Contact Surface Temperature Models for Finite Bodies in Dry and Boundary Lubricated Sliding

1993 ◽  
Vol 115 (3) ◽  
pp. 411-418 ◽  
Author(s):  
Xuefeng Tian ◽  
Francis E. Kennedy
Keyword(s):  
Surface Temperature ◽  
Contact Surface ◽  
Temperature Rise ◽  
Large Scale ◽  
Finite Thickness ◽  
Sliding Contact ◽  
Small Scale ◽  
Heat Sources ◽  
Real Area Of Contact ◽  
Lubricated Sliding

A model is proposed for use in determining the contact surface temperature in dry and boundary lubricated sliding systems. The model uses the concepts of small scale and large scale heat flow restrictions to divide the temperature increase in a sliding contact into two contributions, a nominal surface temperature rise and a local temperature rise. The model is particularly useful in studying the sliding surface temperature in bodies of finite thickness and in cases when the sliding contact area repeatedly sweeps over the same path on one of the contacting solids. Multiple heat sources within the real area of contact can be included, as can the effects of a cooling and/or lubricating fluid. Experiments were carried out to measure the contact surface temperature rise in several dry and boundary lubricated sliding systems. The experimental results were found to agree with the model.

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.

Temperature Rise at the Sliding Contact Interface for a Coated Semi-Infinite Body

1993 ◽  
Vol 115 (1) ◽  
pp. 1-9 ◽  
Author(s):  
X. Tian ◽  
F. E. Kennedy
Keyword(s):  
Surface Temperature ◽  
Temperature Rise ◽  
Peclet Number ◽  
Integral Transform ◽  
Sliding Contact ◽  
Contact Interface ◽  
Péclet Number ◽  
Maximum Surface ◽  
Semi Empirical ◽  
Maximum Surface Temperature

In this paper, a three-dimensional model of a semi-infinite layered body is used to predict steady-state maximum surface temperature rise at the sliding contact interface for the entire range of Peclet number. A set of semi-empirical solutions for maximum surface temperature problems of sliding layered bodies is obtained by using integral transform, finite element, heuristic and multivariable regression techniques. Two dimensionless parameters, A and Dp, which relate to coating thickness, contact size, sliding speed and thermal properties of both coating and substrate materials, are found to be the critical factors determining the effect of surface film on the surface temperature rise at a sliding contact interface. A semi-empirical solution for maximum surface temperature problems of homogeneous bodies, which covers the whole range of Peclet number, is also obtained.

On the scattering of aerodynamic noise

1971 ◽  
Vol 46 (3) ◽  
pp. 577-597 ◽  
Author(s):  
D. G. Crighton ◽  
F. G. Leppington
Keyword(s):  
Large Scale ◽  
Near Field ◽  
Finite Thickness ◽  
Aerodynamic Noise ◽  
Reciprocal Theorem ◽  
Field Energy ◽  
Small Scale ◽  
Sound Waves ◽  
Acoustic Analogy ◽  
Outer Flow

According to the Lighthill acoustic analogy, the sound induced by a region of turbulence is the same as that due to an equivalent distribution of quadrupole sources within the fluid. It is known that the presence of scattering bodies situated near such multipoles can convert some of their intense near field energy into the form of sound waves whose amplitude is far greater than that of the incident field. Calculations are here presented to determine the extent of this conversion, for hard and soft bodies of various shapes, making use of the reciprocal theorem to recast the problem into one of finding the field, near the obstacle, induced by an incident plane wave. If the obstacle is small compared with a wavelength, then its presence is equivalent to an additional dipole (or source) whose greater efficiency as a sound radiator implies that the familiar intensity law I ∝ U8, for far field intensity I against typical turbulence velocity U for an unbounded flow, is replaced by I ∝ U6 (or I ∝ U4) for a hard (or soft) body. For the situation where the scatterer is large compared with wavelength, the prototype problem of a wedge of exterior angle (p/q)π is shown to yield an intensity law I ∝ U4+2q/p for both hard and soft surfaces. This result is shown to hold for the more general ‘wedge-like’ surfaces, whose dimensions are large scale and whose edges may be smoothed out on a small scale, compared with wavelength. The method used involves the matching of an incompressible flow, on the fine scales typical of the edge geometry, to an outer flow determined by the large scale features of the surface. Favourable comparisons are made with previous results pertaining to the two-dimensional semi-infinite duct and to the half-plate of finite thickness.

Finite Element Modeling of Sliding Contact Between Rough Surfaces

2005 ◽  
Author(s):  
L. Pei ◽  
J. F. Molinari ◽  
M. O. Robbins
Keyword(s):  
Large Scale ◽  
Mechanical Design ◽  
Rough Surfaces ◽  
Model Material ◽  
Sliding Contact ◽  
Small Scale ◽  
Contact Algorithm ◽  
Design And Manufacturing ◽  
Critical Issues ◽  
Frictional Forces

Friction and wear are critical issues in mechanical design and manufacturing. As these mechanisms originate at the asperity level, research models increasingly attempt to capture the influence of surface roughness. In this paper, we study the sliding contact between two rough surfaces. We choose silicon as a model material for its wide use in MEMS applications. We implement an update master/slave contact algorithm accounting for periodic boundary conditions. The obtained results shine new light on the link between small-scale contact clusters and frictional forces and wear mechanisms at the large scale.

An Analysis of Surface Temperature Rise at Small Scale Sliding Contacts

2005 ◽  
Vol 890 ◽  
Author(s):  
Sudipto Ray ◽  
S. K. Roy Chowdhury
Keyword(s):  
Surface Temperature ◽  
Temperature Rise ◽  
Surface Forces ◽  
Contact Temperature ◽  
Small Scale ◽  
Surface Adhesion ◽  
Asperity Height ◽  
Sliding Contacts ◽  
Material Parameters ◽  
Scale Roughness

ABSTRACTA great deal of work has been carried out in recent years on temperature rise at the contact between sliding bodies with engineering scale roughness. However, as surfaces become smoother and loading decreases, in applications such as MEMS and NEMS devices, the analysis of surface temperature rise must consider the small-scale asperity height distributions and the surface forces that may be operating at small separations. The paper attempts to predict surface temperature rise at sliding contacts with small-scale roughness considering the influence of relevant parameters. The important observation here is that in addition to the dependence on load, speed and material parameters the contact temperature steadily increases with surface adhesion.

Small-Scale Science to Large-Scale Profession

2000 ◽  
Vol 45 (4) ◽  
pp. 396-398
Author(s):  
Roger Smith
Keyword(s):  
Large Scale ◽  
Small Scale

Development of Physics Learning Module Based on Guided Inquiry with Light Wave Material in Class XI of Senior High School

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Evi Rahmawati ◽  
Irnin Agustina Dwi Astuti ◽  
N Nurhayati
Keyword(s):  
Large Scale ◽  
Learning Strategy ◽  
Student Response ◽  
Average Score ◽  
Small Scale ◽  
Design Development ◽  
Teacher Response ◽  
Student Responses ◽  
Analysis Design ◽  
Scientific Skills

IPA Integrated is a place for students to study themselves and the surrounding environment applied in daily life. Integrated IPA Learning provides a direct experience to students through the use and development of scientific skills and attitudes. The importance of integrated IPA requires to pack learning well, integrated IPA integration with the preparation of modules combined with learning strategy can maximize the learning process in school. In SMP 209 Jakarta, the value of the integrated IPA is obtained from 34 students there are 10 students completed and 24 students are not complete because they get the value below the KKM of 68. This research is a development study with the development model of ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The use of KPS-based integrated IPA modules (Science Process sSkills) on the theme of rainbow phenomenon obtained by media expert validation results with an average score of 84.38%, average material expert 82.18%, average linguist 75.37%. So the average of all aspects obtained by 80.55% is worth using and tested to students. The results of the teacher response obtained 88.69% value with excellent criteria. Student responses on a small scale acquired an average score of 85.19% with highly agreed criteria and on the large-scale student response gained a yield of 86.44% with very agreed criteria. So the module can be concluded receiving a good response by the teacher and students.

Planetary gentrification and urban (re)development

2019 ◽  
Vol 61 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Loretta Lees
Keyword(s):  
Low Income ◽  
Policy Making ◽  
Large Scale ◽  
Urban Redevelopment ◽  
Urban Transformation ◽  
Small Scale ◽  
Income Groups ◽  
Low Income Groups

Abstract Gentrification is no-longer, if it ever was, a small scale process of urban transformation. Gentrification globally is more often practised as large scale urban redevelopment. It is state-led or state-induced. The results are clear – the displacement and disenfranchisement of low income groups in favour of wealthier in-movers. So, why has gentrification come to dominate policy making worldwide and what can be done about it?

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