| Popis: |
This thesis reports an investigation into the mechanics of anisotropic multilayered materials embedded with dislocations. An image technique is developed for solving the problems of infinite bilayers, film-substrates and general N-layer composites. The key contributions are: (1) the development of an image decomposition scheme which is instrumental to the accuracy of the complete solution, and (2) the elimination of singularities from the governing integral equations using certain H and I transforms. Numerical investigations reveal that many factors, e.g., elastic anisotropy and layer inhomogeneity, will significantly influence the image forces acting on the dislocation. Furthermore, a single-ended discrete dislocation pileup model is developed and used to show that the shear strength dependence on layer thickness obeys the Hall-Petch relation quite well for sufficiently thick layers while image forces result in a deviation of the relation for very thin layers. The numerical predictions are in good agreement with a comprehensive set of experimental data for metallic multilayer systems. DOCTOR OF PHILOSOPHY (MPE) |
