Some effects of subsurface stress on wear behaviour

Hills, D.A., 1979. Some effects of subsurface stress on wear behaviour. PhD, Nottingham Trent University.

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Abstract

Wear is studied from applied mechanics aspects only. It is postulated that 'both sliding and rolling pairs wear by the propagation of cracks a short distance beneath the surface, causing the loss of surface layers in the form of thin sheets. This has been called 'delamination'. Fracture mechanics has been assumed to be valid under contact load conditions, and the stress intensification factors for mode II (and where appropriate, mode I) growth are determined. Using a development of the work of others on the use of crack tip plastic zones to find propagation rates, the growth rate of wear cracks is predicted to be consistent with wear rates observed: much more work is needed before a true positive correlation can be established. It is pointed out that wear cracks grow in what is apparently a vacuum, and that, even under the exactly antisymmetrical shear stress distribution of rolling contact, they do not experience equal and opposite periods of mode II growth. Therefore, if only contact stresses were present, it might be expected that wear crack growth parallel to the surface would be unstable, so that wear particles would be equi-axed. This is not observed experimentally, and the creation of tensile subsurface residual stresses is cited as a possible stabilising influence. It is found that such stresses are a likely outcome of shakedown for. Several configurations, and new shakedown limits are found for three dimensional contacts. The effect of residual stresses on wear is. studied experimentally by deliberately building in a static stress system, and the optimum stress to apply is found for several geometries.

Item Type:	Thesis
Creators:	Hills, D.A.
Date:	1979
ISBN:	9781369325997
Identifiers:	Number Type PQ10290350 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Laura Ward
Date Added:	12 Jul 2021 15:46
Last Modified:	24 Jul 2024 14:59
URI:	https://irep.ntu.ac.uk/id/eprint/43422

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