Part 1 - Fulvio COPY Flashcards
(36 cards)
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
2
Q
list 3 disadvantages of composites
A
- brittle failure mechanisms
- high material costs
- high manufacturing costs
3
Q
3 advantages of glass FRPs
A
- high strength
- corrosion resistance
- low cost relative to other composites
4
Q
4 disadvantages of glass FRPs
A
- relatively low elastic modulus
- high elongation
- high specific gravity
- sensitivity to abrasion
5
Q
3 advantages of spray up method
A
- continuous process
- any materials can be used as mould
- error can be corrected by respraying
6
Q
5 disadvantages of spray up method
A
- slow process
- inconsistency
- no control of fibre orientation
- only one sided finish
- environmentally unfriendly
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
8
Q
4 advantages of vacuum bagging
A
- simple design
- works for any fibre/matrix combo
- cheap mould material
- good quality for cost
9
Q
3 disadvantages of vacuum bagging
A
- temp cant exceed 300 deg
- cloth in plastic cover has to be replaced frequently
- time consuming
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`
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
12
Q
3 disadvatages of RTM
A
- long curing time
- hard to make intricate parts
- material waste from spill
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
14
Q
3 disadvantages to VARTM
A
- waste of materials
- complexity of resin inlet design
- only one side has good finish
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
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
1 disadvantage of sheetmoulding compound
- low volume fraction
26
how does compression moulding work
- material preheated and placed in open mould
- pressure applied to force material to contact all areas of mould
27
4 advantages of compression moulding
- wide range of shapes
- consistent
- simple
- can also be used with thermoplastic polymers
28
4 disadvantages of Compression Moulding
- high cost of machine
- long time for temp changes
- expensive moulds
- no complex geometries
29
How does Bulk moulding compound (BMC) work?
thermoset plastic resin blend with fibre reinforcements is formed into a viscous and then injection moulded
30
2 advantages of bulk mulding compoud
- highest volume fraction for short fibre reinforced composites
- good mech properties
31
3 disadvantages of BMC
- high temp and pressure
- random fibre orientation
- cant be used for intricate parts
32
how does injection moulding work?
- 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
4 advantages of IM
- multiple materials can be used at once
- small parts possible
- high volume
- can also be used with thermoplastic polymers
34
3 disadvantages of IM
- high initial tooling and machinery cost
- no complex shaped
- small runs of parts can be costly
35
applications of IM
automotive, sporting goods, small parts
36
which manufacturing methods dont require autoclaving
- Resin Transfer Moulding (RTM)
- Vacuum Asisted Resin Transfer Moulding (VARTM)
