Materials Questions Bank Flashcards

1
Q

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

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2
Q

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

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3
Q

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

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4
Q

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

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5
Q

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

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6
Q

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?

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7
Q

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

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8
Q

Discuss main functions of matrices in composite materials.

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9
Q

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.

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10
Q

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

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11
Q

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

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12
Q

Compare the properties of pitch and PAN based carbon fibres.

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13
Q

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

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14
Q

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

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15
Q

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

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16
Q

Draw typical vacuum bagging layup.

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17
Q

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

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18
Q

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

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19
Q

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.

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20
Q

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

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21
Q

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

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22
Q

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

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23
Q

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

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24
Q

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

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25
Q

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

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26
Q

Discuss cure monitoring methods for the curing of thermoset composites

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27
Q

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

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28
Q

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

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29
Q

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

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30
Q

Describe the phases of fatigue failure of cross ply laminates.

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31
Q

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

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32
Q

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

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33
Q

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

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