scholarly journals Frictional Heating of Tribological Contacts

1995 ◽  
Vol 117 (1) ◽  
pp. 171-177 ◽  
Author(s):  
J. Bos ◽  
H. Moes
Keyword(s):  
Entire Range ◽  
Tribological Behavior ◽  
Mechanical Energy ◽  
Frictional Heating ◽  
Approximate Solutions ◽  
Conductivity Ratio ◽  
Flash Temperature ◽  
Heat Partitioning ◽  
Steady State Heat ◽  
Lubrication Conditions

Wherever friction occurs, mechanical energy is transformed into heat. The maximum surface temperature associated with this heating can have an important influence on the tribological behavior of the contacting components. For band contacts the partitioning of heat has already been studied extensively; however, for circular and elliptic contacts only approximate solutions exist. In this work a numerical algorithm is described to solve the steady state heat partitioning and the associated flash temperatures for arbitrary shaped contacts by matching the surface temperatures of the two contacting solids at all points inside the contact area. For uniform and semi-ellipsoidal shaped heat source distributions, representing EHL conditions and dry or boundary lubrication conditions respectively, function fits for practical use are presented giving the flash temperature as a function of the Pe´clet numbers of the contacting solids, the conductivity ratio, and the aspect ratio of the contact ellipse. These function fits are based on asymptotic solutions for small and large Pe´clet numbers and are valid for the entire range of Pe´clet numbers. By comparison with numerical results they are shown to be accurate within 5%, even for the situation of opposing surface velocities.

Maximum and Average Flash Temperatures in Sliding Contacts

1994 ◽  
Vol 116 (1) ◽  
pp. 167-174 ◽  
Author(s):  
Xuefeng Tian ◽  
Francis E. Kennedy
Keyword(s):  
Temperature Rise ◽  
Entire Range ◽  
Function Method ◽  
Approximate Solutions ◽  
Sliding Contact ◽  
Heat Sources ◽  
Flash Temperature ◽  
Infinite Body ◽  
Average Surface ◽  
Heat Partition

The surface temperature rise for a semi-infinite body due to different moving heat sources is analyzed for the entire range of Peclet number using a Green’s function method. Analytical and approximate solutions of maximum and average surface temperatures are obtained for the cases of square uniform, circular uniform, and parabolic heat sources. Considering the heat partition between the two contacting bodies, solutions of interface flash temperature are presented for the general sliding contact case as well as for the case of sliding contact between two moving asperities.

The Boundary Layer Inside a Conical Surface Due to a Swirling Flow With Throughflow

1976 ◽  
Vol 43 (4) ◽  
pp. 564-566 ◽  
Author(s):  
J. M. Fabian ◽  
G. C. Oates
Keyword(s):  
Boundary Layer ◽  
Entire Range ◽  
Close Agreement ◽  
Swirling Flow ◽  
Approximate Solutions ◽  
Conical Surface

The problem of describing the boundary layer existing inside a conical surface due to the presence of a swirling flow passing through the cone is considered. Approximate solutions based upon the Karman-Polhausen method are obtained for both the laminar and the turbulent cases. The results obtained are in close agreement with known solutions previously obtained in the limits of swirl with no throughflow and throughflow with no swirl. The present results appear to be valid over the entire range of swirl to throughflow ratios.

Thermomechanical Analysis of Elastoplastic Bodies in a Sliding Spherical Contact and the Effects of Sliding Speed, Heat Partition, and Thermal Softening

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
W. Wayne Chen ◽  
Q. Jane Wang
Keyword(s):  
Half Space ◽  
Frictional Heating ◽  
Three Dimensional ◽  
Numerical Algorithms ◽  
Thermomechanical Analysis ◽  
Thermal Softening ◽  
Sliding Speed ◽  
Dependent Strain ◽  
Steady State Heat ◽  
Strain Hardening Behavior

A thermomechanical analysis of elasto-plastic bodies is a necessary step toward the understanding of tribological behaviors of machine components subjected to both mechanical loading and frictional heating. A three-dimensional thermoelastoplastic contact model for counterformal bodies has been developed, which takes into account steady state heat flux, temperature-dependent strain hardening behavior, and interaction of mechanical and thermal loads. The fast Fourier transform and conjugate gradient method are the underlying numerical algorithms used in this model. Sliding of a half-space over a stationary sphere is simulated with this model. The friction-induced heat is partitioned into two bodies based on surface temperature distributions. In the simulation, the sphere is considered to be fully thermoelastoplastic, while the half-space is treated to be thermoelastic. Simulation results include surface pressure, temperature rise, and subsurface stress and plastic strain fields. The paper also studies the influences of sliding speed and thermal softening on contact behaviors for sliding speed ranging three orders of magnitude.

The Stress and Displacement Fields Produced in a Semi-Infinite Solid by a Uniform Heat Source Over a Rectangular Area on the Surface

2003 ◽  
Vol 125 (4) ◽  
pp. 709-712 ◽  
Author(s):  
Yuan Lin ◽  
Timothy C. Ovaert
Keyword(s):  
Heat Flow ◽  
Contact Area ◽  
Frictional Heating ◽  
Displacement Fields ◽  
Closed Form Solutions ◽  
Stress And Displacement Fields ◽  
Uniform Steady State ◽  
Rectangular Area ◽  
Steady State Heat ◽  
Small Parts

An important problem in thermo-mechanical contacts is the determination of the stress and displacement fields caused by heat flow. Heat flow may come from a difference in temperature between the contacting solids, or from frictional heating at the sliding interface. Generally, the distribution of heat flow in a contact area is unknown. In many cases, however, it is approximately uniform or one may divide the contact area into small parts, and in each part the heat flow may be treated as approximately uniform. This work provides closed-form solutions of the stress and displacement fields in a semi-infinite solid caused by uniform steady-state heat flow over a rectangular area on the surface. The material is assumed to be homogeneous and isotropic.

scholarly journals Influence of WS2Nanopowder Addition on Friction Characteristics of ta-C Coating by FCVA Method

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Si-Geun Choi ◽  
Yong-Joong Lee ◽  
Young-Jun Jang ◽  
Dawit Zenebe Segu ◽  
Seock-Sam Kim ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Friction Coefficient ◽  
Tribological Behavior ◽  
Vacuum Arc ◽  
Particle Sizes ◽  
Friction Test ◽  
Alpha Olefin ◽  
Filtered Cathodic Vacuum Arc ◽  
Nano Size ◽  
Lubrication Conditions

The influence of nano-sizeWS2powders on the tribological behavior of ta-C coatings by the filtered cathodic vacuum arc (FCVA) method under boundary lubrication conditions has been investigated. In order to characterize and understand tribological behaviors of nano-sizeWS2powders added to the synthetic oil (poly-alpha-olefin 6), lubricants with different mixture ratios, ranging from 2 to 8 wt%, have been prepared. ta-C coatings fabricated by FCVA method showed that the G-peak in the obtained Raman spectrum was shifted from 1520 to 1586 cm−1, indicating the sp3content increased for samples with the thickness of 156 nm. The average friction coefficient decreased proportionally as the nano-sizeWS2compositions increased up to 4 wt% in PAO6. After the friction test, structures and particle sizes ofWS2phases were also precisely characterized by using XRD and SEM.

A Two-Dimensional Thermoelastic Rough Surface Contact Model

2004 ◽  
Vol 126 (3) ◽  
pp. 430-435 ◽  
Author(s):  
Yuan Lin ◽  
Timothy C. Ovaert
Keyword(s):  
Rough Surface ◽  
Thermal Deformation ◽  
Frictional Heating ◽  
Asperity Contact ◽  
Two Dimensional ◽  
Elastic Deformations ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Thermal Influence ◽  
Rough Surface Contact

By taking into account steady-state heat transfer, and surface distortion due to thermal and elastic deformations, a two-dimensional thermoelastic model is developed for rough surface asperity contact, where the thermal influence function connecting the thermal deformation and the contact pressure is derived based on the Dundurs’ theorem. The model has been shown to be accurate at low as well as high frictional heating conditions by comparison with published results. As an application of this model, the contact problem of a cylinder on a random rough surface is studied in detail.

Effect of Material and Lubrication Conditions on the Underhead Frictional Response in High Strength Socket-Head Screws

2020 ◽  
Author(s):  
Dario Croccolo ◽  
Massimiliano De Agostinis ◽  
Stefano Fini ◽  
Giorgio Olmi ◽  
Francesco Robusto ◽  
...  
Keyword(s):  
Tribological Behavior ◽  
High Strength ◽  
Design Parameters ◽  
Bolted Joint ◽  
Lower Strength ◽  
Coefficient Estimation ◽  
Experimental Campaign ◽  
Proper Design ◽  
Lubrication Conditions ◽  
Current Operating

Abstract The present paper investigates the influence of several design parameters on the frictional response at the underhead in a bolted joint, involving high strength socket-head screws: M8 class 14.9 with black oxidization coating. The experimentation deals with different underhead materials (Steel, Aluminium), lubrication conditions (dry, lubricated) and repeated tightening operations. The awareness of the actual friction coefficients, depending on the current operating parameters, is a useful tool, to support the most proper design of a bolted joint. The experimental campaign has been run by a testing rig for friction coefficient estimation, complying with the recommendations by International Standard ISO 16047 and the automotive Standard VW01131-1 in order to consider the effect of the tightening speed normally adopted in the automotive field. The axial preload generated upon tightening induces a high pressure on the remarkably small underhead surface of the utilized high strength socket-head screws and is therefore likely to affect the tribological response. Consequently, some differences may be expected with respect to the tribological behavior of screws belonging to lower strength grades. This is particularly true, when tightening is done without bearing lubrication, and through several repeated assembly-disassembly operations. The collected data have been processed by the tools of ANOVA and F-Test, in order to assess the significance of each factor, as well as related interactions.

Effect of sulphide layers on the tribological behavior of steels under boundary lubrication conditions

2001 ◽  
Vol 181 (1-2) ◽  
pp. 61-67 ◽  
Author(s):  
Zhang Ning ◽  
Zhuang Da-Ming ◽  
Liu Jia-Jun ◽  
Fang Xiao-Dong ◽  
Guan Ming-Xi
Keyword(s):  
Boundary Lubrication ◽  
Tribological Behavior ◽  
Lubrication Conditions
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