3421 Composites
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Transcript of 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