Modeling the non-linear deformation of a short-flax-fiber-reinforced polymer composite by orientation averaging

The growing usage of short-flax-fiber-reinforced polymer composites in such applications as automotive industry necessitates the prediction of their mechanical response up to and beyond the limit of elasticity. Due to the imperfect, mechanical interlocking-dominated adhesion of natural fibers to most polymers, both fiber debonding and matrix yielding contribute to the non-linear deformation. In the present study, the deformation under an active loading of a short misaligned fiber composite is modeled by the orientation averaging approach, employing an analytical description of the behavior of a unit cell (UC), the parameters of which are determined using a FEM analysis of UC response under selected loading modes. The model is applied to the prediction of stress-strain diagrams in tension of flax/polypropylene composites with different fiber volume fractions.