QUASI BRITTLE MATRIX COMPOSITE MATERIALS: A COMPUTATIONAL APPROACH BASED ON DISCONTINUOUS-LIKE FE AND FRACTURE MECHANICS DEBONDING SIMULATION

In the present paper, the damaging mechanisms observed in fibre reinforced composite materials are simulated. In particular, quasi brittle matrix composites are examined: such cases typically involve the matrix damage associated to the creation and propagation of cracks, whose opening is mitigated by the presence of the reinforcing fibre phase. On the other hand, the effectiveness of fibres on the composite’s load bearing capacity is also heavily affected by the debonding phenomenon. Both degrading mechanisms are considered in the proposed mechanical model: the matrix cracking is accounted for by adopting a discontinuous-like FE approach which allows us to consider cracks depending on the matrix stress field, whereas the fibre-matrix detachment is simulated through a crack growth model based on the critical interface fracture energy; the remote critical stress causing debonding (i.e. crack advancing) can be obtained from the interface SIF. The main mechanical aspects of the developed model are described and, through some numerical examples compared with existing literature data, the two damaging aspects are shown to properly describe the complex phenomena arising in such multiphase materials.