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The purpose of this paper is to study the wear evolution of metro wheels under the conditions of different track sequences, track composition and vehicle load and then to predict wheel wear and to guide its maintenance.

By using the SIMPACK and MATLAB software, numerical simulation analysis of metro wheel wear is carried out based on Hertz theory, the FASTSIM algorithm and the Archard model. First of all, the vehicle dynamics model is established to calculate the motion relationship and external forces of wheel-rail in the SIMPACK software. Then, the normal force of wheel-rail is solved based on Hertz theory, and the tangential force of wheel-rail is calculated based on the FASTSIM algorithm through the MATLAB software. Next, in the MATLAB software, the wheel wear is calculated based on the Archard model, and a new wheel profile is obtained. Finally, the new wheel profile is re-input into the vehicle system dynamics model in the SIMPACK software to carry out cyclic calculation of wear.

The results show that the setting order of different curves has an obvious influence on wear when the proportion of the straight track and the curve is fixed. With the increase in running mileage, the severe wear zone is shifted from tread to flange root under the condition of the sequence-type track, but the wheel wear distribution is basically stable for the unit-type track, and their wear growth rates become closer. In the tracks with different straight-curved ratio, the more proportion the curved tracks occupy, the closer the severe wear zone is shifted to flange root. At the same time, an increase in weight of the vehicle load will aggravate the wheel wear, but it will not change the distribution of wheel wear. Compared with the measured data of one city B type metro in China, the numerical simulation results of wheel wear are nearly the same with the measured data.

These results will be helpful for metro tracks planning and can predict the trend of wheel wear, which has significant importance for the vehicle to do the repair operation. At the same time, the security risks of the vehicle are decreased economically and effectively.

At present, many scholars have studied the influence of metro tracks on wheel wear, but mainly focused on a straight line or a certain radius curve and neglected the influence of track sequence and track composition. This study is the first to examine the influence of track sequence on metro wheel wear by comparing the sequence-type track and unit-type track. The results show that the track sequence has a great influence on the wear distribution. At the same time, the influence of track composition on wheel wear is studied by comparing different straight-curve ratio tracks; therefore, wheel wear can be predicted integrally under different track conditions.

Reducing wear of undercarriage track propulsion systems used in heavy construction equipment decreases the maintenance costs and increases the equipment's life. Therefore, understanding key factors that affect the wear rate is critical. This study is an attempt to predict undercarriage wear.

This research analyzes a sample of track-type dozers in the eastern half of North Carolina (NC), USA. Sand percentage in the soil, precipitation level, temperature, machine model, machine weight, elevation above sea level and work type code are considered as factors influencing the wear rate. Data are comprised of 353 machines. Machine model and work code data are categorical. Sand percentage, elevation, machine weight, average temperature and average precipitation are continuous. ANOVA is used to test the hypothesis.

The study found that only sand percentage has a significant impact on the wear rate. Consequently, a regression model is developed.

The regression model can be used to predict undercarriage wear and bushing life in soils with different sand percentages. This is demonstrated using a hypothetical scenario for a construction company.

This work is useful in managing maintenance intervals of undercarriage tracks and in bidding construction jobs while predicting machine operating expense for each specific job site soil makeup.

The need to examine the integrity of infrastructure in the rail industry in order to improve its reliability and reduce the chances of breakdown due to defects has brought about development of an inspection and diagnostic robot.

In this study, an inspection robot was designed for detecting crack, corrosion, missing clips and wear on rail track facilities. The robot is designed to use infrared and ultrasonic sensors for obstacles avoidance and crack detection, two 3D-profilometer for wear detection as well as cameras with high resolution to capture real time images and colour sensors for corrosion detection. The robot is also designed with cameras placed in front of it with colour sensors at each side to assist in the detection of corrosion in the rail track. The image processing capability of the robot will permit the analysis of the type and depth of the crack and corrosion captured in the track. The computer aided design and modeling of the robot was carried out using the Solidworks software version 2018 while the simulation of the proposed system was carried out in the MATLAB 2020b environment.

The results obtained present three frameworks for wear, corrosion and missing clips as well as crack detection. In addition, the design data for the development of the integrated robotic system is also presented in the work. The confusion matrix resulting from the simulation of the proposed system indicates significant sensitivity and accuracy of the system to the presence and detection of fault respectively. Hence, the work provides a design framework for detecting and analysing the presence of defects on the rail track.

The development and the implementation of the designed robot will bring about a more proactive way to monitor rail track conditions and detect rail track defects so that effort can be geared towards its restoration before it becomes a major problem thus increasing the rail network capacity and availability.

The novelty of this work is based on the fact that the system is designed to work autonomously to avoid obstacles and check for cracks, missing clips, wear and corrosion in the rail tracks with a system of integrated and coordinated components.

This paper aims to analyze the effect of Y₂O₃ mass fraction on the tribological performance of CrNi coating, which solved the problem of wear resistance on AISI H13 steel.

Y₂O₃ reinforced CrNi coatings were fabricated on AISI H13 steel. The microstructure and phases of obtained coatings were analyzed using a super-depth of field microscope and X-ray diffraction, respectively, and the effects of Y₂O₃ mass fraction on the microstructure and wear resistance were methodically investigated using a wear tester.

The average coefficients of friction and wear rates of Y₂O₃ reinforced CrNi coatings decrease with the increase of Y₂O₃ mass fraction, in which the Y₂O₃ plays a role of friction reduction and wear resistance. The wear mechanism of Y₂O₃ reinforced CrNi coating is primary abrasive wear, accompanied by adhesive wear, which is contributed to the grain refinement and dense structure by the Y₂O₃ addition.

The Y₂O₃ was added to the CrNi coating by laser cladding, and the effect mechanism of Y₂O₃ mass fraction on the tribological performance of CrNi coating was established by the wear model.

This paper aims to investigate the effect of Ti₃SiC₂ on the high-temperature tribological behaviors of NiCr coating, which was beneficial to improve the friction-wear performance of hot work mold.

NiCr-Ti₃SiC₂ coatings were prepared on H13 steel substrate by laser cladding. The microstructure, phases and hardness of obtained coatings were analyzed using a super-depth of field microscope, X-ray diffraction and microhardness tester, respectively, and the tribological performance of obtained coatings at 500°C was investigated using a high-temperature tester.

The results show the NiCr-Ti₃SiC₂ coatings are comprised of γ-Ni solid, solution, Ti_xNi_y, TiC and Ti₃SiC₂ phases, and the coating hardness is increased with the increase of Ti₃SiC₂ mass fraction, which is contributed to the fine-grain and dispersion strengthening effect by the addition of Ti₃SiC₂. The NiCr-Ti₃SiC₂ coatings present excellent friction reduction and wear resistance by the synergetic action of Ti₃SiC₂ lubricant and hard phase, and the wear mechanism is predominated by abrasive wear and oxidation wear.

Ti₃SiC₂ phase was used to reinforce the tribological performance of H13 steel at high temperature, and the roles of friction reduction and wear resistance were discussed.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2023-0004/

This paper aims to optimize the operating condition of mechanical parts, whose working surfaces have macro-crack defects, and surface wear properties with macro-cracks are assessed through experimental investigation.

Macro-cracks perpendicular to the direction of sliding were manufactured on discs by electric discharge machining. Tribological tests under oil lubrication were conducted on a ball-on-disc test rig. Their wear processes were monitored with on-line visual ferrography. The cross-sectional profile and morphology of the wear track were analyzed using a T200 profilometer and a scanning electron microscope, respectively. Effects of different crack numbers and various applied normal loads on the wear behavior were studied.

The macro-cracks tend to promote plastic deformation on the contact disc surfaces, and material plastic deformation of the crack edges varies with the magnitude of applied normal loads. Relationship of the duration of running-in period and root mean square index of the particle coverage area with the numbers of crack is approximately linear.

The wear properties of surfaces with macro-cracks were assessed with various crack numbers and with different applied normal loads, and the relationship between the index of particle coverage area and the wear rate was established.

With the increased speed and mileage of high-speed lines, the problem of rail wear is increasing. In actual operation, a large number of abnormal wear phenomena occur on both vehicles and rails during fixed line operation; therefore, the purpose of the study is to explored the rail wear for a variety of vehicles running in mixed operation.

This paper used the universal mechanism multibody dynamics software to establish the CRH2 high speed train (HST) and the CRH3 HST vehicle dynamic models, respectively. The mixed running of HSTs on the effect of rail wear evolution law was analyzed. The rail wear of the two vehicles with different curve radii, different wheel diameters and different under-rail stiffness was compared and analyzed.

The result showed that the rail wear of CRH3 HST is greater than that of CRH2 HST. The rail wear in the tangent track under mixed operation conditions is 25.4% less than when CRH3 HST operated independently. When there is a 1-mm wheel diameter difference, the maximum rail wear of CRH2 HST and CRH3 HST increases by 263% and 44%, respectively. The amount of rail wear is proportional to the under-rail stiffness, and the position of the maximum wear is almost unchanged.

Most studies on the evolution law of rail wear are conducted for a single vehicle type and a single line. This study explored the mixed running of HSTs on the effect of rail wear evolution law.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0276/

Testing of silicon nitride (Si₃N₄) or silicon carbide (SiC), sliding on itself in water, revealed that hydrodynamic lubrication can be obtained at low‐sliding velocity. The purpose of this paper is to study the performance of Si₃N₄‐metals pairs, sliding in water.

Ball on disc unidirectional sliding tests are run with Si₃N₄ against tool steel, stainless steel and cast iron in water. The friction force is recorded continuously and the wear is evaluated at the end of the run by geometric technique. In addition, SiC sliding on itself in oxidant solution (3 per cent solution of CrO₃ in water) is tested.

The measured friction and wear of water‐lubricated Si₃N₄ against metals are higher compared to Si₃N₄ sliding on itself. At the end of the run‐in SiC, lubricated by the oxidant solution, obtains hydrodynamic lubrication and friction and wear are lower than in water‐lubricated SiC.

The experimental results obtained are valid within the range of load and sliding velocity applied – 1‐10 N, 0.04‐0.33 m/s, respectively. The Si₃N₄ sliding against metals in water over sliding distance of 3,000 m has not shown tendency towards hydrodynamic lubrication.

The paper presents test data on friction and wear properties of Si₃N₄ sliding against metals in water. The low friction and ball wear rate of the SiC, lubricated by the oxidant solution, shows the potential of the 3 per cent distilled water solution of CrO₃ to surpass water as a lubricant for SiC sliding bearings.

Since the middle of the 1970s, lubrication of the high rail flange has been used to reduce wear rates. Field tests have been taking place since 1997 to evaluate the differences in wear characteristics between mineral oil based grease and new environmentally adapted greases. The field tests have also investigated whether the addition of graphite contributed to reduced flange wear. The wear reducing effect of trackside lubrication as a function of distance from point of application of the grease was also investigated. The field tests showed that environmentally adapted greases can be used without risk of increased rail wear and that the addition of solid lubricants, such as graphite, has no significant effect on the rate of wear. The highest wear rates were found during winter months when active lubrication stops due to problems associated with the sub‐zero temperatures common in northern Sweden. Year‐round lubrication would be expected to decrease wear rates significantly.

This paper aims to investigate the effects of Cr and Ta additions on the friction performance and corrosion-wear mechanism of Fe90-Al₂O₃ coating in 3.5% NaCl solution.

Cr and Ta reinforced Fe90-Al₂O₃ coatings were prepared on Q235 steel by laser cladding. The effects of Cr and Ta addition on the coefficient of friction (COF) and wear rate of Fe90-Al₂O₃ coating were investigated using a friction tester, and the wear model was established to discuss its corrosion-wear mechanism.

The average COFs of Fe90-Al₂O₃, Fe90-Al₂O₃-10%Cr and Fe90-Al₂O₃-10%Ta coatings in 3.5% NaCl solution are 0.57, 0.42 and 0.75, respectively, and the corresponding wear rates are 9.42 × 10⁻⁷, 5.31 × 10⁻⁷ and 7.02 × 10⁻⁷ mm³ s⁻¹ N⁻¹, respectively. The corrosion-wear resistance of Fe90-Al₂O₃-10%Cr coating is the best among the three kinds of coatings, in which the additions of Cr and Ta play a role in solid solution strengthening.

The Fe90-Al₂O₃ coating was strengthened by the additions of Cr and Ta to improve its corrosion-wear resistance in 3.5% NaCl solution.