An alternative 3D model for damage induced anisotropy and unilateral effect in microcracked materials

Abstract
A three-dimensional model of damage by microcrack growth is proposed to account for the mechanical behavior of quasi-brittle materials (especially for concrete and rocks). The emphasis is put on the induced anisotropy and on the elastic moduli dependence on the opening and closure of microcracks (unilateral effect). This formulation is based first on a damage characterization through the microcrack density distribution, and secondly avoids the use of spectral decompositions generally adopted in literature and which induce some major inconsistencies.