Prediction of Thermal Conductance of Metallic Surfaces in Contact

1963 ◽  
Vol 85 (1) ◽  
pp. 15-24 ◽  
Author(s):  
H. Fenech ◽  
W. M. Rohsenow
Keyword(s):  
Contact Point ◽  
Thermal Contact ◽  
Thermal Conductance ◽  
Hardness Test ◽  
Knoop Hardness ◽  
Metallic Surfaces ◽  
Contact Points ◽  
Iron Aluminum ◽  
Good Agreement

A mathematical analysis of a thermal contact is first carried out on an idealized shape of contact point. The thermal conductance is expressed in terms of the thermal conductivities of the metals and of the fluid filling the voids, the real area in contact, the number of contact points per unit area, and the volume average thickness of the void gaps. A method is given for the determination of the above physical properties of a contact. To use this method the following measurements are needed: Two recorded profiles, perpendicular to one another; and a Knoop hardness test on the softer of the two metals making the contact. The last part of the paper is devoted to the experimental verification of the assumptions made in the theoretical analysis and to the application of the method outlined for the case of an iron-aluminum contact. Good agreement was found between the predicted and measured conductance over a range of pressures from 90 to 2600 psi.

scholarly journals Analysis of the Evolution of the Structure of a Surface With Pyramidal Asperities in Contact With a Hard and Smooth Plane

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Bensaad Bourassia ◽  
Bourouga Brahim
Keyword(s):  
Reference Model ◽  
Contact Point ◽  
Thermal Contact ◽  
Measurement Techniques ◽  
Theoretical Models ◽  
Real Area Of Contact ◽  
Smooth Plane ◽  
Contact Parameters ◽  
Real Area

Abstract This research deals with the evolution of the structure of the sapphire–brass interface due to the variation of contact pressure. This evolution primarily affects the essential parameters that govern the thermal contact resistance (TCR), namely, the contact point density N, the ratio of real area of contact S*, and the distance d separating the median contact planes. The combination of three measurement techniques, namely, profilometry, imaging, and mechanical characterization, was used for the purpose of investigating the structural variation of the interface. Alternatively, the TCR, which prevails at the interface, was estimated. Thus, the object of our study is to propose an original and new experimental approach allowing at the same time the precise measurement of the TCR and the estimate of the contact parameters of the interface studied constituting input data to the theoretical models of TCR. The estimated values given by these last are then compared with those measured. Through this approach, we try to open new ways of experimentation that would tend to reinforce the effort of TCR modeling. The results obtained showed that the roughness parameters Ra and Rq are independent of loading. The roughness Rp, which is considered equal to d, is sensitive to loading and has the same decreasing behavior under the effect of loading. The determination of S*, using the hardness testing, is even more relevant when the effective hardness Hc is considered. Analysis of data for the estimation of the TCR shows that the comparisons with the reference model (Bardon) attest to the relevance of our approach.

Contact Point identification in robot assembly strategies under uncertainty

Robotica ◽  
1998 ◽  
Vol 16 (6) ◽  
pp. 679-690 ◽  
Author(s):  
C. J. Tsaprounis ◽  
N. Aspragathos
Keyword(s):  
Contact Point ◽  
Force Sensor ◽  
Assembly Process ◽  
Assembly Task ◽  
Knowledge Based System ◽  
Knowledge Based ◽  
Contact Points ◽  
Force Signal

In this paper a method for the reduction of the uncertainties in robotised assembly process is presented. The generated assembly strategies are based on the determination of the contact points. The assembly task is divided in two main subtasks, the initial and the main. To reduce the uncertainty of the process a deliberate misalignment of the peg is used.This paper is focused on the determination of the position and the forces at the contact points between the peg and hole under uncertainty. The available data are the force signal retrieved from the force sensor, the geometry of the assembly parts and the geometry of the robot. The analysis presented in this paper is a part of a knowledge-based system, which generates assembly strategies under the presence of uncertainties.

COMPARATIVE ACTION OF VARIOUS OESTROGENIC COMPOUNDS ON MOUSE VAGINAL SIALIC ACIDS (II)

1969 ◽  
Vol 62 (4) ◽  
pp. 663-670 ◽  
Author(s):  
Lars Carlborg
Keyword(s):  
Sialic Acid ◽  
Response Curve ◽  
Sialic Acids ◽  
Clear Cut ◽  
Suitable Parameter ◽  
Sufficient Degree ◽  
Comparative Action ◽  
Relative Potencies ◽  
Good Agreement

ABSTRACT Oestrogens administered in lower doses than necessary to induce full cornification of the mouse vagina induce mucification. It was shown previously that the degree of mucification could be estimated by quantitative determination of sialic acids. A suitable parameter for oestrogen assay was the measurement of vaginal sialic acid concentration which exhibited a clear cut dose response curve. Eleven assays of various oestrogens were performed with this method. Their estimated relative potencies were in good agreement with other routine oestrogen assays. A statistically sufficient degree of precision was found. The sensitivity was of the same order, or slightly higher, than the Allen-Doisy test.

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