Study of fracture toughness and fracture energy in composites

The aim of this work is to give a numerical formula for the ultimate strength under compression in terms of an energy approach (G_e=dU/dA) characterizing energy dissipation during the fracture process. The experimental and numerical models have been elaborated to investigate and to calculate a stress intensity approach (factor K) and an energy approach (crack resistance R, crack extension force G). We considered a two-phase system consisting of a matrix (phase 1) and cylindrical grains (phase 2) dispersed in it - according to the accepted composite (concrete) model.

A plane stress-state substitutes for the real three-dimensional stress-state. The 2D models were made of two components: mortar (based on the cement) and the cylinders of pyrex glass (grains).