• Title/Summary/Keyword: Self-affine surfaces

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Sliding Friction of Elastomer Composites in Contact with Rough Self-affine Surfaces: Theory and Application (자기-아핀 표면 특성을 고려한 유기탄성체 복합재료 마찰 이론 및 타이어 트레드/노면 마찰 응용)

  • Bumyong Yoon;Yoon Jin Chang;Baekhwan Kim;Jonghwan Suhr
    • Composites Research
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    • v.36 no.3
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    • pp.141-153
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    • 2023
  • This review paper presents an introduction of contact mechanics and rubber friction theory for sliding friction of elastomer composites in contact with rough surfaces. Particularly, Klüppel & Heinrich theory considers the self-affine (or fractal) characteristic for rough surfaces to predict adhesion and hysteresis frictions of elastomers based on the contact mechanics of Greenwood & Williamson. Due to dynamic excitation process of elastomer composites while sliding in contact with multiscale surface roughness (or asperity), viscoelastic properties in a wide frequency range becomes major contributor to friction behaviors. A brief description and examples are provided to construct a viscoelastic master curve considering nonlinear viscoelasticity of elastomer composites. Finally, application of rubber friction theory to tire tread compounds in traction with road surfaces is discussed with several experimental and theoretical results.

Microcontacting behaviour of material with fractal rough surface (프랙탈 표면을 가진 공구와 재료의 마이크로 접촉거동해석)

  • Kim, Young-Suk;Hyun, Sang-Il
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.33-37
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    • 2009
  • Finite-element methods are used to study non-adhesive, frictionless rough contact of elastic and plastic solids. Roughness on spherical surfaces is realized by self-affine fractal. True contact area between the rough surfaces and flat rigid surfaces increases with power law under external normal loads. The power exponent is sensitive to surface roughness as well as the curvature of spherical geometry. Surface contact pressures are analyzed and compared for the elastic and plastic solids. Distributions of local contact pressure are shown dependent on the surface roughness and the yield stress of plastic solids.

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EXPLICIT EQUATIONS FOR MIRROR FAMILIES TO LOG CALABI-YAU SURFACES

  • Barrott, Lawrence Jack
    • Bulletin of the Korean Mathematical Society
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    • v.57 no.1
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    • pp.139-165
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    • 2020
  • Mirror symmetry for del Pezzo surfaces was studied in [3] where they suggested that the mirror should take the form of a Landau-Ginzburg model with a particular type of elliptic fibration. This argument came from symplectic considerations of the derived categories involved. This problem was then considered again but from an algebro-geometric perspective by Gross, Hacking and Keel in [8]. Their construction allows one to construct a formal mirror family to a pair (S, D) where S is a smooth rational projective surface and D a certain type of Weil divisor supporting an ample or anti-ample class. In the case where the self intersection matrix for D is not negative semi-definite it was shown in [8] that this family may be lifted to an algebraic family over an affine base. In this paper we perform this construction for all smooth del Pezzo surfaces of degree at least two and obtain explicit equations for the mirror families and present the mirror to dP2 as a double cover of ℙ2.

The Prediction of Rubber Friction considering Road Characteristics (노면 특성을 고려한 고무 마찰 예측 연구)

  • Nam, Seungkuk;Oh, Yumrak;Jeon, Seonghee
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.4
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    • pp.105-110
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    • 2014
  • This paper presents the hysteresis friction of a sliding elastomer on various types of surfaces. The hysteresis friction is calculated by means of an analytical model which considers the energy spent by the local deformation of the rubber due to surface asperities. By establishing the fractal character of the surfaces, the contribution to rubber friction of roughness at different length scales is accounted for. High resolution surface profilometer is used in order to calculate the main three surface descriptors and the minimal length scale that can contribute to hysteresis friction. The results show that this friction prediction can be used in order to characterize in an elegant manner the surface morphology of various surfaces and to quantify the friction coefficient of sliding rubber as a function of surface roughness, load and speed.

Characterization of Surface Roughness and Inhomogeneity of Hot-Rolled Carbon Steels by Using Image Analysis Method and Electrochemical Impedance Spectroscopy

  • Pyun, Su-Il;Na, Kyung-Hwan;Go, Joo-Young;Park, Jin-Ju
    • Journal of the Korean Electrochemical Society
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    • v.6 no.3
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    • pp.217-223
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    • 2003
  • The present work is concerned with characterization of surface roughness and inhomogeneity of four kinds of hot-rolled carbon steels in terms of the fractal dimension and the depression parameter by using image analysis method and electrochemical impedance spectroscopy, respectively. From the analysis of the 3D AFM image, it is realized that all the hot-rolled steel surfaces show the self-affine fractal property. The values of the fractal dimension of the hot-rolled steels were determined by the analyses of the AFM images on the basis of both the perimeter-area method and the triangulation method. In addition, the Nyquist plots were found to be depressed from a perfect semicircle form. From the experimental findings, the changes in the values of the fractal dimension and the depression parameter with chemical composition have been discussed in terms of the change in the value of hardness of base steel.