High-speed Wheel Research Articles

Advancing Ultrasonic Defect Detection in High-Speed Wheels via UT-YOLO.

In the context of defect detection in high-speed railway train wheels, particularly in ultrasonic-testing B-scan images characterized by their small size and complexity, the need for a robust solution is paramount. The proposed algorithm, UT-YOLO, was meticulously designed to address the specific challenges presented by these images. UT-YOLO enhances its learning capacity, accuracy in detecting small targets, and overall processing speed by adopting optimized convolutional layers, a special layer design, and an attention mechanism. This algorithm exhibits superior performance on high-speed railway wheel UT datasets, indicating its potential. Crucially, UT-YOLO meets real-time processing requirements, positioning it as a practical solution for the dynamic and high-speed environment of railway inspections. In experimental evaluations, UT-YOLO exhibited good performance in best recall, mAP@0.5 and mAP@0.5:0.95 increased by 37%, 36%, and 43%, respectively; and its speed also met the needs of real-time performance. Moreover, an ultrasonic defect detection data set based on real wheels was created, and this research has been applied in actual scenarios and has helped to greatly improve manual detection efficiency.

Analysing the rolling contact damage behavior of a high-speed wheel tread — A case study

This study presents the rolling contact fatigue (RCF) mechanism and damage behavior of the motor wheel and trailer wheel of a high-speed EMU operating over 1.73 million kilometers in a wind and sand environment in Northwest China. The results indicate that the profile hardness of the wheel decreases with increasing distance from the surface and finally stabilizes. Within a certain distance from the surface, the hardness of the flange root changes sharply. The surface of the tread hardens, the hardness value increases, and the variation law is similar to that of the plastic deformation of the profile. The wheel treads of the motor and trailer suffer more serious damage, such as cracks, spalling pits, dents and pitting on the surface. The profile damage is mainly characterized by long and thin layered cracks and branch cracks. Cracks located at the root of the flange and outside of the nominal circle tend to propagate toward the inside of the flange and form branch cracks and delamination cracks, which may cause multiple cracks to penetrate each other to form spalling.

Formation mechanisms and three-dimensional characterization of composite inclusion of MnS-Al2O3 in high speed wheel steel

Formation mechanisms and three-dimensional characterization of composite inclusion of MnS-Al2O3 in high speed wheel steel

Investigation on the Formation Pathway of the MnS–Al2O3 Inclusions at Atomic Level in High-Speed Wheel Steel

Investigation on the Formation Pathway of the MnS–Al2O3 Inclusions at Atomic Level in High-Speed Wheel Steel

Research on detection of different metallographic structures of high speed wheel steel based on laser-induced breakdown spectroscopy.

The laser-induced breakdown spectroscopy (LIBS) experimental platform was applied to obtain LIBS spectral the data of 10 CL60 wheel steel samples. The principle component analysis (PCA) was used to preliminarily analyze the macroscopic characteristics of LIBS spectral data. With the spectral intensity and spectral intensity combined with spectral intensity ratio as variables, three spectral correction methods including median filtering, baseline correction and multiple scattering correction (MSC) were used for pretreatment. And the support vector machine (SVM) qualitative model was established to determine the metallographic structure. It was found that the SVM model established by using the pre-processed data of MSC as the input variable has the best effect. The accuracy rate of calibration set is 100%, and the accuracy rate of prediction set is 98.4%. The research has shown that LIBS combined with SVM model can be used for discriminant analysis of different metallographic structures of train wheel steel.

Research Progress of High-Speed Wheel–Rail Relationship

The research on wheel–rail relationship includes the basic theoretical models and corresponding numerical methods of wheel–rail in rolling contact, geometric parameter matching and material matching of them, friction and wear, wheel–rail rolling contact fatigue, wheel–rail adhesion and noise. They are also key theoretical and technical problems of the high-speed train/track coupling system. The basic theoretical models of wheel–rail in rolling contact and the corresponding numerical methods are the basis and one of the basic means for solving other wheel–rail relationship problems. The other is the experimental means. Moreover, the modeling and analysis of coupling behavior of the train and track can only be realized by means of the wheel–rail rolling contact mechanics model and its corresponding numerical method. This paper mainly discusses some research work and achievements on high-speed wheel–rail relationship problems since China opened a high-speed railway system on a large scale. The discussions in this paper include the classic wheel–rail rolling contact theoretical models (analytical forms) and the modern wheel–rail rolling contact theories (numerical methods), their advantages and disadvantages, their application and future development direction of them. The reviewed research progress on the other wheel–rail relationships mainly expounds the thorny problems of the wheel–rail relationship encountered in the operation of China’s high-speed railway, how to adopt new theoretical analysis methods, test means and take effective measures to solve these problems. It also includes research results of similar important reference values performed by international peer experts in related fields. Challenging and unsolved problems in high-speed wheel–rail relationship research are also reviewed in the full text.

Investigation into the evolution of the microcosmic surface of bainitic wheel steel material suffering polygonal wear

With the rapid development of high-speed railway, it is imperative to develop highly comprehensive wheel/rail materials to improve the safe and stable operation of trains. Even though bainitic steel shows excellent resistance to rolling contact fatigue (RCF), its wear resistance is not good enough and whether it is qualified for high-speed wheel materials still needs further investigation. Through conducting rolling wear experiment on carbide-free bainite (FCB) wheel steel, this paper observed the changes of the surface profile lines of the worn specimens regularly and the wear morphology in different stages, and analyzed the changes of the microstructures and hardness on the surface layer, in order to explore the formation of polygonization wear (PolyW) from the angle of the microcosmic surface of bainitic wheel steel. The research revealed that during the process of rolling wear, the nonuniform load caused by mechanical vibration could lead to the appearance of PolyW on the surface of the two-disc specimens of FCB wheel steel. Based on the surface morphology and size variations, three stages could be divided to explain the formation of PolyW: The incubation stage where macromorphology underwent cyclic changes, the development stage where PolyW appeared in some regions and the mature stage where PolyW spread all over the circumference. The wear mode in wave crests was mainly featured by oxidative wear and adhesion wear, and the one in wave troughs was marked by fatigue wear with wear rotations increasing, PolyW on the surface was exacerbated. Compared with wave crests, wave troughs had a larger slip ratio and the additional impact load, so the microstructures experienced severer deformation, the hardness increase was higher and the depth of the hardening layer was greater.

Wear Behavior of High-Speed Wheel and Rail Steels under Various Hardness Matching

Wear Behavior of High-Speed Wheel and Rail Steels under Various Hardness Matching

Exploring the Efficiencies of Spectral Isolation for Intelligent Wear Monitoring of Micro Drill Bit Automatic Regrinding In-Line Systems

Despite the increasing digitalization of equipment diagnostic/condition monitoring systems, it remains a challenge to accurately harness discriminant information from multiple sensors with unique spectral (and transient) behaviors. High-precision systems such as the automatic regrinding in-line equipment provide intelligent regrinding of micro drill bits; however, immediate monitoring of the grinder during the grinding process has become necessary because ignoring it directly affects the drill bit’s life and the equipment’s overall utility. Vibration signals from the frame and the high-speed grinding wheels reflect the different health stages of the grinding wheel and can be exploited for intelligent condition monitoring. The spectral isolation technique as a preprocessing tool ensures that only the critical spectral segments of the inputs are retained for improved diagnostic accuracy at reduced computational costs. This study explores artificial intelligence-based models for learning the discriminant spectral information stored in the vibration signals and considers the accuracy and cost implications of spectral isolation of the critical spectral segments of the signals for accurate equipment monitoring. Results from one-dimensional convolutional neural networks (1D-CNN) and multi-layer perceptron (MLP) neural networks, respectively, reveal that spectral isolation offers a higher condition monitoring accuracy at reduced computational costs. Experimental results using different 1D-CNN and MLP architectures reveal 4.6% and 7.5% improved diagnostic accuracy by the 1D-CNNs and MLPs, respectively, at about 1.3% and 5.71% reduced computational costs, respectively.

Study on Dynamic Pore Water Scouring of Asphalt Pavement by Mesoscopic Simulation Method

Dynamic water scouring caused by high-speed wheel load is an important cause of asphalt pavement water damage, which seriously affects the service life of asphalt pavement. In this paper, the dynamic water scouring simulation calculation model of asphalt pavement was established by mesoscopic level. Through the simulation model, the water scouring phenomenon of saturated and unsaturated pore in pavement caused by high-speed wheel load was discussed and studied, which mainly considered the influence of wheel speed, pore diameter, pore saturation state and other factors. The main conclusions are as follows: The water pressure, velocity and shear force in the pore are positively correlated with the wheel load velocity in both saturated and unsaturated states. The internal water pressure and fluid velocity of large pore are slightly lower than those of small pore, and the smaller the pore size is, the greater the vacuum negative pressure is. In the unsaturated state, the turbulent kinetic energy in the pore is an order of magnitude larger than that of saturated state, and the larger the pore is, the greater the turbulent kinetic energy is, so the water erosion damage of gas-liquid two-phase flowing is more serious than the saturated state.

Polygonal wear mechanism of high-speed wheels based on full-size wheel-rail roller test rig

The polygonal wear of train wheels is common. It increases the wheel-rail interaction force drastically and adversely affects the safety and comfort of the train. The mechanism of the initiation and development of polygonal wear warrants further study. This study performed a high-speed rolling test based on the full-size wheel-rail roller test rig to reproduce the entire process of the generation and development of the polygonal wear on the tested wheelset of CL60 steel in the laboratory. The mechanism of the initiation and development of polygonal wear was analyzed using the test results, the bending resonance of wheelset was considered as an important cause of the polygonal wear in this paper. The basic condition for the polygonal wear formation and its high rate of development was verified. The evolution process of polygonal wear was studied in-depth, and the relationship between axle-box acceleration and polygonal wear was revealed. Effective countermeasures against the development of polygonal wear were proposed. Variable speed operation could mitigate the development of polygonal wear in this paper. The results obtained in this study may provide reference for the further study of the effective countermeasures against the development of polygonal wear.

Investigation on the Formation Pathway of the Mns-Al2o3 Inclusions at Atomic Level in High-Speed Wheel Steel

Investigation on the Formation Pathway of the Mns-Al2o3 Inclusions at Atomic Level in High-Speed Wheel Steel

Generation and Evolution Conditions of Polygonal Wear of High-Speed Wheel

Wheel polygonal wear has long been a problem that confused the safety of railway operation which has important theoretical value and research significance. In this paper, the conditions of polygonal wear of high-speed wheel are analyzed based on the wear model and verified by the field measured data. Considering the wheel track interaction caused by rotation, a finite element model of wheelset rotor dynamics is established. The effects of rotor speed, mass eccentricity, wheelset, and track flexibility on the vibration characteristics of wheelset rotor system and wheel polygonal wear characteristics are analyzed by beam element and solid element, respectively. The results show that the wheel longitudinal vibration is the main reason of wheel polygonal wear, and the wheel polygonal wear follows the law of “constant frequency and divisible.” Its “constant frequency” comes from the wheel track contact vibration, which stimulates the third-order vertical bending vibration of wheelset and the eighth-order coupled bending vibration of track, and the order is equal to the ratio of “constant frequency” to the wheelset rotation frequency.

Experimental Study of Effects of the Third Medium on the Maximum Friction Coefficient between Wheel and Rail for High-Speed Trains

The changes of the friction coefficient between wheel and rail affect the wheel-rail adhesion characteristics of high-speed trains. The adhesion state in the wheel-rail contact area could be distinguished by the maximum friction coefficient between wheel and rail. The wheel-rail adhesion is of great significance for high-speed train traction. In order to study the influence of water, oil, fallen leaves, quartz sand, or their mixtures on the maximum friction coefficient between high-speed wheel and rail, a wheel-rail contact test bed is built to carry out the wheel-rail contact test and wheel-rail friction contact test. The comparative analysis of the test results shows that the axle load has little influence on the maximum friction coefficient between wheel and rail. Water, oil, and fallen leaves would reduce the maximum friction coefficient. Quartz sand could increase the maximum friction coefficient in a short time, while the excessive static friction coefficient would damage the wheel and rail. Besides, the maximum friction coefficient of water, oil, and fallen leaves mixing in pairs is lower than each of them existing alone. Both water and oil could increase the adhesion of quartz sand, and the effect of water is better. Therefore, when the sand still could not meet enough traction, it could be considered to add some water to increase the wheel-rail adhesion.

Electromagnetic Tomography System for Defect Detection of High-Speed Rail Wheel

A novel electromagnetic tomography(EMT) system for defect detection of high-speed rail wheel is proposed, which differs from traditional electromagnetic tomography systems in its spatial arrangements of coils. A U-shaped sensor array was designed, and then a simulation model was built with the low frequency electromagnetic simulation software. Three different algorithms were applied to perform image reconstruction, therefore the defects can be detected from the reconstructed images. Based on the simulation results, an experimental system was built and image reconstruction were performed with the measured data. The reconstructed images obtained both from numerical simulation and experimental system indicated the locations of the defects of the wheel, which verified the feasibility of the EMT system and revealed its good application prospect in the future.

Characterization of High-Speed Alumina Abrasive Grinding Wheel

The high-speed grinding wheel can be defined as a self-sharpening composite structural tool composed from abrasive grains held in a specific binder. The main properties of grinding wheels depend on the type of abrasive elements, grit size, grade, binder and the resulting structure, which is influenced by several crucial technological processing steps. Preparation of an initial mixture of abrasive particles together with permanent binder’s mixture and temporary binder followed by pressing and high-temperature sintering is the essential technological step in the manufacturing of high-quality grinding wheels. High demands placed on functionality and quality together with constantly increasing effort to improve existing properties of grinding tools require detailed characterization of all input raw materials. For further research and development is crucial know, how each technological step can influence the final quality of the product. This contribution is focused on the characterization of four alumina abrasives with different grit size and two in chemical composition different binder mixtures which were used for the production of two different high-speed grinding wheels. Initial abrasive grains, binders and metallographic samples of high-speed grinding wheels were evaluated by means of scanning electron microscopy. The porosity of grinding wheels with different binding agents was also determined ustilizing digital image analysis technique.

The Influence of Surface Dipping and Bulk Filling Agents on Properties of High-Speed Grinding Wheels: Materialographic-Based Numerical Modelling

In order to increase the peripheral speed of grinding wheels of size of Ø 500 × 18 × Ø 200 mm for precise hard metallic surface finishing from conventional 80 m.s-1 up to 138 m.s-1 while still ensuring their safety and reliability, the critical locations in the grinding wheel were evaluated using the finite element analysis. The microstructure of grinding wheel was revealed using the materialographic techniques and the scanning electron microscope images were recorded in the back-scattered electrons mode. The image analysis was used on recorded micrographs for separation of individual material components, i.e. an abrasive, a binder, and pores, and to extract their geometries and spatial relationships. Subsequently, the influence of different filling agents (Young's modulus of 5, 10, 20, and 40 GPa) was studied, considering both surface dipping and bulk filling treatments.

Effect of Upper Bainite on Wear Behaviour of High-Speed Wheel Steel

This paper presents the wear and damage behaviours of the wheel/rail material of ER8 and of U71Mn under the same cycles condition, which were explored using a double-disc rolling wear testing device. The morphology of the worn surface and the morphology of cross sections were observed by laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). Results show that the microstructure of wheel steel includes ferrite, pearlite and upper bainite. As the cycles increased, the weight loss of the wheel steel containing upper bainite is significantly increased when compared with ferrite–pearlite wheel steel, and the plastic layer is more deformed than the ferrite–pearlite wheel steel. The deformation of the upper bainite is easier than the pearlite, and the cementite in the upper bainite presents granularity and short rod-shaped. With only ferrite and pearlite in the microstructure, the main wear mechanism varies from oxidative wear to adhesive wear and eventually into fatigue wear. When the microstructure is composed of ferrite, pearlite and upper bainite, the main wear mechanism changes from oxidative wear to ploughing wear and abrasive wear, and ultimately to fatigue wear.

Wheel wear prediction on a high-speed train in China

The number of operating high-speed trains in China is around 2800 today and 179,200 wheels are under maintenance in one reprofiling period. To help researchers to understand the evolution of the wheel profile and improve the reprofiling strategy of the wheels, this study predicts the development of wheel profiles on a high-speed train as function of mileage and compare simulated worn wheel profiles with measured ones. The methodology includes transient multi-body dynamic simulation, wheel–rail contact calculation and wear calculation with Archard’s model. Calibrated by analysing measurements of worn S1002CN profiles and performing parameters sensitivity study in the wear model, the model is then used to predict the development of a recently designed wheel profile, called S1002CN-RF. The simulation results for S1002CN and S1002CN-RF show that the predicted wheel profiles coincide with the measured ones. Wear prediction of another high-speed wheel profile (LMA) validates that the vehicle performance with respect to wear could be further improved compared to using S1002CN or S1002CN-RF. Finally, the influence of track alignment and operating speed is investigated. The wear increases with the speed increasing up to 300 km/h, but stays almost constant with a further speed increase from 300 to 400 km/h.

Wheel–rail low adhesion issues and its effect on wheel–rail material damage at high speed under different interfacial contaminations

The objective of this paper is to ascertain the wheel–rail low adhesion mechanism using a high-speed wheel–rail rolling contact test rig under different interfacial contaminations. Based on the experimental results, a numerical method was proposed to investigate the wheel–rail wear and rolling contact fatigue due to low adhesion issues. The experimental results indicated that the wheel–rail low adhesion phenomena can happen under interfacial liquid contaminations, especially at high-speed running condition. Preliminary numerical investigations showed that the low adhesion condition can easily lead to sliding hence serious wear, especially at the speed between 160 km/h and 200 km/h. The temperature rise within the contact patch can be significantly more severe once wheel and rail are in full slip, causing rolling contact fatigue due to material softening.