Advance Composite materials

7/31/2019 Advance Composite materials

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Composite Defined

- The term composite is used to

described two or more materials that

are combined to form a structurethat is much stronger than the

individual components.

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Combination of Composite

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Composite Materials

Matrix

Core Materials


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Advantages of Composite

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* High strength to weight ratio

* Strong as a metal part

* Reduced drag* Number of parts and fasteners may bereduced

* Composites dont corrode like metal does.

* Reduced wear


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Uses of Composites

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* Helicopters

* Military Aircraft

* Commercial Aircraft


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Kinds of Reinforcing Fibers

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1. Fiber Glass (Glass cloth)

2. Aramid

3. Carbon / Graphite4. Boron


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- is made from small strands ofmulti silicon glass that are span

together and woven into cloth.

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Fiber Glass (Glass cloth)

- widespread availability and itslow cost make fiber glass one of the

most popular re-enforcing fibers.


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- also known as Electric Glass for its high

electrical resistance.- it is a borosilicate glass commonly used for

re-enforcement because of its low cost andgood strength characteristics.

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a. E - Glass

b. S - Glass- it is a magnesia alumina silicate glass that

is up to 40 percent stronger that E-Glass and Retain

its strength characteristics at higher temperature.- S Glass is used were a very high tensile

strength fiber glass is needed.


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c. C- Glass

- is used in materials that

require chemical resistance.


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- is usually characterized by its yellowcolor, light weight tensile strength and

remarkable flexibility.

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Aramid / Kevlar

- Bullet proof according to the

grade.

Example:Kevlar 129 is bullet proof material

Kevlar 29 is used for boats.


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- is a very strong, stiff re-enforcement.

- this black is very strong, stiff andused for its rigid strengthcharacteristics.

- electrically conductive.

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Carbon / Graphite


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- is made by depositing the element

boron into a thin filament of

tungsten.- has excellent compressive strength

and stiffness and is extremely hard.

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Boron


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- are used when a high temperature

application is needed.

- retains a temperature of 2, 200F.

Examples:

Ceramic is used for the tile of the space

shuttle.

- dissipates the heat quickly.

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Ceramic


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- the selective placement of fibers needed to

obtain the greatest amount of strength in various

application.

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Fiber Science

Victors of fiber placement

1. 0 plies (to react the axial loads) warp

2. 45 plies (react to shear victors) bias3. 90 plies (to react to side loads) wft


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1. Resin

2. Catalyst / Hardener

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MatrixMaterials

Two (2) types of Plastic Risens

1. Thermoplastics use heat to form the past intothe desired shape.

Example: Aircraft Windshield

2. Thermo set resins use heat to force and setthe shape of the part permanently

Example: Structural airframe application


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- are type of thermo setting plastic resin well

known for their outstanding adhesion, strength

and their resistance to moisture and chemicals.

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Epoxy Resin System

- most common matrix system used in composite

fabrication and repair, because:


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1. Extremely flexible in terms of their

applications.2. Exhibits good adhesive characteristics

when used with a broad range of cloth

re-enforcing materials, fillers andsubstrates.

3. After being cared, epoxy resins are

resistance to deterioration by water,acids, bases many chemicals solvents and

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4. Epoxy resins are easily cased at room

temperature or at slightly elevatedtemperatures and they do not require

exotic equipment to process.

5. Epoxy resins are very dimensionallystable they shrink very little during the

curing process and very acceptable for

use of structural parts, mold fabricationmaterial, or tooling fabrication material.

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6. The resins exhibit the strategist

adhesive characteristics of any known

polymeric material.

7. Superior strength long shelf if more

economical for fabrication and repair.

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- when working with resins and catalyst or caring

agents, always follow the procedures specified in

the structural repair manual.- if the resin system requires refrigerated storage

allow each part to warm up to room

temperature before weighing and mixing.

- mix resins in proper ratios.

- mix resins for the proper amount of time

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Working with resin and Catalyst


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- do not mixed large amounts together.

- all resins care by chemical reaction, but some

generate their own heat, thus accelerating the

curing.

- be sure to know the resins pot life beforestarting .

- spread the matrix all over the lay-up in proper

amount to avoid resin rich on resin lean.

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- are thixotropic agent are materials

that are added to resins to control

viscosity and weight, to increaseprofile and strength and to make the

applications of the resin easier.

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Fillers


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1. Micro Balloons are small

spheres of plastic or glasses.

2. Chopped fibers or flox type of

fiber cut into a desired length.

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Types of Fillers


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- are fabrics that have the resin system

already impregnated into the fabric.

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Pre-impregnated Materials


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1. The pre-preg contains the proper

amount of matrix.

2. The re-enforcing fibers are completelyencapsulated with the matrix.

3. Pre-preg fabric eliminates the use to manually

weigh and mix components.4. Pre-preg materials produce a stronger

component or repair.

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Advantages of the Pre-Pregs


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1. Many pre-pregs must be stored in a freezer.2. Many companies do not want to sell small

quantities of a specific weave and resin system,

so a full roll must be purchased.

3. Pre-pregs material is much more expensive

than raw fabric that can be impregnated with the

resin system.

4. Composite components and materials have not

yet been standardized.

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Disadvantages of the Pre-Pregs


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- it is the central member of anassembly.

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Core Materials

Types of Core Materials

- Honeycomb

- Foams

- Balsa wood


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Why use core material?

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Why use core material?

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- this must be applied to the surface

during the curing operation until the

component is fully cured. The

purpose of applying mechanical

pressures is to:

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Applying Pressures


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1. Remove excess resin from the

components ensuring the proper ration of

resin to fiber re-enforcement.

2. Remove air trapped between layers.

3. Maintain the contour of the repairrelative to the original part.

4. Hold the repair securely, preventing any

shifting of the patches during the curingprocess.

5. Compact the fiber layers together.

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a. Shot bags

b. Clecos

c. Spring Clamps

d. Vacuum Bagging

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Methods of Applying Pressures


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- this must be applied to the surface

during the curing operation until the

component is fully cured.

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Shot Bags


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- used in conjunction with pre-shaped

cauls plates to apply pressure to the

repair.

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Clecos


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- allow the pressure to continue even

after the res in flow.

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Spring Clamps


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- the most effective method of

applying pressure to a repair and is

recommended for the use whenever

possible.

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Vacuum Bagging


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- once the repair is made and the

patches in place, the area is covered

with a parting film or a parting fabric(Peel Ply)

- a bleeder material is an absorbent

material that is either placed around

the edges.

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Vacuum Bagging Process


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- a breather material is placed on

one side of the repair to allow air toflow through it and up through the

vacuum valve.

- the two vacuum valve is placed on

top of the breather material to

remove the air from inside thevacuum bag.

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- a sealant type is attached around

the edges of the repair.

- vacuum bagging film is laid out therepair area and the edge are worked

out into the sealant tape to producea airtight seal.

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- the bagging film should be slightly

pressed into the tape until it forms

an airtight seal that covers the part.

- a slit is cut into the bagging film

over the vacuum base, then thevacuum valve is inserted into the

base and sealed airtight.

- the vacuum source is connected to

the vacuum hose and turned on.

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- it is done to make sure the bag is

sealed properly.

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Vacuum Leak Check

Vacuum bagging Films

- are used to cover the components

an seal out air.


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- are used to maintain a positive seal

between the surface of the original

part and the bagging films.

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Sealant Tape

Peel Ply- a nylon or polyester release fabric may

be used next to the wet resin during

operation to transfer excess resin to the

bleeder material without sticking to the

part.


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- are cotton like absorbent materialused to soak up excess resins.

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Bleeders

Breathers

- are cottony materials that allow air to

flow through a valve or over the surface ofthe part throughout the vacuum bagged

area.


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a. Room temperature curingb. heat curing

c. Step curing

d. ramp and Soak curinge. Hear blanket

f. heat guns

g. Heat lamps

h. Oven Curing

i. Auto Claves6/20/2012 44

Methods of Curing


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- some repairs may be cured at room

temperature from 65 - 80 F over a

time span of 8-24 hours, depending

on the type of resin system used.

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Room Temperature Curing


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- the most widely accepted method

of curing structural composites,

employs resins that cure only at

higher temperature.

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Heat Curing


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- is used with a manually operated

controller and requires the

technician to make the adjustments

manually at specific time intervals.

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Step Curing


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- a programmable controller

produces a more sophisticated and

accurate curing than the step curing

process.

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Ramp and Soak Curing


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- are probably the most widely

accepted form of applying heat to a

composite component for the work.

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Heat Blankets


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- have been used to cure composite

parts for many years

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Heat Lamps


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Classification of damage:*Cosmetic Defects a defects on the

outer surface that does not involve

damage to the structural reinforcingfibers.

* Impact damage occurs when aforeign objects strikes the part.

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Assessment and Repair


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*Delamination is the separation of

fabric layers of materials in a

laminate

*Cracks occur in advanced

composite structures just as inmetallic ones.

* Hole damage occur from impact,over-torquing fasteners, or a result

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1. Visual Inspection - used to detectscracks surface irregularities and

surface detects such as delamination

and blistering.2. Coin tap test one of the most

important tools used to detectinternal flaws or delamination.

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Inspection methodology


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Algie composite airframe

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Lancair ES composite parts

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Velocity composite parts

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Advance Composite materials

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