JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 13

Fig. 6: Specific tensile modulus vs. loss factor for various engineering
materials, showing the unique stiffness-damping combination provided by
flax fibre composites

In applications requiring
the stiffness and strength of
carbon – such as a highperformance bicycle frame
– the dynamic properties of
the structure can be further
improved by replacing some
of the carbon by a flax layer,
sandwiched between highstiffness carbon layers.
Using the right amount and
position within the hybrid
structure will generate
what is commonly known
as constrained layer damping, which is schematically
shown in Figure 7. Standard
constrained damping layers are usually made from
highly viscoelastic polymers
with poor structural properties, relatively complicated
to integrate during processing and adding a lot of
weight to the structure. In
comparison, flax is light, has
great structural properties
and is processed the same
way as carbon.

Unidirectional and
biaxial flax fabrics

Fig. 7: Schematic of a thin composite structure composed of carbon fibre faces with
a flax fibre layer sandwiched in-between, acting as a constrained damping layer

oriented at ±45°, providing the required strength
against the cross-sectional
collapse of the tubes,
generally known as hoop
strength. An example of a
flax fibre composite tube
reinforced with power ribs
is displayed in Figure 5.

Strength and damping
In addition to cutting costs
and providing the required
hoop strength of the frame
tubes, the presence of the
flax composite will significantly enhance the damping

properties of the bicycle
frame when compared to
its full-carbon composite
counterpart. Due to their
outstanding damping properties, flax fibre composites
provide an engineering
material with a unique
stiffness-damping combination. While their specific
stiffness is 20-30% higher
than the one of glass fibre
composites, flax fibre composites exhibit three times
higher damping properties
than glass or carbon fibre
composites (Figure 6).

When optimally engineered,
a carbon-flax structure can
exhibit significantly higher
damping behaviour in comparison to its full-carbon
counterpart of equal weight.
In addition to the damping
increase, the right use of flax
layers simultaneously improves the buckling strength
and stiffness of the composite part by up to 25%.
Once more, this is due to
the lower density of flax
fibres. Thus, when replacing an intermediate carbon
layer by a flax layer of
equal weight, the distance
between the remaining top
and bottom carbon layers
is increased, resulting in a
carbon-flax-carbon sandNo80 April 2013

wich structure with higher
stiffness and strength than
the full-carbon reference
part. The fabric areal weight
(FAW) of current flax preforms is generally too high
for this approach, requiring
very thin layers to generate a
large amount of shear at low
deformations. To address
this requirement, Bcomp
has recently developed the
ampliTex© light product
range, composed of very
low FAW unidirectional and
biaxial flax fabrics ranging
from 75 g/m² to 200 g/
m². These fabrics meet the
needs of customers manufacturing different types
of surf boards, paddles,
rackets, as well as bicycle
frames.
These novel solutions
address the next trend in
most sports equipment
developments, which may
be illustrated with the
example of the bicycle
frame. Focusing on optimizing the stiffness-per-weight
ratio over the last decades,
the bicycle industry has
now reached the maximum
in this perspective: today’s
frames are extremely stiff
and weigh very little, but
often at the cost of a high
fragility and poor damping
properties.
As a consequence, the journey in bicycle development
will go towards increasing
the damage tolerance of
these frames, and improving
their damping properties
to improve the “feel” and
comfort of the riders. With
its ampliTex© solutions,
Bcomp is addressing exactly
these needs. n
More information:
www.bcomp.ch

/ jec composites magazine 13


http://www.bcomp.ch

JEC COMPOSITES MAGAZINE - Issue #80 - April 2013

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #80 - April 2013

Cover
Edito
Point of view: hig-end solutuions
Contents
Agenda of Events
COMPANY & BUSINESS In Brief
APPLICATIONS
- Sports & leisure
- Renovation
MARKET
- Singapore
- Education
- Natural fibres
- Biocomposites
FEATURE AERONAUTICS
- Carbon
- Process
- Reinforcement
- Structure
- Bi-angle NCF
- RTM
- Sandwich
- Energy
RESEARCH & DEVELOPMENT
- CAE tools
- CFRP
TECHNOLOGY & INNOVATIONS
- Prepreg
- Material
Index
In the world
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Cover
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 2
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Edito
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Point of view: hig-end solutuions
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 5
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Contents
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 7
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Agenda of Events
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 9
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - COMPANY & BUSINESS In Brief
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Sports & leisure
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 12
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 13
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Renovation
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Singapore
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 16
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 17
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 18
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Education
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 20
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 21
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 22
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 23
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 24
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 25
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Natural fibres
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 27
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Biocomposites
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 29
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 30
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 31
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 32
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Carbon
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 34
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Process
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 36
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 37
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Reinforcement
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 39
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 40
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Structure
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 42
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Bi-angle NCF
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 44
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - RTM
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 46
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Sandwich
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 48
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 49
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Energy
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 51
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - CAE tools
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 53
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 54
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - CFRP
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 56
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 57
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 58
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Prepreg
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 60
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 61
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Material
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 63
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 64
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Index
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - In the world
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 67
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 68
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