Composites Flashcards
What is work hardening?
Is the strengthening of a metal by plastic deformation. This strengthening occurs because of DISLOCATION movements and dislocation generation within the crystal structure of the material.
What is plastic deformation?
Is a process in which permanent deformation is caused by a sufficient load. It produces a permanent change in the shape or size of a solid body without fracture, resulting from the application of sustained stress beyond the elastic limit.
What are ferrous metals?
All ferrous metals are magnetic and give little resistance to corrosion. Eg. Cast Iron
What are non-ferrous metals?
These are metals which do not contain any iron. They are not magnetic and are usually more resistant to corrosion than ferrous metals. Eg. aluminium, copper, lead.
What are the three different types of Polymers?
Thermoplastic
Thermoset
Elastomer
How can you make a metal stronger?
Alloying
Mechanical Treatment
Heat Treatment
Do most metals retain useful ductility?
Yes, even high strength alloys
Especially pure metals, are highly ductile
How does corrosion effect metals?
Metals are the least resistant to corrosions
Do metals have a high electrical and thermal conductivity?
Yes
Are ceramics and glasses brittle?
Yes
Compression is 15 times strength of tension
What is ductility?
Ductility is a solid material’s ability to deform under tensile stress; this is often characterised by the material’s ability to be stretched into a wire.
Do ceramics and glasses have high ductility?
They have a very low (Zero) ductility
Are ceramics and glasses abrasion (scratching & wearing) resistant?
Yes
Are ceramics and glasses corrosion resistant?
Yes
Do Polymers and Elastomers properties depend on temperature?
Yes. Eg. Polymer which is tough and flexible at 20 degrees can be :
brittle at 4 degrees
creeps rapidly at 100 degrees (deformation)
Are Polymers and Elastomers easy to shape and colour?
Yes
Do you usually need to finishing operations for Polymers and Elastomers?
No
Are Polymers and Elastomers corrosion resistant?
Yes
What are Composites?
Composites are two or more materials with markedly different physical or chemical properties combined in a way that they act in concert, yet remain separate and distinct at some level because they don’t fully merge or dissolve into one another.
Eg. Concrete
What are Composites main characteristics?
They can be: Light Stiff Strong Tough
What is Stiffness?
Resistance to elastic deformation
Young’s Modulus, Shear Modulus, Bulk Modulus
What is Strength?
Resistance to plastic flow
Yield Strength, Ultimate tensile strength
What is Toughness?
Resistance to fracture?
Fracture toughness
What are the fundamental properties?
Density
Stiffness
Strength
Toughness
What are the secondary properties?
Temp capability
Formability
Fatigue resistance (crack initiation and growth)
Cost
What are the material requirements for a good reinforcement?
Three Characteristics
- High Stiffness and Strength
- Good shape & surface character for effective mechanical coupling to the matrix
- Does not change the properties of the matrix
Why use Fibre particles for reinforcement?
Aspect Ratio Specifics:
If Aspect Ratio»_space; 1 :
Fibres offer better performance if high stiffness and strength are required in a particular direction
Why use Nanoplatelets for reinforcement?
Aspect Ratio Specifics:
If Aspect Ratio
What is the Aspect Ratio?
a = length / diameter
What is the measure of reinforcement efficiency?
Area / Volume
