Tribology Letters

, Volume 26, Issue 3, pp 235–238 | Cite as

Transition from elastic to plastic deformation as asperity contact size is increased

Article

Contacts between a clean sodium chloride pyramidal shaped asperity and a plane NaCl surface have been investigated by molecular dynamics simulations. For small contacts, a few atoms across, the asperity jumped to contact and behaved elastically as normal load was applied. Then, when the force was reversed to detach the asperity, brittle failure occurred without any damage to the crystalline materials. However, as the contact size of the asperity was increased to 6 × 6 atoms in area, the mechanism of detachment was seen to alter. The jump to contact was elastic and damage free, but the separation could not be achieved elastically, but required plastic deformation, giving extensive energy dissipation and severe damage as edge defects propagated through the asperity. Above this contact size, plastic flow was dominant. However, there is clearly a further transition back to elastic fracture once the asperity becomes large enough for Griffith-type cracking to propagate above 1 μm in size, since large sodium chloride contacts are known to be brittle above the micrometre scale, depending on the presence of crack initiating defects.

Keywords

asperity deformation, brittle/ductile transition, nanometre contacts 

References

  1. 1.
    Tabor D., Winterton R.H. (1969) Proc. R Soc. Lond. A312:435Google Scholar
  2. 2.
    Israelachvili J.N., Tabor D. (1972) Proc. R Soc. Lond. A331:19Google Scholar
  3. 3.
    Tabor D. (1977) J. Colloid Interface Sci. 58:2CrossRefGoogle Scholar
  4. 4.
    McFarlane J.S., Tabor D. (1950) Proc. R Soc. Lond. A202:224Google Scholar
  5. 5.
    Tabor D., Winterton R.H. (1968) Nature 219:1120CrossRefGoogle Scholar
  6. 6.
    Pashley M.D., Pethica J.D., Tabor D. (1984) Wear 100:7CrossRefGoogle Scholar
  7. 7.
    Tabor D. (1959) Proc. R Soc. Lond. A251:378Google Scholar
  8. 8.
    Landman U., Luedtke W.D., Burnham N.A., Colton R.J. (1990) Science 248:454CrossRefGoogle Scholar
  9. 9.
    Cagin T., Che J., Qi Y., Zhou Y., Demiralp E., Gao G., Goddard W.A. (1999) J. Nanoparticle Res. 1:51CrossRefGoogle Scholar
  10. 10.
    Yong C.W., Smith W., Kendall K. (2002) J. Mater. Chem. 12:2807CrossRefGoogle Scholar
  11. 11.
    Yong C.W., Smith W., Kendall K. (2003) Nanotechnology 14:829CrossRefGoogle Scholar
  12. 12.
    Yong C.W., Kendall K., Smith W. (2004) Phil. Trans. R Soc. Lond. A362:1915CrossRefGoogle Scholar
  13. 13.
    Kendall K. (1978) Nature 272:710CrossRefGoogle Scholar
  14. 14.
    Kendall K. (1978) Proc. R Soc. Lond. A361:245Google Scholar
  15. 15.
    Kendall K., Yong C.W., Smith W. (2004) J. Adhesion 81:21Google Scholar
  16. 16.
    W. Smith and T. Forrester, DL_POLY, Version 2.12 (CCLRC, Daresbury Laboratory, UK, 2001)Google Scholar
  17. 17.
    Kendall K. (2001) Molecular Adhesion and its Applications. Kluwer Academic, New York, pp. 235–237Google Scholar
  18. 18.
    Roberts R.J., Rowe R.C., Kendall K. (1997) J. Mater. Sci. 32:4183CrossRefGoogle Scholar
  19. 19.
    G.C. Lowrison, Crushing and Grinding (Butterworth, London, 1974) ch.1–5Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.CCLRC DaresburyDaresbury, Warrington, CheshireUK
  2. 2.Chemical EngineeringUniversity of BirminghamEdgbaston, BirminghamUK

Personalised recommendations