Materials Questions Bank

Question 1

Describe molecular structure of chain polymers and network polymers. Give
examples of such types of polymers.

Question 2

Explain the difference between heterochain polymers, copolymers, and polymer
alloys.

Question 3

Discuss effects of the properties of thermosets and thermoplastics on the fabrication
methods of polymer matrix composite products.

Question 4

State the differences between extrusion blow moulding and injection blow moulding. Can thermosets be moulded using these processes?

Question 5

Discuss product design considerations for parts made of plastics (extruded or
moulded).

Question 6

Describe the differences in mechanical behaviour (modulus of elasticity,
temperature and time dependence) between amorphous and crystalline thermoplastics. How the time dependence of the mechanical properties (creep effects) can be characterised?

Question 7

What are the most attractive characteristics of polymer matrix composites compared
to metals in aerospace applications?

Question 8

Discuss main functions of matrices in composite materials.

Question 9

Explain why it is common to use similar materials for both reinforcement and matrix
in the ceramic matrix composites. Give examples of such composites. Discuss the
advantages and disadvantages of ceramic matrix composites compared with polymer
matrix composites.

Question 10

Explain how Fibre Metal (usually Aluminium) Laminates (FMLs) combine the
advantages of metals and polymer matrix composites. Provide examples of typical
FMLs.

Question 11

Describe how glass fibres are manufactured. Explain what coatings are normally
applied and why these coatings are necessary.

Question 12

Compare the properties of pitch and PAN based carbon fibres.

Question 13

Describe woven fabrics that are used as a reinforcement in composite materials.

Question 14

Describe the properties, advantages and limitations of epoxy resins as matrix
materials in composites.

Question 15

Describe the crystallinity effect on the properties of thermoplastic matrices. Give
examples of crystalline polymers with high temperature resistance and thermal
stability.

Question 16

Draw typical vacuum bagging layup.

Question 17

Draw typical autoclave cycle. Explain why a dwell should be incorporated into the
cycle

Question 18

Give examples of typical thermoplastic “prepregs” (intermediate material forms).

Question 19

How many engineering constants are required to characterise the material
properties of an orthotropic material in 2 dimensions? List these constants and
explain what they are.

Question 20

What is a balanced laminate? How does the behaviour of an
unbalanced laminate differ from that of a balanced laminate?

Question 21

Explain the differences in mechanical behaviour of symmetric and unsymmetric
laminates. Give examples of symmetric and unsymmetric layups.

Question 22

Compare fatigue resistance of composites reinforced with carbon, aramid, and glass
fibres subjected to tension-tension cyclic loading.

Question 23

Describe effects of notches, stress concentrations, and barely visible internal defects
(BVIDs) on fatigue resistance of polymer matrix composites.

Question 24

Compare impact resistance of composites reinforced with carbon, aramid, and glass
fibres.

Question 25

Compare moisture absorption effects on composite material properties at room and elevated temperatures.

Question 26

Discuss cure monitoring methods for the curing of thermoset composites

Question 27

Describe current NDT/NDI techniques sensitive to planar defects (delaminations) in composite structural elements.

Question 28

What are the advantages and disadvantages of radiography in inspection of composites?

Question 29

What is Fick’s law? What parameters influence the amount of moisture absorbed by a composite laminate?

Question 30

Describe the phases of fatigue failure of cross ply laminates.

Question 31

How many independent engineering constants have to be determined to characterise the mechanical properties of a unidirectional laminate? What are they?

Question 32

What are the tests required to determine the engineering properties of a composite lamina.

Question 33

What are A, B and D matrices in the laminate theory? Which parameters do they relate?