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ME 423 Polymers & Polymer Composites

Introduction to CompositeMaterials

ME 423Polymers & Polymer Composites

Dr. Conchr Brdaigh

Dept. of Mechanical Engineering,NUI Galway


Advanced composites

what do they consist of ?

fibres and resins

where are they used ?

- many areas of industry

e.g. Aerospace, Marine, Automotive, Infrastructure,

Wind Energy, Biomedical

Manufacturing processes (Lecture 2)

- Thermosets, Thermoplastics

Introduction to Composites


2/23


Composite Materials

Combination of two or more distinct materialphases into one engineering material

Two components:

- Matrix & Reinforcement

Matrix - Protects Reinforcement- Environmental Tolerance

Reinforcement - Supports Structural Load


Composite Materials

MATRIX + REINFORCEMENT

Polymer Carbon fibreMetal Glass fibre

Ceramic Aramid fibre (e.g. Kevlar)

Metal fibre (e.g. Ti, Al)


3/23


Composite Materials

Short FibresAligned Fibres

Advanced Composites


Carbon Fibres

Courtesy of Tenax Fibers


4/23


May be manufactured from PAN or Pitch Lightweight High performance High strength - intermediate modulus high modulus Lower modulus intermediate strength lower strength High electrical and thermal conductivity Dimensional stability (negative CTE in fibre direction)

Relatively expensive Transversely isotropic Relatively brittle Not very damage resistant

Carbon Fibres


Aramid Fibres

High Tensile Strength at Low Weight

High Toughness & High Modulus Low Electrical Conductivity High Chemical Resistance Low Thermal Shrinkage Excellent Dimensional Stability High Cut Resistance Flame Resistant, Self-Extinguishing

Tends to absorb water (hygroscopic) Problems in compression strength Poor interfacial strength with matrix

Courtesy of EI DuPont De Nemours


5/23


Cheap most widely used reinforcement Properties vary from low to medium Good impact properties Low electrical conductivity Higher failure strains than carbon E-Glass strength, stiffness, weathering,

electrical props. S-Glass higher modulus and strength,

aircraft applics.

C-Glass chemical resistance

Relatively heavy Prone to moisture absorption Can suffer surface damage

Glass Fibres

Courtesy Owens Corning



6/23


Material Properties

Material Modulus Strength Relative

(GPa) (MPa) Density

Steels 203 600-2000 7.8

Aluminium 75 70-80 2.6

Carbon fibre (HM) 340 2500 1.9

Carbon fibre (HS) 230 3200 1.8

Aramid fibre 124 2800 1.45

Glass fibre 76-86 1700 2.5


Thermoset Resins Polyester (GRP) cheap and widest use Epoxy more expensive, better mech props Phenolics fire resistance High temp. polyimides v. expensive

Thermoplastic Polymers Polypropylene cheapest, mainly with glass fibres Nylons industrial uses some with carbon fibres

Polycarbonate, PET more exotic PEI, PES, PPS, PEEK v. high props, v. high cost

Composite Matrices


7/23


Production of Composite PreImpregnated Tape (Prepreg)

Fibres are introduced into resin in continuousresin impregnation process rolled up on paperbacking ready for component manufacturing


UnidirectionalPre-impregnatedTape (Prepreg)

Fabrics

Aircraft

TrailingEdge

+ Pressure + Heat

SUPreM


8/23


Micromechanics Combining Rules

e.g. Rule of Mixtures

E (long) = Ef . Vf + Em . Vm

E (transverse) = EmEfVf . Em + Vm. Ef

Em = Matrix modulus, Vm = matrix volume fraction,Ef = Fibre Modulus, Vf = fibre volume fractionVm + Vf = 1


Composite Material Properties

Material Fibre Modulus Strength

Volume (GPa) (MPa)Steels ---- 203 600-2000

Aluminium ---- 75 70-80

UD CF/Epoxy 0.6 180 1500

UD Kevlar/Epoxy 0.6 76 1400

UD CF/PEEK 0.66 134 2130

UD GF/Epoxy 0.6 50 1200

All composite properties measured in fibre direction


9/23


...the Composite Advantage is Weight

Material Specific SpecificModulus Strength

UD CF/Epoxy 113 937

UD CF/PEEK 84 1330

UD Kevlar/Epoxy 52 965

Aluminium 30 30

UD GF/Epoxy 21 590Steels 26 76-255

Specific properties are normalised by relative density


Improving Fibre Properties

Carbon fibres: Modulus Strength(GPa) (MPa)

T700 (HS) 235 5300

HTS (HS) 238 4300

IM6 / IM7 (IM) 303 5200

HR40 (HM) 381 4800

HS40 (UHM) 441 4400


10/23


Applications of Composites

Where the increased performance/reduced weight willpay for the increased cost of manufacture

Space (antennae, structures,satellite dishes etc)

Military Aircraft (wings, fuselage etc.)

Formula One (practically everything)

Civil aircraft (control surfaces, floor beams, wings ?)

High-speed rotating machinery

Personalised protection (sports, ballistic armour)

Specialised automotive (e.g. Lotus, Ferraris)

Ordered according to value per Kg weight saved:


Composites in use in space/military aircraft since

late 1960s.

Composites in Aerospace

B2 Bomber RAH 66 Comanche Helicopter


11/23


Boeing 777(1988) 7%Airbus A340 (1990) 15%

Airbus A380 (2005) 25%Airbus A400M (2009) 35%

Boeing 787 (2009) 55%Airbus A350 (2010) 40-50%

A380 Boeing 787 (2009)

Airbus A350 (2010)

Composites In Large Aircraft


Interiors

Floor beams, seats,overhead bins, galleys

Structure

Empennage, bulkheads,control surfaces, enginecowlings, fairings etc.


12/23


GF/PhenolicSmoke -detector

housing

CF/Epoxy

spoilers forBoeing

Quartz fibre radome


A 380 Super-Jumbo

Many innovative composite applications 22-25% structural weight in composites


13/23


Boeing 7E7 (planned 2009)

Longer range, more fuel-efficient aircraft Over 50% structural weight in composites


Boeing 7E7 (planned 2009)

First 7m compositefuselage sectionmade in Dec 2004

Enables biggerwindows, lowercabin pressure and

higher humidity


14/23


Airbus A350 (planned 2010)

Competitor to 7E7 based on existing A330 Longer range, more fuel-efficient aircraft More composite intensive than existing


New Aerospace MaterialsFibre-Metal Laminates (e.g. GLARE)

Laminates of Al and CF/Epoxy

Improved impact and fireresistance over Al & composites

Better fatigue resistance thanaluminium

Proposed for upper fuselage ofA-380


15/23


Issues in Aerospace

Composites manufacturing processes stillnot automated sufficiently

Damage tolerance seen to be a problem (epoxy)- ramp rash- developments in thermoplastics- fibre / metal laminates

Composites dont fatigue like aluminium (great!)

Cost.CostCost


Application - Marine


16/23


Composites in Marine/Offshore

Lightweight composite sandwiches are materialof choice for yacht hulls, minesweepers etc.

Offshore oil rigs, risers, platforms with specialresin grades for maritime environment

New closed-mould, in-bag infusion technologieslarger mouldings, less environmental impact

Smart fibre optics embedded in yacht masts


Application - Automotive

Bus interiors and exterior panels


17/23


Bus panels moulded in GF/PP (Twintex)


Application - Automotive

Daimler-Chrysler

Dodge ESX-3

EJ 11


18/23


Composites in Automotive

Mainly short-fibre reinforced thermosets (SMC) andthermoplastics (GMT & filled inj. Mouldings)

Pickup-bed covers, bonnets, front-end carriers,seats, spoilers, rocker and valve covers etc.

Advanced composites structural elements/body

panels being developed - electric carRecyclability & sustainability very important

thermoplastic matricesnatural fibres - flax, jute, sisal, hemp


Application - Infrastructure

Shear reinforcement inconstruction

Reinforcement of support propsor anchor bolts in tunnel

construction


19/23


Strengthening with CFRP laminates

0 100

150

midspandeflection

[mm]

load [kN]

steel reinforced

concrete beam

strengthened withCFRP laminates

after failure

i kb


Composites in Infrastructure

Carbon fibre prices now dropping rapidly, as low as$12/kg for large tows

Rehabilitation of bridges/buildings with CFplates/strips at minimum cost and inconvenience

Seismic retrofitting of columns with CF wraps

All-composite foot bridges from pultruded sections

All-composite vehicular bridges coming into service


20/23


Fig.6: Structural grid structure(Photo: ABB)

Innovative Tubular Grid Structures

Grid structures can bedesigned for optimumproperties - combinations oftorsion & flexure, includeredundant members forimpact & durability


Wind Energy

Wind market growing worldwide at 15%/annum

Blades up to 40m made of glass-fibre/epoxy

Next generation 50-60m for offshore sites size means use of carbon fibre for stiffness

Denmark aims to supply 20% of its ownenergy by wind power by 2010


21/23


40m Wind Turbine Blade


Skins/Shells

Box-Spar

HubConnection


22/23


Application - Biomedical Implants

Composites are anisotropic, so properties can be tailored

by varying fibre volume fraction

by varying the angle of reinforcement

by changing the local density/form of reinforcement

Composites are transparent to radio waves & non

magneticmetals produce artifacts under CAT scans & MRI

Polymer matrices can be bio-inert or biodegradable


Bone Fixation Screws (CF/PEEK)

ETH Zurich


23/23


Bone Fixation Plate (CF/PEEK)

ETH Zurich

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