Wear Calculation Research Articles

Evolution of tooth surface morphology and tribological properties of helical gears during mixed lubrication sliding wear

In mixed lubrication, the interplay of lubricant flows, solid asperity contact, and material wear between tooth surfaces creates complex and unpredictable contact states on tooth surface. To comprehensively understand the interaction between the lubrication and wear characteristics of the rough tooth surfaces of helical gears, this study established a mixed lubrication sliding wear calculation model for helical gears based on the mixed elastohydrodynamic lubrication model and Archard’s model. Specifically, the study aimed to examine the effects of surface topography features on average film thickness, contact area ratio, and accumulated wear at the meshing point. The findings demonstrated that the texture and power spectral density distributions of a non-Gaussian reconstructed surface closely resembled those of the actual ground surface. Furthermore, for non-Gaussian rough surfaces, a larger wavelength ratio enhanced microwedge motion, which increased film thickness and reduced wear. Additionally, a negatively skewed surface demonstrated better lubrication performance compared to both positively skewed and Gaussian surfaces. This improved performance is evident in the smaller contact area ratio and lower accumulated wear value of the negatively skewed surface.

Ultrasonic wave simulation in shrink-fit assembly for the estimation of stress at the contact interference

The investigation of stress distribution in an interference fit contact region is essential information required in fatigue and wear calculations to determine design life, regrinding requirements, and maintenance schedules. The aim of this work was to use ultrasound to non-destructively determine stress in the shrink-fit assembly, with the acoustoelastic theory. This one is based on the dependence of the propagation velocity of the ultrasonic wave with the stress state in the material. When a material is subjected to stress, there is a variation of the propagation velocity of the ultrasonic wave. Three methods have been initiated to ensure that the results will be more real, the first is the analytical calculation using thick-walled cylinder theory and Lamé formulation, then a numerical modeling of the contact between the assembled parts using finite element analysis and the third one is using elastic wave simulation and acoustoelastic theory in order to determine the value of the stress distribution at the interference region.

Methodology for determining the durability of soil-cultivating machines working bodies of parts

The development and creation of high-performance machines for agricultural production is in many cases limited by the insufficient wear resistance of individual parts and assemblies. Russian scientists, engineers and technicians working on the problem of increasing the durability of machines have achieved significant results. However, theoretical conclusions and prerequisites for increasing durability and the method of calculating parts of agricultural machines for durability are not enough. The durability calculations of agricultural machine parts used in some cases during their design are imperfect. In addition, in most cases, there are no reasonable calculations of allowable wear that would ensure high quality machine operation, i.e. these calculations are not related to the tasks of preventive maintenance and operation of machines. A number of scientists have been studying the abrasive wear of working parts of soil-cultivating and seeding machines for decades, but this issue has not yet been finally resolved. Until now, there is no clear understanding of the essence of abrasive wear and the factors that determine it. Most of the work carried out on the study of abrasive wear of parts of working bodies of soil-cultivating machines is of a private nature. There are no works covering the study of the complex set of phenomena that occur during abrasive wear. At present, very little has been studied about the wear capacity of soils, there is no criterion that determines it, and there is no connection between the phenomena of wear of the working parts of soil-cultivating machines and the basic theoretical principles of agricultural mechanics. The study of the wear capacity of soils, as well as the determination of the magnitude of pressures that arise during the interaction of the working parts of agricultural machines with the soil, can be used when calculating the working parts of these machines for durability.

Discrimination of wear performance based on surface roughness parameters arithmetic mean height (Sa) and skewness (Ssk)

Enhancing interfacial contact bearing performance typically involves minimizing the roughness parameter Sa (arithmetic mean height). Yet, exceedingly low Sa incur steep increases in processing costs, indicating that Sa-centric optimization strategies may not be universally suitable for interface performance control. Roughness parameters skewness (Ssk) and kurtosis (Sku) exert a pronounced influence on component contact wear performance. Accordingly, investigating the correlation between Ssk, Sku, and wear performance holds significant promise for enhancing wear resistance. A finite element wear calculation model for rough-surface abrasive wear employing elastic-plastic contact mechanics and the Jump-in-Cycle method. Cylindrical roller dry sliding experiments validate the model's reliability. Integrating this model, a method is proposed for wear performance discrimination based on Sa and Ssk at different loads. It enables the identification of critical roughness parameter values for improved surface wear resistance. The calculated wear model aligns with experiment trends, with predicted surface textures mirroring observed wear surface characteristics. Critical Sa and Ssk diverge under distinct loads. The study underscores the importance of moving beyond the exclusive pursuit of exceptionally low Sa and Ssk. It provides a foundation for reducing workpiece processing costs while optimizing wear performance.

Linear complementarity formulations for contact analysis and wear prediction in gears

This work presents linear complementarity based formulations for contact analysis and wear prediction in gear trains. Assuming steady motion of gears transmitting constant input torque without transmission errors, three sets of linear complementarity formulations are proposed, first for rigid gear teeth, second for gear teeth with skin compliance, and third for gear teeth with full compliance, the last two being new in linear complementarity literature. The developed formulations are used for contact analysis of two examples of gear trains, a pair of spur gears in mesh, and a planetary gear train. The accuracy of the method is tested by considering various time step sizes and stability of the formulations demonstrated for wide range of time steps. Contact forces between meshing teeth are calculated at a pre-defined set of points on the path of contact, and then wear is calculated on gear tooth flank using Archard’s wear equation. These wear calculations are compared with existing results in literature which demonstrate the applicability of the developed LC formulations. Future work is projected to include more state-of-art friction models and extension to 3D contact analysis in helical gear trains.

Three-Dimensional Reconstruction Method of Rail Corrugation Based on the Vision Detection

In order to realize the visual identification of the three-dimensional geometric characteristics of rail corrugation, the three-dimensional reconstruction method of rail corrugation based on vision detection is developed in the present paper. The acquisition equipment is designed to acquire the images of rail corrugation and corresponding depth information. Then, the image preprocessing method is proposed to achieve the automatic segmentation of rail corrugation images. The fitting equation between the image and depth of rail corrugation is obtained, which allows the three-dimensional reconstruction of rail corrugation. Furthermore, based on the finite element model of the wheel-rail system and the wear calculation model, the practicality and effectiveness of the three-dimensional reconstruction method are verified. Results show that the depth-grayscale correlation equation is well fitted with the coefficient of determination of 0.94 and the root mean square error of 0.02. The three-dimensional reconstruction method has an error of 2.63% at the maximum wear depth. When the three-dimensional reconstruction method is applied to the wear prediction of rail corrugation, the wear prediction of rail corrugation with the three-dimensional reconstruction is approximately the same as the actual wear distribution, which has an error of 5.02% at the maximum wear depth. The aforementioned results demonstrate the effectiveness of the three-dimensional reconstruction method of rail corrugation based on the vision detection.

Wear Calculation for a Shaft Lip Seal under Randomly Changing Temperature and Load

Wear Calculation for a Shaft Lip Seal under Randomly Changing Temperature and Load

WEAR LOAD CAPACITY OF CROSSED HELICAL GEARS

The paper presents a wear load capacity of crossed helical gears (gear pair consists of a worm and a helical gear). Crossed helical gears are similar to worm gear pairs, and it is logical to extend the load capacity calculation approach of worm gears for the case of crossed helical gears. One of the disadvantages of crossed helical gear sets is very high running-in wear. The paper explains the transition between running-in and steady-state wear and proposes a joint wear calculation model. The paper outlines a proposal to extend the calculation method for wear load capacity from a worm gear pair to the case of crossed helical gears (a worm with a helical gear). This calculation method for determining the wear load capacity of crossed helical gears is verified for the cases when the wheel is of bronze CuSn12Ni2-C-GCB and sintered steel Fe1.5Cr0.2Mo.

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.

Calculation of wear products falling into the oil as a result of gear teeth wear

The article presents an overview of experimental studies of gear tooth wear, which results in the loss of wear products in the oil unit. The results of experimental studies on the wear of the tooth heads of the driving gears and the knives of the driven gear teeth are presented. The results of calculating the wear of the gear train of the unit after operating time are also presented. The coefficient of distribution of wear products between obvious gears according to the period of oil change in the unit has been established. The dependence of the linear wear of the head and leg of the teeth of the drive gear of the unit after 1000 hours of operation on the meshing height coefficient is calculated. An analytical calculation of the linear wear of gear teeth, an increase in the concentration of wear products in the oil of the unit and a decrease with an increase in the total number of gear teeth, tooth length and engagement module were made, and the results of the test work were given.

Calculation and Analytical Prediction of Coating Wear During Tribological Tests Based on Models of Contact Fatigue Failure

Calculation and Analytical Prediction of Coating Wear During Tribological Tests Based on Models of Contact Fatigue Failure

Eksperimentalna procena biomaziva sa dodatkom nanočestica kalcijum karbonata (CaCO₃) iz otpada ljuske kapice kao tečnosti za sečenje korišćenjem minimalne količine podmazivanja (MKL) u CNC procesu glodanja

Nano-cutting fluid sprayed using the minimum quantity lubricant (MQL) method is one example of a green manufacturing process. Meanwhile, vegetable oil is an appropriate lubricating base oil as it offers very high lubricating performance and environmental friendliness. Further, CaCO₃ nanoparticles are popular for their capacity to improve lubrication properties and performance. However, the optimum impact of utilizing different types of vegetable oil remains inadequately investigated. Therefore, this study aims to analyze the effect of CaCO₃ nanoparticles on the performance of cutting fluid, specifically on the thermophysical, rheological, and tribological properties in the CNC milling process of AISI 1045 Steel material. The nano-cutting fluid was prepared using different vegetable oils (canola, corn, soybean) added with CaCO₃ nanoparticles with a mass concentration of 0.15%. The results showed that the thermophysical properties, including density and viscosity, were highest when using canola oil, and the addition of CaCO₃ to all samples did not significantly affect thermal conductivity. Meanwhile, for the rheological properties, we observed Newtonian for all cutting fluid samples. For tribological properties, canola, and corn oil were better for obtaining a minimum Ra value, while soyabean oil was more effective in reducing cutting temperature. Based on the results of tool wear calculations, each oil presents the best performance in reducing wear, especially with the addition of CaCO₃. For chip formation, on average, the samples produce irregular tooth morphology with C-type, comma, and elongation shapes. Meanwhile, the resulting chip color was dark purple, which changed to dark brown and light brown, then turned silvery white due to wear and tear on the different sides of the chisel.

Accounting for the Temperature Dependence of Hardness in Numerical Simulation of Wear in Pivot-Jewel Bearings

Pivot-jewel bearings are important components in rotor systems and flywheel energy storage systems; the relative rotation speed can reach about 10³ rps under nominal operating conditions, while the lifespan can amount to years. Wear calculations of the contact surfaces are necessary in such scenarios to assess the life cycle of friction joints. Accounting for the variation in the surface hardness due to friction heating can considerably affect the amount of wear in the contact surface.

Calculation of Wear of Metallic Surfaces Using Material’s Fatigue Model and 3D Texture Parameters

Today, when it comes to manufacturing parts and components for various mechanisms, the tendency is to use both approaches – the latest technologies and new material combinations- to achieve a longer product's lifetime. That is why the issue of machine parts' working capacity criteria, one of the most important of which is wear and its prediction, remains vitally important. Having studied the prediction theories of the wear process that have been developed over time, one can state that each has shortcomings that might strongly impair the results, thus making unnecessary theoretical calculations. Also, predicting wear based on lengthy, time-consuming, costly experiments is still prevalent. The article discusses a new wear calculation model, which is based on the application of theories from several branches of science. This model considers the surface texture (3D) parameters' values in modelling the surface's micro-topography with the random field theory while the friction surfaces' destruction – with the fatigue theory. The new wear calculation model is synthesised based on a developed friction surface contact model, providing a more complete surface description, which is essential for wear calculation and gives more accurate results. The proposed new wear calculation formula includes parameters that can be easily determined using modern measurement methods, thus speeding up the product design process and significantly contributing to sustainable development. Experimental studies on the steel-bronze sliding friction pair validated the analytical wear calculations' results.

Gear wear prediction based on the theorem of degradation entropy generation

Tooth surface material loss caused by gear wear alters the surface morphology of gears, which impacts their vibration, noise, and remaining lifespan. Although gear wear modeling and prediction have been extensively studied, this paper proposes a novel approach based on the theorem of degradation entropy generation (DEG). A point-by-point calculation method is introduced to determine the degradation coefficient for each measurement point on the tooth profile, accounting for varying working conditions along the tooth profile during the actual meshing process of the gear pair. First, the FZG gear’s bearing capacity is tested. Next, a surface roughness profilometer is employed to in-situ measure the tooth profile after each load stage. The profile deviation curve and the amount of profile wear following each load stage are obtained by processing the measured profile morphology data. Then, the pitting safety factor for each point on the tooth surface is calculated according to the ISO 6336–22:2018 standard and used to correct the degradation coefficient for that point. Finally, the entropy generation of the system during each load stage of the FZG gear is calculated. The degradation coefficient suggested in the DEG theorem is employed to link gear wear with system entropy generation, realizing gear wear modeling and prediction. The results demonstrate that the gear wear calculation method based on the DEG theorem can accurately predict the evolution of tooth profile surface morphology during the experimental process. This research provides a unified calculation method for surface morphology evolution caused by gear wear during service.

Anti-Wear Design of the Knot-Tripping Mechanism and Knot-Tying Test for the Knotter

Aiming to solve the problem of knot-tripping failure caused by severe wear between the spherical roller and planar cam of the knotter, this paper first establishes a calculation model of the spatial cam contour surface. The knot-tripping mechanism in the knotter is designed as a line-contact curved-surface cam mechanism, with the cutter arm swinging in accordance with sinusoidal acceleration. The design significantly reduces the contact stress between the cam and the roller, compared to the original knot-tripping mechanism. Additionally, it eliminates the impact between the spherical roller and the planar cam. Based on the Archard model, the calculation model for cam-roller wear in the knot-tripping mechanism has been derived and utilized for wear calculation. The wear test results of the knot-tripping mechanism with an aluminum cam show that the curved cam has a wear amount that is 43%, 56%, 46%, and 37% lower than that of the planar cam after tying the knot 200 times, 600 times, 1300 times, and 2000 times, respectively. Under the condition that the twine tension is set to 120 N, and the rotation speed of the fluted disc is 60 rpm, the deviations between the calculated value and the measured value of the wear amount of the curved cam are 9.48%, 6.01%, 7.27%, and 9.95%, respectively. This validates the accuracy of the spatial cam wear model and the correctness of the curved cam design.

Evolution analysis of wheel polygon wear considering the effect of interharmonics in electrical traction drive system

The formation and development of wheel polygon wear (WPW) present significant challenges to the safety of railway vehicle operations. It is widely accepted that WPW occurs due to the mechanical vibration within the wheel-rail system. The output torque produced by the traction motor acts as the primary power source for the vehicle's movement. The pulsating torque, resulting from interharmonics can directly impact the wheelset's dynamic behavior, contributing to the occurrence of WPW. However, the precise mechanism by which interharmonics affect WPW remains incompletely understood. Therefore, this paper aims to establish the link between interharmonics originating from the electric traction drive system and the wheelset vibration. A comprehensive WPW evolution model that incorporates an electromechanical coupling model and a wheel wear calculation model is developed. This model allows to elucidate the intricate mechanism by which interharmonics impact WPW. The analysis indicates that when the locomotive is running at 70 km/h, the pulsating torque generated by the |5f−7f0|interharmonic can excite the 1st-order bending mode of the wheelset. This excitation triggers wheelset resonance, which ultimately leads to the development of 20th-order WPW.

Evaluation of Wear Models for the Wear Calculation of Journal Bearings for Planetary Gears in Wind Turbines

To increase the power density of the electromechanical drive train of wind turbines, journal bearings can be used as planetary gear bearings instead of rolling bearings. This technological change presents new challenges. For example, wind turbine drive systems are subject to dynamic and low-speed operating conditions, which can lead to accelerated abrasive wear of the journal bearings. In addition, oil supply failure or peak loads due to wind gusts and grid and power converter faults could potentially result in catastrophic failure due to adhesive wear in a very short time. Such operating characteristics are, therefore, critical regarding the journal bearing wear lifetime and must be considered in the design. The successful implementation of journal bearings in wind turbines depends on a reliable estimation of adhesive and abrasive wear. In this paper, five different models for the wear calculation of journal bearings are evaluated regarding their suitability for the wear calculation of planetary gear bearings in wind turbines. For this purpose, the following evaluation criteria were defined: parameter uncertainty, parametrization effort, in particular number of parameters, parameterization method, load case dependency of parameters and calculation effort. In order to be able to evaluate the wear models, the wear models are numerically implemented, and the wear of a test journal bearing is exemplarily calculated under load conditions, which are comparable to load conditions in a wind turbine. Relevant influences from the wind turbine system, such as lubricant, material and manufacturing-dependent surface influences, such as roughness and hardness, are considered. The wear models are evaluated with respect to their fulfillment of the defined criteria. The resulting evaluation allows the selection of a wear model that can be used to calculate the wear of planetary gear journal bearings in wind turbines, considering the available input variables.

Berechnungsmethode zur Beurteilung von Verschleiß bei Stahl-Bronze-Wälzpaarungen hinsichtlich Schneckengetrieben

AbstractWorm gears are usually used in industrial applications with the material pairing of hard worm and softer worm wheel, where the failure mode wear often limits the service life. Up to now, extensive, costly and time-consuming component wear tests need to be carried out for each tribological pairing in order to calculate the amount of wear on worm wheels. Therefore, no practical and efficient experimental method is currently available to optimize material-lubricant pairings with respect to wear capacity for worm gear drives. For this reason, a model contact wear test was developed applying a twin-disk test rig. Based on this, the paper covers a new wear calculation method to characterize the wear behavior of steel-bronze rolling-sliding contacts regarding worm wheels. Therefore, the basics for the new calculation method for a model contact will be presented. Furthermore, the validation of the newly developed wear calculation method on the basis of test results of experimental investigations using the twin-disk test rig is addressed. Subsequently, results of the new wear calculation method are compared to results of the wear calculation method for worm wheels for individual tribosystems. Special focus will be given to similar trends in the calculated wear between the worm gear contact and the model contact. This new calculation method enables, in combination with wear tests on the twin-disk machine, efficient information on the wear behavior of worm gears and the development of optimized material-lubricant pairings concerning wear performance for worm gear drives.

Numerical analysis and formula correction of mechanical seal ring wear of slurry pump based on thermal deformation

In view of the excessive wear of the mechanical seal of the slurry pump in the project and the inconsistency between the theoretical wear and the actual wear, this article studies the wear of the mechanical seal of the slurry pump. In this article, a numerical model of mechanical seal wear based on thermal deformation is established. The hardness, wear coefficient and dry friction coefficient of the sealing ring were obtained through experiments, and the wear morphology was collected by the ultra-depth microscope. In this article, the precise calculation of mechanical seal wear is realized, and the seal ring wear depth under single and multiple field conditions is obtained. The wear formula of the mechanical seal is optimized by adding a correction index, and the end face structure of the mechanical seal is improved. The results show that: the seal ring forms a converging surface due to thermal deformation resulting in more severe wear of the inner diameter relative to the outer diameter; the revised wear equation can more accurately predict the life of the nickel-based tungsten carbide alloy mechanical seal, with a 3.2 times increase in expected life after comprehensive end face improvement.