Frictional Properties of a Surface Covered With Soft Metal Surface Film (Surface Topography and Frictional Properties)

1987 ◽  
Vol 109 (3) ◽  
pp. 545-551 ◽  
Author(s):  
Shinobu Kato ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Surface Topography ◽  
Metal Surface ◽  
Metal Film ◽  
Surface Film ◽  
Frictional Coefficient ◽  
Film Surface ◽  
Small Radius ◽  
Radius Of Curvature ◽  
Frictional Properties ◽  
Soft Metal

The friction between a real engineering surface composed of many micro-asperities and a surface covered with soft metal film is discussed. First, the frictional coefficient shows a remarkable load dependency, when a hard single protuberance with a small radius of curvature is slid on a soft metal surface. This load dependence originates from the ploughing effect induced by the cooperation of contact pressure and shearing resistance of the soft metal film deforming on the protuberance surface. Based on this result, the effect of the real engineering surface topography on the frictional properties is studied.

Frictional Properties of a Surface Covered With a Soft Metal Film—Part 1: Experiments on Friction Between a Single Protuberance and a Surface

1981 ◽  
Vol 103 (2) ◽  
pp. 236-242 ◽  
Author(s):  
S. Kato ◽  
K. Yamaguchi ◽  
E. Marui ◽  
K. Tachi
Keyword(s):  
Coefficient Of Friction ◽  
Deformation Mechanism ◽  
Metal Film ◽  
Surface Film ◽  
Thin Metal Film ◽  
Film Properties ◽  
Empirical Expression ◽  
Frictional Properties ◽  
The Coefficient Of Friction ◽  
Soft Metal

Frictional properties in the contact between a hard protuberance and a metal surface covered by a soft thin metal film are examined experimentally. The protuberance used in the experiment is a hard steel ball which simulates asperities on many engineering surfaces. The load dependency of the coefficient of friction and the effects of thickness and hardness of the film on the friction are clarified. The simple empirical expression of friction, which represents the effect of the film properties, is presented, considering the deformation mechanism of the surface film.

Frictional Properties of a Surface Covered With a Soft Metal Film—Part 2: Analysis of Friction Between a Single Protuberance and a Surface

1982 ◽  
Vol 104 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Shinobu Kato ◽  
Katsumi Yamaguchi ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Pressure Distribution ◽  
Coefficient Of Friction ◽  
Metal Film ◽  
Surface Film ◽  
Analytical Investigation ◽  
Friction Characteristic ◽  
Frictional Properties ◽  
The Coefficient Of Friction ◽  
Soft Metal ◽  
Side Flow

Analytical investigation of the evaluation of the coefficient of friction is made to clarify the mechanism of the load dependency of friction, which was obtained in Part 1 of this research, and also to ascertain the effects of the surface film on the friction characteristic. The plastic flow of the soft metal film between a protuberance and the subsurface is presumed, and the pressure distribution originating from the side flow is calculated on the basis of the plasticity theory. The effects of the coefficient of friction of the load, the thickness and hardness of the film, and the radius of the protuberance, are examined. As a result, it is clarified that the load dependency of friction arises from the extremely high pressure distribution generated in the film.

Frictional Properties of a Surface Covered With Soft Metal Film (Interference Effect of Soft Metal Film Deformation Between Two Protuberances)

1985 ◽  
Vol 107 (4) ◽  
pp. 444-451 ◽  
Author(s):  
Shinobu Kato ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Plastic Flow ◽  
Interference Effect ◽  
Metal Film ◽  
Flow Line ◽  
Contact Pressure Distribution ◽  
Frictional Properties ◽  
Frictional Characteristic ◽  
The Coefficient Of Friction ◽  
Soft Metal ◽  
Flow Deformation

The frictional characteristic is examined with reference to a model considering the interference effect of plastic flow (deformation) in soft metal film, when a two-protuberance indentor is slid on a surface covered by electroplated soft metal film. The result is compared with that of a single-protuberance indentor. The coefficient of friction in a two-protuberance indentor, where the interference effect exists, is lower than in a single-protuberance indentor, where the interference effect does not. This fact can well be explained with the configuration of plastic flow line on protuberances described by deforming soft metal film, and the corresponding contact pressure distribution between protuberances and a surface.

Overlapping Allografts Provide Superior and More Reliable Surface Topography Matching Than Oblong Allografts: A Computer-Simulated Model Study

2021 ◽  
pp. 036354652110030
Author(s):  
Hailey P. Huddleston ◽  
Atsushi Urita ◽  
William M. Cregar ◽  
Theodore M. Wolfson ◽  
Brian J. Cole ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Surface Topography ◽  
Osteochondral Allograft ◽  
Cartilage Defects ◽  
Radius Of Curvature ◽  
Cartilage Surface ◽  
3 Dimensional ◽  
Cloud Models ◽  
And Cartilage ◽  
Osteochondral Allografts

Background: Osteochondral allograft transplantation is 1 treatment option for focal articular cartilage defects of the knee. Large irregular defects, which can be treated using an oblong allograft or multiple overlapping allografts, increase the procedure’s technical complexity and may provide suboptimal cartilage and subchondral surface matching between donor grafts and recipient sites. Purpose: To quantify and compare cartilage and subchondral surface topography mismatch and cartilage step-off for oblong and overlapping allografts using a 3-dimensional simulation model. Study Design: Controlled laboratory study. Methods: Human cadaveric medial femoral hemicondyles (n = 12) underwent computed tomography and were segmented into cartilage and bone components using 3-dimensional reconstruction and modeling software. Segments were then exported into point-cloud models. Modeled defect sizes of 17 × 30 mm were created on each recipient hemicondyle. There were 2 types of donor allografts from each condyle utilized: overlapping and oblong. Grafts were virtually harvested and implanted to optimally align with the defect to provide minimal cartilage surface topography mismatch. Least mean squares distances were used to measure cartilage and subchondral surface topography mismatch and cartilage step-off. Results: Cartilage and subchondral topography mismatch for the overlapping allograft group was 0.27 ± 0.02 mm and 0.80 ± 0.19 mm, respectively. In comparison, the oblong allograft group had significantly increased cartilage (0.62 ± 0.43 mm; P < .001) and subchondral (1.49 ± 1.10 mm; P < .001) mismatch. Cartilage step-off was also found to be significantly increased in the oblong group compared with the overlapping group ( P < .001). In addition, overlapping allografts more reliably provided a significantly higher percentage of clinically acceptable (0.5- and 1-mm thresholds) cartilage surface topography matching (overlapping: 100% for both 0.5 and 1 mm; oblong: 90% for 1 mm and 56% for 0.5 mm; P < .001) and cartilage step-off (overlapping: 100% for both 0.5 and 1 mm; oblong: 86% for 1 mm and 12% for 0.5 mm; P < .001). Conclusion: This computer simulation study demonstrated improved topography matching and decreased cartilage step-off with overlapping osteochondral allografts compared with oblong osteochondral allografts when using grafts from donors that were not matched to the recipient condyle by size or radius of curvature. These findings suggest that overlapping allografts may be superior in treating large, irregular osteochondral defects involving the femoral condyles with regard to technique. Clinical Relevance: This study suggests that overlapping allografts may provide superior articular cartilage surface topography matching compared with oblong allografts and do so in a more reliable fashion. Surgeons may consider overlapping allografts over oblong allografts because of the increased ease of topography matching during placement.

The effects of surface topography of nanostructure arrays on cell adhesion

2018 ◽  
Vol 20 (35) ◽  
pp. 22946-22951 ◽  
Author(s):  
Jing Zhou ◽  
Xiaowei Zhang ◽  
Jizheng Sun ◽  
Zechun Dang ◽  
Jinqi Li ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Density Distribution ◽  
Surface Topography ◽  
Thermodynamic Model ◽  
Surface Density ◽  
Distribution Density ◽  
Small Radius ◽  
Surface Distribution ◽  
Nanostructure Arrays

The effects of geometry and surface density distribution of nanopillars on cell adhesion studied by a quantitative thermodynamic model showed that high (low) surface distribution density and large (small) radius result in the “Top” (“Bottom”) mode.

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