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Engineered surfaces in sliding and rolling contact
This has been an active area of research in CUED since the pioneering work of K L Johnson on the plastic
flow and shakedown of surfaces in the early 1960's when the shakedown limit was established as the rational
design criterion for rolling contacts (wheels and rails, rolling bearings, traction drives, etc.). Methods
for estimating its value have been drawn up and reviewed and implications for surface life considered [1-3].
Two current avenues based on this earlier work have recently been explored. Shakedown principles have been
applied in the analysis of the changes in surface topography which take place during repeated sliding
contacts in metals [4-6]: progressive plastic flow of asperities leads to the formation of very thin, filmy
wear debris [7] by a process of plastic ratchetting brought about by the repeated pummelling of the softer
surface by the asperities on the harder. A model for this mild wear regime, which is driven by normal loads
rather than by friction, has been developed [8,9]; the hardness of the wearing surface and the coefficient of
friction at the interface influence the wear rate thought their effect on the plasticity index for repeated
sliding introduced in [8]. In addition, some studies have been made on the application of shakedown
principles to surfaces whose strength properties vary with depth as a result of surface engineering by both
thermo-chemical hardening [11,12] as well as the more complex cases of coated surfaces: in such cases, not
only both the elastic and plastic material properties vary with depth, but account must be taken of the
integrity of the bond between coating and substrate [13-16].
Relevant/recent publications
- Johnson, K. L. 'The application of shakedown principles in rolling and sliding contact' Eur. J. Mech.,
A/Solids, 11, pp155-172 (1992).
- Johnson, K. L. 'Contact mechanics and the wear of metals' in Proceedings of Austrib 94, Perth
(1994).
- Williams, J. A., Dyson, I. N. and Kapoor, A. 'Repeated loading, residual stresses, shakedown and
tribology' Journal of Materials Research., 14, pp1548-1559 (1999).
- Johnson, K. L. and Shercliff, H. R. 'Shakedown of two-dimensional asperities in sliding contact' Int.
J. Mech. Sci, 34, pp375-394 (1991).
- Kapoor, A and Johnson, K. L. 'Steady state topography of surfaces in repeated boundary lubricated
sliding' Proc. 19th Leeds/Lyon Symposium on Tribology (ed. Dowson, D.) Leeds, (1992).
- Kapoor, A. and Johnson, K. L. 'Effect of changes in geometry on shakedown in rolling and sliding contact'
Int. J. Mech. Sci., 34(3), pp223-239 (1991).
- Kapoor, A. and Johnson, K. L. 'Plastic ratchetting as a mechanism of filmy wear in repeated sliding'
Proc. Roy. Soc., A445, pp367-381 (1994)
- Kapoor, A., Johnson, K. L. and Williams, J. A. 'The steady state sliding of rough surfaces' Wear,
175, pp81-92 (1994).
- Kapoor, A., Johnson, K. L. and Williams, J. A. 'A model for the mild ratchetting wear of metals'
Wear, 200, pp38-44 (1996).
- Williams, J. A. 'Wear modelling: analytical, computational and mapping: a continuum mechanics approach'
Wear, 225-229, pp1-17 (1999).
- Kapoor, A. and Williams, J. A. 'Shakedown limits in sliding contacts on a surface-hardened half-space'
Wear, 172, pp197-206 (1997).
- Kapoor, A. and Williams, J. A. 'Shakedown limits in rolling and sliding point contacts on an anisotropic
half-space' Wear, 191, pp256-260 (1996).
- Kapoor, A. and Williams, J. A. 'The effect of interfacial shear strength on the performance of coated
surfaces in repeated sliding' J. Tribology, 119, pp1-8 (1997).
- Wong, S. K., Kapoor, A. and Williams, J. A. 'Shakedown limits on coated surfaces' Thin Solid
Films, 292(1-2), pp156-163 (1997).
- Wong, S. K., Kapoor, A. and Williams, J. A. 'Shakedown limits on coated and engineered surfaces'
Wear, 203-4, pp162-170 (1997).
- Dyson, I. N., Williams, J. A. and Kapoor, A. 'The effect of surface hardening on the shakedown of
elliptical contacts' J. Engineering Tribology, 213, pp287-298 (1999).
Contact Details
For further information on the work summarised above contact Dr J A
Williams at Cambridge University Engineering Department, Trumpington St, Cambridge, CB2 1PZ, UK. Tel:
01223 332641, Fax: 01223 332662. E-mail: jaw@eng.cam.ac.uk
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