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KOMPOSIT

Fibers

Tipe-tipe Komposit BerdasarkanMaterial Penyusunnya

Matrix phase/Reinforcement Phase

Metal Ceramic Polymer

Metal Powder metallurgy parts – combining immiscible metals

Cermets (ceramic-metal composite)

Brake pads

Ceramic Cermets, TiC, TiCNCemented carbides –used in toolsFiber-reinforced metals

SiC reinforced Al2O3 Tool materials

Fiberglass

Polymer Kevlar fibers in an epoxy matrix

Elemental (Carbon, Boron, etc.)

Fiber reinforced metalsAuto partsaerospace

Rubber with carbon (tires)Boron, Carbon reinforced plastics

MMC’s CMC’s PMC’sMetal Matrix Composites Ceramic Matrix Comp’s. Polymer Matrix Comp’s

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Penguatan oleh FiberPada umumnya, komposit terdiri dari matriks yang menyatukan material penguat (reinforcing materials). Material penguat yang paling penting adalah berbentuk fiber yang memberikan kekuatan utama komposit.Namun, fungsi material penguat kadang tidak hanyakekuatan akan tetapi juga dalam hal ketahan atau dayahantar panas dan listrik, dan ketahanan korosi.Pertimbangan lainnya adalah kekakuan (stiffness/modulus elasticity) atau berbagai property yang lain.

Fiber Reinforced Polymer Matrix

Matrix

Reinforcement

•Transfer Load to Reinforcement•Temperature Resistance•Chemical Resistance

•Tensile Properties•Stiffness•Impact Resistance

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Bentuk2 Material PenguatFibers

Penampang lintang bisa lingkaran, persegi, atauhexagonalDiameter --> 0.0001” - 0.005 “Panjang --> L/D ratio

100 -- for chopped fibermuch longer for continuous fiber

ParticulatePartikel kecil yang menghalangi pergerakan dislokasi(pd metal composite) dan memperkuat matriks.For sizes > 1 μm, strength of particle is involves in load sharing with matrix

FlakesFlat platelet form

Berbagai Pertimbangan DesainKomposit

Performansi komposit:Kekuatan, Temperatu, KekakuanTeknik pembuatan (manufacturing process)Pertimbangan umur (life cycle consideration)Harga (Cost)

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Pertimbangan-PertimbanganPemilihan Matrik

End Use Temperature Temperatur operasi(penggunaan)Toughness KetangguhanCosmetic Issues Tampilan, estetikaFlame Retardant Tahan apiProcessing Method Metode pemrosesanAdhesion Requirements Kebutuhan akanperekat

Macam-macam Penguat(reinforcement)

Fiber TypeFiberglassCarbonAramid

Textile StructureUnidirectionalWovenBraid

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Fibers Glass (1)E-glass: Alumina-calcium-borosilicate glass

(electrical applications)

S-2 glass: Magnesuim aluminosilicate glass(reinforcements)

Glass offers good mechanical, electrical, and thermal properties at a relatively low cost.

E-glass S-2 glass

Density 2.56 g/cc 2.46 g/ccTensile Strength 390 ksi 620 ksiTensile Modulus 10.5 msi 13 msiElongation 4.8% 5.3%

Glass – Fibers (2)Jenis fiber yang paling banyak dipergunakanPenggunaan: pipa, tangki, perahu, alat-alat olah ragaKelebihan

Low costCorrosion resistanceLow cost relative to other composites:

KekuranganRelatively low strengthHigh elongationModerate strength and weight

Tipa-tipe:E-Glass - electrical, cheaperS-Glass - high strength

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Aramid Fibers (1)Kevlar™ & Twaron™

Para aramid fiber characterized by high tensile strength and modulus

Excellent Impact ResistanceGood Temperature Resistance

Density 1.44 g/ccTensile Strength 400 ksiTensile Modulus 18 MsiElongation 2.5%

Aramid (Kevlar, Twaron) (2)Penggunaan:

high performance replacement for glass fiberContoh-contoh penggunaan

Armor, protective clothing, industrial, sporting goods

Keuntungan: higher strength and lighter than glassMore ductile than carbon

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Carbon Fiber (1)PAN: Fiber made from Polyacrylonitrile precursor fiber

High strength and stiffnessLarge variety of fiber types available

Standard Modulus Intermediate Modulus

Density 1.79 g/cc 1.79 g/ccTensile Strength 600 ksi 800 ksiTensile Modulus 33 Msi 42 MsiElongation 1.8 % 1.8 %

Carbon – Fibers (2)2nd most widely used fiberExamples

aerospace, sporting goodsAdvantages

high stiffness and strengthLow densityIntermediate costProperties:

Standard modulus: 207-240 GpaIntermediate modulus: 240-340 GPaHigh modulus: 340-960 GPaDiameter: 5-8 microns, smaller than human hair

Fibers grouped into tows or yarns of 2-12k fibers

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Carbon – Fibers (3)Types of carbon fiber

vary in strength with processingTrade-off between strength and modulus

Intermediate modulusPAN (Polyacrylonitrile)

fiber precursor heated and stretched to align structure and remove non-carbon material

High modulus made from petroleum pitch precursor at lower costmuch lower strength

Weight Considerations

Aramid fibers are the lightest1.3-1.4 g/cc

Carbon1.79 g/c

Fiberglass is the heaviest2.4 g/cc

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Strength Considerations

Carbon is the strongest600-800 ksi

Fiberglass400-600 ksi

Aramids400 ksi

Impact Resistance

Kevlar is the toughest

Fiberglass

Carbon

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Stiffness ConsiderationsCarbon is the stiffest

30-40 msi

Aramids14 msi

Fiberglass10-13 msi

Cost Considerations

Fiberglass is cost effective$5.00-8.00/lb.

Aramids$20.00/lb

Carbon$30.00-$50.00/lb

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Fabric Structures

Woven: Series of Interlaced yarns at 90° to each other

Knit: Series of Interlooped Yarns

Braided: Series of Intertwined, Spiral Yarns

Nonwoven: Oriented fibers either mechanically, chemically, or thermally bonded

Woven Fabrics

Basic woven fabrics consists of two systems of yarns interlaced at right angles to create a single

layer with isotropic or biaxial properties.

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Physical Properties

Construction (ends & picks)WeightThicknessWeave Type

Components of a Woven Fabric

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Basic Weave TypesPlain Weave

Basic Weave Types

Satin 5HS

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Basic Weave Types2 x 2 Twill

Basic Weave TypesNon-Crimp

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Braiding

A braid consists of two sets of yarns, which are helically intertwined.

The resulting structure is oriented to the longitudinal axis of the braid.

This structure is imparted with a high level of conformability, relative low cost and ease of manufacture.

Braid Structure

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Types of Braids

Triaxial YarnsA system of longitudinal yarns can be introduced which are held in place by the braiding yarns

These yarns will add dimensional stability, improve tensile properties, stiffness and compressive strength.

Yarns can also be added to the core of the braid to form a solid braid.

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Kesimpulan

Material komposit menjanjikan pilihandesain yang tak terbatas.

Pemilihan Matriks, Fiber, dan Preformsangat penting pada prose sdesain.

Struktur dapat dihasilkan dengan sifat-sifat khusus untuk memenuhi kebutuhanpenggunaan.

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Others Fibers (1)Boron

High stiffness, very high costLarge diameter - 200 micronsGood compressive strength

Polyethylene - trade name: Spectra fiberTextile industryHigh strengthExtremely light weightLow range of temperature usage

Other - Fibers (2)

Ceramic Fibers (and matrices)Very high temperature applications (e.g. engine components)Silicon carbide fiber - in whisker form.Ceramic matrix so temperature resistance is not compromisedInfrequent use

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Fiber Material Properties

Steel: density (Fe) = 7.87 g/cc; TS=0.380 GPa; Modulus=207 GPaAl: density=2.71 g/cc; TS=0.035 GPa; Modulus=69 GPa

Fiber Strength