Contact Pressures and Stresses in One Theoretically Investigated Case

1965 ◽  
Vol 87 (4) ◽  
pp. 1083-1085
Author(s):  
A. I. Petrusevich
Keyword(s):  
Surface Temperature ◽  
Effective Radius ◽  
Radius Of Curvature ◽  
Composite Effect ◽  
Peripheral Speed ◽  
Lubricating Film ◽  
Contact Pressures

The investigated case is: Two rotating steel cylinders, infinitely long and with effective radius of curvature of 5 cm, are loaded to Hertzian pressure of approximately 5000 kg/cm2 and are lubricated by an oil. The composite effect of peripheral speed and viscosity (under a given surface temperature) is necessary to build up a lubricating film with a thickness of 1 micron. The solution is approximate and found by the use of elastohydrodynamic theory.

scholarly journals Selection of CVD Diamond Crystals for X-ray Monochromator Applications Using X-ray Diffraction Imaging

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 396 ◽  
Author(s):  
Stanislav Stoupin ◽  
Thomas Krawczyk ◽  
Zunping Liu ◽  
Carl Franck
Keyword(s):  
Spline Interpolation ◽  
Cvd Diamond ◽  
Effective Radius ◽  
Radius Of Curvature ◽  
X Ray Diffraction ◽  
Average Width ◽  
Rocking Curve ◽  
X Ray ◽  
Single Crystal Diamond ◽  
Diffraction Imaging

A set of 20 single crystal diamond plates synthesized using chemical vapor deposition (CVD) was studied using X-ray diffraction imaging to determine their applicability as side-bounce (single-reflection) Laue monochromators for synchrotron radiation. The crystal plates were of optical grade (as provided by the supplier) with (001) nominal surface orientation. High dislocation density was found for all samples. Distortions in the crystal lattice were quantified for low-index Laue reflections of interests using rocking curve topography. Maps of effective radius of curvature in the scattering plane were calculated using spline interpolation of the rocking curve peak position across the studied plates. For several selected plates, nearly flat regions with large effective radius of curvature were found ( R 0 ≳ 30 - 70 m, some regions as large as 1 × 4 mm 2 ). The average width of the rocking curve for these regions was found to be about 150 μ rad (r.m.s.). These observations suggest that the selected CVD diamond plates could be used as intermediate-bandwidth monochromators refocusing the radiation source to a specific location downstream with close to 1:1 distance ratio.

The effective radius of curvature of partially coherent Hermite–Gaussian linear array beams passing through non-Kolmogorov turbulence

2014 ◽  
Vol 315 ◽  
pp. 130-137 ◽  
Author(s):  
Yongping Huang ◽  
Zenghui Gao ◽  
Fanhou Wang ◽  
Guangpu Zhao ◽  
Zhichun Duan ◽  
...  
Keyword(s):  
Linear Array ◽  
Effective Radius ◽  
Radius Of Curvature ◽  
Partially Coherent ◽  
Kolmogorov Turbulence

Effective radius of curvature of Hermite–Gaussian array beams

2010 ◽  
Vol 42 (6) ◽  
pp. 1054-1058 ◽  
Author(s):  
Guangming Ji ◽  
Xiaoling Ji
Keyword(s):  
Effective Radius ◽  
Radius Of Curvature

The frictional anisotropy of diamond

1981 ◽  
Vol 373 (1755) ◽  
pp. 405-417 ◽  
Keyword(s):  
Critical Load ◽  
Surface Damage ◽  
Diamond Surface ◽  
Radius Of Curvature ◽  
Type I ◽  
Diamond Surfaces ◽  
A Value ◽  
The Coefficient Of Friction ◽  
Contact Pressures ◽  
Critical Contact

This paper describes a study of the friction, in air, of a spherically tipped diamond stylus over the {100} face of a flat diamond surface. The results show that in general the friction is greater when sliding occurs along the <100> direction than along the <110> direction. This cannot be explained in terms of a Coulomb frictional mechanism where the friction is attributed to the climbing of one surface over the asperities on the other, for in that case the coefficient of friction is determined solely by the surface topography and is independent of load. By contrast, the experiments described in this paper show that below a critical load Wc the frictional anisotropy virtually disappears. This critical load is proportional to R 2 , where R is the radius of curvature of the stylus, implying, for Hertzian deformation, a critical contact pressure. For both type I and type II diamonds this critical pressure has a value of the order of 20 GN m -2 . At these and larger contact pressures cathodoluminescent studies of the flat diamond surfaces indicate that the frictional anisotropy is largely due to surface and sub-surface damage produced in preferred crystallographic directions by the sliding process itself. The results are discussed in terms of crack formation and plastic deformation. However, the results do not, as yet, provide an unequivocal account of the mechanism of energy dissipation.

Isothermal Elastohydrodynamic Lubrication of Point Contacts: Part II—Ellipticity Parameter Results

1976 ◽  
Vol 98 (3) ◽  
pp. 375-381 ◽  
Author(s):  
B. J. Hamrock ◽  
D. Dowson
Keyword(s):  
Contact Problem ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Effective Radius ◽  
Radius Of Curvature ◽  
Line Contact ◽  
Point Contacts ◽  
Curvature Ratio ◽  
Minimum Film Thickness ◽  
Ellipticity Parameter

A numerical solution of the isothermal elastohydrodynamic problem for point contacts has been presented which reproduces all the essential features of the previously reported experimental observations based upon optical interferometry. In particular, the two “side lobes” in which minimum film thickness regions occur are shown to emerge in the theoretical solutions. The influence of the ellipticity parameter upon solutions to the point contact problem has been explored in the present paper. The ellipticity parameter (k) was varied from one (a ball on a plate) to eight (a configuration approaching line contact), and it has been shown that the minimum film thicknesses can be related to the well known line contact solutions by remarkably simple expressions involving either (k) or the effective radius of curvature ratio (Ry/Rx).

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