Wear Profile Research Articles

Investigation of railway wheelset profile wear by using computer simulation

The wear of rails and wheels is important problem in rail traffic. The change of the shape of the wheel profile has not only a great influence on the dynamic properties of the vehicle (like stability, safety by passing curved tracks, etc.), but also affects the ride comfort of passengers and environmental insults, in extreme cases it can cause rail derailment. One of the ways to predict these undesired conditions are computer aided simulation analyses. In this article are presented results of wheel profile wear by Archard wear law, when the vehicle of type Model A was driving in track by constant velocity of 30 m/s. The vehicle was traveling along track where the rail profile was defined by standard (UIC 60 profile) with cant of 1:40, or the track profile really measured on the track, the profile S 91700_16 with the cant of 1:20. Simulations were realized by SIMPACK software.

Development of a model for predicting worn profile under the mixed slip conditions

Development of a model for predicting worn profile under the mixed slip conditions

Development of a Model for Predicting Worn Profile of Rail under Mixed Slip

Development of a Model for Predicting Worn Profile of Rail under Mixed Slip

Profilverschleißreduzierung beim Planschleifen*/Profile wear reduction during face grinding - Determination of the influences for profiling in double face grinding with planetary kinematics

Ein ebenes Schleifscheibenprofil ist Voraussetzung für die Fertigung ebener Oberflächen beim Doppelseitenplanschleifen mit Planetenkinematik. Das zuverlässige Bestimmen des Profilverschleißes und die Kenntnis der Wirkzusammenhänge beim Profilieren sind die Grundlage zur Auslegung von Profilierprozessen. Die Entwicklung eines Messsystems zur Bestimmung des Profilverschleißes und die Eingrenzung der Einflussgrößen auf den Abrichtprozess sind die Basis detaillierter Untersuchungen zum Konditionieren der Werkzeuge.   A flat grinding wheel profile is precondition for machining flat surfaces in double face grinding with planetary kinematics. Reliably determining profile wear and knowing the effects during profiling are the basis for designing profiling processes. The development of a measuring system to determine the profile wear and the identification of variables influencing the dressing process are requirements for a detailed investigation of the conditioning process.

The sensitivity of digital intraoral scanners at measuring early erosive wear

ObjectivesTo investigate the sensitivity of intraoral scanners to quantitatively detect early erosive tooth wear. MethodsNatural buccal enamel samples were mounted in acrylic and scanned at baseline with an intraoral scanner (3 M True Definition Scanner, 3 M, USA). Samples were then exposed to 0.3% citric acid pH 3.2 at intervals of 10 min up to a total of 120 min and scanned after each exposure resulting in analysis of 13 datapoints per sample. Each scan was aligned with the baseline and data points super-imposed using an iterative closest point (ICP) algorithm on the acrylic surfaces (Geomagic Control Software, 3Dsystems, Darmstadt, Germany). Wear was measured using maximum profile loss, average profile loss and volume change. Data were normally distributed and Pearson correlations between erosion time and wear measurements assessed. ResultsAfter each 10-minute exposure until 120 min, maximum profile loss (μm) increased from 33.4 to 72.8 μm, average profile loss from 9.1 to 18.6 μm. Wear correlated with increasing acid exposure for both maximum profile loss wear (r = 0.877 p < 0.001) and average profile loss (r = 0.663 p = 0.019) respectively. Volume measurements were inconsistent at this level of wear. ConclusionsUsing scan data obtained from the intra oral scanners (IOS), increasing step height changes were observed with increasing exposures to acid. This study indicates there is potential of scans taken with an IOS to be used to detect early erosive tooth wear. However, precision was low suggesting limitations for minimal changes. Clinical significanceAlthough sub-visual wear was detected by intra-oral scanners on natural enamel surfaces, the accuracy was not sufficient to reliably diagnose that wear had occurred and interpretation of measurements should be done with caution. However, these results may be promising for detecting wear at more advanced stages.

An approach for modelling a clearance revolute joint with a constantly updating wear profile in a multibody system: simulation and experiment

An approach for modelling a clearance revolute joint with a constantly updating wear profile in a multibody system is proposed. Before the contact analysis, the continuous geometric shape of the joint bushing is dispersed to obtain a series of uniformly distributed points of a certain density. By analysing the relative positions between the discrete points and geometric centre of the joint pin, the contact area between the bushing and pin can be estimated and the maximum contact depth can be obtained. Then, the normal contact force and the tangential friction force acting on the point of force application are calculated: after an analysis of the contact force, the wear depth on the contact discrete points is calculated based on Archard’s wear model. The location of the contact discrete point is updated to reconstruct the geometric shape of joint bushing. Finally, taking a planar slider–crank mechanism as an example, the wear characteristics and dynamic response of a revolute joint with clearance are studied by numerical simulation and experimental testing. The results verified that the extent of wear on the joint bushing profile is nonuniform, which is related to the kinetic characteristics of the mechanism. Due to wear, the joint clearance is increased, which further affects the dynamic performance of the mechanism.

Computational modelling of fretting wear of Ti‐6Al‐4V incorporating cyclic plastic deformations and the debris evolution

AbstractIn the present work, a new fretting wear model taking account of the dynamic evolution of the debris layer is proposed to predict the wear profile under gross sliding conditions. The dynamic evolution of the debris layer is described by an exponential function of the debris thickness. A multi‐linear kinematic hardening model is employed to describe the cyclic plastic deformation of Ti‐6Al‐4V. The ejection rate of debris is computed to account for the accumulation of the debris thickness. Different wear configurations are used to validate the predictive ability of the proposed wear model. The simulation results show that the proposed approach provides a reasonable prediction of wear profiles in different wear configurations.

Effect of Aging Temperature on Microstructure and Mechanical Property of Aluminium Brass

Solution treated HA166-6-3-2 aluminium brass was aged at different temperatures by box-type resistance furnace. The effects of aging temperature on the microstructure and mechanical properties of HAl66-6-3-2 aluminium brass were investigated. The results show that the microstructure of aging treated HAl66-6-3-2 aluminium brass is equiaxed β phase, particle phase and dispersed precipitation phase. The precipitated phases appear and gradually increase when the aging temperature is increased. The number of precipitated phase is most at 400°C aging temperature. As the aging temperature increases continuously, the number of precipitated phase decreases and the size of precipitated phase increases, the hardness of aluminium brass presents a trend of rising first and then decreasing, the wear loss of aluminium brass presents a trend of decreasing first and then rising. When the aging temperature is 400°C, the hardness of aluminium brass reaches the maximum value of 320HV1 and the wear loss reaches the minimum value of 0.4065g. Observing the wear profile, the wear mechanism of the alloy is mainly abrasive wear under dry friction conditions.

Modelling of ploughing in a single-asperity sliding contact using material point method

Loading and sliding of a rigid asperity over a substrate results in friction due to shearing of the contact interface and deformation of the substrate. In this article, we introduce the Material Point Method (MPM) based numerical tool to study friction during ploughing of a soft-smooth metallic sheet by a rigid-spherical asperity. The numerical model incorporates a dislocation based physical model for substrate material deformation and interfacial shear strength at the asperity- substrate contact. Initially, the numerical output has been validated using results obtained from the analytical models available in the literature for single-asperity sliding. Finally, the depth of the ploughed wear profile and the overall coefficient of friction obtained from the numerical simulations has been compared with the data obtained from the ploughing experiments and are shown to be in good agreement. Hence, the developed MPM model can be established as a robust tool to model ploughing in a single-asperity sliding contact.

Prediction Model for Liner Wear Considering the Motion Characteristics of Material

A generic model to explore the relationship between the parameters of cone crusher and liner wear is provided in this paper. Relative slide and squeezing between material and liner are considered based on the operating conditions, structure parameters, and material properties. The sliding distance of the material under different conditions is discussed. It is detailed how operating parameters and structural parameters influence the pressure on the liner surface. Considering that the process of liner wear evolves over time, the updating method of the geometry of crushing chamber is adopted. The wear model is derived based on Archard theory and is calibrated with the measured wear profiles of the liner from a PYGB1821 cone crusher. Experiments show that the predicted wear amount is consistent with the measured results. The wear model can be used to predict the wear state of liner and quantify the influence of operating parameters and structural parameters on the liner wear.

Influence of Er,Cr:YSGG laser, associated or not to desensitizing agents, in the prevention of acid erosion in bovine root dentin

This in vitro study evaluated the influence of the Er,Cr:YSGG laser, associated or not to desensitizing agents, in the prevention of acid erosion in bovine root dentin. Eighty dentin specimens were selected and divided into eight groups (n = 10): G1: negative control; G2: positive control (5% fluoride varnish-FV); G3: Er,Cr:YSGG laser; G4: FV+ laser; G5: 3% potassium oxalate; G6: 3% potassium oxalate + laser; G7: biphasic calcium silicate/phosphate gel (gel); G8: gel + laser. Laser parameters: 0.5W, 6.25J/cm2 at 1-mm distance. The erosive drink used was a cola soft-drink (pH = 2.42 at 4°C), lasting 5min, twice a day, with 6-h intervals between the challenges, during 14days. Kolmogorov-Smirnov and Levene's tests were satisfied. The surface roughness data were submitted to ANOVA and Tukey post hoc tests. For the wear profile, Kruskal-Wallis and Dunn post hoc tests were used. Afterwards, the Spearman correlation test was performed. All statistical tests assumed a significance level of 5% (α = 0.05). G1 presented the highest surface roughness value after the erosive challenge (3.586μm2 ± 0.205μm2) and the G7 presented the lowest surface roughness value after the erosive challenge (1.071μm2 ± 0.180μm2). For the lost volume, G4 presented the lowest percentage (9.7% ± 0.9%), while G1 had the highest percentage (41.8% ± 2.5%), both with p < 0.05. There was a weak correlation between the response variables (ρ = 0.33). All groups presented lower values of surface roughness and loss of volume when compared to the negative control group. For the surface roughness, the biphasic calcium silicate/phosphate gel presented the best result. For volume loss, the 5% fluoride varnish + Er,Cr:YSGG laser showed the best results compared to the other groups.

Acoustic Emission-Based Tool Condition Classification in a Precision High-Speed Machining of Titanium Alloy: A Machine Learning Approach

Mechanical and chemical properties of titanium alloy have led to its wide range of applications in aerospace and biomedical industries. The heat generation and its transfer from the cutting zone are critical in machining of titanium alloys. The process of transferring heat from the primary cutting zone is difficult due to poor thermal conductivity of titanium alloy, and it will lead to rapid tool wear and poor surface finish. An effective tool monitoring system is essential to predict such variations during machining process. In this study, using a high-speed precision mill, experiments are conducted under optimum cutting conditions with an objective of maximizing the life of tungsten carbide tool. Tool wear profile is established and tool conditions are arrived on the basis of the surface roughness. Acoustic emission (AE) signals are captured using an AE sensor during machining of titanium alloy. Statistical features are extracted in time and frequency domain. Features that contain rich information about the tool conditions are selected using J48 decision tree (DT) algorithm. Tool condition classification abilities of DT and support vector machines are studied in time and frequency domains.

Evaluation of wear-induced plastic deformation at the trimmed edge of DP980 steel sheets

In order to increase the use of advanced high strength steel (AHSS) for automotive light-weighting, the significant trimming-induced wear damage that AHSS sheets cause to the trim dies should be reduced so as to decrease die maintenance costs and deterioration of the quality of sheared edge. In this research, the wear characteristics in the upper AISI D2 die inserts used for trimming DP980-type AHSS sheets and the wear-induced plastic deformation at the sheared edges of DP980 were studied. Observation of wear profiles at the edge of the upper trim die revealed that material abrasion was the main damage feature. The trimmed edge quality of DP980 deteriorated with the number of strokes, as indicated by an increase in burr width. Plastic strains near the surface of the sheared edge estimated using the displacements of martensite plates, increased from 2.9 at 2.5 μm below the trimmed edge after 40,000th cycles, to 55 after 80,000th cycles. Micro-hardness tests performed to estimate the local flow stresses in the shear affected zone (SAZ) indicated that the flow stress at a distance of 4.5 μm below the trimmed edge increased with the number of trimming cycles to 1.73 GPa in the 80,000th trimmed part.

Investigation on thermal response in fretting sliding with the consideration of plastic dissipation, surface roughness and wear

This study investigates the thermal response of titanium alloy fretting sliding through a numerical approach with the consideration of the friction dissipation, plastic dissipation, surface roughness and wear. The fretting sliding of a cylindrical pad on a specimen with surface roughness is modeled to predict the temperature distribution, the evolution of the wear profile, and the fields of surface and subsurface stresses. Specifically, a thermo-elasto-plastic constitutive model considering the thermal-induced softening of material properties is developed to evaluate the contact pressure and the tangential stress on the surfaces as well as the subsurface stresses in the contacting components. The friction and plastic energy dissipations function together as the heat source to cause the temperature rise in the contact zone. A modified Archard model is used to predict the wear profile of the contact surface and change the contact geometry. The models are then incorporated in the finite element analysis of the fretting sliding to evaluate the thermal response. The influences of the plastic dissipation and the surface roughness on the temperature rise in the fretting sliding are discussed.

A dynamical FEA fretting wear modeling taking into account the evolution of debris layer

A new Finite Element Analysis (FEA) strategy is developed to simulate fretting wear, taking into account the evolution of the debris layer trapped in the interface, so called “third body”. To validate this approach, simulations were compared to experimental results from gross slip Ti-6Al-4V cylinder/plane experiments. Adequate worn surface analyses allow the estimation of both cylinder and plane friction energy wear rates and the debris layer thickness evolution. A third body conversion factor (γ(x)), expressing the proportion of worn thickness transferred to the third body layer (i.e. debris layer) at a given position in the fretted interface is introduced. A coupled Matlab-Python-Abaqus algorithm is developed to simulate the surface wear on plane and cylinder surfaces to formalize the continuous evolution of the debris layer trapped within interface. Quantitative comparisons with experimental results confirmed the interest of this FEA approach. The maximum wear depth, which was underestimated by nearly 80% without considering the third body, is predicted with an error less than 10%. A numerical investigation demonstrates that the elastic properties of the third body do not influence the surface wear profile. Acting as a contact pressure concentrator, the third body effect appears more geometrical than rheological. This third body FEA fretting wear modeling is extended in order to consider both test duration and sliding amplitude effects. Rather good correlations with experiments confirm the interest of this approach.

Predictive Maintenance Optimization for Aircraft Redundant Systems Subjected to Multiple Wear Profiles

Researchers and industry practitioners have recently demonstrated great interest in maintenance planning since it directly impacts the lifecycle cost and availability of systems. Considering the aviation industry, this impact is even more relevant due to high-availability expectations from aircraft operators and high costs incurred when an aircraft becomes out of service. For this reason, some minor maintenance activities are carried out near the gate, between two consecutive flight legs. These activities are referred to as aircraft line maintenance. The usage of prognostics and health management techniques may help the prevention of unexpected events when caused by degrading components. The application of prognostics techniques together with a line maintenance planning optimization approach is not a trivial task and requires sophisticated mathematical approaches especially when dealing with complex and integrated systems. This paper proposes a methodology for predictive line maintenance optimization of redundant aeronautical systems subjected to multiple wear conditions. Degradation trends and future wear values are estimated considering an implementation of a multiple model approach of the extended Kalman filter technique. Planning optimization is based on the minimization of operational costs comprising several aspects of the aviation industry such as dispatch requirements, delays, cancellations, and equipment costs. A case study is conducted using field prognostics data of hydraulic systems to evidence the efficiency and benefit of the proposed methodology.

Numerical model for prediction of tool wear and worn-out pin profile during friction stir welding

Understanding tool wear during friction stir welding (FSW) is important for joining of high melting point metallic (HMPM) materials. Heat transfer and material flow based models developed in past have improved understanding of the FSW process. However, numerical models to predict tool wear and pin profile during FSW of HMPM materials are not available. Thus, the current research has focused on developing a heat transfer and material flow based model to predict tool wear and worn-out tool pin profile of H13 steel during FSW of Cu-0.8Cr-0.1Zr (CuCrZr) alloy. Temperature evolution and material flow are computed by solving conservation equations of mass, momentum and energy. The model thus developed is validated for thermal cycles and tool pin profile for various process parameters. Tool wear is predicted based on forces and stresses acting on the tool. Modified Archard's wear theory is applied to compute tool wear and worn-out tool pin profile. The wear model successfully predicts the worn-out tool pin profile and self-optimized phenomena for various process parameters. The model is also applied to understand the changes in worn-out pin profile during FSW process.

Numerical Prediction of Surface Wear and Roughness Parameters During Running-In for Line Contacts Under Mixed Lubrication

A stochastic model for predicting the evolutions of wear profile and surface height probability density function (PDF) of initial line contacts during running-in under mixed lubrication condition is presented. A numerical approach was developed on the basis of stochastic solution of mixed lubrication, which combined the Patir and Cheng's average flow model for calculation of the hydrodynamic pressure and the Kogut and Etsion's (KE) rough surface contact model for calculation of the asperity contact pressure. The total friction force was assumed to be the sum of the boundary friction at the contact asperities and the integration of viscous shear stress in the hydrodynamic region. The wear depth on the contact region was estimated according to the modified Archard's wear model using the asperity contact pressure. Sugimura's wear model was modified and used to link the wear particle size distribution and the variation of surface height PDF during wear. In the wear process, the variations of profile and surface height PDF of initial line contacts were calculated step by step in time, and the pressure distribution, friction coefficient, and wear rate were updated consequently. The effect of size distribution of wear particles on the wear process was numerically investigated, and the simulation results showed that the lubrication condition in which small wear particles are generated from the asperity contact region is beneficial to reduce friction coefficient and wear rate, and leads to a better steady mixed lubrication condition.

The Patch Wear Profile from SECURE: A Once-Weekly Low-Dose Contraceptive Patch Study [7F

INTRODUCTION: AG200-15 (Twirla®) is an investigational transdermal contraceptive delivery system (TCDS), which delivers daily exposure of levonorgestrel (LNG) and ethinyl estradiol (EE) similar to oral doses of 120 μg LNG and 30 μg EE. We examine various aspects of patch adhesion and wearability with AG200-15 TCDS. METHODS: SECURE was a single-arm, open-label, Phase 3 study conducted in US women 18 years or older, with no restrictions on body mass index or weight (NCT02158572). Subjects recorded patch-related characteristics daily in electronic diaries; irritation/itching and patch adhesion were also evaluated by the investigator at each visit. Irritation/itching scores were rated from 0 (none) to 3 (severe). Patch adhesion scores were rated from 0 (no/small amount of lifting off skin) to 4 (entire patch falling off). RESULTS: In 2,031 women across 13 cycles, 6.2% reported a local site reaction. The subject-rated mean skin irritation/itching score was 1.31, and most women reported their worst skin irritation as none, mild, or moderate (26.2%, 32.0%, and 26.6%, respectively). The investigator-reported mean skin irritation score was 0.18, and most women were determined by the investigator to have none or mild skin irritation (85.0% and 12.6%, respectively). The mean subject- and investigator-rated patch adhesion scores were 0.52 and 0.04, respectively. Treatment discontinuation due to application site irritation/itching occurred in 1.9% of women. CONCLUSION: Overall, results of various subject- and investigator-rated patch characteristics provide favorable support for patch adhesion and wearability of the AG200-15 TCDS.

Wear of the Counterbody at the Research Friction on Carbon Coating–Orientant in Lubricant Environments

The profile wear scars on steel balls are analyzed upon their friction in lubricant against steel coated with monocrystalline carbon doped by tungsten. Bond of ball wear with the lubricant composition and the range of test loads has been established.