Wear Model Research Articles

Effect of EDTA-modified alumina composite abrasive on the CMP performance of sapphire substrate

Sapphire is one of the most widely used substrate materials for semiconductor lighting. With the improvement of chemical mechanical polishing (CMP) processing technology for sapphire substrate, mass production, and cost control requires faster polishing efficiency and better surface quality. In CMP, alumina abrasive is widely used for its high polishing rate, but it also has the disadvantages of easy agglomeration and poor polishing quality. Therefore, ethylenediamine tetraacetic acid (EDTA)-grafted alumina composite abrasives were produced by a two-step process for the sapphire substrate CMP. As demonstrated by time of flight secondary ion mass spectrometry and fourier transform infrared spectroscopy, EDTA has been successfully grafted onto the surface of alumina particles. As shown by the scanning electron microscope, particle size distribution, and zeta potential analyses, the modified alumina composite abrasives exhibit superior dispersion properties than pure alumina particles. CMP experiment results show that the material removal rate (MRR) of the alumina composite abrasives can reach up to 2.6 μm/h, and the surface roughness (Sa) of the sapphire substrate can be reduced to 0.89 nm, which is 53 % higher and 66 % lower than pure alumina, respectively. According to X-ray photoelectron spectroscopy, the chemical etch of modified abrasive particles was strengthened, and the complex reaction occurred throughout the CMP process to generate the C–O–Al structural compound. Meanwhile, the friction coefficient test and contact angle test were combined to create the contact wear model. It shows that the addition of EDTA expands the contact area between the composite abrasives and the surface of substrates, improving the mechanical interaction during CMP. The chemical reaction and mechanical action combine and promote each other to enhance the CMP performance.

Probabilistic model of disc-cutter wear in TBM construction: A case study of Chaoer to Xiliao water conveyance tunnel in China

Probabilistic model of disc-cutter wear in TBM construction: A case study of Chaoer to Xiliao water conveyance tunnel in China

Experimental investigation on the bio-tribocorrosive behavior of Ti6Al4V alloy and 316 L stainless steel in two biological solutions

In this manuscript the tribocorrosive behavior of two common biomaterials adopted in dentistry such as Titanium Grade V and Steel 316 L was investigated by a tribometer equipped with a three electrodes potentiostat and a confocal interferometric apparatus for a deep worn surface analysis. The experiments underlined that the pH and higher concentration of NaCl induced greater material loss, especially in terms of mechanical-chemical combined action which, estimated by synergistic approach, had a significant impact on the total wear. In addition, Titanium Grade V alloy showed a superior tribocorrosive wear resistance respect to Steel 316 L because of its higher hardness. Lastly, a linear correlation between tribocorrosive current and synergistic factor was found out which could be adopted in future analytical wear models.

Unified computational model of thermochemical erosion and mechanical wear in artillery barrel considering hydrodynamic friction

Erosion wear of the artillery barrel is divided into two primary categories: thermochemical erosion and mechanical wear. However, the majority of studies concerning this subject matter emphasize the former, and the latter has not been given enough consideration. To describe the coupling relationship of thermochemical erosion and mechanical wear, this article is inspired by the frictional behavior between the barrel and the projectile and proposes a material degradation model for thermochemical erosion considering frictional temperature rise. Under the coupling of the forced heat convection of high-temperature propellant gas and frictional heat, the friction state between the barrel and the projectile is changed from dry friction to hydrodynamic friction, resulting in a novel mechanical frictional wear model. Subsequently, numerical simulations of the thermochemical erosion and mechanical wear models are carried out. The results show that the erosion wear of the artillery barrel is divided into four regions along the axial direction: thermochemical erosion, thermochemical-mechanical erosion, transition, and mechanical wear regions. Four regions are concentrated in the interval of [0 mm, 500 mm], [500 mm, 1750 mm], [1750 mm, 4000 mm] and [4000 mm, 6800 mm], respectively.

Rail wear rate on the Belgian railway network – a big-data analysis

ABSTRACT This paper presents a big data-based analysis of the rail wear of the whole Belgian railway network measured in 2012 and 2019. Wear rates are reported, discussed, and quantitatively formulated as functions of critical factors in terms of curve radius, annual tonnage (rail age), high rail in curves, an average from both rails in straight tracks at rail top (vertical wear) and gauge corner (45° wear) and for steel grade R200 and R260. The influence of preventive grinding is also analysed. The wear rates are derived in an aggregated manner for the whole network. The wear rates do not show significant change with changes in rolling stock over the years, implying that the wear rates could also hold for other networks. It is found that R200 shows, on average, a 34% higher wear rate than R260. Also, the wear rate per tonnage is lower for high-loaded tracks. Thus, time is a relevant factor in explaining the wear evolution of low-loaded tracks; for instance, the effect of corrosion may have an important role. The paper provides statistically significant information that can be used for wear modelling, understanding and treating rolling contact fatigue based on the wear rate and developing tailored rail maintenance strategies.

FAILURE OF FRICTION BRAKE PAD AGAINST RAPID BRAKING AND IT’S LIFE ENHANCEMENT

This Disc brake have evolved to be a reliable method of decelerating and stopping a vehicle. There have been different designs of disc brake systems for different applications. This review describes different aspects of the components and the materials used in a disc brake system. Despite all the improvements, there are still many operational issues related to disc brakes that need to be understood in greater detail and resolved. The basic principle used in braking systems is to convert the kinetic energy of a vehicle into some other form of energy. During a braking operation not all the kinetic energy is converted into the desired form, some energy might be dissipated in the form of heat and vibrations. Graphene is still a very new material, especially in friction brake compounds. Due to its unique properties and years of testing, we were able to develop a friction material like no other. In the automotive industry, where every major car maker has already filed several patent applications for friction compounds containing graphene, it's clear to see that it is the future of braking pads. New regulations which start from 2025 will prohibit the use of copper powder in disc pads. Graphene is not only an excellent substitute for copper, but a major upgrade in terms of performance. Key Words: Friction Brakes, Disc Brakes, Braking Systems, Brake pads, Heat Transfer, Heat Management, Wear Testing , Wear modeling, Material Doping, Pin on Disc, etc.

A stress-dependent sliding wear model for bileaflet mechanical heart valves

Pyrolytic carbon (PyC) is a common material used in mechanical heart valves. This investigation studies the effects of surface finish on the the sliding wear between two PyC surfaces. The primary application being, the prediction of wear at articulating surfaces within bileaflet mechanical heart valves. An experimental apparatus is designed which allows a cylinder to rotate on a flat plate at a constant frequency and load. The cylinder is harder (greater modulus of elasticity) than the flat surface. Two surface finishes of a single (hard) cylinder and two flat surfaces of different hardnesses (single surface finish) are investigated, for a total of four cases. These four cases are studied at four sliding distances. The exerimental data is used to develop theoretical load and stress-dependent models for sliding abrasive wear. For the boron alloyed PyC material used in this investigation, the load-dependent wear model is most applicable for unpolished cylinders and the stress-dependent model is most applicable for polished cylinders. These two models are used to make theoretical predictions of pivot wear in a bileaflet mechanical valve of the same material. The predictions from the stress-dependent wear model was found to be quite accurate with actual wear measurements. The methods developed in this paper are generalized and applied to other valve designs and materials.

Triboinformatics Modeling of Dry Sliding Wear of High Manganese Hadfield Steel alloys

Triboinformatics Modeling of Dry Sliding Wear of High Manganese Hadfield Steel alloys

DEM analysis of wear evolution and its effect on the operation of a lab-scale HPGR mill

Wear due to compression and abrasion from particles is a critical issue for high pressure grinding rolls (HPGR) mills. Understanding the evolution of wear provides useful insight on its mechanisms and helps to mitigate the issue so mills are operated at their optimal states. This work presented numerical simulations based on the discrete element method (DEM) to analyse the formation and evolution of wear of a lab-scale HPGR mill and to investigate how wear affects mill performance and particle breakage. By coupling the DEM model with the Archard wear model and surface re-meshing, the simulated wear patterns were comparable with those observed in practice, showing a parabolic wear profile wear along the rolls with more severe wear in the centre. In addition, the rear part of the stud, compared with the middle and front parts, experienced more significant wear due to the combined effect of compression and abrasion. While increasing wear had no visible effect on throughput, it reduced mill power draw due to weaker compressive force from the rolls to particles. Furthermore, analysis on particle breakage showed that increasing wear reduced particle breakage and produced coarser products. Increasing wear also caused less damage to particles, suggesting more cycles are required to achieve targeted products.

Nanoscale Wear Triggered by Stress-Driven Electron Transfer.

Wear of sliding contacts causes device failure and energy costs; however, the microscopic principle in activating wear of the interfaces under stress is still open. Here, the typical nanoscale wear, in the case of silicon against silicon dioxide, is investigated by single-asperity wear experiments and density functional theory calculations. The tests demonstrate that the wear rate of silicon in ambient air increases exponentially with stress and does not obey classical Archard's law. Series calculations of atomistic wear reactions generally reveal that the mechanical stress linearly drives the electron transfer to activate the sequential formation and rupture of interfacial bonds in the atomistic wear process. The atomistic wear model is thus resolved by combining the present stress-driven electron transfer model with Maxwell-Boltzmann statistics. This work may advance electronic insights into the law of nanoscale wear for understanding and controlling wear and manufacturing of material surfaces.

Investigation of ultrasonic mechanism and development of tool wear model in ultrasonic elliptic vibration assisted cutting of stainless steel

By analyzing the kinematics and dynamics of ultrasonic vibration under various conditions, the tool wear mechanism in Ultrasonic Elliptic Vibration-Assisted Cutting (UEVAC) were investigated. Two distinct mechanisms for mitigating tool wear emerge: In non-separated UEVAC, the pivotal factor is the reduction of material yield stress through the acoustic softening effect. Conversely, in separated UEVAC, tool wear reduction is attributed to the decrease in average contact stress via stress superposition and the hammer effect. These findings highlight the effectiveness of aligning ultrasonic energy field action times and intensity to reduce stainless steel tool wear rates in non-separated UEVAC. Furthermore, the proposed tool wear model demonstrates robust reliability for separated UEVAC processes.

Physics-informed Gaussian process for tool wear prediction

The tool wear monitoring (TWM) system plays an increasingly important role to ensure high quality finishing and system safety in advanced CNC machining process. The pure data-based TWM approaches generally needs to develop complex machine learning models and require massive sensory data to learn the models to reach high monitoring accuracy, while the physics-based tool wear models are simple but hard to adapt to varied working conditions. In order to incorporate the benefits of both methods, a novel physics-informed Gaussian process model is developed to predict the tool wear. Different from the traditional approaches, three tool wear physical models are introduced to develop the physics-informed Gaussian process regression (PB-GPR) model. The wear model is applied to constrain the mean function of the Gaussian process, so that the PB-GPR is more in line with the actual tool wear. At the same time, the model can initiate small data training to meet limited tool wear labels in practice, and then update the model with new measurements. Multi-sensor signals are collected and multi-domain features are extracted for the model learning. The proposed approach is validated from high speed milling experiments. The results show a significant performance improvement including tool wear prediction accuracy and robustness in extrapolation compared to the conventional machine learning methods.

Research on tool wear modeling of superalloy based on evolutionary cluster analysis

Research on tool wear modeling of superalloy based on evolutionary cluster analysis

Formation mechanism of the double contact bands on the wheel and rail treads of a metro system

The contact band on the wheel and rail is an intuitive representation of the wheel–rail contact relationship that affects the dynamic performance of rail vehicles. In this paper, a vehicle dynamics model and the Archard wear model are established in an integrated way using the actual parameters of a metro train. The mechanism of formation of double contact bands on the wheel and rail in a metro line in China is studied by analysing the geometric combination based on the measured data. The influence of double contact bands on the dynamic performance of the metro vehicle is investigated. To suppress the formation of double contact bands, an optimisation method for asymmetric rail profiles in small radius curves is proposed based on the Kriging Surrogate Model (KSM) and the Particle Swarm Optimisation (PSO) algorithm. Through numerical simulations, it is proved that the optimised rail profiles can improve the curving performance and effectively reduce wheel wear. The methodology proposed in this paper can provide useful information on the mitigation of severe double contact bands on wheel and rail.

Study of the Law Motion of the Micro-EDM Drilling Process

Micro-EDM is an unconventional technology used to machine every type of electrically conductive material regardless of its mechanical properties. Material removal occurs through electrical discharges between the workpiece and the electrode immersed in a dielectric fluid. In drilling operations, the technology is able to realise microholes with excellent quality in terms of precision, quality surface, roundness, and taper to the detriment of the machining time, which is less than other technologies. Several efforts are being made to improve different features related to the process performance that are severely affected by both the operative conditions, such as the electrode material or the type of dielectric, and process parameters. The typical indexes used to characterise the performance are the machining time, the material removal rate, and the geometric indexes. These indexes are very effective and are easily measurable, but they do not give information about the evolution of the drilling process, which could be irregular due to the different phenomena occurring during machining. The aim of this paper is the development of a method able to elaborate the motion law of the electrode during the micro-EDM drilling operation. In order to do this, a single hole was manufactured in several steps, recording both the machining time and electrode wear for each step. In this way, the actual position of the electrode during the drilling can be measured without the use of a predictive model for electrode wear. It was tested to confirm that the multistep procedure did not introduce new phenomena, in contrast to the traditional drilling operation. This method was used to study the effects of the electrode diameter, the type of electrode, the length of the electrode out of the spindle, and the entity of the run-out on the process performance. The tests were executed on titanium alloy sheets using a tungsten carbide electrode and hydrocarbon oil as the dielectric. It was found that the descent of the electrode into the workpiece was not regular, but it depended on the level of debris concentration in the machining zone. The debris concentration was influenced by the type and diameter of the electrode, its length out of the spindle, and, to a lesser extent, the run-out. This method was found to be a useful method for an in-depth analysis of the micro-EDM drilling process, contributing to a better understanding of the physical aspects of the process.

High-temperature wear mechanism of roller cone bit spiral seal

When drilling, the spiral seal of the roller cone bit and the journal are prone to collision and wear, and the friction heat and downhole high temperature will affect the wear process. The friction and wear experiments of the spiral seal material (20CrNiMo–40Cr) at different temperatures were carried out to study the wear mechanism of the spiral seal and journal of roller cone bit at high temperatures to determine the wear amount, friction coefficient and main wear forms. The wear model of friction pairs is established based on the Archard wear model and experimental results; The wear results at different temperatures are obtained by establishing the spiral seal structure model and simulation research of the roller cone bit. The results show that:(1) Through the friction and wear experiment of friction pair materials, the higher the temperature is the greater the wear amount and friction coefficient are. When the temperature exceeds 100 °C, the wear amount and friction coefficient begin to decline with the increase in temperature. By observing the wear surface morphology, abrasive and adhesive wears occur simultaneously, and the main wear form is adhesive wear under high-temperature conditions.(2) The maximum temperature rise caused by friction and the relationship between wear volume and time at different temperatures are obtained through the simulation of the spiral seal structure. Taking the groove depth value as the index to evaluate the sealing effect, the roller cone bit works in the temperature range (25 °C-400 °C), and high-temperature wear does not affect its sealing performance.

Peridynamic modeling of rail wear during sliding contact considering thermal effects

Numerical simulations of rail wear during sliding contact pose significant challenges owing to the complex coupling between thermomechanical contact loads, material properties, and profile changes. This study proposes a modeling approach for rail wear during sliding contact, using nonlocal peridynamic (PD) thermomechanics and a bond damage criterion based on ratchet failure. To facilitate test verification, a two-dimensional PD model for twin-disc testing with elastoplastic materials was developed, and numerical simulations and corresponding twin-disc testing were performed during wheel idling under different loads, idling speeds, and idling times. The PD model accurately predicted rail wear under all operating conditions, exhibiting excellent agreement with the test results, and thus validating the proposed method and supporting the ratchet failure mechanism. Subsequently, thermomechanical modeling of sliding contacts with different creepages was performed. The PD model predicted continuous wear along the contact surface, with an increase in wear depth corresponding to higher creepage values. As the contact temperature increased with creepage, thermal stress and thermal softening caused slight and sharp increases in rail plastic strain, respectively. Therefore, thermal softening is the main factor responsible for the significant increase in wear rate with temperature. Finally, wear results of the PD model and classical Archard’s wear model were compared. The PD models can capture variations in wear rates that are difficult to address using the Archard model.

Prediction of roll wear and thermal expansion based on informer network in hot rolling process and application in the control of crown and thickness

The inaccuracy of roll thermal expansion and roll wear settings affects strip steel plate shape and thickness in hot-rolling process. Roll wear and thermal expansion are nonlinear time series that cannot be neglected in the roll engineering. In order to make up for the shortcomings of the existing models, a novel prediction model of roll thermal expansion and roll wear based on Informer is developed. Firstly, multiple experiments are conducted to determine hyperparameter such as training epoch, dropout, batch size and learning rate. Then, the predicted results of finishing mill group (F1–F7 stand) are compared with the long-short-term memory (LSTM) model, the artificial neural network (ANN) model and the recurrent neural network (RNN) model. The results show that the model based on Informer network has highly accurate in predicting roll thermal expansion and roll wear. Finally, the application results show that the hit rate is 98.412 % within the tolerance range ± 4 μm and the hit rate within the ±40 μm thickness tolerance deviation range reach 98.94 % which proves that the roll wear and thermal expansion model based on Informer has outstanding advantages in the hot rolling shape control system.

Tool anisotropic wear prediction and its influence on surface topography in diamond turning of oxygen-free copper

Oxygen-free copper components are widely used in high energy physics engineering, which are usually fabricated by the diamond machining process for achieving low roughness surface. However, the wear of diamond tool heavily affects the surface quality. In this work, the wear law of diamond tool in machining of oxygen-free copper is studied with consideration of the anisotropy of diamond strength. Firstly, the stress distribution on the tool face in machining is calculated. The results show that the cutting stress near the flank face is larger than that near the rake face. Secondly, the strength distribution of tool cutting edge is modeled. The theoretical prediction reveals that the anisotropy of diamond crystal leads to the great differences in the strength of cutting edge at different positions, and further affects the cutting edge wear resistance. Thirdly, the wear model of diamond tool is established with consideration of cutting stress distribution and tool edge strength, in which the mechanical wear is the dominant wear process. Finally, the variation of the surface roughness is analyzed on the basis of the tool wear through the cutting experiments. The experiment results indicate that the surface material deformation is closely related to the tool cutting edge wear transition area and results in different values of surface roughness. The obtained results can improve the understanding of the diamond tool wear law and estimate the diamond tool wear in machining of oxygen-free copper.

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.