Fracture Analysis of Model Materials as a Substitute of Quasi-Brittle Ceramics

Fracture of quasi - brittle ceramics is a complex field of study. This complexity arises because around the crack tip multiple processes occur influencing the behaviour of the fracture, microcracking and bridging being the most important ones. There is, therefore, a complexity in the modelling of such a fracture due to the multiplicity of parameters. A new approach is proposed: the design and construction of model materials. These materials have enlarged microstructural features that permit the control and variation of the material parameters, as particle size, force between particles, stiffness of the particles and particle stacking. In this communication, one of these model materials is presented: a porous polymer material containing a mixture of poly-methyl-methacrylate (PMMA) spheres with diameters in a range between 100 mu m to 1 mm, in which microstructure can be easily changed. The fracture behaviour of this material can be described with great precision with a fictitious crack model for different environment conditions. With a computer imaging tool the deformation fields of the fracture process zone around the crack tip can be visualized and measured.