Numerical modelling of the fatigue behavior of fibre-reinforced composites

The behavior of fibre-reinforced composites is examined through the formulation of a micromechanical-based model. The elasto-plastic macro constitutive equations for such a class of materials, composed by a matrix phase with elasto-plastic behavior and a fibre-reinforcing phase, is firstly obtained considering an imperfect bond between the matrix and the fibres; a two-parameters model, obtained from energetic considerations and by considering the evolution of the shear stress distribution along a single fibre during the loading process, is formulated to determine the entity of the debonding. Moreover, the progressive damage which occurs in the case of repeated loading is considered to account for the degraded properties of the matrix and of the interface due to fatigue. The proposed model is implemented in a FE code and some numerical simulations are performed in order to assess its reliability.