Effect of two-body and three-body microcontacts under dry friction on contact characteristics

2017 ◽  
Vol 232 (4) ◽  
pp. 706-719 ◽  
Author(s):  
Horng-Wen Wu ◽  
Yang-Yuan Chen
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Contact Area ◽  
External Load ◽  
Wear Debris ◽  
Elastoplastic Deformation ◽  
Particle Diameter ◽  
Body Contact ◽  
Wide Range ◽  
Three Body

The wear debris generation is unavoidable between the contact interfaces of moving components. In three-body contact instances, friction and wear occur at these separate contact points. This paper discusses the characteristics of the three-body contact comprising the abrasive particle in the interface compared to the two-body contact. The results show that for the wear debris or foreign particles present in the interface of the three-body contact, as external load initially increases, the external load is fully borne by the contact characteristics of particle-to-surface. Until the external load rises to a particular critical external load, it enters the real three-body situation, and the critical external load thus increases with an increase in the ratio of particle diameter to surface roughness. For two contact surfaces, the summit deformation is the elastoplastic deformation in a wide range of external loads. As the external load is lower than the critical external load value of the three-body contact, the contact surface is under the particle-to-surface two-body contact, and the elastic deformation of surface peak has the largest proportion of contact area. When the external load is higher than the critical external load value, the elastoplastic deformation contact area quickly dominates, and the total contact area ratio approximates to the surface-to-surface two-body contact situation. In the range of engineering surface roughness (σ = 50–400 nm), at each external load and surface roughness, the total friction coefficient decreases with the increase in the ratio of particle diameter to surface roughness under the three-body contact, and this shows that the friction coefficient of surface-to-surface contact is larger than that of the sphere wear debris between the contact interface. At the same surface roughness, the friction coefficient may increase or decrease with an increase in the external load because it is determined by particle diameter. At the same ratio of particle diameter to surface roughness and external load, the friction coefficient increases with the decreasing surface roughness.

Study of Microcontact Model for Hard Particles Between Rough Surfaces

2005 ◽  
Author(s):  
Jeng-Haur Horng ◽  
Shin-Yuh Chern ◽  
Chih-Hsien Chen ◽  
Ming-Yao Ku
Keyword(s):  
Contact Area ◽  
Rough Surfaces ◽  
Particle Diameter ◽  
Area Ratio ◽  
Contact Load ◽  
Body Contact ◽  
Hard Particles ◽  
Contact Situation ◽  
Three Body ◽  
Contact Area Ratio

Particles are often presented at contact interfaces. In this study, a three-body microcontact model Considering of hard particles and rough surfaces is proposed in order to understand the effects of particles between surfaces on contact characteristics. Both transitional surface-to-surface and particle-to-surface two-body microcontact simulations can be obtained according to the simplification of this model. In the three-body contact situation, the curves of contact area ratio versus dimensionless load are located in the range between two straight lines. The surface-to-surface two-body contact situation is the upper bound and the particle-to-surface two-body contact situation is the lower bound. The contact situation will approach to the pure particle-to-surface two-body contact situation as the value of particle diameter over roughness value of surface increases. The total contact area ratio increases when particle size or particles density decreases, and contact load increases. Contrary to the results for contact area ratio, the dimensionless separation increases when particle density increases or contact load decreases.

scholarly journals Cutting Parameter Optimization in Finishing Milling of Ti-6Al-4V Titanium Alloy under MQL Condition using TOPSIS and ANOVA Analysis

2021 ◽  
Vol 11 (1) ◽  
pp. 6775-6780
Author(s):  
V. C. Nguyen ◽  
T. D. Nguyen ◽  
D. H. Tien
Keyword(s):  
Surface Roughness ◽  
Titanium Alloy ◽  
Titanium Alloys ◽  
Contact Area ◽  
Removal Rate ◽  
Multiple Criteria Decision Making ◽  
Machining Process ◽  
Anova Analysis ◽  
Wide Range ◽  
Cutting Parameter Optimization

Titanium and its alloys give immense specific strength, imparting properties such as corrosion and fracture resistance, making them the right candidate for medical and aerospace applications. There is a wide range of engineering applications that use titanium alloys in a variety of forms. The cost of these alloys is slightly higher in comparison to other variants due to the problematic extraction of the molten process. To reduce costs, titanium alloy products could be made by casting, isothermal forging, radial swaging, or powder metallurgy, although these techniques require some kind of finishing machining process. Titanium and its alloys are difficult to machine due to skinny chips leading to a small cutting tool-workpiece contact area. The thermal conductivity of titanium alloys is too low and the stress produced is too large due to the small contact area, which results in very high cutting temperatures. This paper deals with the experimental study of the influence of the Minimum Quantity Lubricant (MQL) environment in the milling of Ti-6Al-4V alloy considering the optimization of surface roughness and production rate. Taguchi-based TOPSIS and ANOVA were used to analyze the results. The experimental results show that MQL with vegetable oil is successfully applied in the milling of Ti-6Al-4V. The research confirms the suitability of TOPSIS in solving the Multiple Criteria Decision Making (MCDM) issue, by choosing the best alternative at Vc=120m/min, fz=0.065mm/tooth, and ap=0.2mm, where the surface roughness and material removal rate are 0.41µm and 44.1492cm3/min respectively. Besides, ANOVA can be used to predict the best parameters set in the milling process based on the regression model. The parameters predicted by ANOVA analysis do not coincide with any implemented parameters

Three-Body Microcontact Model of Rough Surfaces and Its Application on Polishing of Wafer

2006 ◽  
Vol 505-507 ◽  
pp. 445-450 ◽  
Author(s):  
Jeng Haur Horng ◽  
Jian Shing Lee ◽  
D.C. Du
Keyword(s):  
Lower Bound ◽  
Contact Area ◽  
Rough Surfaces ◽  
Area Ratio ◽  
Body Contact ◽  
Contact Situation ◽  
Three Body ◽  
Straight Lines ◽  
Contact Area Ratio ◽  
Ratio Versus

In this study, a three-body microcontact model for rough surfaces is proposed in order to understand the effects of particles between surfaces on contact characteristics and its application on polishing of wafer. Both transitional surface-to-surface and particle-to-surface two-body microcontact simulations can be obtained according to the simplification of this model. In the three-body contact situation, the curves of contact area ratio versus dimensionless load are located in the range between two straight lines. The surface-to-surface two-body contact situation is the upper bound and the particle-to-surface two-body contact situation is the lower bound. As the value of D/σ increases, the contact situation will approach the pure particle-to- surface 2-body contact situation. The model also is used to study the wear mechanisms of the silicon wafer.

A Model for Contact and Static Friction of Nominally Flat Rough Surfaces Under Full Stick Contact Condition

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
D. Cohen ◽  
Y. Kligerman ◽  
I. Etsion
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Friction Force ◽  
Contact Area ◽  
Rough Surfaces ◽  
Normal Load ◽  
Static Friction ◽  
Contact Condition ◽  
Maximum Friction ◽  
Static Friction Coefficient

A model for elastic-plastic nominally flat contacting rough surfaces under combined normal and tangential loading with full stick contact condition is presented. The model incorporates an accurate finite element analysis for contact and sliding inception of a single elastic-plastic asperity in a statistical representation of surface roughness. It includes the effect of junction growth and treats the sliding inception as a failure mechanism, which is characterized by loss of tangential stiffness. A comparison between the present model and a previously published friction model shows that the latter severely underestimates the maximum friction force by up to three orders of magnitude. Strong effects of the normal load, nominal contact area, mechanical properties, and surface roughness on the static friction coefficient are found, in breach of the classical laws of friction. Empirical equations for the maximum friction force, static friction coefficient, real contact area due to the normal load alone and at sliding inception as functions of the normal load, material properties, and surface roughness are presented and compared with some limited available experimental results.

scholarly journals Two- and three-body contacts in the unitary Bose gas

Science ◽  
2017 ◽  
Vol 355 (6323) ◽  
pp. 377-380 ◽  
Author(s):  
Richard J. Fletcher ◽  
Raphael Lopes ◽  
Jay Man ◽  
Nir Navon ◽  
Robert P. Smith ◽  
...  
Keyword(s):  
Bose Gas ◽  
Many Body ◽  
Body Contact ◽  
Wide Range ◽  
Pairwise Correlations ◽  
Efimov Physics ◽  
Many Body Systems ◽  
Three Body ◽  
Profound Insight

In many-body systems governed by pairwise contact interactions, a wide range of observables is linked by a single parameter, the two-body contact, which quantifies two-particle correlations. This profound insight has transformed our understanding of strongly interacting Fermi gases. Using Ramsey interferometry, we studied coherent evolution of the resonantly interacting Bose gas, and we show here that it cannot be explained by only pairwise correlations. Our experiments reveal the crucial role of three-body correlations arising from Efimov physics and provide a direct measurement of the associated three-body contact.

Synchronous Observation With Friction Measurement Prior to and During Occurrence of Scuffing

2010 ◽  
Author(s):  
Kazuyuki Yagi ◽  
Joichi Sugimura ◽  
Seiji Kajita ◽  
Toshihide Ohmori ◽  
Atsushi Suzuki
Keyword(s):  
Friction Coefficient ◽  
Contact Area ◽  
Wear Debris ◽  
Point Contact ◽  
The Other ◽  
Test Rig ◽  
Friction Measurement ◽  
Inlet Zone ◽  
Sapphire Disc ◽  
Ball On Disc

In the current work, scuffing phenomenon was investigated by a direct observation of a contact area. A ball-on-disc test rig was used, which produced a point contact area between a rotating sapphire disc and a stationary steel ball. Sequence of the friction and photograph in the contact area was synchronously obtained prior to and during occurrences of scuffing. Experiments were conducted in a dry condition and a lubricated condition with hexadecane. In the lubricated condition, wear debris accumulated in the inlet zone entered suddenly into the contact area to sharply increase the friction coefficient. On the other hand, macro plastic flow occurred in the whole contact area in the dry condition during a rapid increase in friction coefficient.

Static Friction Experiments and Verification of an Improved Elastic-Plastic Model Including Roughness Effects

2007 ◽  
Vol 129 (4) ◽  
pp. 754-760 ◽  
Author(s):  
Chul-Hee Lee ◽  
Andreas A. Polycarpou
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Wear Debris ◽  
Normal Load ◽  
Static Friction ◽  
Displacement Rate ◽  
Experimental Measurements ◽  
Roughness Effects ◽  
Elastic Plastic ◽  
Static Friction Coefficient

An experimental study was conducted to measure the static friction coefficient under constant normal load and different interface conditions. These include surface roughness, dwell time, displacement rate, as well as the presence of traces of lubricant and wear debris at the interface. The static friction apparatus includes accurate measurement of friction, normal and lateral forces at the interface (using a high dynamic bandwidth piezoelectric force transducer), as well as precise motion control and measurement of the sliding mass. The experimental results show that dry surfaces are more dependent on the displacement rate prior to sliding inception compared to boundary lubricated surfaces in terms of static friction coefficient. Also, the presence of wear debris, boundary lubrication, and rougher surfaces decrease the static friction coefficient significantly compared to dry smooth surfaces. The experimental measurements under dry unlubricated conditions were subsequently compared to an improved elastic-plastic static friction model, and it was found that the model captures the experimental measurements of dry surfaces well in terms of the surface roughness.

scholarly journals Effect of rolling on the friction coefficient in three-body contact

2019 ◽  
Vol 11 (8) ◽  
pp. 168781401987230
Author(s):  
Almira Miftakhova ◽  
Yang-Yuan Chen ◽  
Jeng-Haur Horng
Keyword(s):  
Friction Coefficient ◽  
Half Space ◽  
Spherical Shape ◽  
Viscoelastic Layer ◽  
Body Contact ◽  
Body Interaction ◽  
System Of Particles ◽  
The Coefficient Of Friction ◽  
Three Body ◽  
Interaction Approach

The contact problem of system of particles rolling over a viscoelastic layer bonded to the rigid half-space was considered. Particles have a spherical shape and their radiuses are distributed along Gauss. Earlier, the friction coefficient was obtained for the particles between surfaces in the relative movement of the surfaces using the three-body interaction method. In this study, the contact area was calculated for a system of particles rolling over the viscoelastic layer bonded to the half-space. Using the three-body interaction approach, the friction coefficient was calculated, taking into account the rolling of particles. The results demonstrate that the coefficient of friction, calculated using the three-body model, decreases when the rolling of particles is taken into account.

Micropitting Generation Mechanism for Gears

2008 ◽  
Vol 2 (5) ◽  
pp. 341-347
Author(s):  
Nobuyoshi Yoshida ◽  
◽  
Tokihiko Taki
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Contact Stress ◽  
Contact Area ◽  
Maximum Stress ◽  
Real Contact Area ◽  
Durability Test ◽  
Metallic Contact ◽  
Real Contact ◽  
Surface Durability

To determine the mechanism behind micropitting, we measured micropit shape occurring in surface durability test, based on the real contact area size formed by asperity interaction in surface roughness. Individual micropitting within surface roughness asperity does not exceed asperity size. Micropitting occurs due to contact stress increased by a high friction coefficient due to metallic contact. Stress analysis showed that maximum stress causes micropitting.

The Effects of Grit Particle Size on Frictional Characteristics of Automotive Braking System

2011 ◽  
Vol 189-193 ◽  
pp. 3511-3516
Author(s):  
Mohd Kameil Abdul Hamid ◽  
Gwidon W. Stachowiak
Keyword(s):  
Particle Size ◽  
Friction Coefficient ◽  
Contact Area ◽  
Wear Debris ◽  
Silica Sand ◽  
Test Rig ◽  
Braking System ◽  
Hard Particles ◽  
Effective Contact

The effect of grit particle size on frictional characteristics was investigated using a vertically oriented brake test rig. Silica sand of grit sizes 50-180 µm, 180-355 µm and 355-500 µm were used in drag mode application. Results showed that the presence of hard particles from environment can influence the friction response significantly. Basically, once the hard particles enter the gap, the value and amplitude of friction coefficient tend to decrease. However, slight increase in friction with smaller particles was recorded due to more hard particles involved in mixing and changing the effective contact area. Better friction stability was related to the presence of smaller grit particles and compacted wear debris to form frictional film on the braking interface.

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