A Simplified Thermal Analysis of Elastohydrodynamic Contacts

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Raynald Guilbault
Keyword(s):  
Contact Zone ◽  
Load Resistance ◽  
Lubricant Film ◽  
Absolute Difference ◽  
Inlet Temperature ◽  
Contact Conditions ◽  
Film Representation ◽  
Elliptical Contact ◽  
Thermal Ehl ◽  
Zone Temperature

Under elastohydrodynamic (EHL) conditions, the temperature in the contact zone determines the load resistance of the lubricant film. Therefore, an efficient assessment of the scuffing risks requires accurate contact temperature predictions. The work presented in this paper develops a simple and prompt temperature model exploitable within any thermal EHL modeling approach. The model incorporates a multilayer lubricant film representation for the heat equation solution. The developments also include an original heat repartition factor expression and a simple formula for handling intermediate values of the Peclet number. The rolling/sliding conditions in the inlet cause temperature rises that also affect the film resistance in the contact zone; this study proposes an inlet temperature rise equation. This formula offers temperature predictions in agreement with reference values. The contact zone temperature predictions for the line of contact problem under sliding/rolling conditions agree remarkably well with published numerical results; for the evaluations presenting the higher absolute difference, the correspondence remained over 94% and 95% for the maximum and mean temperatures, respectively. Both line and elliptical contact conditions were tested and compared to experimental data available in the literature. The analysis evidenced the precision of the estimates; thus attesting to the accuracy of the model under any contact conditions. Finally, the results indicate that, depending on the pressure and speed combination, the shearing zone may occupy around 30% of the film thickness.

A thermal EHL investigation for size effect of finite line contact on bush-pin hinge pairs in industrial chains

2020 ◽  
Vol 72 (5) ◽  
pp. 695-701
Author(s):  
Mingyu Zhang ◽  
Jing Wang ◽  
Peiran Yang ◽  
Zhaohua Shang ◽  
Yi Liu ◽  
...  
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Contact Zone ◽  
Line Contact ◽  
Equivalent Radius ◽  
Content Type ◽  
Oil Film ◽  
Finite Line Contact ◽  
Finite Line ◽  
Thermal Ehl

Purpose This paper aims to study the influence of the dimension change of bush-pin on the pressure, oil film thickness, temperature rise and traction coefficient in contact zone by using a thermal elastohydrodynamic lubrication (EHL) model for finite line contact. Concretely, the effects of the equivalent curvature radius of the bush and the pin, and the length of the bush are investigated. Design/methodology/approach In this paper, the contact between the bush and pin is simplified as finite line contact. The lubrication state is studied by numerical simulation using steady-state line contact thermal EHL. A constitutive equation Ree–Eyring fluid is used in the calculations. Findings It is found that by selecting an optimal equivalent radius of curvature and prolonging the bush length can improve the lubrication state effectively. Originality/value Under specific working conditions, there exists an optimal equivalent radius to maximize the minimum oil film thickness in the contact zone. The increase of generatrix length will weaken the stress concentration effect in the rounded corner area at both ends of the bush, which can improve the wear resistance of chain. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0448.

Report Paper 3: Elastohydrodynamic Lubrication of ‘O’ Ring Seals

1969 ◽  
Vol 184 (12) ◽  
pp. 197-200
Author(s):  
I. A. Gibson ◽  
C. J. Hooke ◽  
J. P. O'Donoghue
Keyword(s):  
Theoretical Analysis ◽  
Film Thickness ◽  
Pressure Gradient ◽  
Contact Zone ◽  
Elastohydrodynamic Lubrication ◽  
Iterative Solution ◽  
Contact Conditions ◽  
Dry Contact

This report gives details of a theoretical analysis of the lubrication of ‘O’ ring seals. Under dry contact conditions the pressure gradient at inlet to the contact zone is infinite, and an iterative solution has been developed to determine the inlet sweep of pressure under conditions of elastohydrodynamic lubrication. The exit film thickness and pressures have also been determined for conditions of variable outlet viscosity and pressure gradient. Typical results for an ‘O’ ring are given for a standard seal section.

Analysis of the Tribological Conditions in Grinding of Polycrystalline Diamond Based on Single Grain Friction Tests Using the Pin-Disk Principle

2018 ◽  
Vol 767 ◽  
pp. 259-267 ◽  
Author(s):  
Frederik Vits ◽  
Daniel Trauth ◽  
Patrick Mattfeld ◽  
Rudolf Vits ◽  
Fritz Klocke
Keyword(s):  
Contact Zone ◽  
Material Removal ◽  
Polycrystalline Diamond ◽  
Grinding Wheel ◽  
Grinding Process ◽  
State Variables ◽  
Wheel Wear ◽  
Grinding Wheel Wear ◽  
Single Grain ◽  
Zone Temperature

Cutting tools made of polycrystalline diamond (PCD) are used for machining of aluminum alloys, fiber-reinforced plastic composites and wood. Compared to cemented carbide tools with geometrically defined cutting edges, PCD tools offer significant advantages with respect to tool life. High demands regarding the cutting edge roughness and the quality of the rake and the flank face usually require a grinding process with diamond grinding wheels. The PCD grinding process, however, is characterized by low material removal rates and high grinding wheel wear. The material removal rate and the grinding wheel wear, in turn, highly depend on the process state variables process force and process temperature. However, the relationship between these process state variables and the process input variables is largely unknown. This work provides a contribution to the closure of this knowledge gap by means of an adapted friction law. A single grain friction test stand using the pin-disk principle was developed, which enables a measurement of the friction force and the contact zone temperature for normal forces and relative speeds that are common in PCD grinding. During the experiments, the specification of the PCD disc, the cross-sectional area of the friction sample made of monocrystalline diamond as well as the process parameters normal force and relative speed were varied. In addition, the tests were carried out without lubrication as well as with a minimum lubrication. A high correlation between the contact force and the coefficient of friction was determined. This relationship was mathematically formulated in a friction law. In addition, a direct influence of the contact force and the relative velocity on the contact zone temperature was identified. The knowledge gained leads to an improved understanding of the PCD grinding process and thus enables a more efficient grinding process design.

Theory of Lubrication and Failure of Rolling Contacts

1961 ◽  
Vol 83 (2) ◽  
pp. 213-222 ◽  
Author(s):  
B. Sternlicht ◽  
P. Lewis ◽  
P. Flynn
Keyword(s):  
Fatigue Life ◽  
Contact Zone ◽  
High Speed ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Inlet Temperature ◽  
Fluid Properties ◽  
Contact Fatigue Life

The fatigue life of rolling-element bearings has been the subject of numerous investigations. Most recently the influence of the lubricant on fatigue failure has been given added emphasis. This paper presents the results of an investigation which was undertaken in order to gain a better understanding of fluid behavior in the contact zone and to determine the influence of the lubricant on rolling contact fatigue life. The investigation had three distinct facets: (a) An analysis was performed on pressure and temperature distribution within the contact zone of rolling disks. In the analysis Reynolds, energy, and elasticity equations were solved simultaneously and fluid properties, such as viscosity dependence on temperature and pressure were included. (b) Dynamic stresses in two contacting cylindrical bodies were measured by means of photoelastic techniques. These measurements were used to test the validity of the analytically predicted stress distribution. (c) High-speed ball-bearing fatigue tests were conducted with two specially blended oils which had the same viscosity at the bearing inlet temperature, but widely different pressure viscosity characteristics. The physical characteristics of the oils were the same as those considered in the analysis. The paper summarizes the work and presents a hypothesis for the failure mechanism.

scholarly journals Influence of machining conditions on friction in metal cutting process – A review

Mechanik ◽  
2019 ◽  
Vol 92 (4) ◽  
pp. 242-248
Author(s):  
Wit Grzesik ◽  
Joel Rech
Keyword(s):  
Tool Wear ◽  
Contact Zone ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Sliding Velocity ◽  
Contact Conditions ◽  
Tool Materials ◽  
Cutting Zone ◽  
Cooling Media ◽  
Cutting Tool Materials

This paper presents a range of variable machining factors which influence substantially friction directly or by the tool wear developed in the cutting zone. The group of direct factors include the workpiece and cutting tool materials coupled, the cutting/sliding velocity, cooling media supplied to the tool-chip contact zone, modification of the tool contact faces by micro-texturing. Special attention was paid to the tool wear evolution and its pronounced effect on changes of the contact conditions.

A Method for Measuring Surface Temperature Between Rolling/Sliding Steel Cylinders

1978 ◽  
Vol 100 (1) ◽  
pp. 110-114 ◽  
Author(s):  
J. W. Kannel ◽  
F. F. Zugaro ◽  
T. A. Dow
Keyword(s):  
Contact Zone ◽  
Heat Generation ◽  
Temperature Rise ◽  
Mineral Oil ◽  
Sliding Contact ◽  
Pressure Data ◽  
Measuring Surface ◽  
Temperature And Pressure ◽  
The Relationship ◽  
Zone Temperature

A special bisignal transducer has been developed which allows pressure and temperature measurements to be made (essentially) simultaneously. With this technique, it is possible to locate the contact zone temperature relative to pressure and evaluate the relationship between heat generation and pressure. Temperature and pressure data obtained using a synthetic mineral oil as the lubricant have been obtained for rolling and rolling-sliding contact in a disk apparatus. The temperature rise through the contact zone has been shown to be on the order of 20–40 C.

scholarly journals Towards Analysis and Optimization for Contact Zone Temperature Changes and Specific Wear Rate of Metal Matrix Composite Materials Produced from Recycled Waste

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5145
Author(s):  
Aydın Güneş ◽  
Emin Salur ◽  
Abdullah Aslan ◽  
Mustafa Kuntoğlu ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Rate ◽  
Contact Zone ◽  
Metal Matrix ◽  
Microstructural Analysis ◽  
Tribological Performance ◽  
Specific Wear Rate ◽  
Structural Problems ◽  
Wide Range ◽  
Zone Temperature

Tribological properties are important to evaluate the in-service conditions of machine elements, especially those which work as tandem parts. Considering their wide range of application areas, metal matrix composites (MMCs) serve as one of the most significant materials equipped with desired mechanical properties such as strength, density, and lightness according to the place of use. Therefore, it is crucial to determine the wear performance of these materials to obtain a longer life and to overcome the possible structural problems which emerge during the production process. In this paper, extensive discussion and evaluation of the tribological performance of newly produced spheroidal graphite cast iron-reinforced (GGG-40) tin bronze (CuSn10) MMCs, including optimization, statistical, graphical, and microstructural analysis for contact zone temperature and specific wear rate, are presented. For this purpose, two levels of production temperature (400 and 450 °C), three levels of pressure (480, 640, and 820 MPa), and seven different samples reinforced by several ingredients (from 0 to 40 wt% GGG-40, pure CuSn10, and GGG-40) were investigated. According to the obtained statistical results, the reinforcement ratio is remarkably more effective on contact zone temperature and specific wear rate than temperature and pressure. A pure CuSn10 sample is the most suitable option for contact zone temperature, while pure GGG-40 seems the most suitable material for specific wear rates according to the optimization results. These results reveal the importance of reinforcement for better mechanical properties and tribological performance in measuring the capability of MMCs.

scholarly journals The effect of temperature on the tribological characteristics of high speed steels under conditions of friction without lubricant on the structural steel 30HGSA

2021 ◽  
Vol 2131 (5) ◽  
pp. 052016
Author(s):  
E V Fominov ◽  
C G Shuchev
Keyword(s):  
Structural Steel ◽  
Contact Zone ◽  
High Speed ◽  
Normal Load ◽  
Dissipative Structures ◽  
Effect Of Temperature ◽  
Friction Zone ◽  
Pin On Disk ◽  
Different Levels ◽  
Zone Temperature

Abstract This article focuses on the study of the effect of temperature in the contact zone on the process of dissipative structures formation on the surfaces of specimens made of high speed steels (HSS) grades with different levels of thermal entropy and absolute thermo-EMF under conditions of friction without lubricant on the structural steel 30HGSA. Tribological tests were performed on the tribometer which implemented a scheme of friction “pin on disk” at constant sliding speed and normal load values. The temperature in the friction zone has changed artificially from 100 to 300°C with a special intelligent heating device. It has been established experimentally that in the process of friction of HSS specimens characterized by low values of absolute thermo-EMF the dissipative structures thickness growth rate over time at temperatures of 200-250oC decreases or remains virtually unchanged; friction coefficient decreases with the increase in temperature. For specimens made of steels with high absolute thermo-EMF the rates of dissipative structures thickness growth and their utmost thicknesses increase when the contact zone temperature increases, which is accompanied by an increase in friction coefficients.

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