The Use of Analog Computers for Determining Surface Parameters Required for Prediction of Thermal Contact Conductance

1964 ◽  
Vol 86 (4) ◽  
pp. 543-550 ◽  
Author(s):  
J. J. Henry ◽  
H. Fenech
Keyword(s):  
Experimental Data ◽  
Unit Area ◽  
Thermal Contact ◽  
Analog Computer ◽  
General Purpose ◽  
Thermal Contact Conductance ◽  
Average Thickness ◽  
Contact Interface ◽  
Contact Conductance ◽  
Surface Profiles

The mathematical analysis of a thermal contact by Fenech and Rohsenow requires knowledge of certain parameters describing the geometry of the contact interface. These parameters are volume average thickness of the void above and below the plane of the contact, the number of contacts per unit area, and the ratio of the actual contact area to the total area. The authors outline a method for determining these parameters graphically. This paper describes a method for obtaining analog voltages of surface profiles of contacting surfaces and the application of a general purpose analog computer to determine the geometric parameters of contact as a function of contact pressure. The results of applying this method are combined with the analysis of Fenech and Rohsenow. The predicted contact conductance is found to agree well with experimental data at mean contact temperatures of 100, 200, and 300 F for load pressures of 100 to 20,000 psi.

Prediction of Thermal Contact Conductance by Surface Deformation Analysis

2001 ◽  
Author(s):  
Vishal Singhal ◽  
Suresh V. Garimella
Keyword(s):  
Surface Deformation ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Deformation Analysis ◽  
Improved Method ◽  
Contact Conductance ◽  
The Real ◽  
Real Area Of Contact ◽  
Surface Profiles ◽  
Real Area

Abstract An improved method has been developed for the prediction of thermal contact conductance between two nominally flat metallic rough surfaces by analysis of the deformation of individual asperities in contact. The deformation of the asperities in contact has been taken into account by considering three different modes of deformation — elastic, elastic-plastic and plastic. The model uses an iterative procedure to determine the real area of contact between the deformed surfaces for a given load, nominal area of contact, surface profiles and material properties of the surfaces in contact. The contact conductance is then determined as a function of the ratio of the real area of contact to the apparent area of contact The predicted variation of contact conductance with load obtained from the model is compared to simplified analytical predictions in the literature as well as to experiments conducted as part of this work.

Effect of Metallic Coatings on the Thermal Contact Conductance of Turned Surfaces

1990 ◽  
Vol 112 (4) ◽  
pp. 864-871 ◽  
Author(s):  
T. K. Kang ◽  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Experimental Data ◽  
Thermal Contact ◽  
Coating Material ◽  
Thermal Contact Conductance ◽  
Enhancement Effect ◽  
Metallic Coatings ◽  
Coating Materials ◽  
Contact Conductance ◽  
Significant Parameter ◽  
Contact Pressures

An experimental investigation was conducted to determine the degree to which the thermal contact conductance at the interface of contacting Aluminum 6061 T6 surfaces could be enhanced through the use of vapor-deposited metallic coatings. Three different coating materials (lead, tin, and indium) were evaluated using four different thicknesses for each coating material. The results verified the existence of an optimum coating thickness, shown to be in the range of 2.0 to 3.0 μm for indium, 1.5 to 2.5 μm for lead, and 0.2 to 0.5 μm for tin. The enhancement factors for thermal contact conductance were found to be on the order of 700, 400, and 50 percent, respectively. Based upon the experimental data, the hardness of the coating materials appears to be the most significant parameter in ranking the substrate and coating material combinations; however, additional experimental data are needed to substantiate this hypothesis. Finally, it was apparent that the thermal contact conductance enhancement effect was greatest at low contact pressures and decreased significantly with increases in the contact pressure.

Measurement of the Thermal Contact Conductance and Thermal Conductivity of Anodized Aluminum Coatings

1990 ◽  
Vol 112 (3) ◽  
pp. 579-585 ◽  
Author(s):  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Coating Thickness ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Aluminum Surface ◽  
Anodized Aluminum ◽  
Contact Conductance ◽  
Surface Measurements

An experimental investigation was conducted to determine the thermal contact conductance and effective thermal conductivity of anodized coatings. One chemically polished Aluminum 6061-T6 test specimen and seven specimens with anodized coatings varying in thickness from 60.9 μm to 163.8 μm were tested while in contact with a single unanodized aluminum surface. Measurements of the overall joint conductance, composed of the thermal contact conductance between the anodized coating and the bare aluminum surface and the bulk conductance of the coating material, indicated that the overall joint conductance decreased with increasing thickness of the anodized coating and increased with increasing interfacial load. Using the experimental data, a dimensionless expression was developed that related the overall joint conductance to the coating thickness, the surface roughness, the interfacial pressure, and the properties of the aluminum substrate. By subtracting the thermal contact conductance from the measured overall joint conductance, estimations of the effective thermal conductivity of the anodized coating as a function of pressure were obtained for each of the seven anodized specimens. At an extrapolated pressure of zero, the effective thermal conductivity was found to be approximately 0.02 W/m-K. In addition to this extrapolated value, a single expression for predicting the effective thermal conductivity as a function of both the interface pressure and the anodized coating thickness was developed and shown to be within ±5 percent of the experimental data over a pressure range of 0 to 14 MPa.

Molecular Dynamics Modeling of the Effect of Thermal Interface Material on Thermal Contact Conductance

2008 ◽  
Author(s):  
U. B. Jayadeep ◽  
R. Krishna Sabareesh ◽  
R. Nirmal ◽  
K. V. Rijin ◽  
C. B. Sobhan
Keyword(s):  
Molecular Dynamics ◽  
Thermal Contact ◽  
Thermal Interface Material ◽  
Thermal Contact Conductance ◽  
Effect Of Temperature ◽  
Computation Method ◽  
Contact Interface ◽  
Dynamics Modeling ◽  
Thermal Interface ◽  
Contact Conductance

Thermal contact conductance is used to indicate the resistance offered by a contact interface to the flow of heat. When an interface material is applied as nano-layered coatings on super-finished contacting surfaces, the possibility of size effects necessitates the use of a discrete computation method for its analysis. Hence, a methodology is proposed which utilizes Molecular Dynamics (MD) simulations to obtain the size affected thermal conductivity of the interfacial layer, which in turn characterizes the thermal contact conductance behavior. Molecular Dynamics codes have been developed, making use of Sutton-Chen many-body potential, suitable for metallic materials. The model includes the asperities at the contact interface, assuming the asperities to be of a simplified geometry. The paper also presents the validation of the codes developed, and parametric studies on the effect of temperature, number of asperities and the material used for thermal interface coating on the size-affected interfacial conductivity.

Thermal Contact Conductance Across Gold-Coated OFHC Copper Contacts in Different Media

2005 ◽  
Vol 127 (6) ◽  
pp. 657-659 ◽  
Author(s):  
Bapurao Kshirsagar, ◽  
Prashant Misra, ◽  
Nagaraju Jampana, and ◽  
M. V. Krishna Murthy
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Contact Pressure ◽  
Thermal Contact ◽  
High Conductivity ◽  
Thermal Contact Conductance ◽  
Ofhc Copper ◽  
Contact Conductance ◽  
Contact Pressures ◽  
Good Agreement

The thermal contact conductance studies across gold-coated oxygen-free high-conductivity copper contacts have been conducted at different contact pressures in vacuum, nitrogen, and helium environments. It is observed that the thermal contact conductance increases not only with the increase in contact pressure but also with the increase in thermal conductivity of interstitial medium. The experimental data are found to be in good agreement with the literature.

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