Within the Finite-Element Plasticity Research Group at the University of Birmingham the interest in finite elements is principally confined to their use in the modelling of elastic-plastic problems (specifically metal-forming processes). The methods employed allow a process to be studied as it develops through time. A number of problems in the modelling of such processes give rise to errors, most notably due to singularities and other complex geometrical anomalies which are the result of complicated die surfaces and other boundaries. These boundary conditions can give rise to severe mesh distortions. The results of this thesis will show that improvements may be made to the modelling of such processes, by using a computer tool to allow remeshing to be carried out where such inaccuracies occur. A number of investigations have been made into such tools in other areas of study and it is hoped, eventually, that those techniques, together with ones developed here may be applied to metal forming in 3-dimensions. The aims of this thesis are to formulate the initial steps towards such an analysis. The work demonstrates how the basics of such techniques might be implemented, concentrating specifically on the transfer of data from an old mesh to a new mesh and simple error measures. Once this data transfer has been implemented it is hoped that future work will produce a fully self-adaptive process, ensuring that remeshing occurs based on algorithms continuously monitoring the potential for errors throughout the process The initial work in this thesis was confined to plane-strain applications. Its methods and implementation are discussed and some results shown. This gave some understanding of the difficulties which would be involved when transferring the techniques developed to a fully 3-dimensional solution. In the 3-dimensional application area are more quantitative work was also undertaken to assess the errors arising from element degeneracy and the ability of the mesh to model steep strain gradients. It should be noted by that full 3-dimensional remeshing, when applied to general metal forming problems, will involve far more sophisticated mesh generation software than is currently, or in the short term future, available.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:503724 |
| Date | January 1993 |
| Creators | Roberts, S. Mark |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0022 seconds