A Contact Resistance Theory for Rough Hemispherical Silver Contacts in Air and in Vacuum

Tribological Properties and Electrical Signal Transmission of Copper–Graphite Composites

“…This is because the size and distribution of the contact junctions at the sliding surface, which determines the electrical resistance, voltage drop, signal fluctuation, and noise generation, strongly rely on the physical properties of the brush and ring and chemistry of friction film produced on the rubbing surfaces [7][8][9]. Contact materials are normally selected by concerning the fact that the electrical signal transmits through the real area of contacts between surface asperities on a K. H. Cho Á U. S. Hong Á K. S. Lee Á H. Jang (&) Department of Materials Science and Engineering, Korea University, 5-1, Anam-dong, Seongbuk-gu, Seoul 136-701, South Korea e-mail: hojang@korea.ac.kr molecular scale.…”

An elastic analysis of the deformation of rough spheres, rough cylinders and rough annuli in contact

“…(17) with the bulk contact area ratio used as a normalizing factor 19 = reff*/rd (19) which will denote the ratio of the effective to the Hertzian contact radius. This quantity has been observed by Barkan and Tuohy (1965) to be approximately 1.7 for rough hemispheres in contact. It will be shown in the following discussion, however, that such a ratio covers a very wide range of values depending on a large number of variables, such as the applied load, material properties, roughness and radius of curvature of the hemispheres.…”

“…Although these results revealed the mechanisms active on contact surfaces under these conditions, the solution, which requires the iteration of three integrals, converges very slowly and, as a result, solution time is long even on a high speed digital computer. Barkan and Tuohy (1965) later made a visual observation of contact between a rough silver hemisphere and an optical flat. They reported that the contact spots spread over an area much greater than that predicted with the Hertzian theory for the case of a sphere, the ratio reported being approximately 1.7.…”

Estimation of lubricant interlayer shear strength under conditions of imperfect boundary lubrication

“…A similar effect in the lowload range was observed by other researchers.21 This may be caused by fringes of the contour site adding to the measured friction force:' and/or from the fact that the size of the contour area on real curvilinear surfaces exceeds that calculated according to the Hertzian assumption of ideal smooth surfaces. 23 In both cases, the z value calculated by the formula z = F / S is exaggerated, since the calculated Hertzian area S is less than the actual area of shear. In this connection, it should be noted that the linear increase of z with growing L observed in earlier experiments was evident only above a certain level of contact pressure as a function of the test conditions.…”