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Composites > Part 1 - Fulvio COPY > Flashcards

Part 1 - Fulvio COPY Flashcards

1
Q

list 5 advantages of composite materials

A
  • high specific mechanical properties
  • flexibility of design options
  • corrosion resistance
  • excellent fatigue strength
  • magnetic and electric conductivity
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2
Q

list 3 disadvantages of composites

A
  • brittle failure mechanisms
  • high material costs
  • high manufacturing costs
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3
Q

3 advantages of glass FRPs

A
  • high strength
  • corrosion resistance
  • low cost relative to other composites
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4
Q

4 disadvantages of glass FRPs

A
  • relatively low elastic modulus
  • high elongation
  • high specific gravity
  • sensitivity to abrasion
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5
Q

3 advantages of spray up method

A
  • continuous process
  • any materials can be used as mould
  • error can be corrected by respraying
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6
Q

5 disadvantages of spray up method

A
  • slow process
  • inconsistency
  • no control of fibre orientation
  • only one sided finish
  • environmentally unfriendly
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7
Q

how does the vacuum bagging method of manufacturing PMCs work

A
  • used to make parts stronger
  • used for wet lay up, pre preg and spray up methods to remove trapped air - more dense
  • thin plastic cover is secured over composite and air is vacuumed out
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8
Q

4 advantages of vacuum bagging

A
  • simple design
  • works for any fibre/matrix combo
  • cheap mould material
  • good quality for cost
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9
Q

3 disadvantages of vacuum bagging

A
  • temp cant exceed 300 deg
  • cloth in plastic cover has to be replaced frequently
  • time consuming
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10
Q

how does resin transfer moulding (RTM) manufacturing work for PMCs

A

the preform (precut pieces of reinforcement) is placed in the mould and the mould is closed and thermoset matrix is injected into the mould, it is all cured and ejected`

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11
Q

8 advantages of RTM

A
  • components have good surface finish on both sides
  • high fibre volume fraction
  • uniformity of thickness
  • inserts can be incorporated
  • uses only low pressure injection
  • easily automated
  • low volatile emission
  • can use a complex mould
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12
Q

3 disadvatages of RTM

A
  • long curing time
  • hard to make intricate parts
  • material waste from spill
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13
Q

5 advantages of VARTM

A
  • non autoclave process
  • complex parts possible
  • no dimensional product limits - less components required - make one big part
  • low equipment cost
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14
Q

3 disadvantages to VARTM

A
  • waste of materials
  • complexity of resin inlet design
  • only one side has good finish
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15
Q

how does resin film infusion (RFI) manufacturing work for PMCs

A
  • epoxy resin is cast in film form and sandwiched between to reinforcement layers
  • layers cut to shape and vacuum bagged
  • heated so resin flows through thickness of part
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16
Q

4 resin film infusion advantages

A
  • high fibre volumes can be accurately achieved
  • high resin mechanical properties
  • lower cost than pre-preg
  • good health and safety
17
Q

2 disadvantages of RFI

A
  • requires an oven and vacuum bagging system
  • not proven outside of aerospace
18
Q

4 advantages of filament winding

A
  • using existing process
  • easy operation
    can make huge parts
  • can also be used with thermoplastics
19
Q

3 disadvantages of filament winding

A
  • curing by heat can be problematic
  • product shape limeted
  • limeted spinning speed
20
Q

how does process for automatic fibre / tape placement change for thermosets and thermmoplastics

A
  • low pressure for thermoset
  • high energy laser beam for thermoplastic
21
Q

4 advantages of Pultrusion

A
  • automated
  • high speed
  • versatile cross sectional shape
  • can be used with thermoplastics
22
Q

3 disadvantages of pultrusion

A
  • issues with die
  • mainly thermoset matrix
  • unidirectional reinforcement
23
Q

how is a sheet moulding compound made

A
  • resin paste transfers onto moving film carrier
  • chopped glass fibres drop onto paste
  • second film carrier places another resin layer on top
  • rollers compact sheet
  • then compression moulded into required shape
24
Q

2 advantages of Sheet moulding compound

A
  • consistency
  • low costs
25
Q

1 disadvantage of sheetmoulding compound

A
  • low volume fraction
26
Q

how does compression moulding work

A
  • material preheated and placed in open mould
  • pressure applied to force material to contact all areas of mould
27
Q

4 advantages of compression moulding

A
  • wide range of shapes
  • consistent
  • simple
  • can also be used with thermoplastic polymers
28
Q

4 disadvantages of Compression Moulding

A
  • high cost of machine
  • long time for temp changes
  • expensive moulds
  • no complex geometries
29
Q

How does Bulk moulding compound (BMC) work?

A

thermoset plastic resin blend with fibre reinforcements is formed into a viscous and then injection moulded

30
Q

2 advantages of bulk mulding compoud

A
  • highest volume fraction for short fibre reinforced composites
  • good mech properties
31
Q

3 disadvantages of BMC

A
  • high temp and pressure
  • random fibre orientation
  • cant be used for intricate parts
32
Q

how does injection moulding work?

A
  • pelletized material added to hopper
  • gravity fed into heated barrel and screw
  • pellets sheared by screw so melt
  • material injected into closed mould at high pressure.
  • cooled
33
Q

4 advantages of IM

A
  • multiple materials can be used at once
  • small parts possible
  • high volume
  • can also be used with thermoplastic polymers
34
Q

3 disadvantages of IM

A
  • high initial tooling and machinery cost
  • no complex shaped
  • small runs of parts can be costly
35
Q

applications of IM

A

automotive, sporting goods, small parts

36
Q

which manufacturing methods dont require autoclaving

A
  • Resin Transfer Moulding (RTM)
  • Vacuum Asisted Resin Transfer Moulding (VARTM)

Composites (14 decks)

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