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Composite materials
John Summerscales
Advanced Composites Manufacturing Centre
School of Marine Science and Engineering
University of Plymouth
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lsNewton’s second law of motion
• Force = mass x acceleration (F = ma)• reduce mass
• same performance with smaller engine, or• improved performance with the same engine
• relative densities (vs water at 1000 kg/m3)• 8000 steel• 2700 aluminium• 2000 glass fibre reinforced plastics• 1500 carbon fibre reinforced plastics
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lsMaterials
• fibres• aramid: orange light tough (e,g, Kevlar)• carbon: black stiff brittle expensive conductor• glass: transparent tough inexpensive
• polymers• thermoplastics: heat-form-cool• thermosets: liquid reactive mixture
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lsBasic rule-of-mixtures 1
• Elastic properties (e.g. density or modulus) of composite calculated by rule-of-mixtures
• EC = ηL . ηO . Vf . Ef + Vm . Em • if the first term of the equation is large,
the second term can be neglected
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lsBasic rule-of-mixtures 2
• EC = modulus of composite
• ηL = fibre length distribution factor
• ηO = fibre orientation distribution factor
• Vx = volume fraction of component x
• Ex = modulus of component x
• subscripts f and m are fibre and matrix respectively
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lsBasic rule-of-mixtures 3
ηL = fibre length distribution factor
• 1 for continuous fibres
• fractional for long fibres
• 0 if fibre below a “critical length”
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lsVariation of E with fibre length:fibre length distribution factor ηl
• Cox shear-lag• depends on
• Gm: matrix modulus
• Af: fibre CSA
• Ef: fibre modulus
• L: fibre length• R: fibre separation
• Rf: fibre radius
< Shear
< Tension
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lsBasic rule-of-mixtures 4
ηO = fibre orientation distribution factor
• a weighted function of fibre alignment,
essentially cos4θ:• 1 for unidirectional• 1/2 for biaxial aligned with the stress• 3/8 for random in-plane• 1/4 for biaxial fabric on the bias angle
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lsVariation of E with angle:fibre orientation distribution factor ηo
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lsBasic rule-of-mixtures 5
• Vf = fibre volume fraction
• 0.15-0.3 for random• 0.35-0.6 for fabrics• 0.6-0.75 for unidirectional
• consolidation pressure:• no pressure gives low value above
• Vf increases with pressure
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lsBasic rule-of-mixtures 6
• Ef = elastic modulus of fibre
• glass = ~70 GPa(equivalent to aluminium)
• aramid = ~140 GPa• carbon = ~210 GPa
(equivalent to steel)
• figures above are lowest valuesi.e. for standard fibres
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lsGlass transition temperature (Tg)
• Tm = crystalline melting point
• Temperature at whichsegmental motion of the chain is frozen out• below Tg polymer is elastic/brittle
• above Tg polymer is viscoelastic/tough
• more rigorous than heat distortion temperature
• Tg for thermoplastics = Tm - ~200°C
• Tg for thermosets follows cure temp.
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• polyester resin ε’ = 0.9-4.0 %• vinyl ester ε’ = 1.0-4.0 %• epoxy resin ε’ = 1.0-3.5 %• phenolic resin ε’ = 0.5-1.0 %
• data from NL Hancox, Fibre Composite Hybrid Materials, Elsevier, 1981.
Matrix crackingmax min
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lsFibre fracture
• S/R-glass ε’ = 4.6-5.2 % …. • E-glass ε’ = 3.37 % ……….…• Kevlar 49 ε’ = 2.5 % …….……….• HS-carbon ε’ = 1.12 % ……………..…• UHM-carbon ε’ = 0.38 %
………………….
• data from NL Hancox, Fibre Composite Hybrid Materials, Elsevier, 1981.
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lsFibre-matrix debonding
• Crack can run through (not shown), or around the fibre
• NB: ~12000 carbon or 1600 glass UD fibres/mm2
a b c
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lsFibre-matrix debonding:
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lsDelamination of layers
• one layer is a lamina (plural = laminae)• several layers in a composite is a laminate• separation of the layers is delamination
• to avoid delamination• 3-D reinforcement (often woven or stitched)• Z-pinning
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lsFibre pullout
• as parts of a fractured composite separate,
the fibres which have debonded can fracture remote from principal fracture plane.
• energy is absorbed by frictional forcesas the fibre is pulled from the opposite face
• debonding and pullout absorbs high energies and results in a tough material
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Marine Composites: state-of-the-art
• Swedish Navy Visby stealth corvette• 600 tons - 72 m long - FRP sandwich
• Royal Navy mine counter measures vessels• 725 tons - 60 m long - monolithic GRP
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Marine Composites: state-of-the-art
• VT Mirabella V sloop rigged yacht• 740 tonnes - 75.2 m long - 90 m mast• CFRP/GRP/polyolefin foam
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Marine leisure
• Power-boats: racing/“gin palaces”• Sailing: ocean racing thro’ boating lake• Diving: wet-suits and air-tanks
• EnvironComp (Halmatic GFRPP boat)• EU BE-3152 : BRPR-CT96-0228• Research, development and evaluation of
environmentally friendly advanced thermoplastic composites for the manufacture of large surface area structures
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Formula 1
• http://www.mclaren.co.uk/
• http://ourworld.compuserve.com/homepages/john_hopkinson/williams.htm
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Road cars
• McLaren F1 road car
http://www.cottingham.co.uk/macf1/road.htm
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Road cars
• Lotus Elise S2
• Reliant Robin 65 (2000)
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Caparo Freestream T1
Graham HalsteadUoP composites graduate – now with McLaren Racing
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Dimitris Katsanis
• BEng CME graduate (project & Olympics)
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Railways• Inter-City 125 locomotive cab
http://home-2.worldonline.nl/~fgvdhurk/hst.htm
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Aircraft specifications
Boeing 737 Concorde Airbus A380
Passengers (189) 100 555
Length 38.4 m 62.1 m 73 m
Wingspan 28.9 m 25.6 m 79.8 m
Height 11.1 m 11.4 m 24.1 m
T/O weight 125 tonnes 185 tonnes 560 tonnes
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Aerospace: Airbus A380The world’s only twin-deck, four-aisle airlinerThe airlines’ solution to growing demand for air travelThe green giant, more fuel-efficient than your carThe dedicated three-deck 150 tonne long-range freighter
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Aerospace: defence
• Joint Strike Fighter (F-35)
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Biomimeticshttp://www.rarebirdphotography.co.uk
Common Tern Ivory Gull
Squacco Stone Curlew
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• Grumman X-29 FSW aircraft 1984 to 1992 http://www.globalsecurity.org/military/systems/aircraft/x-29.htm
Aerospace: defence
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Wind energy
Vestas Blades UK Limited
(formerly NEG-Micon )
Isle of Wightwind turbine blades up to 42 m
developed with ACMC Plymouth
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Key features: offshore wind farm• Middelgrunden
• windfarm length of 3.4 km near Copenhagen, Denmark
• 20 turbines, each 2 MW
• 60 m hub height, 76 m rotor diameter.
• water depth of 2-6 metres
• modified corrosion protection,internal climate control, built-in service cranes.
• 85 000 MWh pa (3% Copenhagen's needs)
• construction March 2000 to March 2001• http://www.worldenergy.org/wec-geis/publications/reports/ser/wind/wind.asp
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Rehabilitation of civil engineering structures• London Underground tunnels
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Bridge structures
• Aberfeldy footbridge over River Tay
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Internet resource for composites
Teaching support materials for MATS324Composites design and manufacture:http://www.tech.plym.ac.uk/sme/mats324
Case studies: offshore structures, naval vessels, yacht hulls, canoes, sailcloth.http://www.tech.plym.ac.uk/sme/composites/marine.htm
Case studies: bridgeshttp://www.tech.plym.ac.uk/sme/composites/bridges.htm
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BEng Mechanical Engineering with Composites
• Year 1 common with Mech Eng/Marine Tech• Year 2 common with Mech Eng• Year 3 in industry ?• Year 4: 40 credits for composites pathway
• composites design and manufacture (20 credits)• selection, characterisation, stress analysis & manufacture
• composites engineering (20 credits practical)• mountain bike suspension/bike front forks• yacht winch handle• skaters trolley/dinghy launching trolley
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Composites graduate destinations
• Aerospace• Air France, Airbus (UK & F), BAe, GKN etc
• Formula 1• Benetton, McLaren, Team Toyota, Williams
• Automotive• Aston Martin Lagonda, BMW (D), • Pininfarina (D), TWR Leafield
• Marine• Carbospars (ES), Princess, Sunseeker
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To contact me
Dr John Summerscales Reynolds Building Room 008
01752.5.86150
07753.56.8733 01752.5.86101 [email protected] http://www.plym.ac.uk/staff/jsummerscales