M6.3 Flashcards
Define composite?
- 2 or more materials combined to increase properties
Simplest composite consists of what 2 elements?
- matrix (adhesives or resins)
- reinforcing material (fabric)
Advantages of fibreglass?
- less expensive than other composites
- does not conduct electricity
What are the 2 most common types of fibreglass?
- E-glass
- S-glass
What are the 2 types of aramid (Kevlar)?
- Kevlar 29
- Kevlar 49
Advantages of aramid (Kevlar) fibres?
- low density
- flexible
- strong
- heat resistance up to 260*c
- non-flammable
- good chemical resistance
- good resistance against abrasion
- high toughness
Carbon fibre advantages?
- high strength
- low density
- low fracture resistance
- high resistance against temp
- good electrical conductivity
Advantages of Boron?
- high compressive strength
- strong
- high stiffness
- hard wearing
Describe warp ?
- length of fabric
- usually stronger than weft as it has more threads
Describe weft?
- run perpendicular to warp fibres
Describe selvedge edge?
-tightly woven edge
- runs parallel to warp threads
- used to prevent edges from unravelling
Describe bias?
- Runs at 45* angle to warp threads
What are the common reinforcing fibres used in aviation?
- fibreglass
- aramid
- boron
- carbon fibre
- ceramic
What are the common types of fabric weaves?
- plain weave
- satin weave
- twill weave
Thermoplastic?
- Heat used to form a shape but it is not permanent
Thermosetting?
- Once heated, it is permanent (cannot be reversible)
What are the 2 fibre reinforced composites?
- laminated composites
- sandwich composites
What are laminate composites?
- 2 or more layers of reinforcing material bonded together
What are sandwhich composites?
- core bonded between 2 thin fibreglass sheets
What’s the advantage of a sandwhich composite over a laminated composite?
- extremely high strength to weight ratio
- at least x10 stronger and weight increased x6
Advantages of plastic in aviation industry?
- lightweight
- corrosion resistance
- impact resistance/chemical resistance
- Durable
Transparent plastics can be manufactured in 2 forms?
- Monolithic
- Laminated
What is the purpose of fabric orientation?
Dictates the strength
What are the 3 characteristics of damage classification for composites?
Negligible
Repairable
Non-repairable
What is a one part sealant?
- ready to use (prepared my manufacturer)
What is a two part sealant?
-requires base sealant and accelerator
- requires mixing
What does storing the film adhesive in a freezer do to the resins cure rate?
- slows down
If the resin is left out at room temperature what will happen?
- It will cure
Examples of NDT testing?
- visual inspection
- audible testing
- Ultrasonic inspection
- Radiography inspection
- Thermograph
- Dye penetrants
- moisture detector
What is cosmetic defects?
- outer surface skin damage (minor)
- no structural damage
What does BVID stand for?
Barely invisible impact damage
What are the 5 basic composite repairs?
- pre cured patches
- potted
- resin injection
- laminated repair (one surface)
- laminated repair (through part)
What are the 4 major types of plastic failure?
- Environmental failure
- Thermal failure
- Chemical failure
- Mechanical failure
What is ‘stop drilling’?
- It prevents further cracking from occurring
- Required to drill holes on the ends of each crack with a 1/8 drill bit
