The hydrodynamics and mechanical behaviour of a soft nip between a rubber-covered roller and a rigid roller has been studied. The thesis reports the developments and the results of a combined theoretical and experimental investigation into the nip flow of Newtonian and non-Newtonian fluids operating under various roller mechanical engagements, speeds and other design parameters. The theoretical model has been developed based on a Finite Element method (FEM) to solve for the equation set of generalised pressure and plane strain elasticity equations under a pure rolling contact. Several numerical studies for Newtonian fluid were then carried out to verify the basis of the present model. As far as the author is aware, no published work has hitherto studied the effect of non-Newtonian fluid flow in a soft contact. The comparison between the present Newtonian and non-Newtonian models suggests considerable variation in the film thickness caused by the shear thinning action in the non-Newtonian fluid. Concurrently, an experimental programme was conducted using a real printing unit which was converted to an experimental test rig. The parameters that were measured were pressure, film thickness, speed and temperature. The results provide detailed behaviour of the rollers investigated, and these were used to verify the predicted nip behaviour. The measured results showed that very small speed differentials occur in the nip, and the hysteresis of the rubber was the major source of the heat build-up in the roller. Also, comparison of predicted and measured pressure showed close agreement for low levels of roller engagement and at low speeds. Systematic numerical case studies were carried out to ascertain the parameters which most affect the nip behaviour. Supported with the comparisons of published data where possible, the results showed that rubber modulus, roller engagement, viscosity and speed were the most influential parameters.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637918 |
| Date | January 1995 |
| Creators | Lim, C. H. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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