Micro-mechanical damage and rough crack closure in cementitious composite materials

A micro-mechanics based damage model is presented which uses the solution of an elastic body with penny-shaped cracks. The major new aspect of the work is the inclusion of a rough crack closure component in the model. The model uses a damage-surface, described in terms of transformed strain components. Inelastic strain components in each direction are computed by considering the total directional strains on an equivalent band of elastic material and then removing the elastic component. Details of the model implementation in a Mathcad sheet are given. The results from a series of single point simulations are given for uniaxial and biaxial tension and compression stress/strain paths. Each path is computed with the full model and with a damage only version of the model which does not simulate crack closure effects. It is shown that the incorporation of the rough contact component allows the model to reproduce dilatant post-peak behaviour in compression and to simulate, with reasonable accuracy, the shape of the biaxial strength envelope for cementitious composite materials