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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 jsummerscales@plymouth.ac.uk http://www.plym.ac.uk/staff/jsummerscales