8/14/2015cme/mse 404g composite overview 1 composites. an overview for cme/mse 404g

04/19/23 cme/mse 404g composite overview

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Composites. An overviewComposites. An overview

For CME/MSE 404G


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OutlineOutline

• Composite examples• Fiber-reinforced

composites• Matrices and fibers• Effects of fiber

orientation

• Multiple lamellae structures

• Fiber/matrix wetting• Composites

manufacturing• Typical composite

design challenges


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Composite examples.Composite examples. Properties, performance, processing, structureProperties, performance, processing, structure

Composite push rod

Tires

Brake shoes


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•Properties

High compressive and tensile strength along the axial direction; (secondary) stiff with respect to torsion, bending and shear; temperature resistance; chemical resistance to lubricants and fuel gases

•Performance

Failure mechanisms: overloading (tensile/compressive), torsion, off axis loading, fatigue, crack growth/delamination less of a concern

•StructureComposite push rods are lighter weight replacements for metallic push rods in use between a cam shaft and a valve rocker in internal combustion engines. These composite push rods are constructed of a bar that is made of carbon fiber. These composite push, bars generally have flat ends to which rounded metal end fittings are bonded, usually by some type of epoxy or adhesive. The composite push rod then attaches to the cam shaft and valve rocker via these rounded metal end fittings.

•ProcessingIn order to construct the composite push rod, the bar is first constructed and then the ends are bonded. The bar is constructed of a plurality of layers of sheets of epoxy impregnated, longitudinally oriented fiber material that are wrapped around a removable mandrel. The sheets of longitudinally oriented fiber material form the inner portion of the push bar and a single outside sheet of epoxy impregnated, woven fiber material that is wrapped around the sheets of longitudinally oriented fiber material forms the outside portion of the bar. The sheets of fiber material are comprised on a fiber, such as carbon, Kevlar, or glass, and the fiber material is resin impregnated with a thermosetting, high temperature, toughened epoxy. Once all of the layers of fiber material are wrapped together, they are heated and compressed to thermo-set the layers into a single composite bar. The mandrel is then removed, leaving a central opening in the bar where the mandrel was located. The ends of the composite bar are then cut to the proper shape and the mating surfaces of the metal end fittings are bonded to the ends of the composite bar via epoxy, thereby completing construction of the composite push rod.

Composite Push Rod For Automobiles

Collin. MSE 556. Spring, 2006


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TiresTiresPerformance Processing

Optimal performance is achieved by proper use and maintenance. Understanding the labeling or sidewall markings is key. Example: P215/65R15 89HP: passenger, vs. LT that has higher ply ratings215: width65: aspect ratioR: radial, vs. belted construction or diagonal construction15: diameter of wheel89: load index--indicates the max weight each tire can supportH: speed rating—measurement of top safe speed the tire can carry a load under specified conditions. (worst to best: Q,S,T,U,H,V,Z,W,Y) *a higher rated tire will give better traction and improved steering response at 50 mph.Also consider:-Max. cold inflation (in psi) see images below!**very important-Load limit (redundant to load index)-treadware grading--how long the tread will last-traction grading—indicates tires ability to stop in a straight line on wet pavement-temp grading—min speed a tire will not fail at high temp.

1. The process begins with the mixing of basic rubbers with process oils, carbon black, pigments, antioxidants, accelerators and other additives, each of which contributes certain properties to the compound. These ingredients are mixed in giant blenders called Banbury machines operating under tremendous heat and pressure. They blend the many ingredients together into a hot, black gummy compound that will be milled again and again.2. This compound is fed into mills which feed the rubber between massive pairs of rollers,feeding, mixing and blending to prepare the different compounds for the feed mills, where they are slit into strips and carried by conveyor belts to become sidewalls, treads or other parts of the tire. Still another kind of rubber coats the fabric that will be used to make up the tire's body. Many kinds of fabrics are used: polyester, rayon or nylon. 3. Another component, shaped like a hoop, is called a bead. It has high-tensile steel wire forming its backbone, which will fit against the vehicle's wheel rim. The strands are aligned into a ribbon coated with rubber for adhesion, then wound intoloops that are then wrapped together to secure them until they are assembled with the rest of the tire. Radial tires are built on one or two tire machines. The tire starts with a double layer of synthetic gum rubber called an innerliner that will seal in air and make the tire tubeless.4. Next come two layers of ply fabric, the cords. Two strips called apexes stiffen the area just above the bead. Next, a pair of chafer strips is added, so called because they resist chafing from the wheel rim when mounted on a car.The tire building machine pre-shapes radial tires into a form very close to their final dimension to make sure the many components are in proper position before the tire goes into the mold.5. Now the tire builder adds the steel belts that resist punctures and hold the tread firmly against the road. The tread is the last part to go on the tire. After automatic rollers press all the parts firmly together, the radial tire, now called a green tire, is ready for inspection and curing. 6. The curing press is where tires get their final shape and tread pattern. Hot molds like giant waffle irons shape and vulcanize the tire. The molds are engraved with the tread pattern, the sidewall markings of the manufacturer and those required by law. Tires are cured at over 300 degrees for 12 to 25 minutes, depending on their size. As the press swings open, the tires are popped from their molds onto a long conveyor that carries them to final finish and inspection.**This is traditional technique by goodyear, new automated processes are used by pirelli.

References: 1010tires.com, goodyeartires.com, us.pirelli.com


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Properties Structure

Physical Properties Universal

Hardness (Shore A,D) 67A

Compression Modulus (psi) 900

Deflection @ 100psi 11.56

Deflection @ 300psi 26.71

Tear Strength (pli) 249

Tensile Strength (psi) 2,950

Ultimate Elongation (%) 690

300% Modulus (psi) 990

Bayshore Rebound (%) 38

Compression Set (%) 13Hardness (Shore A,D) - measures resistance to indentation. A "soft" elastomer & D for "harder" materials.Compression Modulus (psi) - force required to achieve a specific deflection, typically 50% deflection, predicts a material's rigidity or toughness.Tear Strength (pli) - measures the resistance to growth of a nick or cut when tension is applied to a test specimen, critical in predicting work life Tensile Strength (psi) - ultimate strength of a material when enough force is applied to cause it to break, with elongation and modulus, tensile can predict a material's toughness.Ultimate Elongation (%) - percent of the original length of the sample measured at point of rupture. 300% Modulus (psi) - stress required to produce 300% elongation. Bayshore Rebound (%) - resilience of a material. ratio of returned energy to impressed energy. predicts rolling resistance.Compression Set (%) - measures the deformation remaining in an elastomer after removal of the deforming force. In combination with rebound, set values predict an elastomer's success in a dynamic application.

Natural rubber

14 %

Synthetic rubber

27%

Carbon black 28%

Steel 14 - 15%

Fabric, fillers, accelerators,antiozonants, etc.

16 - 17%

Weight % for Passenger Tire

RUBBER PERCENT BY WEIGHT IN A NEW RADIAL PASSENGER TIRE

TREAD 32.6%

BASE 1.7%

SIDEWALL 21.9%

BEAD APEX 5.0%

BEAD INSULATION 1.2%

FABRIC INSULATION 11.8%

INSULATION OF STEEL CORD 9.5%

INNERLINER 12.4%

UNDERCUSHION

3.9%

100.0%

Typical phsyical properties of a universal tire

http://www.p2pays.org/ref/11/10504/html/intro/tire.htm www.superiortire.com

http://www.p2pays.org/ref/11/10504/html/intro/tire.htm

http://www.superiortire.com/


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Brake ShoesBrake Shoes

Density (gm/cc) 1.80 - 2.00

Rockwell Hardness (HRL) 75 – 100

Busting Strength (rpm)> 12,000Max.

Continuous Operating Temp.200°CMax.

Transient Operating Temp. 300°C

*Riveted linings provide superior performance, but good quality bonded linings are perfectly adequate.

*Organic and non-metallic asbestos compound brakes are quiet, easy on rotors and provide good feel. But this comes at the expense of high temperature operation.

*In most cases, these linings will wear somewhat faster than metallic compound pads, so you will usually replace them more often. But, when using these pads, rotors tend to last longer.

*The higher the metallic content, the better the friction material will resist heat.

The pad or shoe is composed of a metal backing plate and a friction lining.

Friction materials vary between manufacturers and type of pad: asbestos, organic, semi-metallic, metallic.

Exotic materials are also used in brake linings, among which are Kevlar® and carbon compounds.

Phenolic polymer matrix composites are used as brake pad/shoe materials. As a new disc/drum materials, aluminimum metal matrix composites (Al MMCs) are attractive for their lightweight (three times lighter than cast iron) properties, higher thermal conductivity, specific heat, superior mechanical properties and higher wear resistance over cast iron.

Casting metal backing plate

Electric Infrared ovens used

Shoe Prep

Washing, Delining ,Shot Blasting, return of shoes to OE specs, relining, riveting

Properties

Processing

Performance

Structure


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Fiber-reinforced compositesFiber-reinforced composites


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Applications. Fiber-reinforced Applications. Fiber-reinforced compositescomposites

• Aircraft and military – F14 horizontal stabilizers, 1969.

• Space – boron fiber-reinforced aluminum tubes, Kevlar/epoxy pressure vessels

• Automotive – body (Class A finish, polyurethanes), chassis (Corvette rear leaf spring), engine

• Sporting goods –weight redution• Marine – boat hulls, decks, bulkheads


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Fiber alignmentFiber alignment

• Unidirectional, continuous

• Bidirectional, continuous

• Unidirectional, discontinuous

• Random, discontinuous

Fibers + matrix + coupling agents + fillers lamina


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Matrix and fiber propertiesMatrix and fiber properties


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Resin PropertiesResin Properties


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Common commercial matricesCommon commercial matrices

• Thermosets: epoxies, polyester, vinyl ester, phenolics, polyimides

• Thermoplastics: nylons, linear polyesters, polycarbonate, polyacetals, polyamide-imide, PEEK, PSul, PPS, PEI

• Metallic – Al alloys, Ti alloys, Mg alloys, copper alloys, nickel alloys, SS

• Ceramic – aluminum oxide, carbon silicon carbide, silicon nitride


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Fiber propertiesFiber properties

• Specific gravity

• Tensile strength, modulus

• Compressive strength, modulus

• Fatigue strength

• Electrical, thermal conductivity

• cost


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Fiber PropertiesFiber Properties


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Effect of fiber diameter on strengthEffect of fiber diameter on strength

Fiber that are formed by spinning processes usually have increased strength at smaller diameters due to the high orientation that occurs during processing.


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Common commercial fibersCommon commercial fibers

• Glass

• Graphite

• Kevlar 49

• PE (Spectra)

• Boron

• Ceramic – SiC, Al2O3


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Effects of fiber orientationEffects of fiber orientationContinous, aligned fibers. Continous, aligned fibers.

Morphology and mechanical properties


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Representative Element of an Representative Element of an Aligned-Fiber BundleAligned-Fiber Bundle


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(a) Micrograph of a carbon epoxy composite(a) Micrograph of a carbon epoxy composite(b) square packing array(b) square packing array


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Stiffness of a unidirectional carbon epoxy Stiffness of a unidirectional carbon epoxy laminate as a function of test angle relative laminate as a function of test angle relative

to fiber directionto fiber direction


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Effect of average fiber volume VEffect of average fiber volume Vff on the axial on the axial

permeability of an aligned-fiber bundlepermeability of an aligned-fiber bundle


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Fiber volume fraction (VFiber volume fraction (Vff))


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Viscosity change and cure cycle for graphite/epoxy Viscosity change and cure cycle for graphite/epoxy composite (Hercules AS4/3501-6)composite (Hercules AS4/3501-6)

In general, matrix viscosity increases with temperature until the polymer cures to the gel state. Above this temperature, local chain motion is restrained by crosslinks, and additional curing for higher crosslinking can require long “post-cure” times.


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Fiber volume fraction VFiber volume fraction Vff versus processing viscosity, versus processing viscosity, µ.µ.

common polymer matrix systems common polymer matrix systems


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Multiple lamellae structuresMultiple lamellae structures

Design issues


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Linear Fiber Structure [0/90/0]Linear Fiber Structure [0/90/0]


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Top and side views of woven Top and side views of woven (interlaced) fibers(interlaced) fibers


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Combination fiber structure showing linear Combination fiber structure showing linear fibers and interlacing through the thicknessfibers and interlacing through the thickness


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Illustration of idealized, linear 3D Illustration of idealized, linear 3D fiber structuresfiber structures


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Stacking sequence of a (0/90Stacking sequence of a (0/90±45)±45)ss

quasi-isotropic layupquasi-isotropic layup

Symmetric lay-ups prevent warping under stress, thermal expansion


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In-plane stiffnesses of various-ply geometries as a function In-plane stiffnesses of various-ply geometries as a function of test angle, relative to the on-axis stiffness of a of test angle, relative to the on-axis stiffness of a

unidirectional laminateunidirectional laminate


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Relative modulus vs. Relative modulus vs. fiber volume fractionfiber volume fraction

Range of obtainable elastic moduli for various composites normalized by the fiber modulus, Ef, versus the fiber volume fraction (configuration indicated)


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Fiber/matrix wettingFiber/matrix wetting

Wetting of the fibers

by the matrix material


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Illustration of spontaneous wetting Illustration of spontaneous wetting (a) at t=t(a) at t=t00 and (b) at t>t and (b) at t>t00

Matrix material is often added to fiber assemblies, and needs to wet the fibers in order to prevent void formation.


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Surface EnergiesSurface Energies


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Resin infiltration of unidirectional glass fibers in Resin infiltration of unidirectional glass fibers in [0/90] layup showing the formation of voids[0/90] layup showing the formation of voids

Resin has wicked into several orthogonal lamellae, forming voids (bubbles). The slight refractive index difference between fiber and matrix allows the fiber directions to be observed.


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Composites processingComposites processing

Hand lay-up,+/- molds, filament winding, pultrusion, resin transfer

molding, vacuum forming


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Schematics of (a) hand layup and (b) Schematics of (a) hand layup and (b) mechanically assisted hand layupmechanically assisted hand layup


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Several bagged composite parts being rolled Several bagged composite parts being rolled into the autoclave for cureinto the autoclave for cure


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Schematic of the filament winding processSchematic of the filament winding process


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Examples of unstable fiber paths in Examples of unstable fiber paths in the filament winding processthe filament winding process


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Filament winding of a rocket motor tubeFilament winding of a rocket motor tubee.g., booster rockete.g., booster rocket


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Schematic of automatic tow Schematic of automatic tow placement process showing seven placement process showing seven

axes of motionaxes of motion


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Automatic fiber placement of the V-22 aft Automatic fiber placement of the V-22 aft fuselage section on the Cincinnati-Milacron fuselage section on the Cincinnati-Milacron seven-axis CNC fiber placement machineseven-axis CNC fiber placement machine


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Inside view of the fiber placed V-22 fuselage Inside view of the fiber placed V-22 fuselage section secured with stiffenerssection secured with stiffeners


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Schematic of the pultrusion processSchematic of the pultrusion process


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Examples of pultruded part cross Examples of pultruded part cross sections including airfoil shapes and sections including airfoil shapes and

structural skins and stiffenersstructural skins and stiffeners


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Examples of pultruded part cross Examples of pultruded part cross sections including airfoil shapes and sections including airfoil shapes and

structural skins and stiffenersstructural skins and stiffeners


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Schematic of the resin transfer modeling Schematic of the resin transfer modeling process showing (a) fiber preform and (b) process showing (a) fiber preform and (b)

resin injection into fiber preform resin injection into fiber preform


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The body panels for the Chrysler Viper are made The body panels for the Chrysler Viper are made by resin transfer molding (RTM)by resin transfer molding (RTM)


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Schematic of the double diaphram Schematic of the double diaphram forming processforming process


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Double-diaphragm-formed parts produced from Double-diaphragm-formed parts produced from graphite/epoxy prepregs and then cured (upper-curved C-graphite/epoxy prepregs and then cured (upper-curved C-

channel; lower-radio-controlled car chassis)channel; lower-radio-controlled car chassis)


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Typical composite design Typical composite design challengeschallenges


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Example of how microstructural details can lead to warping Example of how microstructural details can lead to warping or shape changes in the composite along with the solutions or shape changes in the composite along with the solutions

for the problemfor the problem


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Alternate assembly methods Alternate assembly methods illustrated for a curved C-channelillustrated for a curved C-channel