Numerical analysis of high-speed wheel/rail adhesion under interfacial liquid contamination using an elastic-plastic asperity contact model

2016 ◽  
Vol 231 (1) ◽  
pp. 63-74
Author(s):  
Bing Wu ◽  
Tao Wu ◽  
Zefeng Wen ◽  
Xuesong Jin
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Present Model ◽  
Temperature Fields ◽  
Elastic Model ◽  
Asperity Contact ◽  
Roughness Parameters ◽  
Slip Ratio ◽  
Elastic Plastic ◽  
Train Speed

The objective of this paper is to investigate the high-speed wheel/rail adhesion under interfacial liquids contamination using a numerical model. This model considers the rheological property of interfacial liquids, elastic-plastic deformation of microasperities contact and the temperature across the film thickness. The pressure and the temperature fields can be obtained. The effects of train speed, surface roughness parameters, characteristic shear stress, and the slip ratio are investigated. Furthermore, the present model is compared with the elastic model and the elastic-plastic model without considering the thermal effect. The numerical results show that the train speed and temperature affects the wheel/rail adhesion significantly.

Calculation of Roughness Parameters during Ultrasonic Hobbing from the Viewpoint of the Theory of Elastic-Plastic Contact

2019 ◽  
Vol 973 ◽  
pp. 170-173
Author(s):  
Sergey I. Agapov ◽  
Yuriy I. Sidyakin ◽  
Oleg F. Korpelyanskiy
Keyword(s):  
Surface Roughness ◽  
Analytical Solutions ◽  
Roughness Parameter ◽  
Regression Equations ◽  
Ultrasonic Machining ◽  
Roughness Parameters ◽  
Elastic Plastic ◽  
Fine Pitch

This article analyses the process of occurrence of the surface roughness during the ultrasonic hobbing of the fine pitch gears from the viewpoint of the theory of elastic-plastic contact, and suggests analytical solutions and regression equations to estimate the roughness parameter Ra in both conventional and ultrasonic machining.

Elastic-Plastic Microcontact Analysis of a Sphere and a Flat Plate

2007 ◽  
Vol 23 (4) ◽  
pp. 341-352 ◽  
Author(s):  
J. L. Liou ◽  
J. F. Lin
Keyword(s):  
Surface Roughness ◽  
Flat Plate ◽  
Contact Pressure ◽  
Contact Area ◽  
Normal Load ◽  
Contact Load ◽  
Asperity Contact ◽  
Elastic Plastic ◽  
Deformation Regime ◽  
Maximum Contact

ABSTRACTThe elastic-plastic microcontact model of a sphere in contact with a flat plate is developed in the present study to investigate the effect of surface roughness on the total contact area and contact load. From the study done by the finite element method, the dimensionless asperity contact area, average contact pressure, and contact load in the elastoplastic regime are assumed to be a power form as a function of dimensionless interference (δ/δec). The coefficients and exponents of the power form expressions can be determined by the boundary conditions set at the two ends of the elastoplastic deformation regime. The contact pressures evaluated by the present model are compared with those predicted by the Hertz theory, without considering the surface roughness and the reported model, including the roughness effect, but only manipulating in the elastic regime. The area of non-zero contact pressure is enlarged if the surface roughness is considered in the microcontact behavior. The maximum contact pressure is lowered by the presence of surface roughness if the contact load is fixed. Under a normal load, both the contact pressure and the contact area are elevated by raising the plasticity index for the surface of the same surface roughness.

scholarly journals Surface Quality Assessment after Milling AZ91D Magnesium Alloy Using PCD Tool

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 617 ◽  
Author(s):  
Ireneusz Zagórski ◽  
Jarosław Korpysa
Keyword(s):  
Surface Roughness ◽  
Magnesium Alloy ◽  
High Speed ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Roughness Parameters ◽  
Operational Parameters

Surface roughness is among the key indicators describing the quality of machined surfaces. Although it is an aggregate of several factors, the condition of the surface is largely determined by the type of tool and the operational parameters of machining. This study sought to examine the effect that particular machining parameters have on the quality of the surface. The investigated operation was the high-speed dry milling of a magnesium alloy with a polycrystalline diamond (PCD) cutting tool dedicated for light metal applications. Magnesium alloys have low density, and thus are commonly used in the aerospace or automotive industries. The state of the Mg surfaces was assessed using the 2D surface roughness parameters, measured on the lateral and the end face of the specimens, and the end-face 3D area roughness parameters. The description of the surfaces was complemented with the surface topography maps and the Abbott–Firestone curves of the specimens. Most 2D roughness parameters were to a limited extent affected by the changes in the cutting speed and the axial depth of cut, therefore, the results from the measurements were subjected to statistical analysis. From the data comparison, it emerged that PCD-tipped tools are resilient to changes in the cutting parameters and produce a high-quality surface finish.

Analysis of Traction Curve in Linear Region Considering Volume Viscoelasticity

1999 ◽  
Vol 121 (2) ◽  
pp. 252-258 ◽  
Author(s):  
Narihiko Yoshimura ◽  
Noboru Umemoto ◽  
Tsunamitsu Nakahara
Keyword(s):  
High Pressure ◽  
Shear Stress ◽  
High Speed ◽  
Viscoelastic Model ◽  
Primary Data ◽  
Elastic Model ◽  
Linear Region ◽  
Slip Ratio ◽  
Traction Test ◽  
Theoretical Results

Measurements of the gradient in the linear region of traction curve, where the effects of heat generation and nonlinearity of shear viscosity can be neglected were made for two kinds of synthetic oils, DOP and 5P4E, using a traction tester improved to a precision less than 0.01 percent in slip ratio. The measured results were compared with the theoretical results based on a viscoelastic model for shear stress and on an elastic model for compressibility using primary data of the rheological properties which were obtained not by means of traction test; they were markedly less than the theoretical results under low speed for both oils and also under high speed for DOP. A new analysis of the traction was performed considering volume viscoelasticity for compressibility which relates shear viscoelasticity under high pressure. The theoretical results agree fairly with the measured results.

scholarly journals Adhesive Friction Based on Accurate Elastic-Plastic Finite Element Analysis and n-Point Asperity Concept

2017 ◽  
Vol 11 ◽  
pp. 1-28
Author(s):  
Ajay K. Waghmare ◽  
Prasanta Sahoo
Keyword(s):  
Finite Element Analysis ◽  
Surface Roughness ◽  
Finite Element ◽  
Coefficient Of Friction ◽  
Material Properties ◽  
Asperity Contact ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Plastic Type ◽  
Definition Of

The present work considers analysis of adhesive friction of rough surfaces using n-point asperity concept for statistical definition of surface roughness features, and accurate finite element analysis of elastic-plastic deformation of single asperity contact. The paper describes theoretical study in which whole range of deformation of an n-point asperity viz. from fully elastic, through elastic-plastic, to fully plastic is considered and the intermediate transition regime is treated analytically as well as numerically. Well defined adhesion index and plasticity index are used to study the prospective contact situations arising out of variation in material properties and surface roughness features. Using practical values of material properties and surface roughness parameters, results are obtained for normally applied load, friction force, and coefficient of friction. It is observed that the surfaces undergoing predominantly plastic type of deformation and having moderate to higher adhesion have constant coefficient of friction.

The Dependence of 3D Surface Roughness Parameters on High-Speed Milling Technological Parameters and Machining Strategy

2014 ◽  
Author(s):  
Toms Torims ◽  
Andris Logins ◽  
Pedro Castellano Rosado ◽  
Santiago Gutiérrez ◽  
Rafael Torres
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Production Costs ◽  
Manufacturing Strategy ◽  
Roughness Parameters ◽  
High Speed Milling ◽  
Surface Roughness Parameters ◽  
3D Surface ◽  
3D Surface Roughness ◽  
The Impact

High-speed milling is an effective machining method extensively used in modern material processing. This machining method offers increased efficiency, quality and accuracy of the machined surface as well as considerably reducing overall production costs and machining time. This paper outlines comprehensive research into the impact of the technological strategy and processed materials on carefully selected 3D surface roughness parameters. This research provides manufacturers who use high-speed milling with recommendations on how to better obtain the desired surface roughness parameters. More specifically, it covers multifactorial analysis of the following factors: feed rate, manufacturing strategy, overlap and material influences on the most characteristic 3D surface parameters. The results are based on ANOVA – analysis of variance, where differences between groups of means are analysed using a range of statistical models. Subsequent analysis and respective conclusions identify the most significant factors as being the material and high-speed milling manufacturing strategy. Analytically justified recommendations for manufacturers regarding the preferred high-speed milling strategies are provided. The research concluded that the values of the selected 3D surface roughness parameters in high-speed milling depend significantly on the type of material being machined, milling mode and cutting tool overlap as well as feed. In particular, Sa - the arithmetic mean height, is highly sensitive to the milling mode.

Power Loss in High-Speed Micro Turbomachinery: An Experimental Study

2012 ◽  
Author(s):  
James F. Walton ◽  
Hooshang Heshmat ◽  
Michael Tomaszewski
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Ambient Pressure ◽  
Asperity Contact ◽  
Static Structure ◽  
Power Sources ◽  
Rotor Systems ◽  
Foil Bearings ◽  
Turbogenerator Rotor ◽  
Loss Models

In the paper the authors present the results of a study to investigate the windage and foil bearing losses in modern high-speed micro-turbomachinery such as motors, turboexpanders and turbogenerator rotor systems. Areas investigated include clearance between rotor and static structure; surface roughness; and ambient pressure conditions. Comparisons between experiments and theoretical windage loss models show excellent correlation at high speeds. Testing also indicated that some optimum rotor stator gaps are possible to minimize windage loss and that surface roughness can significantly impact windage. It was also shown that for rotor systems with foil bearings, at lower speeds rapid deceleration occurs. This is most likely due to the reduction in film thickness and onset of asperity contact between rotor and bearing surfaces. As expected ambient pressure also impacts windage losses. The theoretical rotor windage loss models, their range of applicability and key limitations of those loss models are discussed. While bearing losses are not included in theoretical windage loss models, it was shown that they do need to be considered, especially when developing very high speed motor/generators. Approaches to properly account for the wide array of losses in order to develop high power density power sources are recommended.

Enhancement of EDM Performance by Using Copper-Silver Composite Electrode

2020 ◽  
Vol 38 (9A) ◽  
pp. 1352-1358
Author(s):  
Saad K. Shather ◽  
Abbas A. Ibrahim ◽  
Zainab H. Mohsein ◽  
Omar H. Hassoon
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Material Removal ◽  
High Speed ◽  
Composite Electrode ◽  
Removal Rate ◽  
Pure Copper ◽  
High Speed Steel ◽  
Pulse On Time ◽  
Pulse Off Time

Discharge Machining is a non-traditional machining technique and usually applied for hard metals and complex shapes that difficult to machining in the traditional cutting process. This process depends on different parameters that can affect the material removal rate and surface roughness. The electrode material is one of the important parameters in Electro –Discharge Machining (EDM). In this paper, the experimental work carried out by using a composite material electrode and the workpiece material from a high-speed steel plate. The cutting conditions: current (10 Amps, 12 Amps, 14 Amps), pulse on time (100 µs, 150 µs, 200 µs), pulse off time 25 µs, casting technique has been carried out to prepare the composite electrodes copper-sliver. The experimental results showed that Copper-Sliver (weight ratio70:30) gives better results than commonly electrode copper, Material Removal Rate (MRR) Copper-Sliver composite electrode reach to 0.225 gm/min higher than the pure Copper electrode. The lower value of the tool wear rate achieved with the composite electrode is 0.0001 gm/min. The surface roughness of the workpiece improved with a composite electrode compared with the pure electrode.

Friction Force and Stresses Analysis for Contact of Assembled Details

2006 ◽  
Vol 113 ◽  
pp. 334-338
Author(s):  
Z. Dreija ◽  
O. Liniņš ◽  
Fr. Sudnieks ◽  
N. Mozga
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Plastic Deformation ◽  
Friction Force ◽  
Sliding Friction ◽  
Friction Model ◽  
Contact Interface ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

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