Enhanced vibration damping and viscoelastic properties of flax/epoxy composites and their carbon fibre hybrid laminates

The damping and viscoelastic properties of flax/epoxy composites and their carbon fibre hybrid laminates are investigated. For this purpose, four different types of composite laminates using varied stacking sequences were fabricated by vacuum infusion process. The influence of various parameters on the vibration damping behaviour of flax and flax/carbon hybrid systems is investigated by using two techniques:shaker system utilising half-power bandwidth and dynamic mechanical analysis. In order to show the correlations between damping and mechanical properties, three-point bending tests are used to determine the bending stiffness of each stacking sequence. The results indicate that the location and number of flax plies contribute to the damping behaviour while the bending stiffness is mainly governed by location of carbon plies. Results show that the damping ratio varies for each vibration mode. Specimen type D, which contains the fewest number of carbon plies, exhibits higher values for both flexural stiffness and damping ratio compared to configuration B, which has the highest number of carbon layers. When comparing configurations B and C, it is observed that by trading off 8.1% of flexural stiffness, a substantial 34% increase in damping ratio was achieved in the second vibration mode.