enterprises on the development of the effective system for keeping a railway car in working condition throughout its life cycle in the new realities, with the participation of all interested parties, including representatives of specialized scientific institutes and universities, are supported.

The possibility of using controlled rod comb lubricators to reduce the wheel sets wearing of the double-deck passenger cars

The possibility of using controlled rod comb lubricators to reduce the wheel sets wearing of the double-deck passenger cars

Defect Detection of Wheel Set Tread Based on Improved YOLOv5

Defect Detection of Wheel Set Tread Based on Improved YOLOv5

Train tracks with gaps: Applying the probabilistic method to trains

We identify a tradeoff curve between the number of wheels on a train car, and the amount of track that must be installed in order to ensure that the train car is supported by the track at all times. The goal is to build an elevated track that covers some large distance ℓ, but that consists primarily of gaps, so that the total amount of feet of train track that is actually installed is only a small fraction of ℓ. In order so that the train track can support the train at all points, the requirement is that as the train drives across the track, at least one set of wheels from the rear quarter and at least one set of wheels from the front quarter of the train must be touching the track at all times.We show that, if a train car has n sets of wheels evenly spaced apart in its rear and n sets of wheels evenly spaced apart in its front, then it is possible to build a train track that supports the train car but uses only Θ(ℓ/n) feet of track. We then consider what happens if the wheels on the train car are not evenly spaced (and may even be configured adversarially). We show that for any configuration of the train car, with n wheels in each of the front and rear quarters of the car, it is possible to build a track that supports the car for distance ℓ and uses only O(ℓlog⁡nn) feet of track. Additionally, we show that there exist configurations of the train car for which this tradeoff curve is asymptotically optimal. Both the upper and lower bounds are achieved via applications of the probabilistic method.The algorithms and lower bounds in this paper provide simple illustrative examples of many of the core techniques in probabilistic combinatorics and randomized algorithms. These include the probabilistic method with alterations, the use of McDiarmid's inequality within the probabilistic method, the algorithmic Lovász Local Lemma, the min-hash technique, and the method of conditional probabilities.

An Orthogonal Wheel Odometer for Positioning in a Relative Coordinate System on a Floating Ground

This paper introduces a planar positioning sensing system based on orthogonal wheels and encoders for some surfaces that may float (such as ship decks). The positioning sensing system can obtain the desired position and angle information on any such ground that floats. In view of the current method of using the IMU gyroscope for positioning, the odometer data on these floating grounds are not consistent with the real-time data in the world coordinate system. The system takes advantage of the characteristic of the orthogonal wheel, using four vertical omnidirectional wheels and encoders to position on the floating ground. We design a new structure and obtain the position and angle information of a mobile robot by solving the encoder installed on four sets of omnidirectional wheels. Each orthogonal wheel is provided with a sliding mechanism. This is a good solution to the problem of irregular motion of the system facing the floating grounds. In the experiment, it is found that under the condition that the parameters of the four omnidirectional wheels are obtained by the encoder, the influence of the angle change of the robot in the world coordinate system caused by the flotation of the ground can be ignored, and the position and pose of the robot on the fluctuating ground can be well obtained. Regardless of straight or curved motion, the error can reach the centimeter level. In the mobile floating platform experiment, the maximum error of irregular movement process is 2.43 (±0.075) cm and the RMSE is 1.51 cm.

Modeling and analysis of motion with wheel slip of the mobile platform with four wheel drive

The problem of motion with wheel slip of the four wheeled mobile platform has been discussed in this work. Considering the model of dynamics, the formulation of the initial problem of the platform motion and the numerical algorithm for solving this problem has been presented. The Runge-Kutta 4th order method has been used to integrate the equations of motion. Possible cases of motion of the prototype of the mobile platform with four drive modules have been considered. Taking into account the variable values of the active forces caused by the drive torque and changes in the position of the wheels during the platform motion, as well as the resistant forces opposing the active forces at the contact points of the wheels with the ground, the platform motion simulation results have been obtained. Different wheel settings, with controlling the active forces and directions of their settings while driving have been implemented to the model. The results of motion simulations and their analysis have been included. The results presented in the paper show a significant influence of wheel slip on the parameters of the motion of the mobile platform. The computational model presented in the paper enables a good representation of the platform motion parameters, which has been confirmed by comparing the results of simulation tests with the results of experimental tests of motion in relation to a construction solution of the platform other than described in the paper. Further development of the computational model is planned, mainly in order to include the deformability of the wheel suspension systems in the dynamic model of the platform, which will allow for the implementation of wider studies of the motion of such objects, including, for example, in the case of wheels passing through obstacles.

Layout Guide for Design of a Novel Wheelchairs with Circumferential Linkage using Microsoft Word

In recent decades, the aging of the world’s population has intensified, and the number of people with disabilities caused by various disasters and diseases has gradually increased. Most of the elderly, frail and disabled people will choose wheelchairs as their means of transportation. However, ordinary wheelchairs are unable to climb stairs, especially in cities, which seriously limits the range of activities of wheelchair users and affects their daily life. Hence, it is of great significance and value to design an intelligent building climbing wheelchair with appropriate price, stability and safety. This paper designs a multi-functional planetary height adjustable building climbing wheelchair with simple structure and low price. Firstly, a multi-functional building climbing wheelchair based on planetary gear train is designed by using modular design idea, including ground walking mechanism, in place steering mechanism, center of gravity adjustment mechanism and Seat leveling mechanism. The working principle and design characteristics of each mechanism are analyzed in detail. Then, through the analysis of the mathematical model of the climbing mechanism, the dimensional parameters of the three-star wheel set are determined. According to the power demand of wheelchair, the power system is selected and analyzed. It provided a new possibility for the wheelchair application and also for those in need.

3D Modelling of an Integrated Grounding System for High-Speed Trains Considering Rail-Train Current Reflux

The integrated grounding system for high-speed trains consists of two parts: on-board dynamic and fixed terrestrial grounding sub-systems. The on-board grounding sub-system contains working and protective grounding modes, both of which share the rails as the common path for discharging current. Current reflux occurs frequently, which can contribute to the circumflux in the ‘train body – grounding wheel set – rail’ circle, due to the dynamic coupling effects between grounding points. The path and value of the circumflux vary transiently because of the changing impedance between the grounding wheels and rail under the dynamic conditions. In our previous work, a 2D grounding model was built to evaluate the impact from the current reflux, but the lateral and vertical impedances of train bodies and rails were ignored. In practice – when the protective and working grounding is applied independently to rails on the left- and right-hand side separately – the current reflux can be restricted by benefitting from the impedance existing in train bodies and rails. It therefore becomes essential to build a 3D ‘train–rail’ coupling grounding model accounting for the full-dimension impedances, while different grounding distribution protocols is considered to improve the grounding performance.

Experimental study on the relationship between the friction coefficient and interference in locomotive axle press-fitting

PurposeTo address the lack of data in this field and determine the relationship between the coefficient of friction and the interference between locomotive wheels and axles, this study evaluates the theoretical relationship between the coefficient of friction and the interference under elastic deformation.Design/methodology/approachWhen using numerical analyses to study the mechanical state of the contacting components of the wheels and axle, the interference between the axle parts and the coefficient of friction between the axle parts are two important influencing factors. Currently, as the range of the coefficient of friction between the wheel and axle in interference remains unknown, it is generally considered that the coefficient of friction is only related to the materials of the friction pair; the relationship between the interference and the coefficient of friction is often neglected.FindingsA total of 520 press-fitting experiments were conducted for 130 sets of wheels and axles of the HXD2 locomotive with 4 types of interferences, in order to obtain the relationship between the coefficient of friction between the locomotive wheel and axle and the amount of interference. These results are expected to serve as a reference for selecting the coefficient of friction when designing axle structures with the rolling stock, research on the press-fitting process and evaluations of the fatigue life.Originality/valueThe study provides a basis for the selection of friction coefficient and interference amount in the design of locomotive wheels and axles.

The Performance Analysis of the “Train-Rail” Grounding System for High-Speed Trains Considering Circumflux and Train Body Voltage

The ‘train-rail’ integrated grounding system for high-speed trains plays the critical role in providing the unique path for power feedback, which mainly consists of two parts - the on-board dynamic grounding sub-system and the fixed terrestrial grounding sub-system. The on-board dynamic grounding sub-system can be classified into two types of grounding modes – working grounding provides the discharging path for transferring the traction power; while the protective grounding maintains reference ground potential for the train body – both of which share the rail as the common path for discharging current. Thus, the traction current discharged from the working grounding wheel sets flows through the neighboring protective grounding wheel sets back to the train body, forming as the ‘train-rail’ current reflux. The ‘train-rail’ current reflux may result in the appearance of a ‘train body’ (TB) current, which may rise the potential of the train body. The TB current and voltage may cause electromagnetic interference to the on-board equipment, electrochemical corrosion on grounding wheel bearing or even on-board partial temperature surging. In this paper, a ‘train-rail’ coupling integrated grounding model is launched to evaluate both the TB current and voltage. Based on this model, different grounding distribution schemes have been tried and compared, considering the impact brought from TB current and voltage. The external grounding resistors are installed in series at the protective grounding wheel sets implemented, with the aim of restricting the TB current and voltage. Ultimately, the best-performed grounding scheme of installing external resistors is found out.

Effect of Reaction Wheel Imbalances on Attitude and Stabilization Accuracy

In this paper, the study of stabilization accuracy of a satellite equipped with a set of reaction wheels (RW) is presented. The model of motion takes into account possible static and dynamic reaction wheel imbalances. Due to the complexity of the model, which leads to the numerical issues, the effects of dynamic and static imbalances on inertial stabilization are studied analytically. As a result, estimations of the attitude and stabilization accuracy are presented in closed form.

Comparative study on the use of acoustic emission and vibration analyses for the bearing fault diagnosis of high-speed trains

A wheel set bearing is an important supporting component of a high-speed train. Its quality and performance directly determine the overall safety of the train. Therefore, monitoring a wheel set bearing’s conditions for an early fault diagnosis is vital to ensure the safe operation of high-speed trains. However, the collected signals are often contaminated by environmental noise, transmission path, and signal attenuation because of the complexity of high-speed train systems and poor operation conditions, making it difficult to extract the early fault features of the wheel set bearing accurately. Vibration monitoring is most widely used for bearing fault diagnosis, with the acoustic emission (AE) technology emerging as a powerful tool. This article reports a comparison between vibration and AE technology in terms of their applicability for diagnosing naturally degraded wheel set bearings. In addition, a novel fault diagnosis method based on the optimized maximum second-order cyclostationarity blind deconvolution (CYCBD) and chirp Z-transform (CZT) is proposed to diagnose early composite fault defects in a wheel set bearing. The optimization CYCBD is adopted to enhance the fault-induced impact response and eliminate the interference of environmental noise, transmission path, and signal attenuation. CZT is used to improve the frequency resolution and match the fault features accurately under a limited data length condition. Moreover, the efficiency of the proposed method is verified by the simulated bearing signal and the real datasets. The results show that the proposed method is effective in the detection of wheel set bearing faults compared with the minimum entropy deconvolution (MED) and maximum correlated kurtosis deconvolution (MCKD) methods. This research is also the first to compare the effectiveness of applying AE and vibration technologies to diagnose a naturally degraded high-speed train bearing, particularly close to actual line operation conditions.

Research on temperature-magnetic properties based on metal magnetic memory testing technology

during the running of high-speed railway, the vibration and friction between wheel set and track will cause the temperature rise between wheel set and track. The metal magnetic memory detection technology is used to detect the small fault of wheel set, and the temperature will have a certain impact on the magnetic memory signal. In order to study the quantitative relationship between temperature and magnetic memory signal, the temperature magnetic property of 25CrMo4 material is proposed in this paper. Through the temperature magnetic experiment and simulation analysis of the material specimen, it is concluded that when the temperature is lower than Curie point, the magnetic flux leakage of the sheet is basically stable. The value in tangential direction is 130A/m, and the value in normal direction is 0A/m. When the temperature reaches Curie point, the value of the tangential direction changes to 169.9 A/m, and the normal direction is still 0A/m; And the temperature magnetic numerical simulation curve is constructed, which provides the basis for carrying out magnetic signal to material small fault under coupling load, and provides the basis for non-destructive testing.