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Volumn 108, Issue 11, 2004, Pages 3410-3425

Frictional forces and Amontons' law: From the molecular to the macroscopic scale

Author keywords

[No Author keywords available]

Indexed keywords

CHEMICAL BONDS; COMPUTER SIMULATION; DENSITY (SPECIFIC GRAVITY); FRICTION MATERIALS; MATHEMATICAL MODELS; MOLECULAR DYNAMICS; STATISTICAL METHODS; SURFACE ROUGHNESS; WEIBULL DISTRIBUTION;

EID: 1642381109     PISSN: 15206106     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp036362l     Document Type: Article
Times cited : (483)

References (91)
  • 1
    • 0005953871 scopus 로고
    • Friction, Lubrication, and Wear Technology
    • Blau, P., Ed.; ASM International: Materials Park
    • Blau, P. In Friction, Lubrication, and Wear Technology, ASM Handbook; Blau, P., Ed.; ASM International: Materials Park, 1992; Vol. 18, p 74.
    • (1992) ASM Handbook , vol.18 , pp. 74
    • Blau, P.1
  • 2
    • 1642337548 scopus 로고    scopus 로고
    • note
    • One may even think of these two faces as the lateral and normal components of some friction force function F(θ) where θ is the angle at which two bodies or surfaces are being moved relative to each other.
  • 7
    • 1642318213 scopus 로고    scopus 로고
    • note
    • For example, a solid block of metal cannot be sheared except by a very high shear stress, yet this is an example of two smooth surfaces in adhesive contact under no external (normal) load.
  • 9
    • 0003807328 scopus 로고    scopus 로고
    • Persson, B. N. J., Tosatti, E., Eds.; Kluwer Academic: Dordrecht
    • Physics of sliding friction; Persson, B. N. J., Tosatti, E., Eds.; Kluwer Academic: Dordrecht, 1996.
    • (1996) Physics of Sliding Friction
  • 10
    • 1642300166 scopus 로고    scopus 로고
    • note
    • Analogous to the fixed, nonfluctuating average velocity of the molecules in a gas even though at any instant any particular molecular may have almost any velocity.
  • 27
    • 1642388064 scopus 로고    scopus 로고
    • note
    • A number of scientists had previously suggested equations of this form, including Coulomb.
  • 46
    • 1642288768 scopus 로고    scopus 로고
    • note
    • Also called lateral force microscope, an AFM with a lateral force-measuring capability.
  • 49
    • 1642316588 scopus 로고    scopus 로고
    • note
    • All surfaces adhere, however weakly, especially in air. In the original experiments by Leonardo, Amontons, and Coulomb, the surfaces werre rough and hard so that true (adhesive) contact occurred only between a few asperities, and the resulting adhesion was far too small to have a significant or measurable effect on the friction force.
  • 51
    • 0042379819 scopus 로고    scopus 로고
    • Ruths, M. Langmuir 2003, 19, 6788.
    • (2003) Langmuir , vol.19 , pp. 6788
    • Ruths, M.1
  • 58
    • 1642381602 scopus 로고    scopus 로고
    • note
    • We note that, while all the lengths and forces differ by many orders of magnitude, the sliding velocities used in the SFA and FFM studies were similar.
  • 69
    • 1642365273 scopus 로고    scopus 로고
    • note
    • In general, adhesive and nonadhesive refer to the two surfaces interacting across the film between them, whether air or liquid. In other words, it refers to what one would measure when pulling the two surfaces apart. Thus, when separated by a liquid film, the film molecules and film-surfaces forces could be attractive (adhesive) while the surface-surface interaction is not. In our simulations, the direct interactions between the two surfaces is much smaller than the film-surface interactions, and thus adhesiveness, or nonadhesivenes, reflects directly the nature of the interactions between the molecular film and the confining surfaces.
  • 76
    • 1642266129 scopus 로고    scopus 로고
    • note
    • We note here that there relative shear velocity between the two solid surfaces is 1/ms = 0.01 Å/ps so that in a 6-ps interval the relative displacement of the surfaces is a mere 0.06 Å and the relative local geometry of the confining surfaces has hardly changed. Extending the time-averaging interval to larger values, e.g., 36 ps, has little or no effect on the calculated local averaged values.
  • 79
    • 1642269418 scopus 로고    scopus 로고
    • note
    • We comment here on certain specific differences between the conditions employed experimentally and theoretically. (i) The sliding velocity used in the simulations is several orders of magnitude faster than in the experiments. Note, however, that friction forces commonly exhibit a weak dependence (logarithmic or weaker) on the sliding velocity. (ii) The contact used in the simulations is "nominally" flat, that is, a uniform normal stress is applied, while in the SFA experiments, the surfaces are originally curved, leading to a highly nonuniform stress distribution. While the details of this stress distribution may be expected to influence the results, SFA experiments with mica and boundary-lubricated mica surfaces clearly show that a single constant shear stress appears to describe the measured friction forces when these are in the low-load, adhesion-controlled regime, i.e., when F ∞ A.
  • 80
    • 1642267763 scopus 로고    scopus 로고
    • note
    • The more commonly used expressins "energy dissipated" or "energy lost" are misleading since no energy is ever lost; it is only converted or transferred from one form to another or to a different location.
  • 81
    • 1642326287 scopus 로고    scopus 로고
    • note
    • Here the junction is the macroscopic system, composed of smaller segments or "tiles".
  • 82
    • 1642399313 scopus 로고    scopus 로고
    • note
    • By definition, the energy transferred (E) is equal to the product of the friction force (F) and the displacement (x), i.e., E = Fx. The rate of energy transfer is therefore given by dE/dt = F dx/dt = Fv, where v is the sliding velocity.
  • 86
    • 1642383212 scopus 로고    scopus 로고
    • To be published
    • Gao, J. et al. To be published.
    • Gao, J.1
  • 89
    • 85085785345 scopus 로고    scopus 로고
    • note
    • -3), depending on the situation.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.