ABSTRACT
Abstract Fractals structures appear naturally in soils and in rock mechanics. We dis-
cuss the opening of brittle materials via hydraulic fracturing at constant pressure using a square lattice beam model with disorder. In particular, the case in which only beams under tension can break is considered. We discuss under which conditions the resulting cracks may develop fractal patterns. The stress field of the fractal cracks is visualized by photoelastic fringes. Finally we present the selforganization of the network of shear bands of a (non-associate) plastic material under compression and show that the strain rate is a multifractal measure.
