JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World - o - 115

Flax fibre composite for vibration damping design

Fig. 2: (a) Damping properties versus frequency; (b) evolution of the specific loss factor with fibre orientation

Characterization of damping properties
The specific loss factor results are shown in Figure 2a both for
the composites in the 0° fibre direction and for the polymerized
Elium™ resin as a function of the frequency. The Elium™ resin
shows the highest damping factor compared to the composites
and its value decreases rapidly at higher frequency. This result
is linked to the viscoelastic behaviour of the thermoplastic resin. Indeed, at a higher vibration frequency, less time is available
for the damping mechanisms to occur, resulting in lower damping. On the contrary, the composite damping responses show
similar damping profiles and seem to be constant as a function
of frequency. However, the specific damping loss factor for the
flax fibre composite is twice as high as the factor for the glass
fibre composite. The results can be explained by the intrinsic
multi-scale hierarchical nature of flax fibre, which contributes to
friction mechanisms such as intra- and inter-cell wall friction and
hence dissipates vibration energy.
The effect of fibre orientation on the vibration properties is presented in Figure 2 (b). The specific loss factor was found to increase with fibre orientation and reach the maximum value at 45°
in the case of the glass fibre composite and 30° in the case of the
flax fibre composite. By changing the fibre orientation, it is possible to create a composite laminate with a superior damping factor.
An analytical model used to predict the damping loss factor of the
fibre in the composite is shown in Equation 1:

Where ηf , ηr , ηC are the damping loss factors of the fibre, resin and
composite, Vf is the fibre volume fraction, and Ef ,Er are respectively the fibre and resin Young's modulus.
Using this equation, the fibre damping factors found are about

2.1% and 1.0% for flax fibre and glass fibre respectively. Flax fibres
exhibit better damping properties than glass fibres.

Conclusion
Natural fibre-reinforced thermoplastic composites using Elium™
resin were compared with glass fibre composites. The vibration
absorption measurements highlighted the higher functional capability, in terms of damping, of flax fibres versus glass fibres. By
combining flax fibres with thermoplastic resins, it is possible to
design a green composite that meets both the low weight and vibration comfort requirements of the transport industry.
The authors are grateful to the FiMaLin association for its financial support to this study.
More information:
www.estaca.fr
http://laum.univ-lemans.fr
Contact:
thuy-quynh.truong-hoang@estaca.fr
Zouhaier.jendli@estaca.fr
abderrahim.elmahi@univ-lemans.fr

Focus
About ESTACA and the LAUM laboratory
ESTACA is an engineering school specialized in transportation
and a member of the ISAE group and the FiMaLin association.
The Mechanics department of ESTACA'LAB is involved in
developing advanced multifunctional composite materials for
smart structure applications in transport.
LAUM is a Coeducational Research unit of the Université du
Maine (UM) at Le Mans and of the CNRS (Centre National de
Recherche Scientifique) as the UMR 6613.
The research activities of the lab are performed as part of
three teams specialized on complementary themes: Acoustics
and Mechanics of materials, Transducers, Vibrations, Guided
Acoustics and Flow.

No111 March 2017

/ jec composites magazine

115

http://www.estaca.fr http://laum.univ-lemans.fr

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