Wear Equation Research Articles

Numerical Simulation of Wear in Aircraft Carbon-Carbon Composite Disk Brake​

Friction and wear are two major factors affecting the disk brake service life. Carbon-carbon composite materials have good stable friction properties, which enable them to operate as friction material in aircraft brakes application. This article discusses a wear simulation method for predicting the wear amount of c/c composite aircraft brakes under simulated operating conditions. A modified version of Archard’s wear equation is used in 2-D axisymmetric finite element model in order to predict the disk brake friction surfaces wear progression. The finite element commercial software COMSOL Multiphysics 5.5 is used to simulate wear and is presented in this paper. Wear law was implemented as a boundary ordinary differential equation (ODE) in a COMSOL Multiphysics simulation, considering wear depth (thickness) as the independent variable. Frictional heat generation is simulated as heat affects on material thermal properties and as a result surface deformation. Element removal technique is used to simulate the brake disk geometry thickness change due to the material loss during wear. Wear progression with time is presented. Wear model is verified using experimental work from literature.

Effect of Nd2O3 on microstructure, corrosion and wear properties of laser cladding Zr-based amorphous composite coatings on AZ91D magnesium alloy

The preparation of amorphous matrix composite coatings by laser cladding is a applicable approach to improve the surface properties of Mg and Mg alloys. Rare earth elements significantly affect the corrosion and wear resistance of the coatings by influencing the quantity, morphology and distribution of crystalline phases. In the presented work, Zr55Cu30Al10Ni5 + x wt% Nd2O3 (x = 0, 0.5, 1, 1.5, 2, 3) composite coatings were prepared by laser cladding on the AZ91D Mg alloy. The coatings were composed of dendrites, cellular grains, Nd enriched spherical structure and amorphous matrix. Appropriate Nd2O3 addition can refine the size of crystalline microstructure, purify oxygen impurities and increase amorphous content of the coatings, but excessive addition of Nd2O3 (2–3 wt%) causes aggregation and abnormal growth of some crystalline phases and deteriorates the glass forming ability of the coatings. Corrosion resistance of the coating with 1.5 wt% Nd2O3 is the most excellent relying on the highest amorphous and the lowest crystalline phases contents in this coating. Wear resistance of the coatings is all greatly improved compared with the Mg substrate, however that are no linearly related to the hardness and do not follow completely the Archard's wear equation.

Time-delay neural network modeling of the running-in wear process

A time-delay neural network (TDNN) model is developed for describing the variation of the wear rate during the running-in wear process under constant relative sliding velocity. Besides the current value of the normal load, the neural network inputs also include its several preceding values. A specific feature of the TDNN model is that, by analogy with the Archard–Kragelsky wear equation, the neural network incorporates a power-law activation in the output layer for the current load input, which is directly fed into the output neuron along with the outputs of the hidden neurons. A motivation for the choice of such a dynamic artificial neural network model is given, and an intuitive explanation for the TDNN operation is suggested. A predictive capability of the TDNN model is illustrated based on experimental data taken from the literature.

The Computational Approach to Predicting Wear: Comparison of Wear Performance of CFR-PEEK and XLPE Liners in Total Hip Replacement

Wear on articulating bearing surfaces is a key factor causing revision in total hip replacement (THR). Wear debris that releases particles from bearing surfaces might result in adverse soft tissue reactions requiring revision surgeries. In this study, a comprehensive computational wear model based on the Archard wear equation was performed to investigate the wear performance under a three-dimensional (3D) physiological gait cycle, mimicking a normal walking condition (5 million cycles). The study shows that the accuracy of the model is highly dependent on the mesh convergence, the wear fraction, and the scaling factor. The simulations were run to provide a vast amount of detail for the reproducibility of the work. Cobalt chromium (CoCr) on cross-linked polyethylene (XLPE) and CoCr on carbon-fiber-reinforced polyether ether ketone (CFR-PEEK) prototype models were created in silico. The volumetric wear rates for CoCr-on-XLPE were calculated as 0.2989 for CoCr head and 21.0271 for XLPE liner, while for CoCr-on-CFR-PEEK they were 0.3484 for CoCr head and 1.8476 for CFR-PEEK liner. When compared to in vivo and in vitro studies, the wear patterns of these two prototypes are consistent with those of the conventional polyethylene liners in the literature. Although the volumetric wear rate of the CFR-PEEK liner is about 11 times lower than the counterpart of XLPE in MoP implants, the wear rate of CoCr was higher when compared to its use with XLPE. Therefore, CFR-PEEK articulating against orthopa\\edic metals may not be as good an alternative as XLPE, due to higher indicative metallic wear. This detailed computational wear modeling methodology could be utilized in design improvements of implants.

Prediction and Experimental Validation of Aviation Floating Involute Spline

Based on the research on the wear mechanism of floating involute spline coupling, combined with the traditional Archard wear equation, a wear prediction model of aviation floating involute spline coupling was established. The transient simulation of spline coupling with floating distances of 0 mm, 0.3 mm, and 0.6 mm was carried out using Abaqus, and the accuracy of the theoretical model was verified by analyzing the wear and failure parts of the spline coupling. The analysis results show that there is oxidation wear, adhesive wear, abrasive wear, and other wear forms on the tooth surface of the aviation floating involute spline coupling. Under the influence of the floating distance of the spline coupling, the calculation results are closer to the actual working situations. In addition, with increasing floating distance, the wear depth of the tooth surface increases significantly, and the wear depth becomes larger and larger along the floating end. The above study provides a theoretical basis for designing and maintaining aerospace involute spline couplings.

Experimental and numerical study on wear characteristics of steel surfaces involving the tribochemistry of a fully formulated oil. Part II: Computational modelling

Modelling wear characteristics involving the fully formulated oil (FFO) with its tribochemistry is challenging due to its complex chemical components. This paper developed a model to simulate the tribochemistry, wear, and sublayer stress for rough surfaces lubricated with a general FFO with similar recipes and properties or other functional surfaces. The tribochemistry model and the wear model when using FFO were developed based on the existing modelling studies of zinc dialkyldithiophosphate (ZDDP) and experimental results of FFO in Part (I) of this research series. The layered contact model was applied to simulate the sublayer stress under the influence of the real-time tribofilm growth and can expand the computational dimensions. In the wear model, by using the concept of mass conservation, the wear process can be described as follows: the mass of iron lost in the substrate is equal to the mass of iron consumed in the tribochemical reaction, which supplements the removal part of the tribofilm. Considering the different forms of iron in the tribofilm and the substrate, a method was improved to transfer the atomic percentage of iron (Fe at.%) in the tribofilm measured by X-ray photoelectron spectroscopy (XPS) to the wear coefficient in the Archard's wear equation. The simulation results are consistent with the critical tribological experimental results of FFO, such as tribofilm growth and wear evolution. The model also successfully simulates that the tribofilm formation has a buffering effect at the contact interface, and the tribofilm growth is promoted by temperature and shear.

Adjusting for Running-in: Extension of the Archard Wear Equation

Adjusting for Running-in: Extension of the Archard Wear Equation

Wear of Bulk Metallic Glass Alloys for Space Mechanism Applications

Abstract Space-based mechanisms must operate under harsh environments, usually without access for maintenance; failure may result in a loss of a spacecraft. Therefore, space agencies support research on high-performance mechanism designs and materials, one key area being space tribology. Bulk metallic glasses (BMGs) are a class of alloy characterized by their amorphous structure, which results in a material with extremely high strength, corrosion resistance, high hardness, and high elastic limit. BMGs have demonstrated improved wear resistance when compared against traditional engineering materials in similar applications. Four BMG compositions, Zr53Al16Co23.25Ag7.75, Zr49Ti1.96Cu37.24Al9.8Y2, Zr60Ti2Nb2Al7.5Ni10Cu18.5, and Cu47Zr46Al5Y2 (at%), were selected from the literature as potential candidates for space-based mechanisms applications. Wear testing, hardness, profilometry, and scanning electron microscopy (SEM)/energy dispersive X-ray (EDX) spectroscopy analysis were performed on the selected alloys, and their results were compared. High-resolution 3D profilometry and detailed image analysis of wear tracks and volume loss resulted in a critical re-assessment of the Archard wear coefficient. For the compositions tested, the hardness was not a useful predictor of the wear performance as suggested by the Archard wear equation. Processing history and test configuration significantly influenced the wear behavior. The alloy Zr49Ti1.96Cu37.24Al9.8Y2 was found to be the best BMG candidate for space wear applications when taking manufacturability into consideration. BMG hardness and wear test results were compared with similar testing performed on conventional crystalline alloys commonly used in space applications: titanium alloy Ti-6Al-4V ELI, and cold-worked stainless steels AISI 303 and AISI 304.

A Fractional Time-Derivative Model for Severe Wear: Hypothesis and Implications

Based on the example of wear of polymers, which exhibit a power-law time variation of the wear loss under constant loading conditions, a fractional time-derivative wear equation has been introduced. The wear contact problem with a fixed contact zone is solved using the known method of separation of spatial and time variables. It is shown that during the wear process, the contact pressure approaches a uniform distribution over the contact area, which is termed as a quasi-steady-state solution, since the mean volumetric wear rate does not tend to become constant. It is of interest that the contact pressure variation displays a decaying oscillatory nature in the case of severe wear, when the mean volumetric wear rate increases with time.

Optimization lubrication performance of journal bearings with microtexture

PurposeResearchers have not reached an agreement on which biomimetic shape has the best lubrication performance. This paper aims to study the influence of microtexture size, shape and direction on bearing capacity, end leakage, friction coefficient and wear of oil film.Design/methodology/approachDifferent oil film thickness equations considering the microtexture of bearing surface are gained. The two-dimensional finite difference equation and the calculation equation of wear are established.FindingsThe theoretical research shows that the wear value and the wear ratio when long side is perpendicular to the axial direction of the bearing are generally lower than when the long axis is parallel to the axial direction of bearing. The theoretical and experimental results show that the appropriate microtexture shape, such as circular dimple, crescent-shaped dimple, triangular dimple and fish-shaped dimple can improve effectively the lubrication performance of journal bearing and reduce the friction coefficient.Originality/valueThe research has great significance to reduce friction and improve the wear resistance of equipment.

Evaluation method for tooth wear of roller bits based on the fractal dimension of the rock surface

During drilling operations, the drill bit is worn out while breaking the rock. The roller bit is an important rock-breaking tool, but our research on its wear mechanism is still inadequate. Therefore, in response to this problem, this paper establishes a fractal characterization method for surface roughness based on the morphological features of the rock and bit surface. Combining the worn bit surface morphology and energy spectrum analysis results, it is determined that the wear mechanism of roller bit teeth is mainly abrasive wear, fatigue wear and adhesive wear, which are mainly squeezing and spalling. The rock is broken by roller bit under the action of drilling pressure and tangential force, so the contact force model of the single tooth pressed into the rock is established, and the reacting force of the rock on the bit tooth is deduced based on the rock crush conditions. According to the rolling friction characteristics of roller cone bits, the friction coefficient in rolling conditions is calculated. Then, according to the wear mechanism of the cone bit, the actual contact force and real contact area between the cone bit and rock at the bottom of the hole, a roller bit teeth wear equation is established, consisting of rock properties, bit properties and working condition parameters. The bit parameters and drilling parameters are regarded as controllable parameters, and the rock properties are regarded as uncontrollable parameters. In order to highlight the basic parameters of rock, the controllable parameters in the equation are standardized. The calculated wear degree can better reflect the wear ability of rock to drill bit. This result is of great significance for the factor prediction of formation abrasiveness and bit selection.

Calculation of the Grinding Performance of Diamond-Bearing Ceramic Tools

The paper presents a developed a technology for producing a new abrasive material, which is a refractory ceramic matrix made of aluminum oxide with embedded diamond particles. The tests have shown its advantage over traditional diamond-bearing materials when processing high-hardness ceramics. To synthesize a new material with a predetermined set of operational parameters, it is necessary to build a wear model of a friction pair composed of diamond-bearing ceramic material and ceramics. After analyzing the results of other authors’ studies and assessing the morphology of the contacting surfaces, it is assumed that the contact of microroughnesses on the friction surfaces of abrasive diamond-bearing ceramic tools is linearly elastic. The model is built within the framework of the basic wear equation. The composite material surface was modeled by a set of same radius spherical segments; diamond grains were distributed in the material with a given bulk density. The paper uses the concept of an equivalent surface with the power law distributed of microroughnesses tops. A theoretical relationship is obtained between the micro-and macrocharacteristics of the wear process of a composite ceramic friction pair. The authors established theoretically and confirmed experimentally that the grinding productivity increases with an increase in sliding speed, applied load and diamond grain size. The diamond concentration has no significant effect on the workpiece wear. The established dependencies can help to achieve high productivity of diamond ceramic tools.

A computationally efficient method for the prediction of fretting wear in practical engineering applications

A method for simulating fretting wear using the Modified Simplex Method for a contact solution has been developed. The initial separation between two contacting bodies was used as an input to solve the contact force distribution. An average cycle pressure distribution was calculated for the stationary surface over a displacement cycle. The wear depth was calculated for each body based on the modified Archard’s wear equation using the force distributions and the gross sliding distance. The initial separation was updated and the force distribution was solved for the next iteration. Methods for optimizing computational time are presented using a combination of linear jumping and adaptive cycle jumping for the wear depths, and an interpolation weighting method for reducing the grid size. It was found that computational time can be reduced by at least 98% compared with other simulation methods, making this method a viable tool for design. Fretting wear scars and depths were simulated for a cylinder on flat in contact and were found to agree with experimental results and Finite Element modeling results from previous literature. To show the capability of the fretting wear model, three practical applications were simulated: automotive seat sliding rails, steel wire ropes for industrial applications and steam generator tubes for nuclear power stations.

Simulation study on tribological characteristics of magnetic High-Entropy Alloy FeCoNiCrMn

To study the tribological characteristics of the high-entropy alloy FeCoNiCrMn under MoS2-oil lubrication conditions in detail, physical testing is combined with finite element method. At room temperature, a ball-on-disk contact pair is selected with reciprocating motion of 5 mm. The single-factor tests are carried out with variables of load (10~50 N) and speed (4.167~20.833 mm/s), and the related wear equation is obtained. Through the static friction contact finite element simulation, the stress and deformation of the friction pair are investigated (the error about 1%), which provides a basis for the partial displacement boundary conditions of the dynamic contact simulation; in the dynamic contact friction simulation, changes in contact pressure and friction stress are analyzed at different loads and velocities. Furthermore, the dynamic friction contact pressure is used to optimize the wear equation and increase the correlation coefficient from 0.89 to 0.96.

Wear simulation of worm gears based on an energetic approach

Wear phenomena in worm gears are dependent on the size of the gears. Whereas larger gears are mainly affected by fatigue wear, abrasive wear is predominant in smaller gears. In this context a simulation model for abrasive wear of worm gears was developed, which is based on an energetic wear equation. This approach associates wear with solid friction energy occurring in the tooth contact. The physically-based wear simulation model includes a tooth contact analysis and tribological calculation to determine the local solid tooth friction and wear. The calculation is iterated with the modified tooth flank geometry of the worn worm wheel, in order to consider the influence of wear on the tooth contact. Experimental results on worm gears are used to determine the wear model parameter and to validate the model. A simulative study for a wide range of worm gear geometries was conducted to investigate the influence of geometry and operating conditions on abrasive wear.

Delamination-fretting wear failure evaluation at HAp-Ti-6Al–4V interface of uncemented artificial hip implant

Present research aims to develop a finite element computational model to examine delamination-fretting wear behaviour that can suitably mimic actual loading conditions at HAp-Ti-6Al–4V interface of uncemented hip implant femoral stem component. A simple finite element contact configuration model based on fretting fatigue experimental arrangement subjected to different mechanical and tribological properties consist of contact pad (bone), HAp coating and Ti–6Al–4V substrate are developed using adaptive wear modelling approach adopting modified Archard wear equation to be examined under static simulation. The developed finite element model is validated and verified with reported literatures. The findings revealed that significant delamination-fretting wear is recorded at contact edge (leading edge) as a result of substantial contact pressure and contact slip driven by stress singularity effect. The delamination-fretting wear behaviour is promoted under higher delamination length, lower normal loading with higher fatigue loading, increased porous (cancellous) and cortical bone elastic modulus with higher cycle number due to significant relative slip amplitude as the result of reduced interface rigidity. Tensile-compressive condition (R=−1) experiences most significant delamination-fretting wear behaviour (8 times higher) compared to stress ratio R=0.1 and R=10.

A Calculation Method of Surface Wear of Plastic Line Gear Pair Under Dry Friction Conditions

Abstract Parallel line gear pair (PLGP) can achieve pure rolling meshing along its theoretical contact curves under the ideal condition. However, the actual meshing positions may deviate from the theoretical ones under the actual operating conditions, which may result in the alternation of contact pressure distribution and cause relative sliding of the meshing surfaces. Contact pressure and relative sliding are two main factors causing surface wear. A calculation method of surface wear of plastic line gear (LG) pair under dry friction conditions was studied theoretically and experimentally, taking a polyoxymethylene (POM) PLGP as an example. Based on the geometric model of PLGP considering the misalignments under the actual operating conditions, this method employs the three-element model and influence coefficient method to compute the contact pressure with the consideration of the viscoelasticity of the gear material. Archard’s wear equation is applied to calculate the surface wear depth. Results of the wear experiment of the POM PLGP specimens validated the feasibility of the calculation method. This study provides a necessary basis for the engineering application of plastic LG pairs.

Closed Loop Reactive Power Compensation on a Single-Phase Transmission Line

Zinc-aluminium alloys are alloys whose main ingredients stay zinc and aluminium. Other alloying elements clasp magnesium and copper .Zinc Aluminum Alloys over the past decayed are occupying attention of both researches and industries as a promising material for tribological applications. At this moment commercially available Zinc-Aluminium alloys and bearing bronzes due to good cost ability and unique combination of properties. They can also be deliberated as competing material for cast iron, plastics and even for steels. It has been shown that the addition of alloying elements including copper, silicon, magnesium, manganese and nickel can improve the mechanical and tribological properties of zinc aluminum alloys. This alloy has still found limited applications encompassing high stress conditions due to its lower creep resistance, compared to traditional aluminum alloys and other structural materials. This has resulted in major loss of market potential for those alloy otherwise it is excellent material. The aim of this paper is to measure the coefficient of friction and wear under different operating conditions for material with silicon content. Then wear equation will be found out for all the materials experimented under various conditions. In this paper there is discussion of the effect of Silicon on tribological properties of aluminium based Zinc alloy by experiment as well as Ansys software based and compares the same.

Manufacturing of Wear Resistant Iron-Steel: A Theoretical and Experimental Research on Wear Behavior

In this study, four different alloys of steel blocks with a thickness of 15mm were manufactured in order to develop an alternative to steel plates used in wear exposed areas of construction machines, trucks, and asphalt production plants. To further increase the wear resistance of the manufactured steel blocks, their thickness was reduced to 10mm by the hot-rolling method. Wear specimens were obtained from rolled blocks. These specimens were abraded at 20N, 40N, and 60N loads in reciprocating linear motion module ASTM G-33 standards to determine their wear resistance. SEM and EDX analyses were also conducted to see modifications on the worn surfaces. In addition, a theoretical model of wear behaviors was created, calculations were made with Archard wear equation and ANSYS software, and the theoretical and experimental results were compared

Investigation on stress microcycles and mild wear mechanism in gear contact fatigue

AbstractGear contact fatigue is becoming a primary limitation for the growing demand of power density and service life in gear‐driven equipment. The unchecked surface fatigue crack could further cause premature failure and put a serious risk to the safety and reliability of mechanical systems. In this work, an attempt is made to investigate the effects of rolling‐sliding and mild wear on contact fatigue behavior. A contact model is developed to capture the variation of instantaneous pressure and stress field, which are calculated with the transient mixed elastohydrodynamic lubrication (EHL) approach. Rolling‐sliding contact is simulated with the time‐varying roughness topography, which is updated by Archard wear equation. The stress cycles are extracted, and the relative contact fatigue life is obtained by using the Zaretsky criterion. Results suggest that in rolling‐sliding contact, the contact fatigue life is obviously lower compared with pure rolling. The increases in the number and amplitude of stress microcycles is found to be the main contributors to the reduction of fatigue life. Mild wear tends to smooth the surface, subsequently mitigates the stress concentration, and reduces stress cycles, and then decreases the risk of surface contact fatigue.