The damping–modulus relationship in flax–carbon fibre hybrid composites

The trade-off between the elastic modulus and damping capacity as a function of fibre composition in carbon–flax hybrid composite laminates was investigated. Hybrid composite laminates with varying carbon–flax fibre–epoxy content were prepared using a combination of compression moulding and vacuum bagging. The elastic modulus and damping loss coefficients were determined by free-vibration in longitudinal and flexural modes, and modelled using a rule of hybrid mixtures (ROHM) and laminate theory. The models were in close agreement with the experimental data for both the longitudinal and flexural modes and thus appeared to be a feasible method of predicting the stiffness–damping relationship in this system of hybrid composite laminates. The experimental data of the tensile strength was found to also follow the ROHM. However, the experimental data of the flexural strength deviated negatively from the theoretical prediction, exhibiting lower values than the predicted ones.