A modular damage model for quasi-brittle solids - interaction between initial and induced anisotropy

This paper proposes a three-dimensional thermodynamically controlled damage model for a wide class of quasi-brittle materials, the modelling strategy being a continuation of the earlier work, [12-15]. The purpose is to keep an existing modular structure and to introduce new features to its framework. These are: (i) a thrifty insertion of initial orthotropy, (ii) the absence of irreversible strain after loading/unloading cycles (in opposition to rock-like materials described by the initial model) and especially (iii) the competition between initial orthotropy and anisotropy induced by mesocrack growth. The proposed innovation consists in adding second-order fabric tensors in conjunction with a damage tensor in the expression of the thermodynamic potential. Experimental data for a test composite material are simulated by this approach.