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MIAT 105 Materials Metals Day 3 & 4

Third and Fourth Lecture on New Composite Material
by

MIAT 105 WandM

on 30 July 2013

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Transcript of MIAT 105 Materials Metals Day 3 & 4

Materials Composites
Day 3 & 4

EPOXIES (used in 80% of PMCs)

improved strength and stiffness properties over polyesters

excellent corrosion resistance and resistance to solvents and alkalis

much greater capability to flex and strain with the fibers  without micro-fracturing

cured epoxy tends to be very resistant to moisture absorption

much greater capability to flex and strain with the fibers  without micro-fracturing

bond dissimilar or to already-cured materials

bond to almost all sorts of fibers very well

offer excellent results in repair-ability when it is used to bond two different materials together

initially, much more difficult to work with

cure cycles are usually longer than polyesters
Polymer Matrix (cont.)
Composite materials can be molded into complex shapes at relatively low cost.

Composites can be very strong and stiff, yet very light in weight.
So, ratios of strength-to-weight and stiffness-to-weight are for certain types of composites several times greater than steel or aluminum.

Fatigue properties are generally better than for common engineering metals.

Toughness is often greater, too.

Composites can be designed to have high resistance to severe chemical and temperature environments

Possible to achieve combinations of properties not attainable with metals, ceramics, or polymers alone.

Some types of composite materials provide excellent acoustic, thermal and electrical insulation properties when compared to metals.
Some advantages of composite materials
The rapid development and use of modern (artificial) composite materials began in the 1940s having three main driving forces:

1. Military vehicles, such as airplanes, helicopters, and rockets, placed a premium on high-strength, light-weight materials.

2. Polymer industries were quickly growing and tried to expand the market of plastics to a variety of applications.

3. The extremely high theoretical strength of certain materials, such as glass fibers, was being discovered.
Composites (cont.)
Composite properties are determined by 3 factors:

1. The materials used as component phases in the composite.

2. The geometric shapes of the constituents and resulting structure of the composite system.

3. The manner in which the phases interact with one another.
Composites (cont.)
Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct within the finished structure.


There are two categories of constituent materials:
matrix and reinforcement.
At least one portion (fraction) of each type is required.

The matrix material surrounds and supports the reinforcement materials by maintaining their relative positions.


The reinforcements impart their special mechanical and physical properties to enhance the matrix properties.
Composites
Carbon (80-95% carbon) or Graphite (99% carbon) – more expensive than glass fibers, but lower density and higher stiffness with high strength. The composite is called carbon-fiber reinforced polymer/plastic (CFRP).

Aramides (Kevlar™) – Para aramid fibers with highest specific strength, toughest fibers, undergo plastic deformation before fracture, but absorb moisture, and are expensive.

Boron – boron fibers consist of boron deposited on tungsten fibers, high strength and stiffness in tension and compression, resistance to high temperature, but they are heavy and expensive.
Fibers as the Reinforcing Phase (cont.)
Common fibers used are: glass, carbon/graphite, aramids (e.g. Kevlar™ , Twaron™), boron.
These fibers have high specific strength (strength-to-weight ratio) and specific stiffness (stiffness-to-weight ratio).


Glass
- most common and the least expensive, high strength, low stiffness and high density, offers also good electrical and thermal proprieties.
- glass fibers account for over 90% of the fibers used in reinforced plastics
- GFRP consists 30-60% glass fibers by volume
- Two mostly used types: - E-glass (electrical applications)
- S2-glass (reinforcements)
Fibers as the Reinforcing Phase
Possible geometries:
fibers (long or short), particles, and flakes

Possible materials:
ceramics, metals, polymers, or elements such as carbon or boron

Particles and flakes are used in many plastic molding compounds

Of most engineering interest in PMC is the use of fibers as the reinforcing phase

FRP are most closely identified with the term COMPOSITE
Reinforcing Agent
VINYLESTERS

similar or stronger to polyester in performance

have increased resistance to corrosive environments

offer better resistance to moisture absorption than polyester resins

cheaper than epoxy resins

have some difficulty in bonding dissimilar and to already-cured materials

bond very well to fiberglass, but offer a poor bond to Kevlar™ and carbon fibers
Polymer Matrix (cont.)
POLYESTERS 

good mechanical properties, electrical properties and chemical resistance

amenable to multiple fabrication techniques
low cost

highest water absorption & highest shrinkage

only compatible with fiberglass fibers

tend to end up with micro-cracks and are tough to re-bond
Polymer Matrix (cont.)
Thermosetting (TS) polymers are the most common matrix materials
* the principal TS polymers are:
Phenolics – used with particulate reinforcing phases (e.g. bakelite)
Polyesters, vinylesters, epoxies - more closely associated with Fiber Reinforced Polymers (FRPs)

Thermoplastic (TP) molding compounds are composite materials that include fillers or reinforcing agents


Most elastomers are composite materials because nearly all rubbers are reinforced with carbon black.
Polymer Matrix
Major advantages over metals and monolithic ceramics (no fiber reinforcement) include higher temperature capability, weight reduction, better corrosion resistance and adequate damage tolerance.
CMCs are strong and stiff but they lack toughness (ductility).

Applications are in jet and automobile engines, gas turbines, deep-see mining, cutting tools, dies and pressure vessels, medical.
Ceramic Matrix Composites (cont.)
Ceramic matrix composites (CMCs) combine reinforcing ceramic or metal phases with a ceramic matrix to create materials with new and superior properties.

Ceramic matrices (CER) reinforced with ~ <20% metallic (MET) materials are used to be referred to as CERMETS.
Cermets are also considered MMC.
Matrix materials are usually silicon carbide, silicon nitride and aluminum oxide, and mullite (compound of aluminum, silicon and oxygen). They retain their strength up to 3000oF.

Fiber materials used commonly are carbon and aluminum oxide.

Some of the more common discontinuous reinforcements include whiskers, platelets and particulates having compositions of silicon carbide, boron carbide and boron nitride, titanium diboride, etc.
Ceramic Matrix Composites
C = Carbon (graphite), B = Boron, Al2O3 = Alumina
Composite Materials
Serves to strengthen the composite (tensile properties, stiffness, impact resistance)

Can be one of the three basic materials: metal, ceramic, polymers or another element such as carbon (nonmetal) or boron (semimetal)

The reinforcing component may be in the form of:
■ Fibers (Filaments)
- Continuous fibers (long fibers: L/d > roughly 100)
- Discontinuous fibers (short fibers: L/d < roughly 100)
- Whiskers [hairlike single crystals with diameters down to about 1 μm (0.00004 in.) , and L/d>10)

■ Particles (D/d < 5 , d >1 μm )
- Platelets / flakes (basically 2D particles ; d/t >3…5)
- Aggregates / fillers (i.e. gravel + sand for concrete)
- other various/irregular geometries
Composites – REINFORCEMENTS
Protects thermically and chemically & separates reinforcement, transmits forces to reinforcement

► Metal Matrix
– Aluminum, Copper, Nickel, Titanium

► Ceramic Matrix
– glass, cement, refractories, whitewares…

► Polymer Matrix

– Thermoplastics: acrylics, ABS, polyamides (Nylons, Kevlar), polycarbonates, polyethylenes, PVC, polystyrenes…
(Reversible in phase by heating and cooling. Solid phase at room temperature and liquid phase at elevated temperature.)
– Thermosets: polyesters, vinylesters, epoxies, phenolics, polyimides…
(Irreversible in phase by heating and cooling. Change to liquid phase when heated, then follow with an irreversible exothermic chemical reaction. Remain in solid phase subsequently.)

– Elastomers: natural & synthetic rubbers, silicones, polyurethanes…
Composites -MATRICES
Composites (cont.)
Generally speaking, there are various ways of combining constituent materials to make a composite material :
Artificial composite structures replicating the natural structures
COMPOSITE MATERIALS
Comparative qualitative characteristics of Glass, Carbon and Kevlar fibers:
Fibers as the Reinforcing Phase (cont.)
Ceramic matrix composites refer to the advanced/high performance ceramics that have started to be developed in the last 30 years.


Traditional or conventional ceramics covers a variety of nonmetallic, inorganic materials generally in a monolithic form and which are usually processed at high temperature.
These include bricks, pottery, tiles, etc.

Concrete is a particular example of ceramic composite based on cement matrix and reinforced by sand and gravel (aggregates).
Ceramic Matrix Composites
Most common Fiber Reinforced Metal Matrix Composites:
The matrix is more ductile than the reinforcements.

The reinforcement may improve specific strength/stiffness, abrasion resistance, creep resistance, thermal conductivity and dimensional stability of the overall composites.
Metal Matrix Composites (MMC)
[1 + 1 ≠ 2 … 1 + 1 = 5 , and more]
Conveniently speaking there are 4 generations of composites:

1st generation (1940s): Glass Fiber Reinforced Composites
- Remarkably, they still dominate the market today, comprising about 90% of the composites market.

2nd generation (1960s): High Performance Composites in the post-Sputnik era
- Graphite (Carbon), Boron and Aramid (such as Kevlar) fibers were introduced and used in developing higher performance composites
- Metal matrix composites started to be developed.

3rd generation (1970s & 1980s): The Search for New Markets and the Synergy of Properties
- Sports and automobile industries became to use extensively composite materials
- Improved and optimized composites developed by handling the synergy of the composite constituents aided by computer simulations.
- Ceramic matrix composites became to be developed and implemented in technical applications.

4th generation (1990s): Hybrid Materials, Nanocomposites and Biomimetic Strategies
- Hybrid materials developed by mixing organic and inorganic components at the molecular scale and mimicking the nature's process.
- Nanocomposites built up atom by atom (that is at the nanoscale: less than 100 nanometers) in order to make complex materials that can function as devices or micromachines.
Composites (cont.)
In some cases, a third ingredient must be added to achieve bonding of matrix and reinforcement phases.

Called an interphase, this third ingredient can be thought of as an adhesive.
There is always an interface between constituent phases in a composite material.

For the composite to operate effectively, the phases must bond where they join at the interface.
Composites (cont.)
The Interface
Mid-fuselage structure of Space Shuttle Orbiter showing boron-aluminum tubes.
By the mid-1990s, a variety of MMCs had found uses in spacecraft applications:
- carbon-reinforced copper was used in the combustion chamber of rockets,
- silicon carbide-reinforced copper was used in rocket nozzles,
- oxide aluminum and boron-reinforced aluminum was used in the fuselage,
-silicon carbide-reinforced aluminum was used for wings and blades. 
MMC - Applications
The most primitive manmade composite materials were straw and mud combined to form bricks for building construction.

The ancient brick-making process can still be seen on Egyptian tomb paintings.
Composites (cont.)
Microstructure of a southern pine wood
Microstructure of a human bone
Natural Composites
In nature there are the so-called natural composites like wood and bone.
Both of these are constructed by the processes of nature and their structure are in many cases replicated by the engineered/artificial composite materials.

Wood is a composite consisting of cellulose and lignin.
The cellulose fibers (reinforcement) have a high tensile strength and flexibility whereas the lignin provides matrix for binding the cellulose fibers and add the propriety of stiffness.

Bone comprise of a strong but soft protein – collagen (matrix) and a hard & brittle mineral- apatite (reinforcement)
Silicon carbide matrix gas turbine engine combustor liners
F-16 Fighting Falcon F100 engine exhaust nozzle with five ceramic matrix composite divergent seals, identified by the yellow arrows.
The GE Rolls-Royce Fighter Engine Team’s F136 development engine for the Joint Strike Fighter (JSF) contains third-stage, low-pressure turbine vanes made by GE from ceramic matrix composites (CMC).
(F136-powered JSF begins flight testing in 2010)
CMC- Applications
Aluminum reinforced Graphite (particles) used for electronic packaging applications
Aluminum reinforced Silicon Carbide (particles) composite used for electronic package for a remote power controller
The antenna boom on the Hubble Space Telescope is made of a graphite fibers-aluminum composite
MMC – Applications (cont.)
Alumina matrix composite hot-gas filter
Silicon carbide matrix composite radiant burner screen
Alumina matrix composite heat exchanger headers
Alumina matrix composite burner
stabilizer ring
Silicon carbide matrix composite hot gas recirculation fan
CMM- Applications (cont.)
They are processed separately before becoming phases in the composite
The most important of the three classes of synthetic/engineered/manmade composites.

In a PMC, the starting materials are:
a polymer (matrix)

a reinforcing phase
Polymer Matrix Composites (PMC)
CMCs used for thermal protection applications in aerospace/space
CMC materials used to make high power disc brakes
Discontinuous reinforced ceramic matrix industrial wear parts
Cutting tools made by Aluminum oxide reinforced with Silicon carbide (whiskers)
CMM- Applications (cont.)
Particles as the reinforcement
Fillers as the reinforcement
Flat flakes as the reinforcement
Random fiber
(short fiber/whiskers)
Continuous fiber (long fiber)
REINFORCEMENTS (cont.)
Duralcan (Al reinforced with 10% aluminum oxide particulates) and Al reinforced with 20 % silicon carbide particulates are used in bicycle frames for lightweight, high strength, very expensive mountain bikes.
Longitudinal bracing beam
of particle reinforced aluminum
Disk brake caliper for passenger cars of conventional cast
iron (left) and an aluminum matrix composite material with
ceramic fiber (right)
Vented passenger car brake
disk of particle reinforced aluminum
Partial short fiber reinforced
light metal diesel piston
MMC – Applications (cont.)
Rotor blade sleeve used on EC-120 helicopter, made by Aluminum Matrix Composite
High-pressure hydraulic fluid manifold used in V-22 Osprey Tiltrotor aircraft, made by Aluminum Matrix Composite
Nozzle actuator piston rod used onF119 engine for F-22 aircraft , made by Titanium Matrix Composite
Fan exit guide vane used on gas turbine engines, made by Aluminum Matrix Composite
MMC – Applications (cont.)
Performed in molds consisting of two sections that open and close each molding cycle.

Tooling cost is more than twice the cost of a comparable open mold due to the more complex equipment required in these processes.

Advantages of a closed mold are:

1 - good finish on all part surfaces
2 - higher production rates
3 - closer control over tolerances
4 - more complex 3D shapes are possible
Closed Mold Processes
Hand lay‑up

Spray‑up

Vacuum Bagging – uses hand-lay-up, uses atmospheric pressure to compact laminate.

Pressure Bagging – uses hand-lay-up, uses air pressure to compact laminate.


Automated tape‑laying machines

The differences are in the methods of applying the laminations to the mold, alternative curing techniques, etc.
Open Mold Processes (cont.)
Shaping processes that use a single positive or negative mold surface to produce laminated FRP structures .

The starting materials (resins, fibers, mats, and woven rovings) are applied to the mold in layers, building up to the desired thickness.

This is followed by curing and part removal.

Common resins are polyesters and epoxies, using fiberglass as the reinforcement.
Open Mold Processes
The starting materials arrive at the fabrication operation as separate entities and are combined into the composite during shaping
Filament winding and pultrusion, in which reinforcing phase = continuous fibers

The two component materials are combined into some starting form that is convenient for use in the shaping process
Molding compounds (resin matrix with short randomly dispersed fibers, similar to those used in plastic molding).
Prepregs (fibers impregnated with partially cured TS resins to facilitate shape processing).
Combining Matrix and Reinforcement
PMC Processes
Classification of FRP Processes
A charge is placed in lower mold section, and the sections are brought together under pressure, causing charge to take the shape of the cavity.

Mold halves are heated to cure TS polymer.
When molding is sufficiently cured, the mold is opened and part is removed.

Several shaping processes for PMCs based on compression molding
The differences are mostly in the form of the starting materials.
Compression Molding PMC Process
3 classes based on their counterparts in conventional plastic molding:
Compression molding
Transfer molding
Injection molding

The terminology is often different when polymer matrix composites are molded.
Closed Mold Processes (cont.)
In pressure-bag molding the reinforcement and the resin mixed with catalyst are placed in a mold, and a flexible bag is placed over the wet lay-up after a separating sheet (such as cellophane) is laid down.

The bag is then inflated with an air pressure of 20–50 psi. The resin and reinforcement follow the contours of the mold.

After the part is hardened, the bag is deflated and the part is removed.
Pressure Bagging
Carbon fiber prepreg tape is laid in a mold using automated tape laying equipment.
Automated tape‑laying machines operate by dispensing a prepreg tape onto an open mold following a programmed path.

Typical machine consists of overhead gantry to which the dispensing head is attached.

The gantry permits x‑y‑z travel of the head, for positioning and following a defined continuous path.
Automated Tape‑Laying Machines
Use atmospheric pressure to suck air from under vacuum bag, to compact composite layers down and make a high quality laminate.

Layers from bottom include: mold, mold release, composite, peel-ply, breather cloth (resin flow mesh), vacuum bag, also need vacuum valve, sealing tape.
Vacuum Bagging
Liquid resin and chopped fibers are sprayed onto an open mold to build successive FRP laminations.

Attempt to mechanize application of resin‑fiber layers and reduce lay‑up time.

Alternative for step (3) in the hand lay‑up procedure.

Since products made by spray‑up have randomly oriented short fibers, they are not as strong as those made by lay‑up, in which the fibers are continuous and directed.
Spray‑Up Method
Various Forms of Reinforcement Architectures
2D Reinforcement Woven Fabric Construction Variations
Woven/knitted/braided fabric Reinforcement
Cloths ‑ fabrics of woven yarns.


Mats - felts consisting of randomly oriented short fibers held loosely together with a binder.
Fibers as the Reinforcing Phase (cont.)
The most familiar forms of continuous fibers used mostly for laminated FRP composites (having one or more plies) are:
- Woven rovings
- Cloths
- Reinforcing mats

Woven rovings - fabrics consisting of untwisted filaments

- Woven rovings can be produced with unequal numbers of strands in the two directions so that they possess greater strength in one direction
- Such unidirectional woven rovings are often preferred in laminated FRP composites
Fibers as the Reinforcing Phase (cont.)
In some fabrication processes of PMC, the fibers are continuous, while in others, they are chopped into short lengths.

Taking into consideration the fiber orientation there are 3 main categories of fiber reinforcements:
a) One-dimensional reinforcement, in which maximum strength and stiffness are obtained in the direction of the fiber.
b) Planar reinforcement, in some cases in the form of a two-dimensional woven/knitted/braided fabric.
c) Random or three-dimensional in which the composite material tends to possess isotropic properties.
Types of Fiber Reinforcement
= 0.000984 inc.)
(= 0.000394 inc.)
(= 0.00512 inc.)
1 micron = 0.00003937 inc.
Relative cross-sectional areas and shapes of a wide variety of reinforced fibers
Fibers as the Reinforcing Phase (cont.)
Curing in an autoclave, an enclosed chamber equipped to apply heat and/or pressure at controlled levels.
- In FRP composites processing, it is usually a large horizontal cylinder with doors at either end.
Oven curing provides heat at closely controlled temperatures; some curing ovens are equipped to draw a partial vacuum.

Infrared heating - used in applications where it is impractical to place molding in oven.
Curing Methods Based on Heating
Curing is required of all TS resins used in FRP laminated composites.

Curing cross‑links the polymer, transforming it from its liquid or highly plastic condition into a hardened product.

Three principal process parameters in curing:
- Time
- Temperature
- Pressure

There are used 2 basic ways:
- Curing at room temperature
- Curing based on heating
Curing in Open Mold Processes
(1) mold is treated with mold release
agent;
(2) thin gel coat (resin) is applied, to
the outside surface of molding;
(3) when gel coat has partially set,
layers of resin and fiber are applied,
the fiber is in the form of mat or cloth;
each layer is rolled to impregnate the
fiber with resin and remove air;
(4) part is cured;
(5) fully hardened part is removed
from mold.
Oldest open mold method for FRP laminates, dating to the 1940s when it was first used for boat hulls.

Labor‑intensive.

Finished molding must usually be trimmed with a power saw to size outside edges.
Hand Lay‑Up Method
Carbon
Fiberglass
Kevlar + Carbon fibers
Hybrids (woven fabrics) - two or more fibers materials are combined in the composite



Chopped fibers/strands - fibers chopped 1/4 to 2 inches, commonly used in injection and matched die molding.
Fibers as the Reinforcing Phase (cont.)
Carbon fiber yarns
E-Glass fiber roving
In continuous form, individual filaments are usually available as roving - collections of untwisted continuous strands, convenient form for handling.

Continuous fibers in form of yarns (twisted collection of filaments) are also used as continuous reinforcement.
Fibers as the Reinforcing Phase (cont.)
Demold
Cure
Injection
Tool
Preform
A charge of thermosetting resin with short fibers is placed in a pot or chamber, heated, and squeezed by ram action into one or more mold cavities.

The mold is heated to cure the resin.

Name of the process derives from the fact that the fluid polymer is transferred from a pot into a mold.
Transfer Molding PMC Process
Curing normally occurs at room temperature for the TS resins used in hand lay‑up and spray‑up procedures.

Moldings made by these processes are often large (e.g. boat hulls, megawatt class wind turbine blades ), and heating would be difficult due to product size.

In some cases, days are required before room temperature curing is sufficiently complete to remove the part.
Curing at Room Temperature
Triaxial Yarns
Plain Weave
Satin 5HS Weave
2 x 2 Twill Weave
Non-Crimp Weave
Basic Weave and Braid Types
Similar to extrusion (hence the name similarity) but workpiece is pulled through die (so prefix "pul‑" in place of "ex‑").

Like extrusion, pultrusion produces continuous straight sections of constant cross section.

Developed around 1950 for making fishing rods of glass fiber reinforced polymer (GFRP).

A related process, called pulforming, is used to make parts that are curved and which may have variations in cross section throughout their lengths.
Pultrusion
Injection molding is noted for low cost production of plastic parts in large quantities.

Although most closely associated with thermoplastics, the process can also be adapted to thermosets.

Processes of interest in the context of PMCs:
Conventional injection molding
Reinforced reaction injection molding
Injection Molding PMC Processes
Resin‑impregnated continuous fibers are wrapped around a rotating mandrel that has the internal shape of the desired FRP product; the resin is then cured and the mandrel removed.

The fiber rovings are pulled through a resin bath immediately before being wound in a helical pattern onto the mandrel.

The operation is repeated to form additional layers, each having a criss-cross pattern with the previous, until the desired part thickness has been obtained.
Filament Winding
Two resins are heated separately and poured into a mixing container with milled glass fiber.

Once the resins and milled fiber are blended, the composite mixture is injected into a mold cavity and compressed.

The resin quickly reacts and cures to form a composite.
Reinforced Reaction Injection Molding
Filament Winding (cont.)
Fiber orientation
Used for both TP and TS type FRPs.

Virtually all TPs can be reinforced with fibers.

Chopped fibers must be used
Continuous fibers would be reduced by the action of the rotating screw in the barrel

During injection into the mold cavity, fibers tend to become aligned as they pass the nozzle.
Part designers can sometimes exploit this feature to optimize directional properties in the part.
Conventional Injection Molding
Pultrusion (cont.)
Continuous fiber rovings are dipped into a resin bath and pulled through a shaping die where the impregnated resin cures.

The sections produced are reinforced throughout their length by continuous fibers.

Like extrusion, the pieces have a constant cross section, whose profile is determined by the shape of the die opening.

The cured product is cut into long straight sections.
Pultrusion (cont.)
Pultrusion with additional steps to form the length into a semicircular contour and alter the cross section at one or more locations along the length.

Pultrusion is limited to straight sections of constant cross section.

There is also a need for long parts with continuous fiber reinforcement that are curved rather than straight and whose cross sections may vary throughout length
Pulforming is suited to these less regular shapes.
Pulforming
Centrifugal casting
Tube rolling
Continuous laminating
Cutting of FRPs

In addition, many traditional thermoplastic shaping processes are applicable to FRPs with short fibers based on TP polymers
Blow molding
Thermoforming
Extrusion
Other PMC Shaping Processes
Cured FRPs are hard, tough, abrasive, and difficult‑to‑cut.
Cutting of FRPs is required to trim excess material, cut holes and outlines, and so on…
For glass FRPs, cemented carbide cutting tools and high speed steel saw blades can be used.
For some advanced composites (e.g., boron‑epoxy), diamond cutting tools cut best.
Water jet cutting is also used, to reduce dust and noise problems with conventional sawing methods.
Cutting Methods (cont.)
Cutting of FRP laminated composites is required in both uncured and cured states.

Uncured materials (prepregs, preforms, SMCs, and other starting forms) must be cut to size for lay‑up, molding, etc.
Typical cutting tools: knives, scissors, power shears, and steel‑rule blanking dies.
Nontraditional methods are also used, such as laser beam cutting and water jet cutting.
Cutting Methods
[ (±45)2 / 0 ]s
[ 45f / 0 / 90 / 0 ]
[ 0 / 90 ]s
[ 0 / 90 ]s
Laminar composites
Stacked and bonded fiber-reinforced sheets.
-- stacking sequence (e.g. [0/90]s)
-- benefit: balanced, in-plane stiffness.

One example of a relatively complex structure is modern ski and another example is plywood.
Structural composites (cont.)
Aircrafts & Aerospace
Automobile/Transportation
Marine
Chemical plants
Construction
Sporting goods
Biomedical
Electrical
Renewables
Others
Applications of PMCs
Composite sandwich panel (A) with honeycomb core (C) and face sheets (B)
Sandwich Panels
special class of composite materials that is fabricated by attaching two thin but stiff skins to a lightweight but thick core (e.g. foam, honeycomb).

The core material is normally low strength material, but its higher thickness provides the sandwich composite with high bending stiffness with overall low density.

Sandwich panels can be used in variety of applications which include roofs, floors, walls of buildings and in aircraft for wings, fuselage and tailplane skins.

Benefit: small weight, large bending stiffness.
Structural composites (cont.)
Renewables: wind turbine blades, nacelle covers, shafts, solar collectors.
Electrical: Panels, switch gear, insulators, molding compounds, conductive adhesives.
External strengthening of concrete structures with fibre-reinforced composite
Pedestrian FRP bridges
FRP re-bars
Construction: Bridge decks, repair of concrete decks, bridges, columns; FRP re-bars.
Chemical plants: process pipes, tanks, pressure vessels, oil field structures.
Marine: boat hulls (e.g. Catamaran), decks, masts, propeller shafts, wind surfer.
Space Satellite
Delta II rocket
rocket booster cases made wholly of CFRP
intermediate section of the main body made sandwiched CFRP
top cap of the main body (payload fairing) made partly of CFRP
Material distribution on a F22 fighter
Aircrafts & Aerospace: wings, fuselages, landing gears, rudders/elevators, rotor blades, satellite structure.
Others: musical instruments, umbrellas, pens, lighters, chairs, etc.
Glass fiber composite for prothetic foot
Carbon fiber thermoplastic resin hip prosthesis
Carbon fiber-reinforced thermoplastic resin for cervical plate implant
Fiber-reinforced composites for dental bridges
Biomedical: teeth, filler, bone replacements, artificial limbs.
Sporting goods: tennis rackets, golf clubs, hockey sticks, fishing rods, baseball bats, bicycles, skis, canoes, bow, swimming pools.
Automobile/Transportation: body panels and frames, bumpers, leafsprings, drive shafts, seat housing, tyres and other ground transportation vehicles (buses, trams, high speed trains, etc.).
Leafsprings
Door Panels
Seat Cladding /
Trunk Compartments
Headliners
Underbody Shields
Bumpers
All-composite, 30-foot bus
Composite components for high speed trains and urban trams
Composite components for toilet compartments
Complete composite floors for urban and suburban buses
Flame-retardant lightweight panels for passenger train interiors
Sandwich composites for interior panelling in trains
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