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Composites > Part 1 - Fulvio > Flashcards

Part 1 - Fulvio Flashcards

1
Q

What is a composite material

A

combination of two or more materials that result in better properties than the materials individually

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2
Q

difference between compoiste materials and metal alloys

A

in composites, each material retains seperate chemical, physical and mechanical properties

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3
Q

what are the 2 constituents of a composite material

A

matrix and reinforcement

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4
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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5
Q

list 3 disadvantages of composites

A
  • brittle failure mechanisms
  • high material costs
  • high manufacturing costs
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6
Q

what are the 3 functions that the reinforcement material provides

A
  • high modulus of elasticity
  • tensile properties
  • tensile strength
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7
Q

which type of reinforcement fibres does this course focus on

A

continuous fibre composites

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8
Q

list 3 types of continuous fibres

A
  • unidirectional
  • woven
  • non woven
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9
Q

what are the 5 functions that the matrix material provides

A
  • transverse modulus and strength
  • shear modulus and strength
  • compressive strength
  • interlaminar shear strength
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10
Q

what type of matrix does this course focus on

A

polymer matric composites (PMCs)

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11
Q

what is a fibre reinforced polymer (FRP)

A

A PMC with continuous fibres as reinforcement

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12
Q

3 types of FRPs

A
  • glass
  • carbon
  • aramid
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13
Q

3 uses of glass fibre FRPs

A
  • piping
  • tanks
  • boats
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14
Q

3 advantages of glass FRPs

A
  • high strength
  • corrosion resistance
  • low cost relative to other composites
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15
Q

4 disadvantages of glass FRPs

A
  • relatively low elastic modulus
  • high elongation
  • high specific gravity
  • sensitivity to abrasion
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16
Q

3 uses of graphite and carbon FRPs

A
  • aerospace, automotive, sporting goods
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17
Q

3 advantages of graphite and carbon FRPs

A
  • high modulus and strength
  • low density
  • low coefficient of thermal expansion
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18
Q

2 disadvantages of graphite and carbon FRPs

A
  • high cost
  • low impact resistance
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19
Q

3 uses of aramid fibres

A

sporting goods, armour, protective clothing

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20
Q

4 advantages for aramid FRPs

A
  • low density
  • high tensile strength
  • low cost
  • high impact resistance
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21
Q

two types of polymers used in PMCs

A
  • thermosets
  • thermoplastics
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22
Q

what is a thermoset polymer

A

insoluble and infusible after cure because chains are rigidly joined with strong covalent bonds.

after curing, cannot be reshaped and very hard to recycle

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23
Q

what is a thermoplastic polymer

A

formable at high temperatures and pressure because the bonds are weak.

can be reformed many times and is easily recyclable

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24
Q

which type of of polymer is most commonly used in PMCs

A

thermoset

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25
Q

how does wet/hand lay up manufacturing method for PMCs work

A
  • A gel coat is applied to the mould for better surface finish
  • ## resin and reinforcement is places against a one sided mould and allowed to cure
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26
Q

uses of wet/hand lay up process

A

polyester or resin parts - boat hulls, tanks, vessels

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27
Q

3 advantages of wet hand lay up

A
  • low cost tools
  • suitable for versatile range of products
  • easy to change mould/design
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28
Q

3 disadvantages of we hand lay up

A
  • time consuming
  • easy to form air bubbles and disorientation of fibres
  • inconsistency
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29
Q

what is pre preg

A

a composite which comes with resin already added to the reinforcement and can be used for subsequent manufacturing processes
- since it arrives mixed, shelf life is limeted, and must be cured in autoclave

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30
Q

uses of pre preg

A

bikes, planes

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31
Q

5 advantages of pre-preg

A
  • orientation of fibres can be changed
  • intermediate product
  • consistent
  • high productivity
  • can use thermoplastic polymers
32
Q

3 disadvantages of pre-preg

A
  • limeted shelf life
  • storage/transport
  • delamination
33
Q

how does the spray-up method for PMC manufacture work

A
  • resin/reinforcement is sprayed onto mould with spray gun
  • chopped fibres mixed with resin and compacted by roller or vacuum
34
Q

uses of spray up method

A

boats

35
Q

3 advantages of spray up method

A
  • continuous process
  • any materials can be used as mould
  • error can be corrected by respraying
36
Q

5 disadvantages of spray up method

A
  • slow process
  • inconsistency
  • no control of fibre orientation
  • only one sided finish
  • environmentally unfriendly
37
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
38
Q

4 advantages of vacuum bagging

A
  • simple design
  • works for any fibre/matrix combo
  • cheap mould material
  • good quality for cost
39
Q

3 disadvantages of vacuum bagging

A
  • temp cant exceed 300 deg
  • cloth in plastic cover has to be replaced frequently
  • time consuming
40
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`

41
Q

Uses of RTM

A

automotive, wind turbines

42
Q

what is preform

A

pre cut pieces of reinforcement

43
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
44
Q

3 disadvatages of RTM

A
  • long curing time
  • hard to make intricate parts
  • material waste from spill
45
Q

how does vacuum assisted resin transfer moulding (VARTM) manufacturing work for PMCs

A
  • one tool face replaced with a flexible film
  • vacuum created to assist resin flow
46
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
47
Q

3 disadvantages to VARTM

A
  • waste of materials
  • complexity of resin inlet design
  • only one side has good finish
48
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
49
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
50
Q

2 disadvantages of RFI

A
  • requires an oven and vacuum bagging system
  • not proven outside of aerospace
51
Q

how does rfilament windng manufacturing work for PMCs

A

continuous reinforcement (pre impregnated, or impregnated during winding) is wound around a rotating mandrel to form part

52
Q

3 applications of filament winding

A

pressure vessels
rocket motors
sail boat masts

53
Q

4 advantages of filament winding

A
  • using existing process
  • easy operation
    can make huge parts
  • can also be used with thermoplastics
54
Q

3 disadvantages of filament winding

A
  • curing by heat can be problematic
  • product shape limeted
  • limeted spinning speed
55
Q

how does automatic fibre / tape placement manufacturing work for PMCs

A
  • deposits unidirectional pre-preg slit tape
    one ply at a time
  • each ply at different angles to make stronger
56
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
57
Q

how does pultrusion work for PMCs manufacturing

A

reinforcements impregnated by drawing material through resin station and shaped by guiding through heated die

58
Q

4 advantages of Pultrusion

A
  • automated
  • high speed
  • versatile cross sectional shape
  • can be used with thermoplastics
59
Q

3 disadvantages of pultrusion

A
  • issues with die
  • mainly thermoset matrix
  • unidirectional reinforcement
60
Q

applications of pultrusion

A

buildings, automotive

61
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
62
Q

2 advantages of Sheet moulding compound

A
  • consistency
  • low costs
63
Q

1 disadvantage of sheetmoulding compound

A
  • low volume fraction
64
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
65
Q

4 advantages of compression moulding

A
  • wide range of shapes
  • consistent
  • simple
  • can also be used with thermoplastic polymers
66
Q

4 disadvantages of Compression Moulding

A
  • high cost of machine
  • long time for temp changes
  • expensive moulds
  • no complex geometries
67
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

68
Q

2 advantages of bulk mulding compoud

A
  • highest volume fraction for short fibre reinforced composites
  • good mech properties
69
Q

3 disadvantages of BMC

A
  • high temp and pressure
  • random fibre orientation
  • cant be used for intricate parts
70
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
71
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
72
Q

3 disadvantages of IM

A
  • high initial tooling and machinery cost
  • no complex shaped
  • small runs of parts can be costly
73
Q

applications of IM

A

automotive, sporting goods, small parts

74
Q

Do look ocver write check for all of fulvios formulas

A
75
Q

which manufacturing methods dont require autoclaving

A
  • Resin Transfer Moulding (RTM)
  • Vacuum Asisted Resin Transfer Moulding (VARTM)
76
Q
A

Composites (14 decks)

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