Composites Flashcards
Define an alloy
Solid solutions of which basic ingredients form new phases
Define a composite
Mix of different materials. Basic ingredients retain their original chemical and physical properties. Matrix+Reinforcement = Composite. Formed from two or more metals, ceramics or polymers
What are polymer matrix composites
The material uses a polymer based resin in a matrix and a variety of fibres (Glass and carbon)
What are metal matrix composites
Uses metals such as aluminium as a matrix reinforced with fibres such as silicon carbide.
What are ceramic matrix composites
Used in high temp environments, ceramic matrix reinforced with short fibres or whiskers made from silicon/boron carbide
What is the use of fibres in the matrix
Provides strength and stiffness to the composite
What determines a composites properties
The fibre, The resin, the ratio of fibre to resin, geometry and orientation of fibres
What is the equation for elastic modulus in a composite
E=E(f)V(f) + E(m)(1-V(f))
What does the following mean; E, E(m), E(f), V(f), V(m), P, P(m) and P(f)
E - Modulus of composite E(m) - Modulus of Matrix E(f) - Modulus of Fibre V(f) - Volume of Fibre V(m) - Volume of Matrix P - Density of composite P(m) - Density of Matrix P(f) - Density of Fibre
What are rules of mixtures
Expressions to give some properties of composite in terms of the properties contained in the fibre and matrix, quantity and arrangement
Equation for rules of mixtures
P=V(f)P(f)+V(m)P(m)
What is vacuum bag moulding and what are its advantages and disadvantages?
When pressure is applied to a laminate to improve its consolidation.
Advantages - Higher fiber content than standard lay-up.
Disadvantage - Extra process adds cost
What is autoclave moulding and what are its advantages and disadvantages?
Moulding a pre-impregnated composite
Advantages - Resin content accurately set by manufacturer, Resin chemistry can be optimised.
Disadvantages - Cost is higher, tooling needs to be able to withstand process temperatures.
