Influence of Flatness and Waviness of Rough Surfaces on Surface Contact Conductance

2003 ◽  
Vol 125 (3) ◽  
pp. 394-402 ◽  
Author(s):  
S. Sunil Kumar ◽  
K. Ramamurthi
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Threshold Values ◽  
Average Roughness ◽  
Contact Conductance ◽  
Surface Parameters ◽  
Wavy Surfaces ◽  
Effect Of Surface

The effect of surface roughness, waviness and flatness deviations on thermal contact conductance is predicted. Threshold values of the surface parameters which do not adversely influence thermal contact conductance are determined. Flatness deviations less than ten times the average roughness and waviness less than about four times the average roughness do not significantly affect the contact conductance. A correlation is developed for contact conductance in terms of the surface parameters, the material properties and the contact pressure at the joint. Experiments are conducted in vacuum with rough, non-flat and wavy surfaces and the experimental results are demonstrated to agree well with the predictions.

An Approximate Thermal Contact Conductance Correlation

1993 ◽  
Vol 115 (1) ◽  
pp. 131-134 ◽  
Author(s):  
V. W. Antonetti ◽  
T. D. Whittle ◽  
R. E. Simons
Keyword(s):  
Surface Roughness ◽  
Test Data ◽  
Surface Texture ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Average Roughness ◽  
Contact Conductance ◽  
Surface Asperity ◽  
Rms Error

An approximate thermal contact conductance correlation which does not depend upon the surface asperity slope was developed. Published surface texture data for 65 specimens were used to establish a relationship between the average roughness and the RMS asperity slope, which was then used to develop a new approximate thermal contact conductance correlation. The investigation was conducted for a range of surface roughness typical of contacting surfaces. Comparison to limited test data and to 2080 simulated contact joints, indicates the new approximate thermal contact conductance correlation has an expected RMS error of approximately 23 percent.

Thermoelastic Instability of Two-Conductor Friction System Including Surface Roughness

2004 ◽  
Vol 71 (1) ◽  
pp. 57-68 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Critical Speed ◽  
Thermal Contact ◽  
The Body ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Thermoelastic Instability ◽  
Special Cases ◽  
Conducting Bodies

A model is developed to investigate the mechanism of thermoelastic instability (TEI) in tribological components. The model consists of two thermally conducting bodies of finite thickness undergoing sliding contact. Appropriate governing equations are derived to predict the critical speed beyond which the TEI is likely to occur. This model takes into account the surface roughness characteristics of the contacting bodies as well as the thermal contact conductance at the interface. Analytical expressions are provided for the special cases neglecting the disk thickness and the thermal contact conductance. An extensive series of parametric simulations and discussion of the implication of the results are also presented. The simulations show that the difference in material properties and geometry of the two conducting bodies has a pronounced influence on the critical speed. A special case of the model shows that the threshold of TEI critical speed is pushed to a much higher level when the conducting bodies have identical material properties and are geometrically symmetric. It is also shown that the perturbed wave generally tends to move with the body with higher thermal conductivity.

Influence of Temperature Distribution on Tighten Force in Tie-Bolt Fastened Rotor With Considering Thermal Contact Conductance

2015 ◽  
Author(s):  
He Peng ◽  
Ning Xu ◽  
Zhansheng Liu
Keyword(s):  
Surface Roughness ◽  
Thermal Expansion ◽  
Temperature Distribution ◽  
Contact Pressure ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Axial Position ◽  
Contact Conductance ◽  
Pressure Surface ◽  
Axial Temperature

Tighten force has much influence on tie-bolt fastened rotor dynamics. Temperature distribution in tie-bolt fastened rotor results in thermal expansion of rotor and rods. The difference of thermal expansion between rotor and rods causes the variation of bolt load. With considering the thermal contact conductance, the thermal model of tie-bolt fastened rotor was established by finite element method and the axial temperature distribution was obtained. The influences of surface roughness, nominal contact pressure and axial position of contact on axial temperature distribution were analysed. Based on temperature distribution in the tie-bolt fastened rotor, the variation of tighten force was investigated. Results show that nominal contact pressure, surface roughness and axial contact arrange have different influences on the variation of tighten force with temperature.

Thermal Rectification in Similar and Dissimilar Metal Contacts

1991 ◽  
Vol 113 (1) ◽  
pp. 30-36 ◽  
Author(s):  
P. F. Stevenson ◽  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Heat Flow ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Thermal Rectification ◽  
Material Type ◽  
Stainless Steel 304 ◽  
Nickel 200

An investigation was conducted to verify experimentally the existence of thermal rectification and to determine the effect of surface roughness and material type. Four pairs of test specimens were evaluated: one with a smooth Nickel 200 surface in contact with a rough Nickel 200 surface, one with a smooth Stainless Steel 304 surface in contact with a rough Stainless Steel 304 surface, one with a smooth Nickel 200 surface in contact with a rough Stainless Steel 304 surface, and finally, one with a smooth Stainless Steel 304 surface in contact with a rough Nickel 200 surface. The thermal contact conductance was measured for heat flow from both the smooth to rough and rough to smooth configurations for all four pairs. The results indicate that thermal rectification is a function of surface characteristics, material type, and heat flow direction. For similar materials in contact, some thermal rectification was observed with heat flow from the rough surface to the smooth surface resulting in a higher value of contact conductance. For dissimilar materials, the thermal contact conductance was highest when the heat flow was from the Stainless Steel 304 to Nickel 200. In these cases, the surface roughness was shown to be of secondary importance.

The Influence of Interfacial Thermal Contact Conductance on Resistance Spot Weld Nugget Formation

2010 ◽  
Vol 97-101 ◽  
pp. 3239-3242 ◽  
Author(s):  
Yong Bing Li ◽  
Xin Min Lai ◽  
Guan Long Chen
Keyword(s):  
Surface Roughness ◽  
Numerical Models ◽  
Thermal Contact ◽  
Welding Process ◽  
Weld Nugget ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Resistance Spot ◽  
Roughness Surface ◽  
Nugget Formation

Resistance spot welding process is strongly related to interfacial contact behaviors. The effects of thermal contact is rarely investigated so far and generally ignored in numerical models. In this work, a parametric FE model, which considers the variation of the surface roughness of the electrodes and workpieces, has been developed to investigate the effects of thermal contact on weld nugget formation. With the parametric model, four cases, e.g. ideal smooth surface, minimal roughness surface and maximum roughness surface for steel sheets and electrodes of as-received condition, and highly rough electrode surface, are investigated. Researches show that when the surface roughness of the electrodes exceeds some limit, the thermal contact conductance will substantially affect the weld nugget formation, therefore, must be considered in numerical models to precisely predict welding process.

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