this is the 3rd time, last time I said; I already posted this question 2rd time

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this is the 3rd time, last time I said;

I already posted this question 2rd time now someone didn't answer the whole thing this is a 2rd refund please just answer all parts:

You are required to answer all parts of the question. Our professor gave it as you see it as a single question, so to save time getting a refund and posting again just please.

I know the rule is 1 question at a time in material science at our university this is a single question!!

And correctly clear writting please.

it would be a pain for me to separate them, since I have a fair bit of them.

And finally please do not write on a piece of paper then take a single photo with your mobile phone its going to be blured we can't see it use a photo copier. otherwise take multiple close up photos if mobile is all you have.

3. a) Name five things that would have to be specified for a composite material for a reasonable idea of its behaviour to be predicted. (5 marks) b) Why are the following fibres stronger than the same materials in their bulk form? i) glass ii) carbon iii) A1203 iv) polyethylene (4 marks) c0 which two are stiffer in their fibrous form than in their bulk form? (2 marks) d) Describe how carbon fibre is produced, including an explanation of how its C5 marks) structure and properties are induced. e) What is the most common matrix used for carbon fibre reinforced composites and why? (4 marks)

Explanation / Answer

1. Five things to get idea of its behviour are:

a) Diameter

b) specific gravity

c) Modulus

d) tensile strength

e) Failure strain

2. Fibers are significantly stronger than bulk materials because:

– They have a far more “perfect” structure, i.e. their crystals are aligned along the fiber axis.

– There are fewer internal defects, especially in direction normal to fiber ori t ti en a on, and hence there are lesser number of dislocations.

At larger scales, the degree of structural perfection within a material sample is far less that what is present at small scales. For this reason fibers of several engineering materials are far more strong than their equivalent bulk material samples.

3. Glass and Polyethylene are stiffer in fibrous form than in bulk form.

4. A typical sequence of operations used to form carbon fibers from polyacrylonitrile:-

Spinning

Stabilizing

Carbonizing

Treating the surface

Sizing

5. Carbon (C), special silicon carbide (SiC), alumina (Al2O3) and mullite (Al2O3–SiO2) fibres are most commonly used for Carbon Fibre Reinforced Composites

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