Composties And Non-Metallic

Question 1

What is a composite?

Answer 1

Two or more materials combined to form a much stronger structure
A matrix
A reinforcing material

Question 2

Advantages of composites

Answer 2

High strength to weight ratio
Reduction in parts and fasteners
Reduction of wear
Corrosion resistant

Question 3

Disadvantages of composites

Answer 3

Expensive

Not easy to repair - trained staff required

Question 4

What do reinforcing materials give?

Answer 4

Strength

Question 5

What is Nomex?

Advantages?

Answer 5

Fibre.

High thermal stability, temperature and flame resistant

Question 6

What is fibreglass made from? How?

Answer 6

Molten silica glass. Spun together and woven into a cloth

Question 7

Advantages of fibreglass

Disadvantages

Answer 7

Low cost

Weighs more than other fibres
Less strength than other fibres

Question 8

Two most common types of fibreglass?

Answer 8

E glass (electricity resistant) 
S glass (very high tensile strength)

Question 9

What is primary, secondary, and tertiary?

Examples?

Answer 9

Primary - critical area
Secondary - not safety critical
Tertiary - not safety critical

Engines
Fuselage
Doors

Question 10

What colour is Aramid?

Advantages?

Answer 10

Yellow

Light weight
Excellent tensile strength
Heat resistant up to 260C
Good chemical resistance

Question 11

Advantages of Kevlar?

Disadvantages?

Answer 11

Man made organic fibre
High tensile strength and flexibility

Difficult to cut
Absorbs up to 8% moisture

Question 12

Advantages of Carbon Fibre (CFRP)

Answer 12

High strength
High E module
Low density
Electrically conductive

Question 13

What is Warp?

Answer 13

Thread runs along the length of the fabric

Question 14

What is Weft/fill?

Answer 14

Runs perpendicular to the warp fibres

Question 15

What is Selvedge?

Answer 15

Tightly woven edge which runs parallel to the warp edge

Question 16

What is Bias?

Answer 16

Runs at 45 degrees to the warp threads

Question 17

What is Uni Directional?

Answer 17

One direction

Question 18

What is Bi Directional?

Answer 18

Two or more directions

Question 19

What is Quasi-isotropic?

Answer 19

Uni and Bi and diagonal altogether

Question 20

What do New Matrix Materials have?

Answer 20

Good stress distribution
Heat resistant
Chemical resistant
Good durability

Question 21

What are Resins?

Answer 21

A type of plastic broken into two categories:

Thermoplastic
Thermosets

Question 22

What are Thermoplastics?

Answer 22

Use heat to form the part into a specified shape, and this shape is not permanent

Question 23

What are Thermosets?

Answer 23

Once heated, form a permanent shape, cannot be reformed. Most common one used

Question 24

Two types of Resins?

Answer 24

Epoxy

Phenolic

Question 25

Advantages of a Thermoset resin?

Answer 25

Good strength and resistance to moisture and chemicals Good for bonding non-porous and dissimilar materials Used in prepreg materials

Question 26

Safety Precautions with electrical bonding of components

Answer 26

Flame spray Bonding jumpers Aluminium wires woven into top layer Aluminium foil sheet bonded to top layer All dust is harmful Wear all PPE

Question 27

Three types of plastic

Answer 27

Polymerisation Polycondensation Polyaddition

Question 28

What is Polymerisation?

Answer 28

Carried out in the presence of a catalyst, creating a chemical reaction, this creates Monomer from polymers. No waste by products Polythene

Question 29

What is Polycondensation

Answer 29

Chemical reaction between two similar and dissimilar units Polyester

Question 30

What does an Adhesive do?

Answer 30

Bonds two or more surfaces together

Question 31

Advantages of Adhesives

Answer 31

Economical Distribute stress at bonding point No need for fasteners Moisture and Corrosion resistant

Question 32

What does the moisture and corrosion resistance of an adhesive depend on?

Answer 32

Resistance to slippage and shrinkage Malleability Cohesive strength Surface tension

Question 33

Types of adhesive

Answer 33

``` Synthetic Thermosetting Thermoplastic Solvent Plastic ```

Question 34

Two thixotropic agents?

Answer 34

Micro balloons - diameters from 10 to 300 micron balls, forms a paste, trowelled onto surface, sanded/filed Aerosol - white powder

Question 35

What does a Resin Adhesive do?

Answer 35

Ensures cohesion of composite material

Question 36

What are the four most common Resin Adhesives?

Answer 36

Polyester Epoxy Vinyl Ester Phenolic

Question 37

How are Epoxy Hardeners cured?

Answer 37

Chain reaction linking resin molecules

Question 38

Disadvantages of Epoxy hardeners?

Answer 38

Toxic - can cause dermatitis

Question 39

What is shelf life?

Answer 39

Storage time

Question 40

What is pot life?

Answer 40

How long after mixing, a substance can be used