金属接触の統計的機構

概要

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It is well known that static frictions between metal surfaces fluctuate violently when measured repeatedly. This fluctuation is usually ascribed to unavoidable variations of the degree of contamination for contact surfaces. The authors remark that a part of the fluctuation of static frictions must be ascribed to that of intimacies of contact between the surfaces, considering that the problem must be a statistical phenomenon. The intimacy of contact can be expressed in the area of real contact or the number of real contact points for the surfaces. The electrical conductance is used as a measure of real contact area or the number of real contact points for contact surfaces of planes, spheres and needle points. As a result of the investigations, the frequency distributions for the electrical conductance or the area of real contact are found not to be Gaussian's, but Poisson's. This means that the phenomena of contact between metal surfaces are of statistical nature ; each surface has an infinite number of small protuberances, of which the probabilities of contact are very small when both surfaces are brought to contact with each other. The experimental results are found to coincide well with the results of the statistical calculation. Effects of the degrees of surface finish and those of lubrication are investigated, and the mean area of real contact point is estimated at 10_<-3>mm^2.
一般社団法人日本機械学会の論文
1954-02-25