Tensile and compressive damaged response in Flax fibre reinforced epoxy composites

Composite reinforcement by natural fibres like Flax do not enjoy the same popularity in engineering design as Carbon or Glass fibres on account of the relatively immature mechanical data on Flax-composites. Tensile and compressive mechanical properties are determined for Flax-fibre-reinforced-Epoxy composite. Damaged response is followed through SEM observations and by measuring evolving stiffness and permanent deformation. Specimens are repeatedly loaded-unloaded at progressively increasing maximum loads until failure, allowing a quantitative description of in-plane modulus and inelasticity evolution. Stiffness degradation rates do not necessarily correlate with inelastic straining rates, and modulus may remain unchanged while still accumulating inelastic strains - therefore both modulus and inelastic strain need evaluating to fully describe the material damaged response. Damage initiates within the fibre or at fibre-matrix interface; matrix-related damage appears not critical to damage initiation and progression. The reported data is valuable for the development of predictive models of damaged-condition response in Flax-epoxy structures.