Unit 47 – The characteristics and applications of fibre-reinforced
polymer composites
Bow:
Hickory Archery bow:
• Before FRPs in older times they used Hickory wood to create the main body of the
bow, when the intended shape of the bow is achieved then a thin layer liquid tree
sap is applied to give it extra strength and bond the wood fibres together.
Mechanical Properties of Hickory wood:
• Tensile strength (ultimate) is the maximum stress that the bow can withstand (152
MPA) while being stretched or pulled before reaching the breaking point.
• Youngs modulus is a property of the material that tells you how easily the material
can be stretched and deformed this is calculated as the ratio of tensile strength to
strain. The young’s modulus for Hickory wood is (15.3 GPa) (Meier, 2008)
• Flexural strength or also known as modulus of rupture is the woods ultimate
strength before ultimate failure. The flexural strength of hickory is (139 MPa) (Meier,
2008)
• Compressive strength is the maximum amount of stress the material can undergo
without fracture. The compressive strength of Hickory is (54 MPA)
• Yield strength or also known as work to maximum load is the maximum amount of
stress needed to elastically deform the part, this means the part it can still go back
into its original shape without any deformation, After the yield strength is passed the
material will enter the plastic deformation which means the component is
permanently deformed and it cannot go back into its original form or shape. The
yield strength for hickory is (6 MPa) (Meier, 2008)
Two suitable FRPs to replace Hickory wood and their Characteristics:
1. Carbon Fibre:
• There are 3 main classification/grading for carbon Fibre:
1. Type 1: The final heat treatment process for the carbon fibre
reinforced polymer is carried out above 2000 Celsius which
allows it to have a high modulus or also known as young’s
modulus.
, 2. Type 2: The heat treatment process for the CFRP is carried out
at 1500 or above this will result in the material/part to have
yield high strength.
3. Type 3: The heat treatment process is carried out at 1000
Celsius for a long period of time anywhere from 14 to 18 hours
then controlled cooled down, this will result low yield but high
flexural strength.
• Carbon Fibre has a high strength to weight ratio, Carbon fibre it has a density of 1.75
g/cm3 or 1750 kg/m3. The weight to strength of the material is calculated force per
unit area at failure divided by the density of the material and from this you get the
weight to strength which is 1013 KN. (Pooja Bhatt, 2017) This makes one of the
greatest materials out there it its very light compared to titanium which has a
density of 4420 kg/m3. This makes carbon fibre 75% lighter, and it has the same
strength as titanium, this makes it a great choice in many applications.
• Carbon Fibre has a very low Thermal Expansion due to the special mixture of matrix
used. When Carbon Fibre expands due to heat the area affected by the heat can
expand by 0.05 mm up to 0.5 mm, but this is very low thermal expansion rate and if
it’s considered during designing it can be avoided very easily.
• Carbon fibre is corrosion resistant due to the Matrix used to reinforce it however the
matrix can be damaged by UV lights which is a huge issue, but this can be prevented
by using a UV resistant finish or varnish.
• Carbon fibre is very brittle due to the many layers of fibres used which covalent bond
with the matrix this causes brittleness, when carbon fibre is bent to is maximum or
near its maximum the epoxy layer will crack then straight away the entire part will
fail and due to this issue, it’s very hard to notice if there are any issues with it.
• Also, Carbon fibre always comes in black as this cannot be coloured due to the
process used to make the fibres. The process heats up the fibres and due to this and
the chemicals used to treat the fibres will remove any colouring used to change the
colour of the fibres and because of this process makes it impossible to change the
colours of the carbon fibres.
• Carbon fibre can also be penetrated by x rays so this can be used as a non-
destructive testing method
• Carbon fibre has a great environmental impact due to the manufacturing process
used to create the carbon fibres (it produces a lot of CO2s) and the amount of
chemicals used, this process is carried out in a controlled environment and all the
gases, and the toxic fumes created are disposed of in a safe way as required by the
law. But this is does not remove the fact that barely 20% of all CFRP are recycled due
to the different chemicals mixed into the resin which does not allow it to be
recycled. All carbon fibre parts/ components made have a minimum life expectancy
of 50 year because after 50 years carbon starts to decompose. However, if the part is
well maintained it can last well over 100 years.
• Carbon fibre is very expensive due to the high demand and low supply, the low
supply is due to the sophisticated machinery used to create the carbon fibres which
polymer composites
Bow:
Hickory Archery bow:
• Before FRPs in older times they used Hickory wood to create the main body of the
bow, when the intended shape of the bow is achieved then a thin layer liquid tree
sap is applied to give it extra strength and bond the wood fibres together.
Mechanical Properties of Hickory wood:
• Tensile strength (ultimate) is the maximum stress that the bow can withstand (152
MPA) while being stretched or pulled before reaching the breaking point.
• Youngs modulus is a property of the material that tells you how easily the material
can be stretched and deformed this is calculated as the ratio of tensile strength to
strain. The young’s modulus for Hickory wood is (15.3 GPa) (Meier, 2008)
• Flexural strength or also known as modulus of rupture is the woods ultimate
strength before ultimate failure. The flexural strength of hickory is (139 MPa) (Meier,
2008)
• Compressive strength is the maximum amount of stress the material can undergo
without fracture. The compressive strength of Hickory is (54 MPA)
• Yield strength or also known as work to maximum load is the maximum amount of
stress needed to elastically deform the part, this means the part it can still go back
into its original shape without any deformation, After the yield strength is passed the
material will enter the plastic deformation which means the component is
permanently deformed and it cannot go back into its original form or shape. The
yield strength for hickory is (6 MPa) (Meier, 2008)
Two suitable FRPs to replace Hickory wood and their Characteristics:
1. Carbon Fibre:
• There are 3 main classification/grading for carbon Fibre:
1. Type 1: The final heat treatment process for the carbon fibre
reinforced polymer is carried out above 2000 Celsius which
allows it to have a high modulus or also known as young’s
modulus.
, 2. Type 2: The heat treatment process for the CFRP is carried out
at 1500 or above this will result in the material/part to have
yield high strength.
3. Type 3: The heat treatment process is carried out at 1000
Celsius for a long period of time anywhere from 14 to 18 hours
then controlled cooled down, this will result low yield but high
flexural strength.
• Carbon Fibre has a high strength to weight ratio, Carbon fibre it has a density of 1.75
g/cm3 or 1750 kg/m3. The weight to strength of the material is calculated force per
unit area at failure divided by the density of the material and from this you get the
weight to strength which is 1013 KN. (Pooja Bhatt, 2017) This makes one of the
greatest materials out there it its very light compared to titanium which has a
density of 4420 kg/m3. This makes carbon fibre 75% lighter, and it has the same
strength as titanium, this makes it a great choice in many applications.
• Carbon Fibre has a very low Thermal Expansion due to the special mixture of matrix
used. When Carbon Fibre expands due to heat the area affected by the heat can
expand by 0.05 mm up to 0.5 mm, but this is very low thermal expansion rate and if
it’s considered during designing it can be avoided very easily.
• Carbon fibre is corrosion resistant due to the Matrix used to reinforce it however the
matrix can be damaged by UV lights which is a huge issue, but this can be prevented
by using a UV resistant finish or varnish.
• Carbon fibre is very brittle due to the many layers of fibres used which covalent bond
with the matrix this causes brittleness, when carbon fibre is bent to is maximum or
near its maximum the epoxy layer will crack then straight away the entire part will
fail and due to this issue, it’s very hard to notice if there are any issues with it.
• Also, Carbon fibre always comes in black as this cannot be coloured due to the
process used to make the fibres. The process heats up the fibres and due to this and
the chemicals used to treat the fibres will remove any colouring used to change the
colour of the fibres and because of this process makes it impossible to change the
colours of the carbon fibres.
• Carbon fibre can also be penetrated by x rays so this can be used as a non-
destructive testing method
• Carbon fibre has a great environmental impact due to the manufacturing process
used to create the carbon fibres (it produces a lot of CO2s) and the amount of
chemicals used, this process is carried out in a controlled environment and all the
gases, and the toxic fumes created are disposed of in a safe way as required by the
law. But this is does not remove the fact that barely 20% of all CFRP are recycled due
to the different chemicals mixed into the resin which does not allow it to be
recycled. All carbon fibre parts/ components made have a minimum life expectancy
of 50 year because after 50 years carbon starts to decompose. However, if the part is
well maintained it can last well over 100 years.
• Carbon fibre is very expensive due to the high demand and low supply, the low
supply is due to the sophisticated machinery used to create the carbon fibres which
