Damage model for quasi-brittle solids: Coupled effects of induced and initial anisotropy

A three-dimensional thermodynamically controlled damage model for a wide class of quasi-brittle materials is proposed, extending earlier works. The features concerned are the insertion of initial orthotropy, a modification involving the absence of irreversible strain after loading / unloading cycles (in opposition to rock-like materials concerned with the initial model) and, especially, the competition between initial orthotropy and anisotropy induced by mesocrack growth. Finally, the frictional sliding at the interface fiber / matrix after debonding is briefly introduced for a class of ceramic composites.