Incremental Wear Research Articles

Evaluation of Specific Wear Coefficient of Sliding Contact Pairs through Tribological Experiments

In fuel handling machine of Prototype Fast Breeder Reactor, colomony-5 is extensively used for hardfacing of rubbing surfaces. To avoid the challenges associated with hardfacing of the components, it is proposed to eliminate hardfacing by using a forged component of a suitable material. 440C steel is a candidate material for this application. Hence, experiments were conducted to evaluate the tribological properties of 440C steel under various conditions seen during the operation. The tests were carried out using pin on disc tribometer by varying the load from 10-20 N and sliding speed from 5-30 mm/s. Friction and specific wear coefficients were evaluated from the experiments. Besides, Global Incremental Wear Model (GIWM) was used for prediction of wear behaviour of the steel.

Vibration Analysis Approach to Model Incremental Wear and Associated Sound in Multi-Contact Sliding Friction Mechanisms

Abstract This paper proposes a simplistic approach toward estimating incremental wear in a multi-contact scenario using a vibrational analysis approach and in turn goes a step forward to model its associated sound. Predicted wear depth and frictional sound are compared to the experimental values obtained using a standardized pin-on-disc tribometer setup affixed with a free-field microphone to capture air-borne noise. The results show good conformity between the proposed analytical model values and the standardized experiments, hence ensuing that within certain limitations, the proposed model and the intended approach can effectively be used as a good estimator of wear and its sound in a multi-contact scenario.

Distribution and Prediction of Incremental Cutter Flank Wear in High-Efficiency Milling

In the milling of titanium alloy workpieces, tool wear seriously affects the surface quality of a workpiece and its tool life. It is of great significance to study the influence of instantaneous contact stiffness on instantaneous friction variables and incremental wear, which is of great significance for the realization of control over the degree of flank wear and improving the service life of cutter teeth. In this paper, an experiment to monitor cutting with a Ti6Al4V workpiece with a high-feed milling cutter was carried out; according to the experimental results, the wear area of the flank face of the cutter tooth was determined. The feature points of the flank were selected, and an instantaneous contact stiffness calculation method for the flank was proposed. The infinitesimal method was used to characterize the distribution of the contact stiffness of the flank, and the evolution characteristics of instantaneous contact stiffness distribution under the influence of vibration were obtained. According to the calculation results, the instantaneous distribution of flank wear depth was calculated. A grey correlation degree was used to reveal the correlation between the instantaneous contact stiffness of the flank face and wear depth, and a positionable wear-prediction model based on the instantaneous contact stiffness of the flank was proposed. Based on a BPNN (back propagation neural network), a prediction model for flank wear was established. The results showed that the above model and method could accurately predict the instantaneous wear of the tool flank.

Experimental and numerical investigation on wear behavior of carbon-fiber-reinforced carbon matrix composite used in rotary gas seals

This paper presents a numerical method for simulating progressive wear of the carbon-fiber-reinforced carbon matrix composite used in rotary gas seals due to high experimental cost. In this study, the carbon-fiber-reinforced carbon matrix composite wear rates are experimentally measured, and a formula for the carbon-fiber-reinforced carbon matrix composite wear rates and material design parameters (orientation angles and densities) and operating parameters (load and velocities) is fitted as an input to the wear simulation. A finite element incremental wear simulation procedure for the pin-on-disk wear problem is presented by calculating the local nodal wear rate and wear direction and by introducing the Arbitrary Lagrangian Eulerian adaptive meshing method. In the procedure, the relation between the anisotropy of carbon-fiber-reinforced carbon matrix composite and the varied orientation angle is considered. Results show that the calculated wear volume agrees well with the experimental data. And then the numerical methodology is utilized to investigate the effects of time, orientation angle and operating conditions on the disk wear. The developed numerical methodology could be applied to other sliding wear problems in engineering machinery.

Modeling and Simulation of Cage Wear in Solid-Lubricated Rolling Bearings

Cage not only separates the rolling elements but play an essential role of lubricant supplier in solid lubricated rolling bearings, thereby lubricating the rolling contacts. In such bearings, whose service life can be significantly extended by targeted cage wear, a better understanding and a reliable prediction of the wear is necessary in order to achieve a further increase in the service life. In order to predict wear and eventually their life-time is a complex phenomenon as it involves several transfer processes taking place in the rolling and sliding contacts. The lifespan of such bearings can be determined by performing numerous lifetime experiments. Global lifetime model for solid-lubricated rolling bearings does not exist so far like a conventional bearing life model. Therefore, a dynamic simulation strategy based on Adams multibody simulation environment to predict and model wear at cage pocket interface have been proposed. An incremental wear simulation approach based on Fleischer wear law is introduced. Uniform global wear of the cage pocket depending on the recalculation of cage geometry and converted frictional energy for each wear increment is calculated. Simulation results show good accordance with the experimental results. The importance and suitability of such a wear simulation approach will be enunciated in this paper.

A Methodological Approach for Incremental Fretting Wear Formulation

A methodological approach based upon wear energy formulation for prediction of fretting wear in crowned spline couplings is presented. This approach is also applicable to a variety of wear problems which involve sliding Hertzian contact. It begins with a general contact formulation for identification of fretting regimes by Mindlin’s theory and for a non-conforming Hertzian contact of dissimilar surfaces. A conventional non-incremental wear energy model has been used to predict wear volume and to verify the suitability of wear energy model for the given experimental conditions. An analytical general model for incremental prediction of fretting wear depth and volume evolution is developed. This theory refers generally to elliptical contact problems and is validated against experimental data in case of a circular contact. Finally, the theory has been applied for incremental wear depth and volume estimation of crowned spline couplings working in misaligned conditions. The variations in coefficient of friction owing to open loop applied load have been experimentally fitted. The simulated and experimental results are then compared showing a good agreement with each other.

Rapid simulation procedure for fretting wear on the basis of the method of dimensionality reduction

We suggest a numerical procedure for rapid simulation of fretting wear in a contact of two bodies subjected to tangential oscillations with a small amplitude. The incremental wear in each point of contact area is calculated using the Reye–Archard–Khrushchov wear criterion. For applying this criterion, the distributions of pressure and relative displacements of bodies are required. These are calculated using the method of dimensionality reduction (MDR).

Contact Thermal Analysis and Wear Simulation of a Brake Block

The present paper describes an experimental test and a coupled contact-thermal-wear analysis of a railway wheel/brake block system through the braking process. During the test, the friction, the generated heat, and the wear were evaluated. It was found that the contact between the brake block and the wheel occurs in relatively small and slowly moving hot spots, caused by the wear and the thermal effects. A coupled simulation method was developed including numerical frictional contact, transient thermal and incremental wear calculations. In the 3D simulation, the effects of the friction, the thermal expansion, the wear, and the temperature-dependent material properties were also considered. A good agreement was found between the results of the test and the calculations, both for the thermal and wear results. The proposed method is suitable for modelling the slowly oscillating wear caused by the thermal expansions in the contact area.

Identification of wear process parameters in reciprocating ball-on-disc tests

Wear test results are presented for a spherical indenter in reciprocal motion interacting with soft (aluminium alloy) and hard (construction steel) substrates. The aim of this paper is to provide evidence of the evolution of the contact zone, specification of wear scar depth and surface roughness in the contact zone. Numerical analysis of the interaction of the sliding sphere with the wear track provided contact zone dimensions, although these differed from the experimental data. The incremental wear factor is also introduced in the paper, while the formulae for the wear volume of the sphere recommended by ASTM have been improved.

Simple parameters to predict effect of surface damage on fretting fatigue

This paper presents two empirical parameters for the prediction of fretting. The first is a simple parameter, D fret 1, which is shown to correlate test data against fretting fatigue life in terms of the so-called running conditions of contact displacement and normal load. The second, more complex, parameter is shown to have the ability to capture: (i) the effect of relative slip on fretting fatigue life and (ii) a well-known fretting fatigue contact size effect in a more rational framework. This parameter combines a multiaxial fatigue parameter, the constants for which can be obtained from plain-fatigue testing, and a surface damage parameter D fret 2, which represents the surface damaging effect of fretting, the tribological constants for which can be obtained from fretting wear and fretting fatigue test data. A key benefit of D fret 2 is that it circumvents time-consuming incremental wear simulations.

Simulation of friction and wear in DLC/steel contacts for different loading histories and geometries: Ball-on-plate configuration and piston–cylinder-contacts

DLC-coatings are used in industry for wear protection of highly loaded tribological contacts. Because the transfer of the wear results from model experiments to realistic contact conditions is not yet possible, long lasting endurance-tests have to be performed. As part of the development of a predictive tool, a recently developed unified dissipative energy model has been applied to different loading histories and geometries, such as ball-on-plate and piston–cylinder-geometry. Predictions of the friction coefficient and the wear depth, which were obtained from a Global Incremental Wear Model (GIWM), are in good agreement to experiments and successfully validate the transferability of the model.

Modelling of unlubricated oscillating sliding wear of DLC-coatings considering surface topography, oxidation and graphitisation

The improvement of high-performance anti-wear diamond-like carbon-coatings (DLC-coatings) for industrial applications is usually supported by using an oscillating sliding model test. A ball-on-disc setup allows the simulation of accelerated conditions in an unlubricated contact at increased contact pressure. Although the wear behaviour of DLC-coatings has been frequently investigated in literature, wear models for the prediction of the coating's lifetime and for the quantification of wear in the steel counterpart are missing. In this study a unified wear model has been developed based on the dissipated energy approach. This novel model includes evolution equations for the quantitative description of the surface topography of the coated sample, the oxidation of the 100Cr6 steel counterpart as well as the characteristic graphitisation of the DLC-coating. It has been implemented in the Global Incremental Wear Model (GIWM), which accounts for the geometry change during wear and allows a fast wear calculation and model development by simulating all important quantities of the model tests. This GIWM has been validated with experimental results and its predictive capabilities have been demonstrated for different types of DLC-coatings.

A study on the interaction between fretting wear and cyclic plasticity for Ti–6Al–4V

The fretting wear behaviour of Ti–6Al–4V is experimentally investigated using a cylinder-on-flat specimen arrangement for different loads, strokes and numbers of fretting cycles, including partial slip and gross sliding conditions. An elastic–plastic, finite element (FE) based, incremental wear simulation approach is employed to study the evolution of the surface and sub-surface fretting variables, using a kinematic hardening (continuum) plasticity model to represent the cyclic plasticity behaviour. The predicted evolution of plastic deformation and fretting variables, such as contact pressure, relative slip, sub-surface stresses and critical-plane Smith–Watson–Topper (multiaxial) fatigue parameter, due to the simulated wear are compared with the observed wear scar characteristics and locations of crack initiation. It is shown that the characteristics of predicted plastic strain and damage accumulation are significantly different for the gross sliding and the partial slip cases and that the differences can be correlated with the observed differences in surface morphology and surface cracking. It is shown that the location of plasticity due to shear yielding at the surface promotes wear across the contact region for the gross sliding case and at the stick–slip interface for the partial slip case.

Tribological characterization and numerical wear simulation of microcomponents under sliding and rolling conditions

Increasing requirements for higher power densities and further miniaturisation in microsystem technology result in highly loaded micromechanical systems. Regarding these applications, the friction and wear behaviour of self-mated Si3N4 ceramic and WC-Co hardmetal has been characterized in laboratory micro tribometers. Experiments under unidirectional sliding and rolling conditions were carried out in air of 50% relative humidity as well as lubricated with water. Results from the model tests were used as input dataset for a numerical simulation tool Global Incremental Wear Model (GIWM) to predict volumetric wear as a function of operating conditions. The laboratory tests indicated that WC-Co as well as Si3N4 are applicable for microsystems running in water, due to their high wear resistance and low friction coefficient. Furthermore it was shown, that the numerical simulation can help to reduce the experimental effort by reliable predicting wear under different operating conditions, provided that the active wear mechanisms are comparable.

Finite element simulation of fretting wear-fatigue interaction in spline couplings

This paper describes a finite element based method for simulating the effects of material removal, associated with fretting wear, on fretting fatigue parameters in a spline coupling. An incremental wear simulation technique is implemented with a single tooth finite element model of the coupling for symmetric loading, assuming equal wear on all teeth, using a comparatively coarse mesh model, for computational efficiency. A surface interpolation technique is implemented to map the predicted distributions of wear onto a non-symmetric, 360° (18-tooth) model, with detailed refinement on one tooth, to predict the effect of wear on the evolution of stress, strain and fatigue parameters and on subsequent life prediction. The life prediction is based on a critical plane multiaxial fatigue parameter approach, along with cumulative damage for combined load cycles and for wear induced changes in the fatigue parameters. Furthermore, the effect of wear due to the rotating bending moment and fluctuating torque on fretting fatigue damage accumulation is presented. Low frequency, torque and axial loading induced wear, leading to gross slip conditions on all teeth, is predicted to reduce fretting fatigue parameters and hence increase life. In contrast, higher frequency, rotating moment and fluctuating torque induced wear, corresponding to partial slip conditions, is predicted to increase fretting fatigue parameters away from the contact edges and hence lead to fretting fatigue cracking away from the contact edges and, for the case studied here, to a reduction in predicted life, as observed experimentally. The results are interpreted vis-à-vis published test data for scaled aeroengine splines.

Third-body wear of highly cross-linked polyethylene in a hip simulator

The wear performance of a radiation cross-linked melted ultrahigh-molecular-weight polyethylene (UHMWPE) articulating against 28-mm cobalt chrome femoral heads in the presence of third-body particulate debris was investigated in a hip simulator and compared with the wear of conventional UHMWPE. Particles of aluminum oxide or bone cement containing barium sulfate were added to the serum. In the presence of aluminum oxide particles, the incremental wear rates of conventional UHMWPE averaged as high as 149 ± 116 mg/million cycles compared with 37 ± 38 mg/million cycles for the highly cross-linked components. The difference in the average weight loss was statistically significant at P < .01. With bone cement particles, the conventional UHMWPE components had an average incremental wear rate of 19 ± 5mg/million cycles, and the wear rate of the highly cross-linked UHMWPE components was 0.5 ± 0.7 mg/million cycles.

Sucker Rod Wear In Directionally Drilled Steamflood Wells

Abstract Husky Oil's Thermal Operations District in the Lloydminster, Saskatchewan area, has had extensive experience with sucker rod wear in directionally drilled steamflood wells. Husky's two major steamflood projects, the Aberfeldy Steamflood Pilot (steam drive) and the Pikes Peak Pilot (cyclic with some post-cyclic stream drive), have drilled and produced directional wells from pads since 1983. As expected, the frequency of wear-related sucker rod failures in directionally drilled wells is much higher than in conventional vertical wells. Through careful data gathering and analyses, Husky has attempted to quantify the degree of incremental wear as well as identify the controlling mechanism(s) (i.e. maximum dog-leg, maximum hole angle, etc.). Rod wear-related problems are described in depth. The frequency and location in the rod string of the wear-related failures are compared with a number of parameters to determine the major factors contributing to rod wear. The various methods and items tested by Husky to reduce and control rod wear are described and discussed. A summary of conclusions based on the data as well as a suggested rod/tubing maintenance program are included in this paper. Introduction Husky Oil Operations Ltd. has been active in the Lloydminster, Saskatchewan / Alberta, heavy oil fields since 1946 and currently operates over 2000 producing wells and five active enhanced oil recovery (EOR) pilots. The Lloydminster operators produce from a series of lower Cretaceous sands at depths between 400 m and 600 m. The sands are reasonably clean, moderately sorted, and poorly consolidated. Porosity can vary between 25% and 35%. Permeability ranges from 0.5 darcies to 8 darcies. The oil produced in the area is dense and viscous. Density is generally between 911 kg/m3 and 980 kg/m3. Viscosity can be as high as 131 Pa •s. The original-oil-in-place in the Lloydminster area has been estimated at 500 million m3(1). Probably less than 10% is recoverable by conventional means, EOR recoveries have been estimated at 25%. Pad Well Completions Husky began drilling EOR wells from pads in 1983. The advantages of pad drilling are well documented and accepted by the operating companies in the area. The close spacing used in the EOR pilots (as low as 1 ha), the reduced cost of fluid injection and production lines, the centralization of facilities, and the large reduction in surface area requirements make pad drilling of EOR wells especially attractive. Husky currently has over 100 pad wells in its EOR pilots. Pad sizes vary between 3 and 14 wells. The wells are typically equipped with 178 mm casing, 89 mm EUE tubing, 22 mm grade C sucker rods, and 64 mm rod (insert) pumps. When the first pad wells were brought on stream in 1983 (at the Pikes Peak Cyclic Steam Pilot), the field personnel were expecting to have significant rod wear problems. The frequency of rod wear-related servicing was higher for the new wells but not alarmingly so. The installation of rod rotators and the implementation of a rod maintenance program kept the problem under control.

The interdependence of wear events during slow sliding — A statistical viewpoint

In this short paper we report an attempt to describe wear statistically during slow sliding. On application of the Durbin-Watson test on experimentally obtained wear rate data, the incremental wear at one point in time is found to be influenced by earlier events at the sliding interface. This influence becomes increasingly pronounced when higher loads are applied. This is thought to be due to the greater amount of damage sustained by the asperities (as a result of a higher load), thereby allowing the effects of this damage to persist longer; the asperities have a memory of past events at the sliding interface.

The Assessment of Fabric Wear and Handle Caused by Increments of Accelerator Abrasion in Dry Conditions Part I: Changes in Some Fabric Mechanical Properties as a Result of Abrasion

In this paper, sane aspects of the physical and mechanical properties of woven fabrics, such as mass, thickness, stiffness, air-permeability, and compression, are considered as criteria for assessing the effects of damage caused by changes in frictional abrasion when the Accelerator Tester is used. Two 100% cotton woven fabrics were used in the experiment. Results show that changes occurred in fabric properties as a result of incremental wear. The mass per square metre, coercive couple, and flexural rigidity show a consistent decrease, while thickness, air–permeability, and compression show inconsistent increases with increasing time of abrasion.

The Assessment of Fabric Wear and Handle Caused by Increments of Accelerator Abrasion in Dry Conditions Part II: Correlation between Objective and Subjective Methods of Assessing Fabric Handle

An account is given of a study of subjective–assessment parameters, namely, stiffness, smoothness, and softness by paired–comparison tests on two 100% cotton fabrics given six incremental levels of abrasion treatment in an Accelerator under dry conditions and with ten judges. A pillory box with two hand holes was used in order that a subject could not see the fabric being handled. The ranking orders of objective and subjective measurements for the fabrics are correlated with each other by using the Spearman rank correlation coefficient. It is shown that there is correlation between the change in perception as a result of incremental wear and the change in physical properties such as stiffness and compression.