4F4 Study on Evaluation Method of Thermal Contact Resistance : Contact between Flat Rough Surfaces under Low Pressure

Thermal contact resistance plays an important role in many domains, such as microelectronics and nuclear reactors. This paper proposes a more comprehensive model for the prediction of constriction resistance of rough contact between nominally flat surfaces in vacuum. Firstly, a 3D geometrical asperity contact model is proposed based on the analysis of the profile of actual engineering surface. In this model, the contact is not simplified as a rough surface contacting with a perfectly smooth surface, but described as two rough surfaces. Oblique contact is considered and the effects of several parameters such as the shape of the asperity, the depth of interference, and the radial distance between the centerlines of the contacting asperities are investigated. Some mathematical derivations for constriction resistance are performed, and a series of numerical simulations are also carried out, covering a wide range of values of these parameters in practice applications. A comprehensive correlation for constriction resistance as a function of these parameters is finally obtained by nonlinear curve fitting, and it is validated through some comparisons and it can be used to predict more accurately the thermal contact resistance between rough surfaces.

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A Multiscale Model of Thermal Contact Resistance Between Rough Surfaces

Journal of Heat Transfer ◽

10.1115/1.2927403 ◽

2008 ◽

Vol 130 (8) ◽

Cited By ~ 40

Author(s):

Robert L. Jackson ◽

Sushil H. Bhavnani ◽

Timothy P. Ferguson

Keyword(s):

Contact Resistance ◽

Thermal Contact Resistance ◽

Multiple Scales ◽

Rough Surfaces ◽

Thermal Contact ◽

Multiscale Model ◽

New Model ◽

Surface Features ◽

Contact Models ◽

Rough Surface Contact

A new multiscale model of thermal contact resistance (TCR) between real rough surfaces is presented, which builds on Archard’s multiscale description of surface roughness. The objective of this work is to construct the new model and use it to evaluate the effects of scale dependent surface features and properties on TCR. The model includes many details affecting TCR and is also fairly easy to implement. Multiscale fractal based models often oversimplify the contact mechanics by assuming that the surfaces are self-affine, the contact area is simply a geometrical truncation of the surfaces, and the pressure is a constant value independent of geometry and material properties. Concern has grown over the effectiveness of frequently used statistical rough surface contact models due to the inadequacies in capturing the true multiscale nature of surfaces (i.e., surfaces have multiple scales of surface features). The model developed in this paper incorporates several variables, including scale dependent yield strength and scale dependent spreading resistance to develop a new model that can be used to evaluate TCR. The results suggest that scale dependent mechanical properties are more influential than scale dependent thermal properties. When compared to an existing TCR model, this very inclusive model shows the same qualitative trend. Results also show the significance of capturing multiscale roughness when addressing the thermal contact resistance problem.

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