Composite Manufacturing Flashcards

DMM1: Manufacturing Deck 8

1
Q

What is a prepreg ?

A

Carbon fibres with the thermoset resin impregnated into its structure, the resin is partially cured making think flexible sheets which can be reformed and fully cured

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2
Q

describe AFP (automatic fiber placement)

A

robot systems which place unidirectional prepreg slit tapes on a large mold forming the product one layer at a time
mould is then covered with a release film and heated in a vacuum autoclave to cure the resin

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3
Q

describe ATL Automatic Tape Laying)

A

robot systems which place unidirectional prepreg wide tapes on a large mold forming the product one layer at a time
mould is then covered with a release film and heated in a vacuum autoclave to cure the resin

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4
Q

What is the purpose of a dwell temperature in an autoclave curing process?

A

this stage causes the resin to become more viscous before curing allowing it to more deeply inpregnate the material

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5
Q

Describe SMC (Sheet moulding compound)

A

glass fibres are chopped up and thermoset resin is added into the resulting glass fibre pulp

rollers compress the mixture into thick sticky sheets

layers of these sheets are placed into a mould curing under heat and pressure

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6
Q

Describe composite pultrusion

A

think lengths of fibres are continously woven into a mat or veil which is dipped in resin

then it is heated in a die to give the correct cross section, pulling forces continously pull more fibers through the die in a single continous part

the long extrusion is cut to the desired lengths.

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7
Q

Describe RTM (Resin Transfer Moulding)

A

a long weave of fibre preform iis cut into think sheets

the sheets are stacked and heated over a mould allowing it to cure in place

the excess is trimmed away to create the final product

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8
Q

what is the difference between unidirection and fabric sheets?

A

unidirection has all the fibres in a single direction and is held together with a binding material whereas fabric has fibres in two or more directions and is woven together

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9
Q

Describe VARTM (Vacuum assisted resin transfer moulding)

A

dry preforms are mounted over a mould
resin is drawing over the preform with a vaccuum pump
it then cures under atmospheric pressure

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10
Q

What are some problems with VARTM (Vacuum assisted resin transfer moulding)?

A

resin flows along the smallest path creating dry points with no resins, creating weakness where the resin hasnt reached

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11
Q

Describe Fibre Winding

A

long fibres of compostie are drawn through a resin bath and woven over cylindrical mould where it cures forming the final shape

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12
Q
A
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