Composites

This blog page can be used for a last minute revision on the topic of 'Composites' from the material science course.

Composites

- Composites are made up of  matrix and reinforcement .

Matrix 

- To bind the reinforcement together

- Distribute stress

- Maintain ductility and toughness
- To protect the reinforcement against abrasion and environmental effects.
- To transfer the load to the reinforcement

Reinforcement

- Carry the load

- Give strength and the stiffness

Properties of Composites

- Isotropic which is independent of direction

- Anisotropic which is dependent of direction

Unidirectional continuous fibre reinforced composite

-  The composite will be  stronger in the vertical direction . As the tensile strength will be stronger in the direction which is parallel to the fibers arrangement.

Rules of mixture

σc= σm*Vm+ σ fVf

Ec=EmVm+ EfVf

ƿc= ƿmVm+ ƿfVf

σm* = Stress in the matrix at fiber failure

σf = Tensile strength of fiber

Vf = Volume ratio of fiber

Vm = Volume ratio of matrix

E = Young’s modulus

Ƿ = Density

Ff/Fm = EfVf/EmVm

Ff/Fm = The ratio of the load carried by the fibers to that carried by the matrix

Ef = Young’s modulus of fiber

Vf = Volume ratio of fiber

Em = Young’s modulus of matrix

Vm = Volume ratio of matrix