Characterization of the Mechanical and Vibration Behavior of Flax Composites with an Interleaved Natural Viscoelastic Layer

This study presents an analysis of the mechanical and vibration behavior of a flax fibre reinforced composites with and without an interleaved natural viscoelastic layer. Two types of elastic and viscoelastic cross ply laminates [0(2)/90(2)](s) and [0(2)/90(2)/NR](s) have been characterized experimentally using different mechanical and vibrational tests. The elastic laminate is composed of natural long flax fibre and greenpoxy resin while the viscoelastic laminate is composed of a natural viscoelastic layer and two elastic composites. First, both types of specimen composites were studied using uni-axial tensile tests under the same conditions. A comparison between the two composites behaviors has been realized. Then, Acoustic Emission (AE) has been often used for the identification and characterization of micro failure mechanisms and damage in laminates. Finally, experimental vibration analyses were carried out on the composites with and without an interleaved natural viscoelastic layer. Throughout a series of resonance vibration tests, the evolution of the Young modulus and the modal damping were evaluated. The effect of the viscoelastic layer on the mechanical and vibration behavior of the elastic composite has been investigated and analyzed. It has been shown that the viscoelastic layer improves with a significant way the modal properties of the flax fibre reinforced composite.