JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 51

Music instruments from carbon, glass or flax fibres

Fig. 7: Cellist Benjamin Glorieux performs a solo during the glass fibre cello's
première

perimental-minded cellists are
drawn to the instrument for its
specific sonic palette. For the instrument's première in Brussels,
cellist Benjamin Glorieux put a
spotlight under his chair, illuminating the instrument and adding
a visual aspect to a cello solo like
never before.

Conclusion
Carbon offers a high-quality
alternative to wood.
By changing the fibre direction and thickness of the
soundboards, the sound
of the instruments can be
changed, which offers great
possibilities for the further

development of high-quality
carbon fibre instruments.
Violins or cellos made from
flax or glass fibre are not yet
commercially available, yet
the authors' research shows
these materials have great potential in both the sound they
produce and their visual appeal to musicians.
More information:
Tim.Duerinck@UGent.be
Acknowledgements
The authors would like
to thank FWO (Research
Foundation Flanders grant nr.
1180217N) for funding this
research, professor W. Van
Paepegem and professor M.

Kersemans from the department of Materials, Textiles
and Chemical Engineering
(MaTCh) - Ghent University,
G. Verberkmoes from the department of Design - Royal
Academy of Fine Arts & Royal
Conservatory and professor
M. Leman and Dr. L. Nijs from
the department of Art, Music
And Theater Sciences - Ghent University. Ghent University and Hogent - School of
Arts Ghent are acknowledged
for providing logistic support.
The authors would also like
to thank Lineo for donating
the Flaxtape™ material used
to make the flax violin and
cello.

Why are flax fibres in violins and cellos an interesting
second choice, next to carbon and glass fibres?
Tim Duerinck is probably the first musical instrument designer and manufacturer who compared in a systematic and scientifically sound way the use of composites with different fibre reinforcements. As mentioned in the paper, the choice of carbon
and glass fibre composites is justified by their high stiffness and light weight, and their lower sensitivity to changes in ambient
temperature and humidity conditions, compared to wood.
Figure 1 shows the specific bending stiffness (plate bending) of unidirectional carbon, glass and flax fibre-reinforced composites
as a function of the fibre volume fraction. In the practical range between 15 and 50% fibre volume fraction, carbon fibre composites outperform others but, maybe surprisingly for many, flax fibres come as a close second, better than glass
Ignaas Verpoest,
fibres. This is due to the fact that in terms of absolute stiffness values, flax and glass fibres are almost equal (65
Composite Materials Group,
Materials Engineering Department vs. 70 GPa), whereas the density of flax fibres is approximately half that of glass (1.45 vs. 2.55 kg/lit). Hence, for
structures loaded in bending (as most of the components in a violin or cello are), flax fibre composites are an
KU Leuven
interesting second choice, next to carbon fibres.
(University of Leuven)
The reason why flax fibres might be, for certain violins or cellos, a better choice than carbon fibres is related
to their damping capacity, which in turn is determined by their internal structure on the micro- and
even nano-level.
A material's damping properties are intrinsically related to the "mobility" of the atoms or molecules
that compose it. In glass fibres, the strong three-dimensional bonds in the oxydic structure prevent
such a mobility, and make them vibrate like a monolithic solid. In carbon fibres, the mobility is somewhat higher because the oriented (but curled) graphitic plates are only bonded to each other by weak
secondary bonds, allowing some relative motion. However, this is largely compensated by the higher
stiffness of the graphitic layers themselves, resulting in material damping properties that are not so
different from those of glass fibres.
The internal structure of flax fibres (and all plant-based fibres) goes even a step further; on the
Fig. 1: Specific stiffness in (plate) bending of
unidirectional composites, with two metals as molecular level, (one-dimensional) stiff cellulose molecules are bonded to each other by (two-dimena reference
sional) weak secondary bonds, allowing more mobility than in the graphitic structure of carbon fibres.
Moreover, a second and third level of mobility are added because, inside the elementary fibres, the
cellulose micro-crystals are bonded to each other by mainly amorphous and compliant substances (such as hemicellulose, lignins, pectins, etc.),
as are the elementary fibres to each other in what is called the middle lamella. These three levels of possible mobility (their relative contribution
is not discussed here, and is hard to measure) result in a high damping capacity of flax fibres, making them suitable for musical instruments with
"controlled" loudness and tonal colour.
To fully exploit the stiffness potential of flax fibres, new preforms had to be developed because "traditional" flax (or linen) woven textiles do not
provide the theoretically achievable stiffness. This is due to the fibre misorientations inside the twisted yarns, and the out-of-plane "crimp" in
woven textiles (see: Flax & Hemp Fiber Composites, a market reality - The biobased solutions for the industry, eds. Verpoest et al., JEC and CELC,
Paris, 2018). The European Flax and Hemp Confederation, CELC, motivated and encouraged the flax industry to develop new preforms that make
it possible to take full advantage of flax' potential as a reinforcement for composites, such as weaves with low-twist yarns, or unidirectional layers,
such as Lineo's Flaxtape™ material used in this study.

N°129 July - August 2019

/ jec composites magazine

51



JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019

Cover
Edito
Moving composites forward: on the shoulders of giant
Contents
NEWS
In brief
Successful partners
Agenda
BUSINESS
Matrix - CFRP composite manufacturing trends
Cost - A brand-new approach for economically competitive composites
MANUFACTURING
Fibre placement - Replacing individual unit tests by integrated process control
NDT - Optical metrology improves the production of composite products at every step
Initiative - Spotlights from the world of lightweighting
FEATURE SPORTS & LEISURE - The largest testing ground
Success story - DPS designs the world’s most advanced skis
Carbon - New type of unidirectional prepreg for sport applications with complex shapes
Additive manufacturing - lnnovative composite bicycle frame
Textile - Porcher lndustries: excellence in sports and leisure
Innovations - Sports on the scene at JEC World 2019
Carbon - The next generation of high-performance rigging
Standardisation - Research, innovation and development for composite marine and offshore applications
SOLUTIONS
Infrastructure - Can carbon-reinforced concrete replace steel in the long run?
Art - “Train your brain, think disruptive, outside the box and follow your visions!”
Music - Music instruments from carbon, glass or flax fibres
Watch - A watch ahead of its time
In the world - Composites visit the doctor
TECHNOLOGY
Ageing - Effects of ageing on the mechanical and structural properties of glass/epoxy composite pipes in seawater
Inside the lab - Advanced Composites Research Group – Queen’s University Belfast
Index
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JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 68
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Cover
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 2
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Edito
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Moving composites forward: on the shoulders of giant
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 5
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Contents
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 7
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - In brief
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 9
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Successful partners
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Agenda
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Matrix - CFRP composite manufacturing trends
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 13
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 14
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Cost - A brand-new approach for economically competitive composites
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 16
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 17
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 18
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Fibre placement - Replacing individual unit tests by integrated process control
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 20
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - NDT - Optical metrology improves the production of composite products at every step
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 22
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 23
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Initiative - Spotlights from the world of lightweighting
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 25
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 26
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Success story - DPS designs the world’s most advanced skis
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 28
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Carbon - New type of unidirectional prepreg for sport applications with complex shapes
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 30
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Additive manufacturing - lnnovative composite bicycle frame
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 32
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Textile - Porcher lndustries: excellence in sports and leisure
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 34
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 35
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Innovations - Sports on the scene at JEC World 2019
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 37
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Carbon - The next generation of high-performance rigging
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 39
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Standardisation - Research, innovation and development for composite marine and offshore applications
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 41
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 42
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Infrastructure - Can carbon-reinforced concrete replace steel in the long run?
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 44
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 45
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 46
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Art - “Train your brain, think disruptive, outside the box and follow your visions!”
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 48
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Music - Music instruments from carbon, glass or flax fibres
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 50
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 51
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Watch - A watch ahead of its time
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 53
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - In the world - Composites visit the doctor
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 55
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Ageing - Effects of ageing on the mechanical and structural properties of glass/epoxy composite pipes in seawater
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 57
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 58
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 59
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 60
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 61
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Inside the lab - Advanced Composites Research Group – Queen’s University Belfast
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 63
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 64
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 65
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - Advertisers
JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 67
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