JEC COMPOSITES MAGAZINE - Issue #129 - July/August 2019 - 50

SOLUTlONS music

Fig. 2: The YouTube video Making a
Cello From Carbon (by hand) shows
the entire building process of the
prototypes including handcrafting
the patterns, making the glass fibre
moulds, producing the VARTM carbon
parts and assembly

ite parts using the vacuum-assisted resin-transfer moulding
(VARTM) process at Ghent University. The composite parts were
acoustically optimized by varying
the thickness of the lay-up, making the soundboard stiffer in the
centre and more flexible towards
the edge. This is similar to a conventional wooden soundboard,
which is thicker in some regions
and thinner in others.
The required thickness was calculated using the classical laminate
theory. The composite parts were
then assembled in the workshop
to finished instruments.
The entire building process of
a carbon cello can be found on
YouTube, in a video titled Making
a Cello From Carbon (by hand).
The prototypes were studied
through various methods ranging
from modal analysis, which was
used to study vibrational behaviour revealing signature modes of
acoustic importance (Figure 4),
acoustic measurements, to how
the instruments are perceived by
listeners and musicians in double-blind tests.
An example of what was learned
is that changing the fibre direction in the lay-ups has a significant effect on the perceived loudness and tonal colour of a violin.
Thus, by changing the (an)isotropy of the carbon soundboards,
the instrument's sound can be
changed to fit the desire of the
musician.

50

Fig. 6: The inside of the glass fibre cello
before putting in the soundpost
Fig. 3: Violin with a top plate made of unidirectional flax fibre composite

Fig. 4: Modal analysis performed with a 3D laser Doppler vibrometer (Polytec PSV
500 3D HV Xtra) at Ghent University on a conventional violin, revealing its signature
acoustic modes. From left to right: A0 274 Hz, B1- 462 Hz, B1+ 561 Hz

Fig. 5: Violin with a carbon-Nomex sandwich top plate

What about flax?
First of all, flax was found to be
visually attractive to many musicians, some of them even mistaking it for wood.
The material results in a slightly
heavier soundboard with more
damping, resulting in an instrument that is less loud than its carbon counterpart. The tone colour described as warm, soft and
round is much appreciated by listeners and musicians alike, which
makes it a favourite for many.
The material's lower ecological
footprint is an added benefit.
Many musicians are hesitant
towards non-natural materials
for music instruments, claiming

jec composites magazine / N°129 July - August 2019

they sound "plastic" or "cold".
Although no evidence of this
was found in scientific tests, an
instrument made from flax might
be more easily accepted in the
conservative world of (classical)
music instruments.
And sandwich materials?
Luthiers have always sought after
the lightest and stiffest wood to
make their instruments.
They believe it results in an instrument that projects more, or in
other words, a louder instrument.
A logical next step in the effort
to create the most lightweight
soundboard and thus, the loudest
acoustic music instrument, are

Scan to discover

sandwich materials.
To investigate this, a violin with
a soundboard made from a sandwich material with carbon fibre
composite skins and a honeycomb core (Nomex®) was created. The violin was found to be
very loud. One violinmaker who
tried the instrument even proclaimed "this is too much; it should
be forbidden!". Perhaps indeed, the
team went too far with this one;
many professional violin players
are already half-deaf in their ear
closest to the instrument. Yet,
the insights gained provide interesting opportunities to tailor the
loudness of an instrument to the
musician's desire. More specifically, less loud instruments such as
acoustic guitars or ukuleles could
benefit from this.
Glass fibre
Finally, a glass fibre cello was
also made. To counter the higher weight of the material, the
above-mentioned
sandwich
technology was used to create a
see-through instrument that is
impossible to walk by without
looking. Especially, more ex-



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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