Wheel-Rail Contact Wear, Work, and Lateral Force for Zero Angle of Attack—A Laboratory Study

1984 ◽  
Vol 106 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Sudhir Kumar ◽  
D. L. Prasanna Rao
Keyword(s):  
Angle Of Attack ◽  
Point Contact ◽  
Lateral Force ◽  
Wear Volume ◽  
Wear Process ◽  
Railroad Industry ◽  
Contact Wear ◽  
Rail Wear ◽  
Work Done ◽  
Wear Index

Most of the wear indices, used in the railroad industry for predicting wheel/rail wear, are functions of angle of attack between wheel and rail. Further, the wear problem has been studied in terms of wear coefficients which relate the wear volume to the work done in the wear process. The wear-work principle, as applicable to wear indices and coefficients, is enunciated and its implications are discussed. An analysis of the wheel/rail interaction as a two point contact problem is presented. To establish the validity of the theory and applicability of the indices, results from a series of four experiments on a quarter scale laboratory rig are reported. The experiments are with “zero angle of attack” and an externally applied lateral load on the wheel, representing the idealized operation of a perfect radial truck. It is observed that contrary to the prediction, based on most of the suggested indices, there is noticeable wear of both wheel and rail even under zero angle of attack. It is concluded that lateral forces should be explicitly included in wear index formulation. Calculated values of wear coefficients, in the range 7.7E-5 to 38.0E-5 for the case of total contact slip and 21.6E-5 to 120.8E-5 for the case of adhesive or micro slip, indicate the effect of plastic flow in the contact when the Holm-Archard relation is assumed valid. Approximate validity of the Derby wear index, based on energy considerations, indicates that indices which are primarily functions of angle of attach are not quite valid for predicting field wheel/rail wear. It is also concluded that the wear-work principle as formulated in the paper can be considered to be reasonably valid.

scholarly journals WHEEL–RAIL WEAR INVESTIGATION ON A HEAVY HAUL BALLOON LOOP TRACK THROUGH SIMULATIONS OF SLOW SPEED WAGON DYNAMICS

Transport ◽  
2018 ◽  
Vol 33 (3) ◽  
pp. 843-852 ◽  
Author(s):  
Yan Quan SUN ◽  
Maksym SPIRYAGIN ◽  
Colin COLE ◽  
Dwayne NIELSEN
Keyword(s):  
Dynamic Behaviour ◽  
Railway Track ◽  
Contact Friction ◽  
Slow Speed ◽  
Wear Process ◽  
Contact Wear ◽  
Rail Wear ◽  
Heavy Haul ◽  
Curve Radius ◽  
Heavy Haul Railway

Heavy haul railway track infrastructure are commonly equipped with balloon loops to allow trains to be loaded/unloaded and/or to reverse the direction of travel. The slow operational speed of trains on these sharp curves results in some unique issues regarding the wear process between wheels and rails. A wagon dynamic system model has been applied to simulate the dynamic behaviour in order to study the wheel–rail contact wear conditions. A wheel–rail wear index is used to assess the wear severity. The simulation shows that the lubrication to reduce the wheel–rail contact friction coefficient can significantly reduce the wear severity. Furthermore, the effects of important parameters on wheel–rail contact wear including curve radius, wagon speed and track superelevation have also been considered.

Study on Using Numerical Method to Predict Wear Volume of Rail

2011 ◽  
Vol 335-336 ◽  
pp. 339-342
Author(s):  
Cai Yun Wang ◽  
Peng Shen ◽  
Qi Yue Liu
Keyword(s):  
Numerical Method ◽  
Simulation Experiment ◽  
Reference Value ◽  
Rolling Contact ◽  
Wear Behaviour ◽  
Wear Volume ◽  
Contact Wear ◽  
Rail Wear ◽  
Calculation Results ◽  
Curve Radius

This paper describes an numerical method and simulation experiment investigation on the rail wear affected by the curve radius and axle load etc. the effects of curve radius and axle load on The effects of axle load and curve radius on total slippage of contact particles and friction work of wheel/rail are investigated with numerical methods are analyzed by kalker’s program CONTACT. The effect of curve radius and axle load on rolling wear behaviour of rail is investigated by simulation experiment. It is indicated that axle load and curve radius are important factors to effect rolling contact wear of wheel-rail, and there is a linear relationship between wear volume of rail and friction work of wheel/rail; The preliminary empirical formula between wear volume of rail sample and friction work is given by analysis the experimental and calculation results, the formula offers a certain reference value for researching wear of wheel-rail and predicting wear volume of rail.

scholarly journals Multiple point contact wear prediction and source identification scheme using a single channel blended airborne acoustic signature

2020 ◽  
Vol 53 (3) ◽  
pp. 283-288
Author(s):  
Muhammad Atayyab Shahid ◽  
Tariq Mairaj Khan ◽  
Kevin Lontin ◽  
Kanza Basit ◽  
Muhammad Khan
Keyword(s):  
Source Identification ◽  
Single Channel ◽  
Point Contact ◽  
Multiple Point ◽  
Wear Prediction ◽  
Identification Scheme ◽  
Contact Wear ◽  
Acoustic Signature

A friction based approach for modeling wire bonding

2013 ◽  
Vol 2013 (1) ◽  
pp. 000208-000212 ◽  
Author(s):  
Simon Althoff ◽  
Jan Neuhaus ◽  
Tobias Hemsel ◽  
Walter Sextro
Keyword(s):  
Contact Area ◽  
Copper Wire ◽  
Point Contact ◽  
Welding Process ◽  
Friction Model ◽  
Ultrasonic Power ◽  
Physical Effects ◽  
Wedge Bonding ◽  
Work Done ◽  
Do So

A model approach for wedge/wedge bonding copper wire is presented. The connection between wire and substrate is based on a variety of physical effects, but the dominant one is the friction based welding while applying ultrasound. Consequently, a friction model was used to investigate the welding process. This model is built up universal and can be used to describe the formation of micro welds in the time variant contact area between wire and substrate. Aim of the model is to identify the interactions between touchdown, bond normal force, ultrasonic power and bonding time. To do so, the contact area is discretized into partial areas where a Point Contact Model is applied. Based on this approach it is possible to simulate micro and macro slip inside the contact area between wire and substrate. The work done by friction force is a main criterion to define occurring micro joints which influence the subsequent welding.

Wear Performance of GCr15 Friction Pairs with Effect of Initial Radial Micro-Grooves

2019 ◽  
Vol 11 (1) ◽  
pp. 56-61
Author(s):  
Wei Yuan ◽  
Shengkai Mei ◽  
Song Li ◽  
Zhiwen Wang ◽  
Jie Yu ◽  
...  
Keyword(s):  
Wear Rate ◽  
Abrasive Wear ◽  
Electrical Discharge Machining ◽  
Friction Pair ◽  
Wear Volume ◽  
Fatigue Wear ◽  
Wear Performance ◽  
Wear Process ◽  
Groove Test ◽  
On Line

Background: Grooves may inevitably occur on the surface of the friction pair caused by severe wear or residual stress, which will play an important role on the reliability of machine parts during operation. Objective: The effect of the micro-grooves perpendicular to sliding direction on the wear performance of the friction pairs should be studied. Method: Micro-grooves can be machined on discs of friction pairs using electrical discharge machining. On-line visual ferrograph method was used to monitor the wear process to research the wear rate changing characteristic. Profilemeter and metallurgical microscope were used to observe the wear scars. Results: Comparing to the non-groove test, i) in one-groove test, wear volume and rate were approximate the same, and the wear scar was smooth, ii) when the grooves more than 4, the test running-in stage will be obviously prolonged, particularly for the test with 8 grooves on the disc, the duration of running-in stage is 4 times than that without grooves on specimen, and the wear rate and volume increase significantly, and then decrease with fluctuation, iii) the abrasive wear can be avoid with the debris stagnating in the groove, however, fatigue wear will significantly emerge. Conclusion: Abrasive wear can be avoided and smooth running-in surfaces can be obtained with proper amount of initial radial micro-grooves.

An Investigation of the Impacts of Contact Parameters on Wear Coefficient

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
V. Janakiraman ◽  
S. Li ◽  
A. Kahraman
Keyword(s):  
Surface Roughness ◽  
Point Contact ◽  
Viscosity Coefficient ◽  
Rolling Contact ◽  
Wear Coefficient ◽  
Wear Process ◽  
Contact Formulation ◽  
Model Combining ◽  
Roughness Amplitude ◽  
Disk Rolling

In this study, the wear depths under different loads, speeds, lubricant temperatures, and surface roughness amplitudes are experimentally determined using a twin-disk rolling contact setup. A point contact wear model combining a contact formulation and Archard's wear equation in an iterative manner is developed to simulate the wear process of the experiments. By matching the measured and predicted wear profiles, the wear coefficients under different operating and surface conditions are determined. It is found that the wear coefficient increases when either the load or the surface roughness amplitude increases and decreases as the lubricant pressure-viscosity coefficient increases. Within the operating ranges considered, it is observed that the lubricant pressure-viscosity coefficient is the most influential parameter on wear, the load has the least impact, and the surface roughness amplitude is in between. Lastly, a regression formula is given for the estimation of Archard's wear coefficient.

scholarly journals The Influence of an Upstream Pylon on Open Rotor Aerodynamics at Angle of Attack

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Nishad G. Sohoni ◽  
Cesare A. Hall ◽  
Anthony B. Parry
Keyword(s):  
Potential Field ◽  
Angle Of Attack ◽  
Separated Flow ◽  
Rotor Blades ◽  
Tip Vortex ◽  
Rotor Wake ◽  
Rotor Aerodynamics ◽  
Open Rotor ◽  
Urans Cfd ◽  
Work Done

The aerodynamic impact of installing a horizontal pylon in front of a contra-rotating open rotor engine, at take-off, was studied. The unsteady interactions of the pylon's wake and potential field with the rotor blades were predicted by full-annulus URANS CFD calculations at 0 deg and 12 deg angle of attack (AoA). Two pylon configurations were studied: one where the front rotor blades move down behind the pylon (DBP), and one where they move up behind the pylon (UBP). When operating at 12 deg AoA, the UBP orientation was shown to reduce the rear rotor tip vortex sizes and separated flow regions, whereas the front rotor wake and vortex sizes were increased. In contrast, the DBP orientation was found to reduce the incidence variations onto the front rotor, leading to smaller wakes and vortices. The engine flow was also time-averaged, and the variation in work done on average midspan streamlines was shown to depend strongly on variation in incidence, along with a smaller contribution related to change of radius.

THE ABILITY OF NANOCOMPOSITE CARBON COATINGS TO WITHSTAND FRICTION UNDER SEVERE CONDITIONS

Tribologia ◽  
2019 ◽  
Vol 287 (5) ◽  
pp. 115-124
Author(s):  
Sławomir ZIMOWSKI ◽  
Marcin KOT ◽  
Grzegorz WIĄZANIA ◽  
Tomasz MOSKALEWICZ
Keyword(s):  
Carrying Capacity ◽  
Steel Substrate ◽  
Point Contact ◽  
Limit Load ◽  
Scratch Test ◽  
Load Carrying Capacity ◽  
Indentation Method ◽  
Wear Process ◽  
Tribological Tests ◽  
Load Carrying

The paper presents an analysis of the micromechanical properties of selected thin, hard anti-wear coatings of the type nc-TiN/a-C and nc-TiC/a-C, which were deposited by magnetron sputtering on a steel substrate. The load carrying capacity of the nanocomposite coatings was analysed in point contact with the use of indentation method, a scratch test, and friction test in contact with a ceramic ball. The hardness and modulus of elasticity of the coatings were determined by an instrumented indentation method using a Vickers indenter. The coating adhesion to the substrate was examined in a scratch test. Tribological tests in sliding contact with an Al2O3 ball were made at various loads to determine the limit load in which normal friction occurs. The results of tribological tests were compared with the resistance to plastic deformation index (H3/E2). It was found that the basic micromechanical parameters of coatings provide important information concerning durability and load carrying capacity. However, while predicting wear, it is also important to investigate the nature of the wear process during friction. The wear nature of the nc-TiN/a-C and nc-TiC/a-C coatings depends on the load value and the number of forced loads.

Simultaneous Measurement of Surface Topography and Friction Force by a Single-Head Lateral Force Microscope

1995 ◽  
Vol 117 (2) ◽  
pp. 334-340 ◽  
Author(s):  
C.-J. Lu ◽  
Zhaoguo Jiang ◽  
D. B. Bogy ◽  
T. Miyamoto
Keyword(s):  
Friction Coefficient ◽  
Surface Topography ◽  
Friction Force ◽  
Rotation Angle ◽  
Point Contact ◽  
Lateral Force ◽  
Wear Depth ◽  
Optical Head ◽  
Lateral Force Microscope ◽  
Normal Deflection

Although friction force measurements using one sensor to detect both the normal deflection and rotation angle of a scanning probe are convenient and popular, the critical issues regarding the calibration of the instruments have not been fully studied. A Lateral Force Microscope (LFM), modified from the Point Contact Microscope (PCM), is used to simultaneously measure the surface topography and friction force. An optical head is used to measure the normal bending deflection and rotation angle of the cantilever that carries the diamond tip. Emphasis is put on the development of reliable calibration procedures for obtaining the normal deflection and rotation sensitivities of the optical head as well as the spring constants in the bending and torsion modes. The friction loop, which is essential for friction measurements, is investigated in detail. The LFM is used to measure a two-phase composite to show its ability to distinguish different materials on a surface. Wear tests on a single-crystal silicon <100> surface show different friction coefficient regimes, depending on the applied load. For small loads, there is no wear and the friction coefficient is constant. For larger loads, the friction coefficient and wear depth increase with normal load.

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