Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

# Questions

### Quick questions

You should be able to answer these questions without too much difficulty after studying this TLP. If not, then you should go through it again!

1. Which of the following materials has the highest Coefficient of Thermal Expansion (CTE)?

 a alumina b aluminium c copper d mild steel

2. In the experiment to determine Young's Modulus, hanging a weight on the cantilever beam leads to a measurement of vertical displacement, d. This value is related to the applied load and the Young's Modulus by the following equation:

$\delta = \frac{1}{3}\frac{{P{L^3}}}{{EI}}$

What does I represent in the equation?

 a the applied load b Young's Modulus c the second moment of area d the distance between the clamp and the position of the weight on the bimetallic strip

3. Which of the following materials has the higher value of Young's Modulus?

 a alumina b aluminium c copper d mild steel

4. What do αA and αB represent with respect to materials A and B in the following equation which calculates the misfit strain?

Δε = (αA - αBT

 a the thickness of the two materials b the thermal diffusivities of the materials c temperature changes d thermal expansivities

### Deeper questions

The following questions require some thought and reaching the answer may require you to think beyond the contents of this TLP.

1. Explain in terms of atomic structure and bonding why polymers tend to have lower stiffnesses and higher expansivities than metals and ceramics.

2. From the data given in the properties table suggest a suitable pair of metals for the construction of a bimetallic strip. What other factors do you think might in practice be relevant for making such a choice?