+ Composites. An overview For CME/MSE 556 8/10/2015 cme/mse 556 composite overview 1.

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Composites. An overviewFor CME/MSE 556

04/19/23 cme/mse 556 composite overview1

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Composites trendsRate of growthTechnology areas (headings)Materials (keywords, concepts)

04/19/23 cme/mse 556 composite overview 2

+Literature growth rate

04/19/23cme/mse 556 composite overview

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+What is being done?


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+2000 Section Headings


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CA sections (80) are chemistry,

biochemistry, macromolecular,

applied, and physical/inorganic/ or

analytical

+2000 Concepts


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Concepts are analogous to

keywords (controlled vocabulary)

+2010 Sectionsbased on review articles


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CA sections (80) are chemistry,

biochemistry, macromolecular,

applied, and physical/inorganic/ or

analytical

+2010 Conceptsbased on review articles


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Concepts are analogous to

keywords (controlled vocabulary)

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9Section headings – what’s changed?

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10keywords– what’s changed?

+Outline

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. Properties, performance, processing, structure

Composite push rodTiresBrake 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

Tires


Performance 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


15Properties 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/

Brake 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

+Composites applications (high volume).


+Aircraft/militaryweight reduction, increased payload

Boron fiber/epoxy skins for F-14 stabilizers (1969)

Carbon fibers: 1970

VSTOL (1982): 25% carbon fiber

F-22: 25% carbon fiber composites; titanium (39%); aluminum (10%)

B-2 (Stealth): outer skin is carbon fiber-reinforced polymer


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+In-class question

How much of the Boeing Dreamliner is made of composites?


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+Why composites in aircraft?

Reduction in components and fasteners – lower fabrication and assembly costs

Higher fatigue and corrosion resistance – reduce maintenance and repair costs

Tailoring the airframe stiffness to local aerodynamic stresses! Change fiber orientation angle to adjust wing shape Stacking sequence affects ability to withstand lift and drag

loads


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+Space: weight reduction

Boron-fiber reinforced aluminum tubes

Sandwich laminate of carbon fiber (CF) composite face sheets + aluminum honeycomb core

Ultrahigh modulus CF epoxy tubes

Kevlar 49 fiber reinforced epoxy pressure vessels


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+Automotive

Class A finish

SMC – sheet molding compound; lighter, lower tooling costs, parts integration

SRIM – structural reaction injection molding; randomly oriented fibers in polyurethane or polyurea

Unileaf E-glass fiber/epoxy springs (Corvette), 1981

Manufacturing: very high volume parts (100 – 200 parts per hour); SRIM + compression molding

Resin transfer molding: BMW roof; reduced weight = lower center of gravity


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Materials selection


+Performance requirements

Loading type: axial, bending, torsion, combination

Loading mode: static, fatigue, impact, shock,…

Service life

Service environment: T, % RH, chemicals

Component integration

Manufacturing processes (high or low volume)

Cost: materials, processing, assembly, recycle, reuse, recover (all the R’s)


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Fiber-reinforced composites


+Applications. Fiber-reinforced composites 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 alignment

Unidirectional, continuous

Bidirectional, continuous

Unidirectional, discontinuous

Random, discontinuous


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Fibers + matrix + coupling agents + fillers lamina

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Matrix and fiber properties


+Resin Properties


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+Common 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 properties

Specific gravity

Tensile strength, modulus

Compressive strength, modulus

Fatigue strength

Electrical, thermal conductivity

cost


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+Fiber Properties


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+Effect of fiber diameter on strength


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

+Common commercial fibers

Glass

Graphite

Kevlar 49

PE (Spectra)

Boron

Ceramic – SiC, Al2O3


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Effects of fiber orientationContinous, aligned fibers. Morphology and mechanical properties


+Representative Element of an Aligned-Fiber Bundle


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


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+Stiffness of a unidirectional carbon epoxy laminate as a function of test angle relative to fiber direction


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+Effect of average fiber volume Vf on the axial permeability of an aligned-fiber bundle


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+Fiber volume fraction (Vf)


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


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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.

+ Fiber volume fraction Vf versus processing viscosity, µ. common polymer matrix systems


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Multiple lamellae structuresDesign issues


+Linear Fiber Structure [0/90/0]


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+Top and side views of woven (interlaced) fibers


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


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+Illustration of idealized, linear 3D fiber structures


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+Stacking sequence of a (0/90±45)s quasi-isotropic layup


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Symmetric lay-ups prevent warping under stress, thermal expansion

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


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+Relative modulus vs. fiber volume fraction


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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 wetting

Wetting of the fibers by the matrix material


+Illustration of spontaneous wetting (a) at t=t0 and (b) at t>t0


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

+Surface Energies


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


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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 processingHand lay-up,+/- molds, filament winding, pultrusion, resin transfer molding, vacuum forming


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


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


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+Schematic of the filament winding process


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+Examples of unstable fiber paths in the filament winding process


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+Filament winding of a rocket motor tube, e.g., booster rocket


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+Schematic of automatic tow placement process showing seven axes of motion


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


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


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+Schematic of the pultrusion process


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+Examples of pultruded part cross sections including airfoil shapes and structural skins and stiffeners


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+Examples of pultruded part cross sections including airfoil shapes and structural skins and stiffeners


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


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


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+Schematic of the double diaphram forming process


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+ Double-diaphragm-formed parts produced from graphite/epoxy prepregs and then cured (upper-curved C-channel; lower-radio-controlled car chassis)


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Typical composite design challenges


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


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+Alternate assembly methods illustrated for a curved C-channel


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Chapter 1Mallick; ME, University of Michigan - Dearborn


The text is structured around conventional composites, e.g., materials that might be use in

transportation, construction, or consumer applications.

+General terms

Fiber

Matrix

Laminate

Composite – fibers/particles, D ~ 10-6 m

Nanocomposite – fibers/particles, D ~ 10-9 m


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+Typical properties

Tensile strength

Yield strength

Tensile modulus

Impact strength

Coefficient of thermal expansion

Thermal conductivity


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+Composites: design advantages

Reinforce parts/structures in the direction of major stresses

Fabricate curved panels with low pressure

Zero coefficient of thermal expansion (CTE) parts

Skin/core systems Sandwich beam, plate, or shell Al skin with fiber-reinforced polymer High fatigue/high damage tolerance


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Composites offer flexibility in design

+Metals/composites comparison

Yielding, plastic deformation

Necking, brittle fracture,…

CTE: high

k/: moderate

Elastic stress-strain; energy absorbed at micro-scale (like yielding)

Damage quite different

CTE: lower (1/3 to 1/10)

k/: higher or lower

MetalsFiber-reinforced composites

(FRCs)


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Damping: not so much

Corrosion: specific oxidation mechanisms in the environment

Damping: high internal damping, good vibrational energy adsorption, low noise transmission

Corrosion: moisture absorption, UV, high T; metal matrix – interfacial corrosion can be a problem


(FRCs)


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Manufacturing: casting, forging, …; fasteners;

Manufacturing: can be lower energy, near net shape manufacturing, parts integration


(FRCs)


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+ Composites. An overview For CME/MSE 556 8/10/2015 cme/mse 556 composite overview 1.

Documents

composite overview

vocabulary slide

analytical slide

sheets of fiber material

push bar

oriented fiber material

carbon fiber

woven fiber material