1. Give 4 types of matrices used in composite materials

Ceramic, metal, polymer, carbon and graphite

2. Give 4 types of reinforcements used in composite materials

Fibres, whisker, laminar, particulate, microshperes

3. Give 3 advantages and 3 disadvantages of composite materials

Advantages: lower density, higher directional properties, versatility and tailoring, combination of others properties

Disadvantages: poor recyclability, complex costing, anisotropic properties, can be damaged, matrix degradation

4. What a typical Young’s modules of a resin?

1 to 10 GPa

5. What is a typical range of Young’s modulus of a reinforcement?

Between 100 and 400 GPa

6. What is the shape of Hall Petch equation?

It is a function of 1

√D where D is the length characteristic of the material (grain size etc)

7. What is the basic rule of mixture?

σ a=f σvf +(1−f )σvm

Where σa is the applied stress, σvf is the stress in the fibre, σvm is the stress in the matrix and f the volume fraction of fibre in the composite

8. In composite with long fibers is loaded in axial compression, what is the most likely failure mode?

Buckling

9. In this case what is the shape of the stress at which it will fail?

Buckling stress: σ b÷ E( dl )2

where, E is the Young’s modulus of the fiber, d its diameter and L its length

10. The probability of survival of a fibre is a function of which parameters (5)?

L the average length of fibers, σo the probable fracture strength of a fiber of length Lo, σ the applied stress, m the Weibull modulus