AN EXPERIMENTAL--COMPUTATIONAL APPROACH TO THE INVESTIGATION OF DAMAGE EVOLUTION IN DISCONTINUOUSLY REINFORCED ALUMINUM MATRIX COMPOSITE

摘要

A combined experimental-computational approach to study the evolution of microscopic damage to cause failure in commercial SiC particle reinforced DRAs is dealt with. Determination of aspects of microstructural geometry that are most critical for damage nucleation and evolution forms a motivation for this work. An interrupted testing technique is invoked where the load is halted in the ma- terial instability zone, following necking but prior to fracture. Sample microstructures in the severely necked region are microscopically examined in three dimensions using a serial sectioning method. The micrographs are then stacked sequentially on a computer to reconstruct three-dimensional microstructures. Computer simulated equivalent microstructures with elliptical or ellipsoidal particles and cracks are con- structed for enhanced efficiency, which are followed by tessellation into meshes of two- and three-dimen- sional Voronoi cells. Various characterization functions of geometric parameters are generated and sensitivity analysis is conducted to explore the influence of morphological parameters on damage. Micro- mechanical modeling of two-dimensional micrographs are conducted with the Voronoi cell finite element method (VCFEM). Inferrences on the initiation and propagation of damage are made from the two-dimen- sional simulations. Finally, the effect of size and characteristic lengths of representative material element (RME) on the extent of damage in the model systems is investigated.