Wear Problems Research Articles

Investigation of combined rock-breaking ability of sawblade and conical pick

To solve the problem of severe wear and low rock-breaking efficiency of a conical pick during rock cutting, a method of rock-breaking using a sawblade and conical pick is proposed, which can improve the rock-breaking ability and efficiency. Test benches for the sawblade rock cutting and conical-pick breaking were established to verify the numerical simulation model and improve the numerical simulation accuracy. The numerical simulation model of sawblade and conical-pick rock-cutting was used to investigate the effect of the cutting parameters on cutting performance. Based on the numerical simulation results of rock-breaking, a prediction model of the cutting force and specific cutting energy consumption for combined rock-breaking with a sawblade and conical pick was developed. This provides a comparative analysis basis for the combined rock-breaking capacity of sawblades and conical picks as well as traditional conical-pick rock-breaking. The results indicate that the cutting force, specific cutting energy consumption, and rock-breaking efficiency of combined rock-breaking with a sawblade and conical pick are better than those of the traditional conical pick. The research results provide a theoretical foundation for applying a combined rock-breaking method to sawblades and conical picks in engineering practice.

Research on Ultrasonic Vibration Assisted Grinding Technology of Quartz Fiber Reinforced Ceramic Matrix Composites

Ceramic matrix composites have good mechanical properties and high temperature resistance, but it is difficult to process. In order to solve the problems of fast tool wear and low machining efficiency in the dry grinding process, ultrasonic vibration assisted grinding technology of quartz fiber reinforced ceramic matrix composites is adopted in this paper. Grinding force, machining efficiency, tool wear and surface roughness are analyzed through the comparison experiment between the conventional grinding and the ultrasonic vibration assisted grinding. The influence of the ultrasonic vibration assistance and process parameters on machining quality and tool life is further obtained. According to the findings, when compared to traditional grinding, ultrasonic vibration grinding can lower the grinding force by 25% to 58% and the surface roughness by up to 16%. The tool life and machining efficiency can be significantly increased with the help of ultrasonic vibration.

Analysis of Wheel Wear and Wheel-Rail Dynamic Characteristics of High-Speed Trains under Braking Conditions

When high-speed trains operate under braking conditions, the wheel-rail interaction increases significantly, which can lead to more serious wear problems. To analyze the evolution of wheel wear and the dynamic characteristics of wheel-rail under braking conditions, this paper first carries out long-term monitoring of the service state of wheel-rail during the operation period. The study analyzed the matching characteristics of the measured wheel-rail profile and calibrated the wear model by using the collected data. The resulting wear prediction model was then used to examine the wheel wear characteristics under braking conditions. The research results indicate that during the operation period, the wheel experiences tread concave wear within a range of ±20 mm of the rolling circle, at a rate of approximately 0.05 mm per 10,000 km. Meanwhile, the rail experiences top surface wear at a natural rate of about 0.09 mm per year. Concave wear causes the contact point of the wheel-rail to appear in two zones, resulting in a sudden change of contact geometric parameters. The concave worn wheel and rail with a 60 N profile have better matching compared to the 60 rail profile. Increasing the braking torque and wheel-rail friction coefficient will significantly increase the wheel wear depth on straight sections. On small-radius curve sections, rail side lubrication can significantly reduce high rail side wheel flange wear. A worn concave wheel can lead to unfavorable wheel-rail contact geometry characteristics and increase low-frequency components in the vehicle’s lateral dynamic response.

Influence of diamond-like carbon coatings and micro-texturing on friction and wear of seal interfaces: Experiment and simulation study

For mechanical seal friction vice in dry friction conditions, due to friction wear serious failure, is the slurry pump and other instruments in the operation of the process of the urgent need to solve the problem. In this paper, in order to optimize and enhance the friction and wear problem of mechanical seal end face of slurry pump. Surface treatment of mechanical sealing rings with diamond-like carbon (DLC) coating and surface microtexturing, and at different rotational speeds and normal forces, the surface hardness, wear coefficient and dry friction coefficient of the sealing rings were analyzed by experimental comparison, and the wear morphology was collected by electron microscopy, having analyzed the results of the sets of, the end face structure of the mechanical seal was optimized. Based on Archard wear model simulation calculations, the seal ring wear depth and wear quality were obtained. The results show: under dry friction conditions, the synergistic effect of the DLC coating and the surface micro-texture (MT), the coefficient of friction is reduced by approx. 68% and the quality and depth of wear is minimized. Excessive speeds and normal forces are more prone to wear behavior caused by abrasive wear. Simulation results of surface treatment groups, DLC / MT group maximum wear depth is the smallest; wear quality test and simulation of the maximum error within 15.7%. The results of the study can provide a basis for a phosphoric acid plant slurry pump mechanical seal design.

Prediction of Sucker Rod-tubing Wear Depth in Surface Drive Screw Pump Production Wells

With the wide application of ground drive screw pump in the process of oil production, the wear problem of screw pump sucker rod-tubing is becoming more and more prominent. In order to systematically study the wear of the rod and tube of the screw pump production well and quantify the wear of the rod and tube, this paper establishes a calculation model of the contact force of the screw pump sucker rod by analyzing the force of the rod and tube string in the three-dimensional wellbore trajectory. Based on the indoor rod and tube wear simulation experiment, combined with the wear efficiency theory, a prediction model of sucker rod-tubing wear under different working conditions was established, and an example well calculation was carried out. The results show that the force of sucker rod is mainly affected by sucker rod size, submergence degree and other factors, and the wear of sucker rod and tubing is mainly affected by working time, rotational speed and wear efficiency. The research results can not only accurately carry out accurate quantitative calculation of downhole rod and tube wear, but also provide theoretical and technical basis for prediction of rod and tube wear depth.

Theoretical study on wheel wear mechanism of high-speed train under different braking modes

The high-speed train wheel wear problem persists throughout the whole service cycle, including the traction-braking stage, constant-speed stage, acceleration and deceleration stage, and so on. This article focuses on the wheel wear of high-speed trains under various braking modes. Firstly, high-speed motor cars and trailers are created, and the two are linked by the coupler buffer device, and the former considers detailed gear transmission system. A comprehensive wheel wear prediction process is then established based on the vehicle model, wheel-rail contact model, wear model, and wheel tread update strategy. Secondly, vehicle model and wheel wear prediction procedure are validated using the measured dynamic data and worn wheel profile. Thirdly, common braking modes and emergency braking modes are used for the braking process of high-speed trains. Finally, wheel wear and wear mechanism of high-speed trains during braking process is revealed. The results demonstrate that with the increase of braking mode level, the amplitude of longitudinal creepage also increases synchronously, while lateral creepage and spin creepage do not change significantly. According to wheel wear depth under different braking processes, the order from large to small is emergency braking mode >8-level common braking mode >6-level common braking mode >4-level common braking mode >3-level common braking mode >B1-level common braking mode. Furthermore, with the increase of rail slope, wheel wear is increasing during braking process. With the increase of friction coefficient, wheel wear depth decreases gradually during braking process.

Thermal failure optimization of foil thrust bearings

The problems of wear and failure seriously endangers the operational quality and life of foil bearings. This work establishes a thermo-elastic-hydrodynamic foil thrust bearing model to investigate thermal failure performance and compare it with an elastic-hydrodynamic model. The study analysis the thermo-elastic mechanism and thermal seizure behavior of three different bump foil models. Alterations in foil parameters and structure to optimize the risk of bearing thermal failure. Findings indicate that the bump foil design has a significant impact on the risk of thermal failure, and the bump foil's fixed position determines the characteristic of the thermal seizure risk. The integrated bump foil design exhibits superior load performance and risk resistance compared to the separated type. The inner radius of the bump foil is greater than 13.5 mm and the thickness is less than 125 μm, which helps reduce the risk of thermal failure. Consequently, the proposed optimization is beneficial for the design and operation of foil bearings resist thermal failure.

An investigation on the performance of vehicle brake pads developed from Cortaderia selloana based biomass

AbstractNowadays, researchers are making intense efforts to develop biomass-based industrial products. This study developed low-metallic and asbestos-free samples based on Cortaderia selloana (12–15% and 18% ratios), a natural species, to contribute to the brake pad field. The developed samples’ friction coefficient and wear rate experiments were carried out on a brake pad test device with a load of 1 MPa and a disk rotation speed of 6 m/s, according to the TS555 standard. Scanning electron microscopy and electron-dispersive x-ray analysis were performed on the worn surfaces of the samples. According to the results obtained, the wear rate increased while the average friction coefficient decreased in the brake pad samples using 18% Cortaderia selloana content in the sample content. In scanning electron microscopy analysis, primary and secondary plateau formations were observed on the worn surfaces of all samples. At the same time, samples containing 15% and 18% Cortaderia selloana also showed signs of abrasive wear. High friction coefficient and low wear rate are expected for brake pads to be used in automobiles. In general, the friction of brake pads must be within the range, and it is always necessary to balance the friction to avoid driver discomfort. However, except for some racing applications, a high coefficient of friction is only sometimes desirable, which can cause rotor wear problems. As a result of this research, a consistent friction coefficient and low wear rate for the brake pads with the brake pad sample containing 12% Cortaderia selloana.

Methods of increasing the physical and mechanical strength of the working surface of rolling rolls

The article discusses the problem of rapid wear of the work rolls of a twenty-high rolling mill for plastic deformation of nitinol. The purpose of this study is a comparative analysis of hardening methods and the feasibility of their use to increase the hardness of a roller tool. As a result, a method of ion implantation of work rolls with boron and nitrogen was identified that is preferable for implementation and deeper experimental study.

Influence of Shape, Installation and Rotation Motion Errors on Tin Bronze Clearance Seal of Rotary Joint

The rotary joint is the key device of the marine clutch. Once the seal fails, the power cannot be transmitted. In view of the above problems, this research studies the influence of shape, installation and rotation motion errors on clearance seal. The results show that compared with the absence of roundness error, the roundness error of the shaft will increase the leakage by about 2.5-4.9 %. The cylindrical error of the bushing will reduce the leakage, but it will bring more serious friction, wear and life problems. The existence of radial installation error will increase the leakage, and the larger the radial installation error, the more obvious the flow field extrusion, the higher the unevenness of the pressure field in the whole flow field. The existence of angular installation error will reduce the leakage, but it will cause more serious friction and wear, resulting in a sharp increase in temperature. The leakage increases by about 0.68 % when the radial installation error is 0.1 mm, and the rotary motion error further increases the leakage by about 0.15 %. The above research can provide theoretical support for the structural design and optimization of the rotary joint tin bronze clearance seal.

Research on flow distribution optimization of flue gas cooler based on numerical simulation

Based on Fluent, the flow distribution in flue gas cooler and its inlet and outlet flue in a power plant was numerically simulated. The calculation results show that the flue gas velocity distribution at the import of flue gas cooler was imbalance. The no uniform distribution of flue gas velocity can easily lead to problems such as wear, ash deposition and uneven heat transfer. To address the problem of uneven distribution of flue gas velocity, a diversion structure is designed and installed in the inlet flue of flue gas cooler. The numerical calculation results show that compared with the original flow distribution structure, the diversion structure can make the flow distribution of the flue gas cooler and its inlet and outlet flue more uniform, which can effectively avoid the problems of wear, ash deposition and uneven heat transfer.

Research On Discharge Plate Of Plough Tripper Based On Discrete Element

The plough discharger is the key device of the belt conveyor, which targets the wear problem of the baffle. In this paper, the coal particle model is established by EDEM, the normal cumulative contact energy and tangential cumulative contact energy of discharge baffles with radius of 1.6m, 2.5m, 4.5m and 8m are obtained, as well as the average velocity of coal particles contacting discharge baffles with different curvature radii, and the wear of the baffle with different curvature under the same working conditions are studied. The optimal radius of curvature was selected through analysis. It provides a basis for the future design of the discharger baffle.

Research of operation mode of high-speed trains on the effect of rail wear evolution law

PurposeWith 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.Design/methodology/approachThis 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.FindingsThe 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.Originality/valueMost 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.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0276/

Research on the design method for uniform wear of shield cutters in sand–pebble strata

AbstractDuring shield tunneling in highly abrasive formations such as sand–pebble strata, nonuniform wear of shield cutters is inevitable due to the different cutting distances. Frequent downtimes and cutter replacements have become major obstacles to long‐distance shield driving in sand–pebble strata. Based on the cutter wear characteristics in sand–pebble strata in Beijing, a design methodology for the cutterhead and cutters was established in this study to achieve uniform wear of all cutters by the principle of frictional wear. The applicability of the design method was verified through three‐dimensional simulations using the engineering discrete element method. The results show that uniform wear of all cutters on the cutterhead could be achieved by installing different numbers of cutters on each trajectory radius and designing a curved spoke with a certain arch height according to the shield diameter. Under the uniform wear scheme, the cutter wear coefficient is greatly reduced, and the largest shield driving distance is increased by approximately 47% over the engineering scheme. The research results indicate that the problem of nonuniform cutter wear in shield excavation could be overcome, thereby providing guiding significance for theoretical innovation and construction of long‐distance shield excavation in highly abrasive strata.

Numerical research on contact friction force with different structural brush seal hysteresis characteristics under differential pressure

The problems of leakage, frictional wear, and flow heat transfer caused by the hysteresis characteristics of brush seals are prominent, and existing models for solving the hysteresis characteristics of brush seals have convergence difficulties owing to the extreme degree of nonlinearity caused by additional contacts. In this study, numerical models based on the finite element software ABAQUS were proposed to address the hysteresis characteristics of brush seals with three different structures: basic, low-lag hysteresis, and low-wear high-pressure bearing. The models accounted for the contacts between: the brush, brush and the baffle, and brush and the rotor, while damping was introduced to improve the convergence of the models. The hysteresis of the three structures under differential pressure was investigated and compared with theoretical calculations and experimental test results. The hysteresis of the bristles was normalised by the contact force, the shift of the contact area, and the contact friction force when the hysteresis effect occurred in the brush seal. The results show that the basic model has the most obvious hysteresis characteristics in the presence of differential pressure. Although the low-lag hysteresis model and the low-wear high-pressure bearing model have the weakest hysteresis effect, the deformation variables of the last row of bristles of these two structures are larger than those of the basic model; therefore, the contact position is prone to fatigue fracture. Simultaneously, the hysteresis effect was verified by varying the contact area and contact friction force, and it was found that the larger the contact area and contact friction force, the larger the hysteresis.

Study on wear behavior and mechanism of 6007 Si3N4 full-ceramic ball bearing under different load conditions

This study investigated the effects of various load conditions on the wear characteristics of Si3N4 full-ceramic ball bearings in response to 6007 Si3N4 full-ceramic ball bearing operation-related wear problems. Using an ABLT-1A tester, the wear behavior of 6007 Si3N4 ceramic ball bearings was investigated under loads of 100, 500, and 800 N, with a rotation speed of 6000 r/min and a duration of 12,000 min. The test load, and the 100 and 500 N radial loads had an equilibrium temperature difference of about 1.91°C, while the 500 and 800 N radial loads exhibited an equilibrium temperature difference of about 2.35°C. Each group’s temperature rate difference is evident. Bearing internal clearance increased by 35.7%, 50.34%, and 56.1%, respectively, and the fault frequencies of the bearing elements appeared within the vibration signal. The surface roughness of each component of the bearing increased with the increase in the test load, while a large number of plow grooves and spalling appeared on the surface, and severe cage wear was observed. Results show that when load, temperature, clearance, runout, and frequency domain amplitude increased, the following were observed: development of rolling body surface spalling and a large area of wear spot; raceway surface crater along the direction of movement of the fur-row; obvious scratches were observed on the cage surface in the pocket hole edge melting phenomenon; the cage became the bearing system’s "weak link.” The test results are a reference value for the wear behavior of Si3N4 full-ceramic ball bearings under this test load.

Study on growth behavior and properties of LDH nanosheet arrays enhanced Ni-based coatings on Mg-Li alloy

For the application of lightweight alloys, the corrosion and wear problems of magnesium-lithium (Mg-Li) alloys have always been important problems that cannot be ignored. The coupling protection of multiple technologies has gradually become a new trend. In this study, layered double hydroxides (LDH) nanosheet arrays were in-situ grown on Ni-P coating by the electroless plating technology combined with hydrothermal synthesis technology. The optimum deposition conditions (temperature-time-pH) were selected by orthogonal test. The surface morphology, structure, corrosion resistance and wear resistance of LDH/Ni composite coatings under different conditions were systematically studied by SEM, XRD, FT-IR, DSC, electrochemical and tribological tests. The growth mechanism of LDH suitable for Ni-P coating surface was proposed by analyzing the growth process of LDH nanosheet arrays. The results showed that the condition of 125 °C-12 h-13 was conducive to the growth of LDH nanosheet arrays. Compared with the Ni-P coating and the composite coating under other conditions, the LDH125°C-12h-13/Ni composite coating has the lowest self-etching current density (7.50 × 10−7 A·cm−2) and the average friction coefficient (0.35). The defect sealing effect and Cl− barrier property of LDH effectively improved the corrosion resistance of the coating. The frictional properties were improved by lubrication and heat absorption properties of LDH. In addition, it was found that the growth of LDH on the Ni-P coating surface followed the mechanism of “deposition nucleation-diffusion growth”.

Wear and RCF problems of metro wheel/rail systems: Phenomena, causes and countermeasures in China

Wear and rolling contact fatigue (RCF) problems observed on metro wheel/rail systems in China in the last 15 years are summarized and explained from the aspects of phenomena, causes, and validated countermeasures. Presented wheel/rail wear in the lateral direction includes wheel flange wear, rail side wear, and abnormal wear of wheels such as differential, hollow, groove, and channel wear. As for irregular wear on wheel and rail running surfaces, the focus is on four and two important cases for wheel and rail, respectively, i.e., low-order wheel polygonal wear, high-order wheel polygonal wear, wheel stochastic out-of-roundness (OOR), wheel corrugation, short-pitch rail corrugation on the tracks with resilient and conventional fasteners, and rail corrugation on damping sleeper tracks. Finally, some unusual RCF problems occurring on wheel and rail surfaces are presented.

Super-Low Friction Electrification Achieved on Polytetrafluoroethylene Films-Based Triboelectric Nanogenerators Lubricated by Graphene-Doped Silicone Oil.

The novel proposal of Wang's triboelectric nanogenerator (TENG) has inspired extensive efforts to explore energy harvesting devices from the living environment for the upcoming low-carbon society. The inevitable friction and wear problems of the tribolayer materials become one of the biggest obstacles for attaining high-performance TENGs. To achieve super-low friction electrification of the TENGs, the tribological and electrical behaviors of the sliding-mode TENGs based on polytetrafluoroethylene (PTFE) films and metallic balls under both dry friction and liquid lubrication conditions were investigated by using a customized testing platform with a ball-on-flat configuration. Most interestingly, a super-low friction coefficient of 0.008 was achieved under graphene-doped silicone oil lubrication. The corresponding wear rate of the PTFE film was drastically decreased to 8.19 × 10-5 mm3/Nm. Simultaneously, the output short-circuit current and open-circuit voltage were enhanced by 6.8 times and 3.0 times, respectively, compared to the dry friction condition. The outstanding triboelectrical performances of the PTFE film when sliding against a steel ball are attributed to the synergistic lubricating effects of the silicone oil and the graphene nanosheets. The current research provides valuable insights into achieving the macro-scale superlubricity of the TENGs in practical industrial applications.

Study on Friction and Wear Properties of Copper-Impregnated Carbon Slide Plate Under Different Humidity Conditions

The pantograph–catenary system is one of the most commonly used power-receiving modes of metro trains. Its friction and wear performances are related to the safety and stability of train operation. In this study, a copper-impregnated carbon slide plate material, widely used in numerous metro lines in China, is considered as the research object. The problem of abnormal wear of slide plates caused by the decrease in relative humidity in the autumn and winter in tunnels is studied. Current-carrying friction and wear tests under humidity conditions of 20%, 30%, and 40% relative humidity (RH) are performed to reveal the mechanism of seasonal abnormal wear of slide plates and provide a reference for the service of pantograph slide plates under low-humidity conditions. The results reveal that relative humidity significantly influences the wear process of slide plates; further, the wear rate decrease with an increase in relative humidity. As observed by laser scanning confocal microscopy, with an increase in the relative humidity, the mechanical wear of the slide surface is weakened, arc erosion is enhanced, and surface roughness is increased. The Raman spectral scan showed that with the increasing humidity, the graphitization of the surface material decreased significantly, and the molecular structure changed greatly. Scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS) analysis reveal that under high humidity conditions, a relatively complete oxide film forms on the slide plate and plays a role in lubrication and protection.