WORK-OF-FRACTURE OF BRITTLE MATERIALS WITH MICROCRACKING AND CRACK BRIDGING

The fracture mechanics basis of fracture energies is considered through micromechanical phenomena in the crack tip frontal process zone, the following crack wake and crack bridging regions of brittle materials, such as cement-based materials, rocks, ceramics, and ceramic composites. The discussion is mainly focused on the work-of-fracture parameter (gamma(wof)) as a material characteristic for representing the resistance to crack extension. Theoretical considerations of the dependence of gamma(wof) on the unnotched remaining ligament length of the fracture test specimen lead to the concept of the 'essential work-of-fracture, gamma(e)'. The experimental results obtained for three different types of ceramic materials support the theoretical predictions.