MECH 473 ~ LECTURE 15: COMPOSITES LECTURE 15: COMPOSITE MATERIALS By: Casey Keulen.

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MECH 473 ~ LECTURE 15: MECH 473 ~ LECTURE 15: COMPOSITES COMPOSITES LECTURE 15: LECTURE 15: COMPOSITE COMPOSITE MATERIALS MATERIALS By: Casey Keulen By: Casey Keulen

Transcript of MECH 473 ~ LECTURE 15: COMPOSITES LECTURE 15: COMPOSITE MATERIALS By: Casey Keulen.

Page 1: MECH 473 ~ LECTURE 15: COMPOSITES LECTURE 15: COMPOSITE MATERIALS By: Casey Keulen.

MECH 473 ~ LECTURE 15: MECH 473 ~ LECTURE 15: COMPOSITESCOMPOSITES

LECTURE 15:LECTURE 15:

COMPOSITE COMPOSITE MATERIALSMATERIALS

By: Casey KeulenBy: Casey Keulen

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COMPOSITESCOMPOSITES-Composite materials-Composite materials are engineered materials made are engineered materials made

from two or more constituent materials that remain from two or more constituent materials that remain separate and distinct while forming a single componentseparate and distinct while forming a single component

-Generally, one material forms a continuous matrix while -Generally, one material forms a continuous matrix while the other provides the reinforcementthe other provides the reinforcement

- The two materials must be chemically inert with respect - The two materials must be chemically inert with respect to each other so no interaction occurs upon heating until to each other so no interaction occurs upon heating until

one of the components melts, an exception to this one of the components melts, an exception to this condition is a small degree of interdiffusion at the condition is a small degree of interdiffusion at the

reinforcement-matrix interface to increase bondingreinforcement-matrix interface to increase bonding

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COMPOSITESCOMPOSITES

Can you think of any examples Can you think of any examples of where composites are used?of where composites are used?

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COMPOSITESCOMPOSITESComposites can be found in:Composites can be found in:

-Boat hulls-Boat hulls-The aerospace industry (structural components as well -The aerospace industry (structural components as well

as engines and motors)as engines and motors)-Automotive parts (panels, frames, dashboards, body -Automotive parts (panels, frames, dashboards, body

repairs)repairs)-Sinks, bathtubs, hot tubs, swimming pools-Sinks, bathtubs, hot tubs, swimming pools

-Cement buildings, bridges-Cement buildings, bridges-Surfboards, snowboards, skis-Surfboards, snowboards, skis

-Golf clubs, fishing poles, hockey sticks-Golf clubs, fishing poles, hockey sticks-Trees are technically composite materials, plywood-Trees are technically composite materials, plywood

-Electrical boxes, circuit boards, contacts-Electrical boxes, circuit boards, contacts--EverywhereEverywhere

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COMPOSITESCOMPOSITES

Composites can be classified by their Composites can be classified by their matrix material which include:matrix material which include:

-Metal matrix composites (MMC’s)-Metal matrix composites (MMC’s)

-Ceramic matrix composites (CMC’s)-Ceramic matrix composites (CMC’s)

-Polymer matrix composites (PMC’s) or -Polymer matrix composites (PMC’s) or sometimes referred to as organic matrix sometimes referred to as organic matrix

composites (OMC’s)composites (OMC’s)

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COMPOSITESCOMPOSITES

MMC - Metal Matrix CompositesMMC - Metal Matrix Composites-The matrix is relatively soft and flexible.-The matrix is relatively soft and flexible.

-The reinforcement must have high strength and stiffness-The reinforcement must have high strength and stiffness

-Since the load must be transferred from the matrix to the -Since the load must be transferred from the matrix to the reinforcement, the reinforcement-matrix bond must be strong.reinforcement, the reinforcement-matrix bond must be strong.

MMC use:MMC use:

-Two types of particulates ( dispersion strengthened alloys -Two types of particulates ( dispersion strengthened alloys and regular particulate composites)and regular particulate composites)

-Or long fiber reinforcements-Or long fiber reinforcements

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COMPOSITESCOMPOSITES

PMC - Polymer Matrix CompositesPMC - Polymer Matrix Composites-The matrix is relatively soft and flexible-The matrix is relatively soft and flexible

-The reinforcement must have high strength and stiffness-The reinforcement must have high strength and stiffness

-Since the load must be transferred from matrix to -Since the load must be transferred from matrix to reinforcement, the reinforcement-matrix bond must be strongreinforcement, the reinforcement-matrix bond must be strong

CMC – Ceramic Matrix CompositesCMC – Ceramic Matrix Composites-The matrix is relatively hard and brittle-The matrix is relatively hard and brittle

-The reinforcement must have high tensile strength to arrest -The reinforcement must have high tensile strength to arrest crack growthcrack growth

-The reinforcement must be free to pull out as a crack extends, -The reinforcement must be free to pull out as a crack extends, so the reinforcement-matrix bond must be relatively weakso the reinforcement-matrix bond must be relatively weak

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DISPERSION STRENGTHENED DISPERSION STRENGTHENED MMC’SMMC’S

-Dispersion strengthened alloys can be considered as composites -Dispersion strengthened alloys can be considered as composites because there is little or no interaction between the two components because there is little or no interaction between the two components

and the reinforcement is not soluble in the metal matrix.and the reinforcement is not soluble in the metal matrix.

-The dispersoids are usually 10-250 nm diameter oxide particles and -The dispersoids are usually 10-250 nm diameter oxide particles and are introduced by physical means rather than chemical precipitation.are introduced by physical means rather than chemical precipitation.

-They are located within the grains and at grain boundaries but are not -They are located within the grains and at grain boundaries but are not coherent with the matrix as in precipitation hardeningcoherent with the matrix as in precipitation hardening

-The dispersed particles are sufficiently small in size to impede -The dispersed particles are sufficiently small in size to impede dislocation movement and thus improve yield strength as well as dislocation movement and thus improve yield strength as well as

stiffness.stiffness.

-Dispersion strengthened alloys are somewhat weaker than precipitation -Dispersion strengthened alloys are somewhat weaker than precipitation hardened alloys at room temperature but since overaging, tempering, hardened alloys at room temperature but since overaging, tempering, grain growth or particle coarsening do not occur on heating, they are grain growth or particle coarsening do not occur on heating, they are

stronger and more creep resistant at high temperatures.stronger and more creep resistant at high temperatures.

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SINTERED ALUMINUM SINTERED ALUMINUM POWDER (SAP) COMPOSITESPOWDER (SAP) COMPOSITES-SAPs have an aluminum matrix with aluminum oxide -SAPs have an aluminum matrix with aluminum oxide

(Al(Al22OO33) particulate) particulate

-The matrix can be strengthened by %14-The matrix can be strengthened by %14

SAPs are produced using different methods, two examples SAPs are produced using different methods, two examples are as follows:are as follows:

-Al and Al-Al and Al22OO33 powders are blended then compacted at high powders are blended then compacted at high

pressure then sintered like a ceramic.pressure then sintered like a ceramic.

-Al powder is heated in air to form a thick film of Al-Al powder is heated in air to form a thick film of Al22OO33 on on

each particle, when the powder is compacted the Aleach particle, when the powder is compacted the Al22OO33 film film

fractures into tiny particles and becomes surrounded by fractures into tiny particles and becomes surrounded by the Al during sintering the Al during sintering

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SINTERED ALUMINUM SINTERED ALUMINUM POWDER (SAP) COMPOSITESPOWDER (SAP) COMPOSITES

Properties of SAP Properties of SAP compared to 2024-T8, compared to 2024-T8, 7075-T6 and a boron 7075-T6 and a boron

fiber strengthened fiber strengthened 1100 alloy.1100 alloy.

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THORIA-DISPERSED THORIA-DISPERSED COMPOSTIESCOMPOSTIES

-An important group of dispersion-strengthened composites is -An important group of dispersion-strengthened composites is thoria-dispersed (TD) metalsthoria-dispersed (TD) metals

-Thorium is an element on the periodic table (atomic number 90)-Thorium is an element on the periodic table (atomic number 90)

-A common example is TD-nickel-A common example is TD-nickel

TD-nickel composites roduced by:TD-nickel composites roduced by:-Powders of metallic Th and Ni are ball -Powders of metallic Th and Ni are ball milled, compacted at high pressure and milled, compacted at high pressure and then sintered.then sintered.-The compact is then heated in air and -The compact is then heated in air and oxygen diffuses in to react with Th metal oxygen diffuses in to react with Th metal to form a fine dispersion of ThO2.to form a fine dispersion of ThO2.-This method, internal oxidation is also -This method, internal oxidation is also used for fabricating the W-ThO2 used for fabricating the W-ThO2 composites.composites.

Electron micrograph of TD-Ni with 300 nm diameter ThO2 particles (X2000)

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CEMENTED CARBIDESCEMENTED CARBIDES(CERMETS)(CERMETS)

-Cemented carbides are an example of regular particulate MMC’s -Cemented carbides are an example of regular particulate MMC’s (as opposed to dispersion strengthened MMC’s)(as opposed to dispersion strengthened MMC’s)

-Carbides such as WC (tungsten-carbide) are used for cutting tool -Carbides such as WC (tungsten-carbide) are used for cutting tool inserts but this hard ceramic is very brittle so it cracks or chips inserts but this hard ceramic is very brittle so it cracks or chips under impact loads, to remedy this cobalt is used as a matrixunder impact loads, to remedy this cobalt is used as a matrix

-Co-WC (cobalt tungsten-carbide) cermets are produced by -Co-WC (cobalt tungsten-carbide) cermets are produced by pressing Co and W powders into compacts, which are heated pressing Co and W powders into compacts, which are heated

above the melting point of Coabove the melting point of Co

-On cooling the carbide particles become embedded in the -On cooling the carbide particles become embedded in the solidified Co, which act as a tough matrix for the WC particlessolidified Co, which act as a tough matrix for the WC particles

-In addition to its strength and toughness, Co is also selected -In addition to its strength and toughness, Co is also selected because it wets the carbide particles to give a strong bondbecause it wets the carbide particles to give a strong bond

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CEMENTED CARBIDESCEMENTED CARBIDES(CERMETS)(CERMETS)

-Cemented carbides are commonly used as inserts for -Cemented carbides are commonly used as inserts for cutting toolscutting tools

-I’m sure you’ve seen these in the machine shop-I’m sure you’ve seen these in the machine shop

Figure (from left to right):

Cutting tool inserts, a milling tool and a lathe tool

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PARTICULATE MMC’S FOR PARTICULATE MMC’S FOR ELECTRICAL CONTACTSELECTRICAL CONTACTS

-Electrical contacts used in switches, relays and motors -Electrical contacts used in switches, relays and motors must be quite wear resistant to stand up in service must be quite wear resistant to stand up in service

-Highly conductive metals such as Cu and Ag are relatively -Highly conductive metals such as Cu and Ag are relatively soft and thus show excessive wear when used as contacts soft and thus show excessive wear when used as contacts

resulting in arcing and poor electrical conduction.resulting in arcing and poor electrical conduction.

-The goal is to produce a contact that is both a good -The goal is to produce a contact that is both a good conductor and has excellent wear propertiesconductor and has excellent wear properties

-This is done by using silver reinforced with tungsten -This is done by using silver reinforced with tungsten particles, the Ag is a terrific conductor while the W provides particles, the Ag is a terrific conductor while the W provides

good wear propertiesgood wear properties

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PARTICULATE MMC’S FOR PARTICULATE MMC’S FOR ELECTRICAL CONTACTSELECTRICAL CONTACTS

-The composite is made in two stages:-The composite is made in two stages:

-First a low density compact with interconnected -First a low density compact with interconnected pores is produced by pressing and firing tungsten pores is produced by pressing and firing tungsten

powders (figure a and b)powders (figure a and b)

-Liquid silver is then infiltrated into the connected -Liquid silver is then infiltrated into the connected voids under vacuum (figure c)voids under vacuum (figure c)

b c

-The final product has a continuous Ag and W structure which provides good electrical conductivity and wear resistance

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CAST METALCAST METALPARTICULATE MMC’SPARTICULATE MMC’S

-Al alloys for automotive connecting rods and pistons can be -Al alloys for automotive connecting rods and pistons can be strengthened and hardened by the addition of SiC (silicon strengthened and hardened by the addition of SiC (silicon

carbide) particles.carbide) particles.

-The SiC particles are introduced at a temperature at which the -The SiC particles are introduced at a temperature at which the alloy is in the solid plus liquid state, ie., by “compocasting”.alloy is in the solid plus liquid state, ie., by “compocasting”.

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CAST METALCAST METALPARTICULATE MMC’SPARTICULATE MMC’S

Compocasting of Al-SiC:-Partially solidified alloy is stirred to break up dendrites (fig. a)

-Particles of SiC are added at this temperature (fig. b)-In a pressure die casting machine, the solid mixture becomes

thixotropic to form a high density casting (fig. c)

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CAST METALCAST METALPARTICULATE MMC’SPARTICULATE MMC’S

Microstructure of cast Al Alloy reinforced with particles of SiCMicrostructure of cast Al Alloy reinforced with particles of SiCmagnified X125magnified X125

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RULE OF MIXTURESRULE OF MIXTURES

For particulate composites, the rule of mixtures predicts the For particulate composites, the rule of mixtures predicts the density of the composite as well as other properties density of the composite as well as other properties

(although other properties may vary depending on how the (although other properties may vary depending on how the dispersed phase is arranged)dispersed phase is arranged)

Density, Density, , is given as a fraction, , is given as a fraction, ff, as:, as:

ffmmc ff

Where the subscripts Where the subscripts mm and and ff refer to the matrix and fiber. refer to the matrix and fiber.

fm ff 1 that Note

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RULE OF MIXTURESRULE OF MIXTURESFor fiber reinforced composites, the rule of mixtures predicts For fiber reinforced composites, the rule of mixtures predicts

the density of the composite as well as electrical and the density of the composite as well as electrical and thermal conductivity along the direction of the fibers if they thermal conductivity along the direction of the fibers if they

are continuous and unidirectional.are continuous and unidirectional.

Density, Density, , is given as a fraction, , is given as a fraction, ff, as:, as:

ffmmc ff

Thermal and electrical energy can be transferred through the composite at a rate that is proportional to the volume fraction,

f of the conductive material

fm ff 1 that Note

ffmmc KfKfK ffmmc ff For thermal conductivity:For thermal conductivity: For electrical conductivity:For electrical conductivity:

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RULE OF MIXTURESRULE OF MIXTURESIn a composite material with a metal matrix and ceramic In a composite material with a metal matrix and ceramic

fibers, the bulk of the energy would be transferred fibers, the bulk of the energy would be transferred through the matrix.through the matrix.

In a composite consisting of a polymer matrix containing In a composite consisting of a polymer matrix containing metallic fibers, the energy would be transferred metallic fibers, the energy would be transferred

through the fibers.through the fibers.

When the fibers are not continuous or unidirectional, the When the fibers are not continuous or unidirectional, the simple rule of mixtures may not apply.simple rule of mixtures may not apply.

For example, in a metal fiber-polymer matrix composite, For example, in a metal fiber-polymer matrix composite, electrical conductivity would be low and would electrical conductivity would be low and would depend on the length of the fibers, the volume depend on the length of the fibers, the volume

fraction of fibers and how often the fibers touch one fraction of fibers and how often the fibers touch one another.another.

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RULE OF MIXTURESRULE OF MIXTURESThe rule of mixtures can also be used to predict the modulus of The rule of mixtures can also be used to predict the modulus of

elasticity when the fibers are continuous and unidirectional. elasticity when the fibers are continuous and unidirectional.

Parallel to the fibers, the modulus of elasticity may be as high as:Parallel to the fibers, the modulus of elasticity may be as high as:

ffmmc EfEfE

ffc EfE

However, when the applied load is However, when the applied load is very large, the matrix begins to deform very large, the matrix begins to deform and the stress-strain curve is no and the stress-strain curve is no longer linear. Since the matrix now longer linear. Since the matrix now contributes little to the stiffness, the contributes little to the stiffness, the modulus is approximated by:modulus is approximated by:

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RULE OF MIXTURESRULE OF MIXTURES

Perpendicular to the fibers, the modulus of elasticity may be as Perpendicular to the fibers, the modulus of elasticity may be as high as:high as:

There are many good examples provided in your text by Askland and Phule in the chapter, “Composites: Teamwork

and Synergy in Materials”. Review this chapter and the examples provided.

m

m

f

f

c E

f

E

f

E

1

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FIBER REINFORCED FIBER REINFORCED COMPOSITESCOMPOSITES

-Fiber reinforced composites provide improved strength, -Fiber reinforced composites provide improved strength, fatigue resistance, Young’s modulus and strength to fatigue resistance, Young’s modulus and strength to

weight ratio over the constituent materials.weight ratio over the constituent materials.

-This is achieved by incorporating strong, stiff, yet brittle -This is achieved by incorporating strong, stiff, yet brittle fibers into a more ductile matrix.fibers into a more ductile matrix.

-Generally speaking the fiber supplies the strength and -Generally speaking the fiber supplies the strength and stiffness while the matrix binds the fibers together and stiffness while the matrix binds the fibers together and

provides a means of transferring the load between fibersprovides a means of transferring the load between fibers

-The matrix also provides protection for the fibers-The matrix also provides protection for the fibers

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CHARACTERISTICS OF FIBER CHARACTERISTICS OF FIBER REINFORCED COMPOSITESREINFORCED COMPOSITES

-Many factors must be considered when designing a fiber--Many factors must be considered when designing a fiber-reinforced composite including the length, diameter, orientation, reinforced composite including the length, diameter, orientation,

amount and properties of the constituents, and the bonding amount and properties of the constituents, and the bonding between them.between them.

-The method used to produce the final product is also very -The method used to produce the final product is also very important as it dictates the type of properties just mentioned as important as it dictates the type of properties just mentioned as

well as the quality of the product.well as the quality of the product.

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CHARACTERISTICS OF FIBER CHARACTERISTICS OF FIBER REINFORCED COMPOSITESREINFORCED COMPOSITES

Fiber length and diameter: Fiber dimensions are characterized by Fiber length and diameter: Fiber dimensions are characterized by their aspect ratio their aspect ratio l/dl/d where where ll is the fiber length and is the fiber length and dd is the is the

diameter.diameter.

The strength improves when the aspect ratio is large.The strength improves when the aspect ratio is large.

Typical fiber diameters are from 10 Typical fiber diameters are from 10 m to 150 m to 150 m. m.

Fibers often fracture because of surface imperfections. Making Fibers often fracture because of surface imperfections. Making the diameter small reduces its surface area, which has fewer the diameter small reduces its surface area, which has fewer

flaws.flaws.

Long fibers are preferred because the ends of the fiber carry less Long fibers are preferred because the ends of the fiber carry less of the load. Thus the longer the fiber, the fewer the ends and the of the load. Thus the longer the fiber, the fewer the ends and the

higher the load carrying capacity of the fibers. higher the load carrying capacity of the fibers.

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CHARACTERISTICS OF FIBER CHARACTERISTICS OF FIBER REINFORCED COMPOSITESREINFORCED COMPOSITES

-As can be seen -As can be seen from this plot, the from this plot, the

strength of the strength of the composite composite

increases as the increases as the fiber length fiber length

increases (this is a increases (this is a chopped E-glass-chopped E-glass-epoxy composite)epoxy composite)

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FIBER ORIENTATIONFIBER ORIENTATION

-Maximum strength is -Maximum strength is obtained when long fibers are obtained when long fibers are

oriented parallel to the oriented parallel to the applied loadapplied load

-The effect of fiber orientation -The effect of fiber orientation and strength can be seen in and strength can be seen in

the plotthe plot

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FIBER ORIENTATIONFIBER ORIENTATION

-The properties of fiber -The properties of fiber composites can be composites can be

tailored to meet different tailored to meet different loading requirementsloading requirements

-By using combinations of -By using combinations of different fiber orientation different fiber orientation quasi-isotropic materials quasi-isotropic materials

may be produced may be produced

Figure (a) shows a unidirectional arrangement

Figure (b) shows a quasi-isotropic arrangement

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FIBER ORIENTATIONFIBER ORIENTATION

-A three dimensional -A three dimensional weave is also possibleweave is also possible

-This could be found -This could be found when fabrics are knitted when fabrics are knitted

or weaved together or weaved together

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FIBER PROPERTIESFIBER PROPERTIES

In most fiber-reinforced composites, the fibers are strong, stiff In most fiber-reinforced composites, the fibers are strong, stiff and lightweight.and lightweight.

If the composite is to used at elevated temperatures, the fiber If the composite is to used at elevated temperatures, the fiber should also have a high melting temperature.should also have a high melting temperature.

The specific strength and specific modulus of fibers are The specific strength and specific modulus of fibers are important characteristics given by:important characteristics given by:

TS

Strength Specific E

modulus Specific

Where Where TSTS is the tensile strength, is the tensile strength, EE is the elastic modulus is the elastic modulus and and is the density. is the density.

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FIBER PROPERTIESFIBER PROPERTIES

-On the left is a graph -On the left is a graph showing specific strength showing specific strength vs. specific modulus for vs. specific modulus for different types of fibersdifferent types of fibers

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TYPES OF FIBERSTYPES OF FIBERS

Some commonly used fibers for polymer matrix composites: Some commonly used fibers for polymer matrix composites:

-Glass fibers-Glass fibers

-Carbon fibers -Carbon fibers

-Aramid fibers-Aramid fibers

Some commonly used fibers for metal matrix composites:Some commonly used fibers for metal matrix composites:

-Boron fibers-Boron fibers

-Carbon fibers-Carbon fibers

-Oxide ceramic and non-oxide ceramic fibers-Oxide ceramic and non-oxide ceramic fibers

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GLASS FIBERSGLASS FIBERS-Due to the relatively inexpensive cost glass fibers are the -Due to the relatively inexpensive cost glass fibers are the

most commonly used reinforcementmost commonly used reinforcement

-There are a variety of types of glass, they are all compounds -There are a variety of types of glass, they are all compounds of silica with a variety of metallic oxidesof silica with a variety of metallic oxides

Designation: Property or Characteristic:

E, electrical low electrical conductivity

S, strength high strength

C, chemical high chemical durability

M, modulus high stiffness

A, alkali high alkali or soda lime glass

D, dielectric low dielectric constant

-The most commonly used glass is E-glass, this is the most -The most commonly used glass is E-glass, this is the most popular because of it’s costpopular because of it’s cost

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CARBON FIBERSCARBON FIBERS

-Carbon fibers have gained a lot of popularity in the last two -Carbon fibers have gained a lot of popularity in the last two decades due to the price reductiondecades due to the price reduction

““Carbon fiber composites are five times stronger than 1020 Carbon fiber composites are five times stronger than 1020 steel yet five times lighter. In comparison to 6061 aluminum, steel yet five times lighter. In comparison to 6061 aluminum, carbon fiber composites are seven times stronger and two carbon fiber composites are seven times stronger and two

times stiffer yet still 1.5 times lighter”times stiffer yet still 1.5 times lighter”

-Initially used exclusively by the aerospace industry they are -Initially used exclusively by the aerospace industry they are becoming more and more common in fields such as becoming more and more common in fields such as automotive, civil infrastructure, and paper productionautomotive, civil infrastructure, and paper production

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ARAMID FIBERSARAMID FIBERS

-Aramid fibers are also becoming more and more -Aramid fibers are also becoming more and more commoncommon

-They have the highest level of specific strength of all -They have the highest level of specific strength of all the common fibersthe common fibers

-They are commonly used when a degree of impact -They are commonly used when a degree of impact resistance is required such as in ballistic armourresistance is required such as in ballistic armour

-The most common type of aramid is Kevlar-The most common type of aramid is Kevlar

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COMPARATIVE COST OF FIBER COMPARATIVE COST OF FIBER REINFORCEMENTREINFORCEMENT

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COMMERCIALLY AVAILABLE COMMERCIALLY AVAILABLE FORMS OF REINFORCEMENTFORMS OF REINFORCEMENT

-Filament: a single thread like fiber-Filament: a single thread like fiber

-Roving: a bundle of filaments wound to form a large -Roving: a bundle of filaments wound to form a large strandstrand

-Chopped strand mat: assembled from chopped filaments -Chopped strand mat: assembled from chopped filaments bound with a binderbound with a binder

-Continuous filament random mat: assembled from -Continuous filament random mat: assembled from continuous filaments bound with a bindercontinuous filaments bound with a binder

-Many varieties of woven fabrics: woven from rovings-Many varieties of woven fabrics: woven from rovings

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MECH 473 ~ LECTURE 15: MECH 473 ~ LECTURE 15: COMPOSITESCOMPOSITES

COMMERCIALLY AVAILABLE COMMERCIALLY AVAILABLE FORMS OF REINFORCEMENTFORMS OF REINFORCEMENT

Above Left: RovingAbove Left: Roving

Above Right: FilamentsAbove Right: Filaments

Right: Close up of a rovingRight: Close up of a roving

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COMMERCIALLY AVAILABLE COMMERCIALLY AVAILABLE FORMS OF REINFORCEMENTFORMS OF REINFORCEMENT

Random mat and woven fabric

(glass fibers)

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COMMERCIALLY AVAILABLE COMMERCIALLY AVAILABLE FORMS OF REINFORCEMENTFORMS OF REINFORCEMENT

Carbon fiber woven fabric

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MATRIX MATERIALSMATRIX MATERIALS

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POLYMER MATRIX MATERIALPOLYMER MATRIX MATERIAL-There are two basic categories of polymer matrices:-There are two basic categories of polymer matrices:

-Thermoplastics-Thermoplastics

-Thermoset plastics-Thermoset plastics

-Roughly 95% of the composite market uses thermosetting -Roughly 95% of the composite market uses thermosetting plasticsplastics

-Thermoseting plastics are polymerized in two ways:-Thermoseting plastics are polymerized in two ways:

-By adding a catalyst to the resin causing the resin to ‘cure’, -By adding a catalyst to the resin causing the resin to ‘cure’, basically one must measure and mix two parts of the resin basically one must measure and mix two parts of the resin

and apply it before the resin curesand apply it before the resin cures

-By heating the resin to it’s cure temperature-By heating the resin to it’s cure temperature

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POLYMER MATRIX MATERIALPOLYMER MATRIX MATERIALCommon thermosetting plastics:Common thermosetting plastics:

--PhenolicsPhenolics: good electrical properties, often used in : good electrical properties, often used in circuit board applicationscircuit board applications

--EpoxiesEpoxies: low solvent emission (fumes) upon curing, low : low solvent emission (fumes) upon curing, low shrink rate upon polymerization which produces a shrink rate upon polymerization which produces a

relatively residual stress-free bond with the reinforcement, relatively residual stress-free bond with the reinforcement, it is the matrix material that produces the highest strength it is the matrix material that produces the highest strength

and stiffness, often used in aerospace applicationsand stiffness, often used in aerospace applications

--PolyesterPolyester: most commonly used resin, slightly weaker : most commonly used resin, slightly weaker than epoxy but about half the price, produces emission than epoxy but about half the price, produces emission when curing, used in everything from boats to RVs to when curing, used in everything from boats to RVs to

piping to Corvette bodiespiping to Corvette bodies

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METAL MATRIX MATERIALMETAL MATRIX MATERIAL

Common Metal Matrices:Common Metal Matrices:

-Metal martices include aluminum, magnesium, copper, -Metal martices include aluminum, magnesium, copper, nickel, and intermetallic compound alloysnickel, and intermetallic compound alloys

--MMCs are better at higher temperatures than PMCs MMCs are better at higher temperatures than PMCs although production is much more difficult and expensivealthough production is much more difficult and expensive

-MMCs can have applications such as fan blades in -MMCs can have applications such as fan blades in engines, clutch and brake linings, engine cylinder liners, engines, clutch and brake linings, engine cylinder liners,

etc.etc.

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MANUFACTURING WITH MANUFACTURING WITH POLYMER MATRIX MATERIALSPOLYMER MATRIX MATERIALS

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

-The method of manufacturing composites is very -The method of manufacturing composites is very important to the design and outcome of the productimportant to the design and outcome of the product

-With traditional materials one starts out with a blank piece -With traditional materials one starts out with a blank piece of material ie: rod, ingot, sheet, etc and works it to produce of material ie: rod, ingot, sheet, etc and works it to produce

the desired part. the desired part.

-However, this is not the case with polymer-matrix -However, this is not the case with polymer-matrix composites.composites.

-With these composites the material and the component -With these composites the material and the component are being produced at the same time, therefore we aim for are being produced at the same time, therefore we aim for the product to be a net or near net shape with little to no the product to be a net or near net shape with little to no

post processingpost processing

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Hand Lay-Up/Spray-UpHand Lay-Up/Spray-Up-Oldest and most commonly used manufacturing method -Oldest and most commonly used manufacturing method

-Usually used to produce polyester or epoxy resin parts such as boat -Usually used to produce polyester or epoxy resin parts such as boat hulls, tanks and vessels, pick-up truck canopieshulls, tanks and vessels, pick-up truck canopies

-The method is quite simple, the resin and reinforcement is placed -The method is quite simple, the resin and reinforcement is placed against the surface of an open (one sided) mold and allowed to cure or against the surface of an open (one sided) mold and allowed to cure or

in the case of spray-up the resin/reinforcement is sprayed onto the in the case of spray-up the resin/reinforcement is sprayed onto the mold with a spray gunmold with a spray gun

-Often a gel coat is applied to the mold prior to -Often a gel coat is applied to the mold prior to produce a better surface quality and protect the produce a better surface quality and protect the composite from the elementscomposite from the elements-A gel coat is a resin usually 0.4 to 0.7 mm -A gel coat is a resin usually 0.4 to 0.7 mm thick, commonly seen on the outer surface of thick, commonly seen on the outer surface of smaller boatssmaller boats

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Hand Lay-Up/Spray-UpHand Lay-Up/Spray-Up-The pros of this process include: low initial start up cost, easy to -The pros of this process include: low initial start up cost, easy to

change mold/design, on-site production possible (ie portable process) change mold/design, on-site production possible (ie portable process)

-The cons include: labor intensive, the quality of parts depends on -The cons include: labor intensive, the quality of parts depends on operator’s skill and therefore inconsistent, only one good side to the operator’s skill and therefore inconsistent, only one good side to the

part part

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

PrepregPrepreg

-A pregreg (short for preimpregnated) is a composite that -A pregreg (short for preimpregnated) is a composite that comes with the resin already added to the reinforcementcomes with the resin already added to the reinforcement

-This means that the only concern when working with -This means that the only concern when working with prepreg is shaping the partprepreg is shaping the part

-Since the resin is already mixed (resin and catalyst) there -Since the resin is already mixed (resin and catalyst) there is a limited shelf lifeis a limited shelf life

-For the same reason prepreg must be cured in an oven or -For the same reason prepreg must be cured in an oven or autoclaveautoclave

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

PrepregPrepreg-Prepreg can be used in a few different ways-Prepreg can be used in a few different ways

-It can be placed against a mold similar to the hand lay-up method-It can be placed against a mold similar to the hand lay-up method

-Once placed in the mold the material must be compressed and cured -Once placed in the mold the material must be compressed and cured according to a specific pressure/temperature cycleaccording to a specific pressure/temperature cycle

-This is often done by means of a vacuum bag where a thin plastic cover is -This is often done by means of a vacuum bag where a thin plastic cover is secured overtop of the composite and the air is vacuumed out secured overtop of the composite and the air is vacuumed out

-This process can reduce manufacturing time and produce a stronger part-This process can reduce manufacturing time and produce a stronger part

(if a knitted preform is used)(if a knitted preform is used)

-Another process used is ‘automated tape lay-up’-Another process used is ‘automated tape lay-up’

-This process uses a large automated roller similar to a packing tape roller -This process uses a large automated roller similar to a packing tape roller

-The roller applies the tape with pressure which eliminates the need for a -The roller applies the tape with pressure which eliminates the need for a vacuum bagvacuum bag

- Automated tape lay-up is used to produce large parts, generally in - Automated tape lay-up is used to produce large parts, generally in aerospace applications and is also capable of 3-d partsaerospace applications and is also capable of 3-d parts

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

PultrusionPultrusion-Similar to extrusion of metal parts -Similar to extrusion of metal parts

-Pultrusion involves pulling resin-impregnated glass strands through a die-Pultrusion involves pulling resin-impregnated glass strands through a die

-Standard extruded shapes can easily be produced such as pipes, -Standard extruded shapes can easily be produced such as pipes, channels, I-beams, etc.channels, I-beams, etc.

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

PultrusionPultrusion

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Filament WindingFilament Winding

-A continuous reinforcement, either previously impregnated or impregnated -A continuous reinforcement, either previously impregnated or impregnated during winding is wound around a rotating mandrel to form a composite partduring winding is wound around a rotating mandrel to form a composite part

-Pros: fast lay-up speed, very accurate and repeatable product, possibility to -Pros: fast lay-up speed, very accurate and repeatable product, possibility to use continuous fiberuse continuous fiber

-Cons: expensive equipment, high cost for mandrel, poor surface finish, -Cons: expensive equipment, high cost for mandrel, poor surface finish, some shapes not possiblesome shapes not possible

-Examples: oxygen bottles for firemen, rocket motors, tennis rackets, shafts-Examples: oxygen bottles for firemen, rocket motors, tennis rackets, shafts

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Filament WindingFilament Winding

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Filament WindingFilament Winding

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Resin Transfer MoldingResin Transfer Molding

-Resin transfer molding is a manufacturing method that is -Resin transfer molding is a manufacturing method that is quite similar to injection molding where plastic is injected quite similar to injection molding where plastic is injected

into a closed moldinto a closed mold

-In the RTM process the preform (precut piece(s) of -In the RTM process the preform (precut piece(s) of reinforcement) is placed in the mold, the mold is closed reinforcement) is placed in the mold, the mold is closed

and the thermoset plastic matrix is injected into the mold, and the thermoset plastic matrix is injected into the mold, once the matrix is cured the part is ejectedonce the matrix is cured the part is ejected

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Resin Transfer MoldingResin Transfer Molding

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MANUFACTURING OF POLYMER-MANUFACTURING OF POLYMER-MATRIX COMPOSITESMATRIX COMPOSITES

Resin Transfer MoldingResin Transfer MoldingPros:Pros:

-Complex components can be produced-Complex components can be produced-Components have two good surfaces-Components have two good surfaces

-Component can be created within a fairly tight tolerance-Component can be created within a fairly tight tolerance-High level of repeatability-High level of repeatability

-Process can be automated and repeated-Process can be automated and repeated-Process can be numerically modeled and analyzed-Process can be numerically modeled and analyzed

Cons:Cons:-Molds often need to be designed using trial and error methods-Molds often need to be designed using trial and error methods

-‘race tracking’ may occur-‘race tracking’ may occur-‘wash out’ may occur-‘wash out’ may occur

-Air voids are easily formed with poor process parameters-Air voids are easily formed with poor process parameters

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Resin Transfer MoldingResin Transfer Molding

Researcher from Aerospace Manufacturing Technology Center in Montreal molding members for a helicopter

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THE ENDTHE END

ANY QUESTIONS?ANY QUESTIONS?