Improving the damping properties of carbon fibre reinforced composites by interleaving flax and viscoelastic layers

The purpose of this paper is to investigate how the damping properties of structures made of carbon laminates can be increased when flax and viscoelastic layers are interleaved into the carbon laminates. The viscoelastic layers are constituted of Vinyl Ethylene Acetate (EVA) and are considered to take advantage of their high vibration damping. Their dynamic properties are very dependent on the frequency and accordingly a fundamental and extensive analysis was implemented. This dependency was identified from free vibrations of aluminium-EVA-aluminium sandwich beams. In a similar way, the damping coefficients of carbon and flax laminates were determined from flexural vibrations of test beam specimens. Next, a parametric analysis based on the finite element method is proposed to show how the flax and EVA layers could be arranged to improve the damping properties of carbon laminates. Finally, the study of a carbon structure permits to highlight the interest of flax-viscoelastic association to enhance its damping by 25-45% without affecting its dynamic behaviour.