Numerical analysis of the influence of fiber distribution on damage initiation in CFRP

The mechanical behaviour of composite materials is strongly dependent on the microstructure and fiber distribution. The analysis of the stresses and damage in fiber interfaces and its relationship to the geometrical distribution of the fibers can provide an estimation of the mechanical performance of the composite component. This work focuses on the development of 2D numerical models of composite material reinforced by longitudinal fibers, making use of periodic boundary conditions. The damage initiation at fiber interfaces is related to the randomness of the distribution. The cooling effect due to temperature variation during the manufacturing process is also accounted for. These analyses have been carried out both as damaged interfaces in the whole structure and for individual fibers, studying the stresses induced at the interface. As expected, a strong effect of the randomness of the fiber arrangement on the damage initiation has been found. Normal and shear stresses in the fiber interfaces have been analysed and related to the geometric distribution randomness. It is found that the distance between neighbouring fibers affects the normal and shear stress at the interface. The geometrical distribution around individual fibers also affects the directions where maximum shear and normal stresses appear.