scholarly journals A Study of Coefficient of Friction of UHMWPE in Various Contact Conditions and Measurement of Contact Temperature.

2003 ◽  
Vol 69 (677) ◽  
pp. 121-127
Author(s):  
Keiji IMADO ◽  
Atuyoshi MIURA ◽  
Masuji NAGATOSHI ◽  
Hiroomi MIYAGAWA ◽  
Hidehiko HIGAKi
Keyword(s):  
Coefficient Of Friction ◽  
Contact Temperature ◽  
Contact Conditions

EXPERIMENTAL STUDY OF THE ROLLING–SLIDING CONTACT CONDITIONS IN A PA66/STEEL GEAR USING TWIN-DISC TEST RIG: FRICTION AND WEAR ANALYSIS

2015 ◽  
Vol 22 (06) ◽  
pp. 1550074
Author(s):  
MEFTAH MBAREK ◽  
SADOK RHAIEM ◽  
MOHAMED KHARRAT ◽  
MAHER DAMMAK
Keyword(s):  
Coefficient Of Friction ◽  
Angular Speed ◽  
Linear Increase ◽  
Contact Temperature ◽  
Test Rig ◽  
Contact Conditions ◽  
Slip Ratio ◽  
The Coefficient Of Friction ◽  
Adhesive Interactions ◽  
Different Diameters

This study investigates the effects of sliding ratio on the tribological response of the contact between the teeth of a metal/polymer gear in the regions close to the pitch point. For this purpose, a new twin-disc test rig was developed on the basis of two discs of different diameters rotating one above the other at the same angular speed. Two different materials were used: non-alloyed structural steel (C45) and polyamide (PA66). The effect of the slip ratio (4%, 12%, 20% and 28%) was studied at a constant pressure of 34 MPa and a constant angular speed of 300 rpm. In addition, the contact conditions were controlled with measurements of the two discs surface temperatures. The results indicate that the wear and the friction are closely related to the contact temperature generated by the sliding phenomenon. At low slip ratio (4% and 12%), the coefficient of friction and the temperature are characterized by a quasi-linear increase with time, and the wear increases slowly. At higher slip ratio (20% and 28%), the coefficient of friction and the temperature presents a steady state, and the wear increases dramatically. During the test, a film of transferred PA66 is formed on the steel surface causing the development of adhesive interactions between the contacting discs which increase the friction coefficient and the contact temperature. The high thermal conductivity of steel as compared to that of the polymer can reduce enormously the contact temperature generated by the sliding process.

A Microscopic Approach to Determine Electrothermal Contact Conditions During Resistance Spot Welding Process

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
P. Rogeon ◽  
R. Raoelison ◽  
P. Carre ◽  
F. Dechalotte
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Electrical Contact ◽  
Welding Process ◽  
Contact Temperature ◽  
Macroscopic Model ◽  
Contact Conditions ◽  
Imperfect Contact ◽  
Resistance Spot ◽  
Nugget Growth

This study deals with resistance spot welding process modeling. Particular attention must be paid to the interfacial conditions, which strongly influence the nugget growth. Imperfect contact conditions are usually used in the macroscopic model to account for the electrical and thermal volume phenomena, which occur near a metallic interface crossed by an electric current. One approach consists in representing microconstriction phenomena by surface contact parameters: The share coefficient and the thermal and electrical contact resistances, which depend on the contact temperature. The aim of this work is to determine the share coefficient and the contact temperature through a numerical model on a microscopic scale. This surface approach does not make it possible to correctly represent the temperature profiles, with the peak temperature, observed in the immediate vicinity of the interface and thus to define, in practice, the contact temperature correctly. That is why another approach is proposed with the introduction of a low thickness layer (third body) at the level of the interface the electric and thermal resistances of which are equivalent to the electrical and thermal contact resistance values. In this case, the parameters of the model are reduced to the thickness of the arbitrarily fixed layer and equivalent electric and thermal conductivities in the thin layer, the partition coefficient and the contact temperature becoming implicit. The two types of thermoelectric contact models are tested within the framework of the numerical simulation of a spot welding test. The nugget growth development is found to be much different with each model.

scholarly journals Tribological capabilities of chiral nematic liquid crystal additives in mineral motor oil

2020 ◽  
Vol 12 (7) ◽  
pp. 168781402094547
Author(s):  
Vadim Mokshin
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Coefficient Of Friction ◽  
Friction Pair ◽  
Contact Temperature ◽  
Test Machine ◽  
Regression Equations ◽  
Motor Oil ◽  
Oil Additives ◽  
Chiral Nematic

This article presents the results of experimental investigation of tribological properties of commercial mineral motor oil with chiral nematic (also known as twisted nematic or cholesteric) liquid crystal additives. Cholesteryl stearate and valerate (fatty acid cholesterol esters) liquid crystals were used as oil additives in investigation. Tribological experiments were performed using a block-on-disc-type tribo-test machine at constant experiment time and sliding velocity conditions. The load (contact pressure), concentration of liquid crystalline additive in oil and Rz roughness of steel–steel friction surfaces were taken as variable parameters. The mean coefficient of friction of steel–steel friction pair lubricated by oil with and without liquid crystal additives and near-contact temperature were taken as dependent variables. Regression equations were then derived for each lubricant and tribological efficiency of liquid crystals as oil additives was evaluated. It was established that coefficient of friction of steel–steel friction pair and near-contact temperature are reduced to about a half in the presence of liquid crystal additives. Results of tribological experiments show that tribological efficiency of liquid crystals as oil additives increases with increase in their molecular mass.

scholarly journals Effect of Coating and Low Viscosity Oils on Piston Ring Friction under Mixed Regime of Lubrication through Analytical Modelling

Lubricants ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 124
Author(s):  
Anastasios Zavos
Keyword(s):  
Coefficient Of Friction ◽  
Piston Ring ◽  
Roughness Parameter ◽  
Contact Conditions ◽  
Low Viscosity ◽  
Mixed Regime ◽  
Uncoated Steel ◽  
Coating Morphology ◽  
Friction Prediction ◽  
The Impact

This paper presents the impact of coating topography in piston ring-liner conjunction under mixed regime of lubrication using low viscosity oils. The study provides a time efficient analytical model including mixed-hydrodynamics regime of lubrication under different contact conditions. The method modified the expressions of the contact load and area of Greenwood-Tripp model in order to capture the real asperities interaction into contact. The model represents the tribological behavior of a thin top ring at Top Dead Centre, where boundary and mixed conditions are predominant. Electroplated CrN and PVD TiN coated rings were studied to predict the ring friction. The results are compared with an uncoated steel ring. The CrN coating shows slighter coefficient of friction, due to the coating morphology and roughness parameters. The TiN coating presents thicker lubricant films and higher coefficient of friction because the surface topography is quite rough with high peaks. This can be explained because of the major contribution of the roughness parameter and asperity slope in the boundary friction prediction.

Effect of contact temperature, normal load and dry sliding velocity on the coefficient of friction and wear behavior of nickel based super alloy

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rama Krishna S. ◽  
Patta Lokanadham
Keyword(s):  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Normal Load ◽  
Contact Temperature ◽  
Sliding Velocity ◽  
Friction And Wear Behavior ◽  
Alloy Material ◽  
The Coefficient Of Friction ◽  
Super Alloy

Purpose The purpose of the present paper aims to, study the coefficient of friction and wear behavior of nickel based super alloys used in manufacturing of gas and steam turbine blades. In present paper, parametric study focuses on normal load, dry sliding velocity and contact temperature influence on coefficient of friction and wear of a nickel based super alloy material. Design/methodology/approach Experimental investigation is carried out to know the effect of varying load at constant sliding velocity and varying sliding velocity at constant load on coefficient of friction and wear behavior of nickel based super alloy material. The experiments are carried out on a nickel based super alloy material using pin on disk apparatus by load ranging from 30 N to 90 N and sliding velocity from 1.34 m/s to 2.67 m/s. The contact temperature between pin and disk is measured using K-type thermocouple for all test conditions to know effect of contact temperature on coefficient of friction and wear behavior of nickel based super alloy material. Analytical calculations are carried out to find wear rate and wear coefficient of the test specimen and are compared with experimental results for validation of experimental setup. Regression equations are generated from experimental results to estimate coefficient of friction and wear in the range of test conditions. Findings From the experimental results, it is observed that by increasing the normal load or sliding velocity, the contact temperature between the pin and disk increases, the coefficient of friction decreases and wear increases. Analysis of variance (ANOVA) is used to study the influence of individual parameters like normal load, dry sliding speed and sliding distance on the coefficient of friction and wear of nickel based super alloy material. Originality/value This is the first time to study effect of contact temperature on the coefficient of friction and wear behavior of nickel-based super alloy used for gas and steam turbine blades. Separate regression equations have been developed to determine the coefficient of friction and wear for the entire range of speed of gas turbine blades made of nickel based super alloy. The regression equations are also validated against experimental results.

Modeling and Optimization of Friction and Wear Characteristics of Ti3Al2.5V Alloy Under Dry Sliding Condition

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Mukund Dutt Sharma ◽  
Rakesh Sehgal ◽  
Mohit Pant
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Experimental Results ◽  
Contact Temperature ◽  
Dry Sliding ◽  
Sliding Velocity ◽  
Average Coefficient ◽  
Maximum Contact ◽  
Friction And Wear Characteristics

Modeling of dry sliding friction and wear behavior of Ti3Al2.5V alloy sliding against EN31 steel using a multi-tribotester has been presented. Mathematical model equations in the form of natural log transformation for wear rate (WR), average coefficient of friction (μa), and a square root transformation for maximum contact temperature (Tm) considering the effect of tribological variables have been developed and validated by comparing them with the experimental results. The authors claim novelty with regard to modeling and optimization of friction and wear characteristics of Ti-3Al2.5V alloy. The results reveal that the magnitude of wear rate and maximum contact temperature increases with increase in sliding velocity and increasing normal load with few exceptions. Whereas average coefficient of friction first increases with increasing sliding velocity up to 2.51 m/s, and then decreases at highest sliding velocity. The load is found to have strongest influence on both wear rate and average coefficient of friction followed by sliding velocity, whereas sliding velocity has strongest influence on the maximum contact temperature followed by load. The perturbation plot results are also in accordance with the analysis of variance (ANOVA) analysis. The theoretical and experimental results have an average error of 5.06%, 1.78%, and 1.42%, respectively, for wear rate, average coefficient of friction, and maximum contact temperature. Optimization resulted in a maximum desirability of 0.508 at a load of 60 N and a sliding velocity of 1.5 m/s. For these values, the predicted minimum wear rate is 0.0001144 g/m, the coefficient of friction is 0.3181, and the tool-tip temperature is 59.03 °C.

The Influence of Thermal Deformation on the Contact Temperature of Sliding Asperities

1992 ◽  
Vol 59 (2S) ◽  
pp. S102-S106
Author(s):  
C.-J. Lu ◽  
D. B. Bogy
Keyword(s):  
Surface Temperature ◽  
Integral Equations ◽  
Contact Pressure ◽  
Singular Integral ◽  
Contact Area ◽  
Thermal Deformation ◽  
Singular Integral Equations ◽  
Contact Temperature ◽  
Contact Conditions ◽  
Usual Assumption

The effect of thermal deformation on contact temperature is investigated by considering a spherical asperity sliding on the surface of a semi-infinite insulated solid. The usual assumption that thermal deformation does not change the contact conditions is examined. The problem is mathematically formulated using appropriate Green’s functions to derive singular integral equations for the contact pressure. The relations between the radius of contact area, indentation, surface temperature, and moving velocity are calculated. A two asperities model is used to explain the load partition due to thermal deformation.

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