3421 composites

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CompositesTECH 3421


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What are Composites?

Two or more distinct materials that keep their own

properties.

The goal is to achieve a synergistic relationship between

the different components.The category of composites can include

● Plated parts

● Clad parts

● Coated metals● Reinforced concrete

Generally, the term refers to a material with a matrix and a

reinforcement


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Matrix and Reinforcement

Matrix functions (word means supporting or

enclosing structure)

● Acts as a binder

● Controls physical shape and dimensions

● Transfers the load to the reinforcement

● Protects the reinforcement

btw... the first use of the word matrix to refer to "cyberspace" was in 1976 R.

Holmes Dr. Who: Deadly Assassin (BBC TV script) 50

Engin. How can you intercept thought patterns within the matrix itself? The

Doctor : By going in there. By joining it. (OED)


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Why use Composites

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-density/generics.jpg

http://www.youtube.com/watch?v=hjErH4_1fks


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Matrix and Reinforcement

The reinforcement functions:

● To enhance mechanical properties

● Usually the primary load bearing element

● Can be fibers or particles (long, oriented

fibers offer the best strength)

Physical properties of the material are affected

by the reinforcement...

● Density

● Thermal expansion & Conductivity

● Vibration Dampening


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Matrix and Reinforcement Materials

● Polymers

● Metals

● Ceramics

● Carbon

http://commons.wikimedia.org/wiki/File:Carbon_fiber.jpg


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About Carbon Fiber...

Extremely strong. High stiffness, high

tensile strength, low weight, high chemical

resistance, high temperature tolerance.

Production starts with a polymerprecursor (usually rayon, polyacrylonitrile

[PAN]) which is heated to drive off non-

carbon atoms. Oriented carbon crystal

strands form and bond side to side.

Fiber is etched and sized (coated)

Fiber is then wound and/or woven

http://www.youtube.com/watch?v=c3SZiRYJzH8http://www.youtube.com/watch?v=c3SZiRYJzH8http://www.youtube.com/watch?v=c3SZiRYJzH8http://www.youtube.com/watch?v=4t1pBvTDNXEhttp://www.youtube.com/watch?v=4t1pBvTDNXEhttp://www.youtube.com/watch?v=4t1pBvTDNXEhttp://www.youtube.com/watch?v=c3SZiRYJzH8http://www.youtube.com/watch?v=4t1pBvTDNXEhttp://www.youtube.com/watch?v=q0mQk1s4tKo


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Carbon Fiber

http://www.youtube.com/watch?v=IeST0vfDuhwhttp://www.youtube.com/watch?v=IeST0vfDuhw


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Natural Composites

Wood

● Lignin

● Cellulose

http://commons.wikimedia.org/wiki/File:Abies_concolor_tangential.jpg


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Lignin as a CF Precursor

http://www.youtube.com/watch?v=nLcZKGwS3zEhttp://www.youtube.com/watch?v=nLcZKGwS3zE


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Natural Fiber Reinforcement

Sometimes natural fibers are used as

reinforcement in a thermoplastic matrix (see

Micarta).

Examples include:

● Coconut fiber (coir) [used in 2012 Ford Focus]● Cotton fiber

● Sisal● Kenaf

● Hemp

● Jute

http://en.wikipedia.org/wiki/Jute

http://en.wikipedia.org/wiki/Micartahttp://en.wikipedia.org/wiki/Micarta


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Common Matrix Materials

The most common matrix materials are

thermosetting polymers.

● Polyesters (low cost, but low strength) most

popular

● Epoxies

● Bismaleimides

● Phenolics● Polyimides


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Common Reinforcement Materials

● E-Glass (almumino-borosilicate glass)

● Aramid (example is Kevlar)

● Carbon (or Graphite)

Can be in the form of:

● Strand (twisted bundle of filaments)

● Tow (untwisted bundle)

● Filaments● Fabrics

● Pre-impregnated tapes

● Pre-forms


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Composites Manufacturing

The most common methods of manufacturing

composites are:

● Manual lay-up

● Automated lay-up

● Filament winding

● Pultrusion

● Resin transfer molding


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General Lay-Up Procedure

Coating mold with release agent

Coating mold with gel-coat

Laying up fibers into moldImpregnating with matrix material

Rolling to remove trapped air

This process is repeated to layer the fibersCuring (often in a vacuum bag)


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Manual Lay-Up

Cutting and impr egnating the fibers manually.

http://www.youtube.com/watch?v=MWUxhC6-q0chttp://www.youtube.com/watch?v=a7F5roYYvC8http://www.youtube.com/watch?v=MWUxhC6-q0chttp://www.youtube.com/watch?v=a7F5roYYvC8http://www.youtube.com/watch?v=a7F5roYYvC8http://www.youtube.com/watch?v=MWUxhC6-q0c


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Automated Fiber Placement

CNC AFP machines

Can lay pr epreg fibers and tapes

Tape machines require shape to be r elativelyflat to avoid wrinkles and overlaps.

Fiber machines can lay-up more complicated

geometry

http://www.youtube.com/watch?v=RX43s8-0cR4http://www.youtube.com/watch?v=-qAaJwm11dghttp://www.youtube.com/watch?v=RX43s8-0cR4http://www.youtube.com/watch?v=RX43s8-0cR4http://www.youtube.com/watch?v=RX43s8-0cR4http://www.youtube.com/watch?v=-qAaJwm11dghttp://www.youtube.com/watch?v=-qAaJwm11dghttp://www.youtube.com/watch?v=-qAaJwm11dghttp://www.youtube.com/watch?v=RX43s8-0cR4


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Braided Lay-up

Applies technology used for hose reinforcement

braiding.

Alt. Video

http://www.youtube.com/watch?v=j19na8LMBnEhttp://www.youtube.com/watch?v=j19na8LMBnEhttp://www.youtube.com/watch?feature=player_embedded&v=Omz2H1tHbQwhttp://www.youtube.com/watch?v=j19na8LMBnE


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Filament Winding

Wrapping a narrow fiber tow around a mandrel

Can be

● Helical● Hoop

Mandrel either collapses, is left in place, or is

dissolved away.

http://www.youtube.com/watch?v=1A3vaJaNDLYhttp://www.youtube.com/watch?v=1A3vaJaNDLY


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Spray-Up

Resin and fibers are sprayed together. Gun

chops continuous reinforcement into small

strands.

http://www.youtube.com/watch?v=QRYT0HqzuCshttp://www.youtube.com/watch?v=QRYT0HqzuCshttp://www.youtube.com/watch?v=QRYT0HqzuCs


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Curing

Can be done at room temperature

Sometimes with heated air assist

OvensHeated platen presses

Autoclaves

Curing often involves using vacuum bag orpressure bag (internal bladder) molding


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Pultrusion

Pr oduces long, straight shapes of a given

pr ofile (much like extruded shapes)

http://www.youtube.com/watch?v=4MoHNZB5b_Yhttp://www.youtube.com/watch?v=4MoHNZB5b_Yhttp://www.youtube.com/watch?v=4MoHNZB5b_Yhttp://www.youtube.com/watch?v=aXq1hrzne2khttp://www.youtube.com/watch?v=4MoHNZB5b_Y


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Resin Transfer Molding (RTM)

Used to create large, complex items for high

production, such as shower enclosures,

cabinets, aircraft parts, automotive

components.

Mold halves are loaded with reinforcement

material.Resin is pumped in and cures.

http://www.youtube.com/watch?v=1u-2GvhghQAhttp://www.youtube.com/watch?v=1u-2GvhghQAhttp://www.youtube.com/watch?v=1u-2GvhghQAhttp://www.youtube.com/watch?v=1u-2GvhghQAhttp://www.youtube.com/watch?v=1u-2GvhghQA


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Vacuum Resin Infusion

Reinforcement is placed in one or two-sided

mold. Vacuum pulls r esin into the mold.

http://www.youtube.com/watch?v=VodfQcrXpxchttp://www.youtube.com/watch?v=VodfQcrXpxchttp://www.youtube.com/watch?v=VodfQcrXpxchttp://www.youtube.com/watch?v=VodfQcrXpxc


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Composites Fabrication and

Assembly

Composites can be machined, Drilled and

sawn.

Tooling must be sharp and resistant to

abrasion.

Commonly, tools are carbide or diamond

tipped.

Delamination is a primary problem whenmachining or drilling composites.

Composites are often bonded with adhesive

and/or mechanical fasteners.


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Recommended

Machining of Composites Materials

Composites in Aviation

NASA TP AFP CryogenicFelt Bicycle Manufacturing

Modern Marvels - Carbon
http://www.youtube.com/watch?v=c3SZiRYJzH8&list=UU8Ol-nPFJ-tCAV997_bejzw&index=11&feature=plcphttp://www.youtube.com/watch?v=c3SZiRYJzH8&list=UU8Ol-nPFJ-tCAV997_bejzw&index=11&feature=plcphttp://www.youtube.com/watch?v=mSpx-nPhE-Qhttp://www.youtube.com/watch?v=uLFesrWzlkshttp://www.youtube.com/watch?v=wXxn-8OA8Ac&feature=relatedhttp://www.youtube.com/watch?v=4hH3VrSedoM&feature=related

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