ﺐﮐﺮﻣ ﺩﺍﻮﻣ ﮏﻴﻧﺎﮑﻣ - IAUNresearch.iaun.ac.ir/pd/atrian/pdfs/UploadFile_5041.pdf · Mechanics of Composite Materials نﺎﯾﺮﻄﻋ ﺮﯿﻣا ... 3.MechanicsofCompositeStructures,L.P.Kollar&G.S.Springer,Cambridge

Mechanics of Composite Mechanics of Composite

MaterialsMaterials

93-94

Islamic Azad University, Najafabad Branch, A.Atrian 2

References:

1. MECHANICS OF COMPOSITE MATERIALS, ROBERT M. JONES, Taylor &Francis, 1990

2. Mechanics of Composite Materials, Autar K. Kaw, 2nd Edition, Taylor &Francis, 2006

3. Mechanics of Composite Structures, L.P.Kollar & G.S.Springer, CambridgeUniversity Press, 2003

4. Fundamentals of Composite Materials, Vincent K. S. Choo, KNOWENACADEMIC PRESS, INC, 1990

5. MECHANICS AND ANALYSIS OF COMPOSITE MATERIALS, Valery V. Vasiliev& Evgeny V. Morozov, ELSEVIER, 2001

6. Metal Matrix Composites, Karl U. Kainer, WILEY-VCH, 2006

)( .7

Islamic Azad University, Najafabad Branch 3

Evaluation:

Project (Word, PDF): 25%--FE simulation or research projectFE simulation or research project--Final project must be in word template, edited and justified text with B Final project must be in word template, edited and justified text with B NazaninNazanin 13 13 for Farsi font and for Farsi font and Times New Roman Times New Roman 12 12 for English font.for English font.

Final: 75%--Chapters Chapters 1 1 (close book), (close book), 22--4 4 (open book)(open book)

Targets:-Knowing all kinds of composite materials-Selection & applications of composite materials-Manufacturing methods of composite materials-Analysis of composite materials


Table of Contents:

Chapter1: Introduction to Composite Materials (2 weeks)

Chapter2: Macromechanical Analysis of a Lamina (4 weeks)

Chapter3: Micromechanical Analysis of a Lamina (3 weeks)

Chapter4: Macromechanical Analysis of a Laminate (3 weeks)

And: Simulation of a fibrous composite in ABAQUS

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Chapter Chapter 11Introduction to Composite MaterialsIntroduction to Composite Materials

Definition Classification Applications Manufacturing

www.Scaled.com

Islamic Azad University, Najafabad Branch, A. Atrian


Introduction to Composite MaterialsIntroduction to Composite [email protected]@gmail.com

1.Definition:

Composite materials:-A composite is a structural material that consists of two or more combinedconstituents that are combined at a macroscopic level and are not soluble in eachother.-The key is the macroscopic examination of a material wherein the componentscan be identified by the naked eye.-Different materials can be combined on a microscopic scale, such as in alloying ofmetals, but the resulting material is, for all practical purposes, macroscopicallyhomogeneous, i.e., the components cannot be distinguished by the naked eye andessentially act together.

Natural Composites: Wood: The lignin matrix isreinforced with cellulose fibers Bone: The bone-salt plates made ofcalcium and phosphate ions reinforcesoft collagen

History:-Plywood in ancient Egyptians (1500 B.C)-Strengthening mud bricks by straw or bamboo shoots-Medieval swords and armor with layers of differentmetals (1800 A.D)-Glass fibers reinforced resins in boats & aircrafts(1930s)


Introduction to Composite MaterialsIntroduction to Composite Materials

2.Advantages, Limitations: Strength, StiffnessStrength, StiffnessCorrosion resistance, Wear resistanceCorrosion resistance, Wear resistanceAttractiveness, WeightAttractiveness, WeightFatigue lifeFatigue lifeTemperatureTemperature--dependent behaviordependent behaviorThermal conductivityThermal conductivityThermal insulation, Acoustical insulationThermal insulation, Acoustical insulation

Composites can improve these properties

For example, the strength of a graphite/epoxy unidirectional composite could be the same as steel, but the specific strength is three times that of steel.

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Approximate shipments of polymer-based compositesin 1995

Limitations: HighHigh costcost ofof fabricationfabrication HardHard toto recyclerecycle RepairRepair isis notnot aa simplesimple processprocess comparedcompared toto thatthat forfor metalsmetals MoreMore complexitycomplexity ofof MechanicalMechanical characterizationcharacterization CompositesComposites dodo notnot havehave aa highhigh combinationcombination ofof strengthstrength andand fracturefracture toughnesstoughnesscomparedcompared toto metalsmetals

Use of composites in the space shuttle



3.Classification:

Composites:

Matrix (The continuous phase):Purpose is to: Transfer stress to other phases Protect phases from environment

Classification: MMC, CMC &

Dispersed phase:Purpose is to: Enhance matrix properties (reinforcing)

Classification: Fiber, Flake, Particle



Types of composites

In case of the reinforcement

geometry--Fiber: Kevlar, Glass, Carbon, BoreFiber: Kevlar, Glass, Carbon, Bore--FlakeFlake--ParticulateParticulate

In case of the matrix material

--Metal Matrix Composite (MMC)Metal Matrix Composite (MMC)--Ceramic Matrix Composite (CMC)Ceramic Matrix Composite (CMC)--Organic Matrix Composite:Organic Matrix Composite:

PolymerPolymerCarbonCarbon

Structural--LaminateLaminate--BimetalBimetal--SandwichSandwich

Nanocomposites

FGM (Functionally Graded Material)

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Types of composites

Laminated--LaminateLaminate--BimetalBimetal--SandwichSandwich

Lamina (Fibrous)

Short Fiber:Short Fiber:--Regular fibersRegular fibers--Irregular fibersIrregular fibers

Long Fiber:Long Fiber:--UnidirectionalUnidirectional--Bidirectional (woven or fabric) Bidirectional (woven or fabric)

Particulate

Combinations of some or all of the first three

types




4.Fibrous Composite Materials:

Long Fiber (Continuous):-Unidirectional (a)-Bidirectional (woven fabric) (b)

Short Fiber (Discontinuous):-Regular fibers-Irregular fibers (c)

Whisker: A whisker has essentially thesame near-crystal-sized diameter as afiber, but generally is very short andstubby, although the length-to diameterratio can be in the hundreds.

Note:Long fibers in various forms are inherently much stiffer and stronger than thesame material in bulk form:Compare fracture stress of 20 MPa for glass plate with 2800 to 4800 MPa for glassfibers.

Why: In fibers, the crystals are aligned along the fiber axis. Moreover, there are fewer internal defects in fibers than in bulk material. For example, in materials that have dislocations, the fiber form has fewer dislocations than the bulk form.



Question: What are the main reasons for using fibers of thin diameter?

Fibers able to bend without breaking arerequired in manufacturing of compositematerials, especially for woven fabriccomposites: Ability to bend increases with adecrease in the fiber diameter and is measuredas flexibility.

As the fibers become smaller in diameter, the chances of an inherent flaw in thematerial are reduced: A steel plate may have strength of 689 MPa, while a wire madefrom this steel plate can have strength of 4100 MPa.

For higher ductility and toughness, andbetter transfer of loads from the matrix tofiber, composites require larger surfacearea of the fibermatrix interface: For thesame volume fraction of fibers in a composite,the area of the fibermatrix interface isinversely proportional to the diameter of thefiber.

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Introduction to Composite MaterialsIntroduction to Composite MaterialsMechanical performance of composites depends on:1.Fiber (Length, Orientation, Shape, Material)2.Matrix (Material)3.FiberMatrix Interface4.Distribution of reinforcement in matrix5.Volume fraction of each constituent material

Fiber & wireproperties

Note: High specific strength is suitable for aerospace applications.


4 important fiber factors:1.Length2.Orientation3.Shape4.Material


Introduction to Composite MaterialsIntroduction to Composite MaterialsFibers Material:

-Organic: Kevlar-Inorganic: Carbon, Graphite, Glass, Boron, Quartz,Silicon Carbide, Alumina-Metal Fibers (wire): St, Br, Ti, W, Mo

Kevlar (trade name of aramid fiber):

An aramid fiber is an aromatic organic compound made of carbon, hydrogen, oxygen,and nitrogen.

Advantages: lowest density between fibers (S=1.45), high tensile strength, low cost,& high impact resistance. Its specific strength is 8 times greater than titanium & 10times greater than steel & aluminum.

Drawbacks: low compressive properties and degradation in sunlight, low workingtemperature (less than 200 C), low ability to stand against compressive loads, lowspecific modulus

Types: Kevlar 29 & Kevlar 49. Both types of Kevlar fibers have similar specificstrengths, but Kevlar 49 has a higher specific stiffness.Kevlar 29 is mainly used in bulletproofbulletproof vestsvests, ropesropes, and cablescables.For CNGCNG capsulecapsule & High performance applications in the aircraftaircraft industryindustry use Kevlar 49.



Kevlar:Manufacturing: The fiber is produced by making a solution of proprietary polymersand strong acids such as sulfuric acid. The solution is then extruded into hotcylinders at 392F (200C), washed, and dried on spools. The fiber is then stretchedand drawn to increase its strength and stiffness.

Quartz:It is similar to glass fibers and isobtained by high-speedstretching of quartz rods madeof (under temperature of about2200C) fused quartz crystals orsand.

Islamic Azad University, Najafabad Branch, A. Atrian 17


Glass:Glass is the most common fiber used in polymer matrix composites.

Advantages: high strength, low cost, high chemical resistance, & good insulatingproperties.

Drawbacks: low elastic modulus, poor adhesion to polymers, high specific gravity,sensitivity to abrasion(reduces tensile strength), and low fatigue strength.

Types:EE--glassglass (also(also calledcalled fiberglass)fiberglass):: The E in E-glass stands for electrical because it wasdesigned for electrical applications. However, it is used for many other purposes now,such as decorationsdecorations and structuralstructural applicationsapplications.SS--glassglass:: The S in S-glass stands for higher content of silica. It retains its strength athigh temperatures compared to E-glass and has higher fatigue strength. It is usedmainly for aerospaceaerospace applicationsapplications.CC--glassglass:: The C stands for corrosion. It is used in chemical environments, such asstoragestorage tankstanksRR--glassglass:: used in structuralstructural applicationsapplications such as constructionconstructionDD--glassglass:: (dielectric) used for applications requiring low dielectric constants, such asradomes (i.e: radar+dome)AA--glassglass:: (appearance) used to improve surface appearance.Combination types such as EE--CRCR glassglass (E-CR stands for electrical and corrosionresistance) and ARAR glassglass (alkali resistant) also exist.



Glass:

Manufacturing: Glass fibers are made generally bydrawing from a melt. The melt is formed in a refractoryfurnace at about 25502550FF (1400C) from a mixture thatincludes sand, limestone, and alumina. The melt is stirredand maintained at a constant temperature. It passesthrough as many as 250 heated platinum alloy nozzles ofabout 394394 inin (10m) diameter, where it is drawn intofilaments of needed size at high speeds of about 361361 mi/hmi/h(25 m/s). These fibers are sprayed with an organic sizingsolution before they are drawn. The sizing solution is amixture of binders, lubricants, and coupling and antistaticagents; binders allow filaments to be packed in strands,lubricants prevent abrasion of filaments, and couplingagents give better adhesion between the inorganic glassfiber and the organic matrix.Fibers are then drawn into strands and wound on aforming tube. Strands are groups of more than 204filaments. The wound array of strands is then removedand dried in an oven to remove any water or sizingsolutions.



Schematic of manufacturing glass fibers



Carbon & Graphite:Are carbon and graphite the same?No, they are different. Carbon fibers have 93 to 95% carbon content, but graphite hasmore than 99% carbon content. Also, carbon fibers are produced at 24002400FF (1316C),and graphite fibers are typically produced in excess of 34003400FF (1900C).

The advantages of graphite fibers: high specific strength and modulus, lowcoefficient of thermal expansion, & high fatigue strength. Graphite fibers are verycommon in high-modulus and high-strength applications such as aircraftaircraft componentscomponents,etc.

Drawbacks: high cost, low impact resistance, and high electrical conductivity.

Manufacturing: Graphite fibers have been available since the late 1800s. However,only since the early 1960s has the manufacturing of graphite fibers taken off. Graphitefibers are generally manufactured from three precursor materials: rayonrayon,polyacrylonitrilepolyacrylonitrile (PAN)(PAN), and pitchpitch. PAN is the most popular precursor.

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Stages of manufacturing a carbon fiber from PAN-based precursors

Question: discuss aboutmanufacturing techniques ofcarbon & graphite fibers?




Boron:

boron fibers are made by vapor depositing boron on a tungsten wire and coating theboron with a thin layer of boron carbide.

Note: Why carbon or graphite fibers are produced very thin (far thinner than humanhairs), they can be woven into fabric. In contrast, The boron fibers due of itsmanufacturing method are about the diameter of mechanical pencil lead, so theycannot be bent or woven into fabric.

Specific Modulus and Specific Strength of Typical Fibers, Composites, and Bulk Metals

Question: Discuss &compare the propertiesof most used fibers?



5.Matrix Materials:

Purpose:-Support of the fibers or whiskers-Protection of the fibers or whiskers-Stress transfer between broken fibers or whiskers

Typically, the matrix is of considerably lower density, stiffness, and strengththan the fibers or whiskers. However, the combination of fibers or whiskersand a matrix can have very high strength and stiffness, yet still have lowdensity.

Types:11--PolymersPolymers22--MetalsMetals33--CeramicsCeramics44--CarbonCarbon



1.Polymer Matrix Composites (PMCs):

Types: RubbersRubbersThermoplastics: Thermoplastics: Nylon, Polyethylene, Polycarbonate, Polypropylene (PP) & Polysulfone ThermosetsThermosets: : Polyesters, Epoxy, Polyimide, Phenolic &

Limitations: low operating temperatures high coefficients of thermal and moisture expansion low elastic properties in certain directions.

Various polymers used in advanced polymer composites: Epoxy Phenolics Acrylic UrethanePolyamide

The most common fibers used in PMCs: Glass Graphite Kevlar Carbon



PhenolicsPhenolics:: The advantages are low cost and high mechanical strength Drawbacks include high void content.

PolyestersPolyesters:: The advantages are low cost and the ability to be made translucent; Drawbacks include service temperatures below 170F (77C),brittleness, and high shrinkage of as much as 8% during curing.

EpoxiesEpoxies:: Epoxy resins are the most commonly usedresins. They are low molecular weight organicliquids containing epoxide groups. The advantages are high mechanicalstrength and good adherence to metals andglasses. drawbacks are high cost and difficulty inprocessing.

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Introduction to Composite MaterialsIntroduction to Composite MaterialsQuestion: Why Epoxy is the most common type of matrix material?

Although epoxy is costlier than other polymer matrices, it is the most popular PMCmatrix. More than two-thirds of the polymer matrices used in aerospace applications areepoxy based.The main reasons why epoxy is the most used polymer matrix material are: High strength Low viscosity and low flow rates, which allow good wetting of fibers and preventmisalignment of fibers during processing Low volatility during cure Low shrink rates, which reduce the tendency of gaining large shear stresses of thebond between epoxy and its reinforcement Available in more than 20 grades to meet specific property and processingrequirements.

Differences between Thermosets & Thermoplastics




Typical applications of PMCs: AircraftAircraft SpaceSpace Sporting goodsSporting goods Medical devicesMedical devices MarineMarine

polyurethane-carbon seat for new BMW electric vehiclehttp://utech-polyurethane.com

Lamborghini carbon-fiber reinforced plastics (CFRP) technology used in: front frame structureexterior panelscrash boxesmajor suspension componentswheels and drive shafthttp://www.zerotohundred.com/



Compare polymer properties with metals

Question: What are prepregs?


Introduction to Composite MaterialsIntroduction to Composite MaterialsManufacturing techniques of polymer matrix composites:

Filament windingFilament winding(used generally for making pipes and tanks to handle chemicals)-Wet winding-Dry winding

PultrusionPultrusion

Wet/Hand lay upWet/Hand lay up

Autoclave formingAutoclave forming(used to make complex shapes and flat panels for structures in which lowvoid content and high quality are important)

Resin transfer molding Resin transfer molding (RTM)(RTM)(used extensively in the automotiveindustry because short production runsare necessary).


Introduction to Composite MaterialsIntroduction to Composite Materials2.Metal Matrix Composites (MMCs):

Types: Common matrix examples include Al, Mg, Ti, & Ni-Cr alloys

Metal matrix composites are mainly used to provide advantages overmonolithic metals such as steel and aluminum.

The ceramic reinforcement is selected by its performance attributes: carbon/graphite brings lubricitylubricity silicon carbide (SiC) brings stiffness and wear resistance alumina (AL2O3) brings strength at elevated temperatures

These advantages include: Higher specific strength and modulus by reinforcing low-densitymetals, such as Al & Ti; Lower coefficients of thermal expansion & thermal & electricalconductivity by reinforcing with fibers with low coefficients of thermalexpansion, such as graphite & silicon carbide; Maintaining properties such as strength at high temperatures.

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Introduction to Composite MaterialsIntroduction to Composite MaterialsAdvantages of MMCs over polymer matrix composites: Higher elastic properties; Higher service temperature; Insensitivityto moisture; Higher electric and thermal conductivities; Better wear,Fatigue, and Flaw resistances.

The drawbacks of MMCs over PMCs include: Higher processing temperatures and higher densities.


Question: Do anyproperties degrade whenmetals are reinforced withfibers?-Yes, it may reduce ductility& fracture toughness



Schematic presentation of the manufacturing process for PM-MMCs

Applications: SpaceSpace MilitaryMilitary TransportationTransportation

Manufacturing techniques:

MeltingMelting metallurgicalmetallurgical processprocess PowderPowder metallurgicalmetallurgical processprocess Diffusion bondingDiffusion bonding

MMC brake disk-functionally reinforced gradient (FRG)http://www.relinc.net/adv-materials/metal-matrix-composite/


Introduction to Composite MaterialsIntroduction to Composite Materials3.Ceramic Matrix Composites (CMCs):

Types: Ceramic matrix composites (CMCs) have a ceramic matrix such as alumina,SiC, Carbon, Mullite (Al2O3-SiO2) reinforced by fibers such as carbon orsilicon carbide.

Advantages: High strength, Hardness, High service temperature limits for ceramics,Chemical inertness, & Low density.

However, ceramics bythemselves have low fracturetoughness. Under tensile orimpact loading, they failcatastrophically Reinforcingceramics with fibers, such assilicon carbide or carbon,increases their fracturetoughness.


Introduction to Composite MaterialsIntroduction to Composite MaterialsManufacturing techniques: CMCsCMCs cancan bebe castcast fromfrom aa moltenmolten slurryslurry aroundaround stirredstirred--inin fibersfibers withwith randomrandomorientationorientation oror withwith preferredpreferred flowflow--directiondirection orientationorientation.. CMCsCMCs cancan bebe vaporvapor depositeddeposited aroundaround aa collectioncollection ofof alreadyalready inin--placeplace fibersfibers.. PlasmaPlasma sprayingspraying PowderPowder metallurgymetallurgy methodsmethods CastingCasting DiffusionDiffusion weldingwelding

LAS: Lithium aluminosilicate, CAS: Calcium aluminosilicate

Applications: InIn highhigh temperaturetemperature areasareas ininwhichwhich metalmetal andand polymerpolymermatrixmatrix compositescomposites cannotcannot bebeusedused (thermal(thermal shieldsshields inin spacespacevehicles,vehicles, gasgas turbine,turbine, && etc)etc) CuttingCutting tooltool insertsinserts ininoxidizingoxidizing andand highhigh--temperaturetemperature environmentsenvironments.. BrakeBrake discsdiscs SlideSlide bearingsbearings

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A typical application of CMCs:The GE Rolls-Royce Fighter Engine Teams F136 Engine for the Joint Strike Fighter (JSF) The first commercial use of CMCs in a jet engines hot section (combustor and turbine areas) (2010). Parts made from CMSs (SiC ceramic fibers and ceramic resin): thirdthird--stage, lowstage, low--pressure turbine vanespressure turbine vanesoo manufactured through a highly sophisticated process, and further enhanced with manufactured through a highly sophisticated process, and further enhanced with proprietary coatings?proprietary coatings?

http://www.eng.fea.ru/FEA_news_600.html

Advantages:1. They are lightweight 1/3th the density of metal: providing weight reduction and thus, better fuel efficiency. 2. They are durable and more heat resistant than metals, requiring less cooling air, and thereby improving overall engine efficiency.


Introduction to Composite MaterialsIntroduction to Composite Materials4.Carbon Matrix Composites:

Carboncarbon composites use carbon fibers in a carbon matrix. Thesecomposites are used in very high-temperature environments of up to 6000F(3315C), and are 20 times stronger and 30% lighter than graphite fibers

Advantages:Carbon is brittle and flaw sensitive like ceramics Reinforcement of a carbonmatrix allows the composite to fail gradually and also gives advantages suchas ability to withstand: high temperatures low creep at high temperatures, low density good tensile and compressive strengths high fatigue resistance high thermal conductivity high coefficient of friction

Drawbacks: high cost low shear strength oxidations at high temperatures


Introduction to Composite MaterialsIntroduction to Composite MaterialsManufacturing techniques: vaporvapor depositiondeposition onon anan alreadyalready inin--placeplace fiberfiber systemsystem.. liquidliquid materialmaterial cancan bebe infiltratedinfiltrated aroundaround inin--placeplace fibersfibers andand thenthen carbonizedcarbonized ininplaceplace byby heatingheating toto highhigh temperaturetemperature.. TheThe processprocess involvinginvolving liquidliquid infiltrationinfiltration andandcarbonizationcarbonization mustmust bebe repeatedrepeated manymany timestimes becausebecause carbonizingcarbonizing thethe liquidliquid resultsresultsinin decreaseddecreased volumevolume ofof thethe matrixmatrix.. UntilUntil thethe voidsvoids cancan nono longerlonger bebe filledfilled (they(theybecomebecome disconnecteddisconnected asas densificationdensification continues),continues), thethe potentialpotential matrixmatrix strengthstrengthandand stiffnessstiffness havehave notnot beenbeen achievedachieved.. LowLow--pressurepressure carbonizationcarbonization

Applications: Space shuttle nose conesSpace shuttle nose cones Aircraft brakesAircraft brakes Mechanical fastenersMechanical fasteners

Lightweight, scratch resistance CMC (C/C) encasement for CARRERA chronograph



6.Particulate Composite Materials:

1.Nonmetallic Particles in Nonmetallic Matrix Composite MaterialsConcrete, Mika/Glass (electrical applications because of good insulating and machining qualities), Glass/Plastic (similar applications)

2.Metallic Particles in Nonmetallic Matrix Composite MaterialsAl powder and perchlorate oxidizers in a flexible organic binder such aspolyurethane or polysulfide rubber (Solid-rocket propellants), Al flakes inpaint,

3.Metallic Particles in Metallic Matrix Composite MaterialsLead particles in copper alloys (to improve the machinability, applications:self lubricant bearings),



4.Nonmetallic Particles In Metallic Matrix Composite Materials

Cermet: Ceramics particles suspended in a metal matrix:1.oxide particles: Such cermets are used in tool making & high-temperatureapplications where erosion resistance is needed

2. carbide-based: carbides of W, Cr & Ti

ManufacturingManufacturing techniquestechniques:: ??

Titanium carbide(TiC) in either a nickelor a cobalt matrix: forhigh-temperatureapplications such asturbine parts.

Tungsten carbide(WC) in a Co matrix: formachine parts requiringvery high hardness suchas wire-drawing dies,valves, etc.

Chromium carbide ina cobalt matrix: It hashigh corrosion andabrasion resistance; italso has a coefficient ofthermal expansion closeto that of steel, so iswell-suited for use invalves.

Cermets are also used as nuclear reactor fuel elements and controlrods: Fuel elements can be uranium oxide particles in stainless steelceramic & boron carbide (B4C) in stainless steel is used for control rods.



7.Laminated Composite Materials:

Types: Bimetals Clad metals Sandwich structures Laminated fiber-reinforced composites

The properties that can be emphasized by lamination: strength & stiffness & low weight corrosion & wear resistance beauty or attractiveness thermal insulation & acoustical insulation

Design of laminated composites includes constraints on optimizing &constraining factors such as: Cost Mass as related to aerospace and automotive industry to reduce energy cost Stiffness (to limit deformations) as related to aircraft skins to avoid buckling Thermal and moisture expansion coefficients as related to space antennas tomaintain dimensional stability

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BimetalsBimetals:: for temperature-measuring devices, vessels & energy absorbant (apolymeric layer sandwiched by two metal skin) & etc.

CladClad MetalsMetals:: The cladding or sheathing of one metal with another is done toobtain the best properties of both. For example: high-strength Al alloys do not resist corrosion; however, purealuminum and some Al alloys are very corrosion resistant but relatively weak.Thus, a high-strength aluminum alloy covered with a corrosion-resistant Alalloy is a composite material with both high strength and corrosionresistance.



Introduction to Composite MaterialsIntroduction to Composite MaterialsSandwichSandwich StructuresStructures:: Theyre 3-layered laminates consisting of thin facingsand a light-weight honeycombhoneycomb or foamfoam or core.

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Applications: InIn aerospaceaerospace && automotiveautomotive industriesindustries:: fuselage,fuselage, energyenergy absorptionabsorption && InIn laminatedlaminated glassglass::Ordinary window glass: durable enough to retain its transparency under the extremesof weather, brittle & dangerous when breaked.-A plastic called polyvinyl butyral is very tough (deforms to high strains withoutfracture), but is very flexible and susceptible to scratching.-Safety glass is a layer of polyvinyl butryal sandwiched between two layers ofglass. The glass in the composite material protects the plastic from scratching andgives it stiffness. The plastic provides the toughness of the composite material.


Introduction to Composite MaterialsIntroduction to Composite MaterialsLaminatedLaminated FiberFiber--ReinforcedReinforced CompositesComposites::

Lamina (Ply or Layer): a flat(sometimes curved as in a shell)arrangement of unidirectional fibers orwoven fibers in a matrix (e.g. boron-epoxy & graphite-epoxy)

Laminate: A laminate is a bonded stack of laminae withvarious orientations of principal material directions in thelaminae. The layers of a laminate are usually bondedtogether by the same matrix material that is used in theindividual laminae.

A major purpose of lamination is: toto tailortailor thethe directionaldirectional dependencedependence ofof strengthstrength &&stiffnessstiffness ofof aa compositecomposite materialmaterial toto matchmatch thethe loadingloadingenvironmentenvironment ofof thethe structuralstructural elementelement

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Fabric:Fabric: Unidirectional Bidirectional: Plain, Twill, Satin, Basket, Leno

Manufacture of Laminated FiberManufacture of Laminated Fiber--Reinforced Composite Materials:Reinforced Composite Materials:

Winding

Laying

Molding

Filament windingTape laying or wrappingCloth winding or wrapping

BasketPlainLenoTwillSatin


Introduction to Composite MaterialsIntroduction to Composite Materials8.Nanocomposites:

Consist of materials that are of the scale of nanometers (10^9 m). Theaccepted range to be classified as a nanocomposite is that one of theconstituents is less than 100 nm.

Adding particles like carbon nano tube or ceramic nano particles (alumina,SiC, B4C, & etc) to polymeric or metallic matrix (Al, mg, ) can produce anano composite.

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Processing techniques: Mechanical Thermo-mechanical Powder Metallurgy Non-equilibrium Chemical/Electrical

Powder Metallurgy: Spark plasma sintering (SPS) Selective laser sintering (SLS) Hot isostatic pressing (HIP) Hot pressing Hot extrusion Cold pressing and sintering Cold isostatic pressing (CIP)+sintering



9.Functionally Graded Materials (FGM):

A functionally graded material (FGM) is a two-component compositecharacterized by a compositional gradient from one component to theother. In contrast, traditional composites are homogeneous mixtures.

FGMs were invented in 1984 during the space-plane projects in Japan.

Applications: AerospaceAerospace ThermalThermal ShieldShield SensorSensor (FGPM)(FGPM) BiomedicalBiomedical

Graded Cu/W composite produced by electrochemical gradation

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Processing techniques (FGMs):

Controlled mold filling

Centrifugal Powder Forming

Powder Metallurgy: Centrifugal powder forming (CPF),Spark Plasma Sintering (SPS), Selective Laser Sintering(SLS), Hot Isostatic Pressing (HIP), & etc.

Melt processing: Centrifugal casting, Sedimentation casting, Controlled mold filling , & etc.

Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD)

Using magnetic forces


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10.Fabrication and characterization of a typical metal-matrixnanocomposite (MMNC) using powder metallurgy (Al7075-SiC):

1- Materials: Al7075 powder as the matrix (gas atomized, 100 um, irregular morphology) SiC as the reinforcing particles (average 50 nm, nearly spherical morphology)


Agglomeration

50


2- Processing

a. Ultrasonic vibration (to prevent clustering )

mixing manually Suspending mixture in ethanol ultrasonic vibration for 30 min drying


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Introduction to Composite MaterialsIntroduction to Composite Materialsb. Mechanical milling (to uniform mixing)-milling the mixture in a planetary ball mill temperature? atmosphere? ball-to-powder mass ratio? No. of balls? time duration? rotational speed? additives?


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c. Powder consolidation (pressing and sintering)- Pouring the milled powder in the die hole- Using one of the below techniques:Hot quasi-static pressingHot dynamic compaction Or: HIP, Hot extrusion, &


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d. Characterization (mechanical & microstructural) Density (Archimedes) Micro-hardness (Vickers) Quasi-static compressive test (ASTM) Dynamic compressive test (Split Hopkinson Pressure Bar: SHPB) Diametrical compressive test (Brazilian disk) Wear test (Pin-on-disk)


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SEM micrograph


Agglomeration (clustering) of nano particles in Al7075-10 vol% SiC nanocomposite

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Temperature effect

What are the strengthening mechanisms in particle-reinforced composites?


Temperature effects on microstructure and qualityof Al7075 dynamically compacted sample



11.Mechanical Behavior of Composite Materials

Homogeneous: A homogeneous body has uniform properties throughout,i.e., the properties are independent of position in the body.

Isotropic: An isotropic body has material properties that are the same inevery direction at a point in the body, i.e., the properties are independentof orientation at a point in the body.

Note: Composite materials areoften both inhomogeneous &anisotropic

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There are two points of view tostudy the composite materials:

MicromechanicsMicromechanics:: the study of compositematerial behavior wherein the interactionof the constituent materials is examined ona microscopic scale to determine theireffect on the properties of the compositematerial.

MacromechanicsMacromechanics:: the study of compositematerial behavior wherein the material ispresumed homogeneous and the effectsof the constituent materials are detectedonly as averaged apparent macroscopicproperties of the composite material.


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ﺐﮐﺮﻣ ﺩﺍﻮﻣ ﮏﻴﻧﺎﮑﻣ - IAUNresearch.iaun.ac.ir/pd/atrian/pdfs/UploadFile_5041.pdf · Mechanics of Composite Materials نﺎﯾﺮﻄﻋ ﺮﯿﻣا ... 3.MechanicsofCompositeStructures,L.P.Kollar&G.S.Springer,Cambridge