EXPLICIT MODELLING OF CRACK INITIATION AND PROPAGATION IN THE MICROSTRUCTURE OF A CERAMIC MATERIAL GENERATED WITH VORONOI TESSELLATION

摘要

Explicit modelling of crack propagation in the microstructure of a ceramic material generated with Voronoi tessellation. Ceramic materials are currently used for both vehicle and personnel armour since they can be very effective in stopping ballistic projectiles by breaking and/or eroding them. However, such armour is generally fairly heavy and does not have multihit capability, mainly due to excessive fragmentation during impact. The development of new ceramics for armour is further hindered by the limited understanding of the mechanisms involved in their success and therefore what the characteristics of ideal ceramics would be. This work studies the initiation of cracks in ceramic microstructures, as in many armour ceramics (e.g alumina) the main cause of failure is inter-granular crack propagation. To simulate this phenomenon the mesh of a polycrystalline aggregate is first created and then crack propagation along grain boundaries is modelled. A method to generate three-dimensional meshes of polycrystalline aggregates based on Hardcore Voronoi tessellation of random points distribution is presented. The mesh created is enriched by introducing contacts along the grain boundaries to explicitly simulate the propagation of inter-granular cracks. Finally, the numerical results are compared with micro-cantilever beam tests