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Innovative Manufacture
Dr Jim MethvenSchool of MACEThe University of Manchester
jimmethven@manchester.ac.uk
Manchester Engineering Association, March 15, 2011
What is Innovation?
o Something Newo Something Differento Something Clevero Something Original
Implies Creativity
Many responses to a single stimulus
Manchester Engineering Association, March 15, 2011
Why Innovate? Drivers?
o Modern industrial practice – empowerment, leano Kaisan – Continuous improvemento Competitivenesso Cost, quality, speed, environmental impact
Manchester Engineering Association, March 15, 2011
Who cares?
o Not Customerso Not the Bank Managero Not the MDo Not … Anyone?
o (compare with TV chefs)
Manchester Engineering Association, March 15, 2011
The Design Map
Market
Manufacturing Route
Artefact
Material
OpticalElectricalPhysicalThermal
Mechanical“Special”
Functions
Note the direction of this arrow!!!
There’s no connection here
Cost, Number
Shape, Size, Complexity
Packaging,Distribution
Manchester Engineering Association, March 15, 2011
The Design Path –Train Journey
Never arrives but enjoys the journey: should be put down
Start
Finish
Steps are milestones such as decisions, investment, prototypes, tooling, pilot manufacture, etc. Some have to be re-traced
Manchester Engineering Association, March 15, 2011
Market Information - ONS
Household Items %
Microwave 83
Washing Machine 92
Dishwasher 25
Fridge/Freezer 93
Tumble Drier 53
Video Recorder 88
CD Player 76
Satellite Receiver 37
Mobile Phone 52
Population UK %
Under 16 19
16-34 25
35-65 40
Over 65 16
Total population of the UK is 60.9 million
Total working population is 29.5 million
o Market information is essential in the design process. Market data are available (free) from the Office for National Statistics (www.statistics.gov.uk/)
o Use this information to get a rough estimate of the market size for an artefact
Manchester Engineering Association, March 15, 2011
Design for Stiffness (Flexural Rigidity)
D=EI
Increase E by creating a composite material that incorporates reinforcing fibres
Increase I by creating a sandwich structure that incorporates a lightweight core
Increase I by increasing the thickness, t.
D depends on t3
BUT Cooling time depends on t2
t
Typical thermoplastic
Increase I by creating ribs on the “back” surface. Wall thickness is reduced so cycle time is reduced AND stiffness is increased
Manchester Engineering Association, March 15, 2011
Which plastics are used to make … ?
bottle cap seals LDPEbottle caps HDPE LDPE PSbottles (general) LDPE PP PS
bottles (medical) PP
bottles (carbonated drinks) PET
bottles (lubricating oil) LDPE
bottles (shampoo, cleaning fluids, milk and fruit juice) HDPE
bowling balls HDPEbowls PS HIPS PMMA
boxes (general) PS PMMA
boxes (stacking) HDPE LLDPE
boxes (fish, meat and eggs) PS
bra clips PA
brackets and structural components in office products PPE PCManchester Engineering Association, March 15, 2011
Materials Properties
o BPFn www.bpf.co.uk/
o BPRn www.britishplastics.co.uk/
o Tangram Technology … n http://www.tangram.co.uk/
o Polyinnovation … n www.manchesterpolymergroup.com/
o Matwebn www.matweb.com/
o Engineering Tips Forumn http://www.eng-tips.com/
Manchester Engineering Association, March 15, 2011
Processes
o Thermoplasticso Reversibleo Heating, melting,
metering, cooling
o Thermosetso Irreversible o Heating, metering,
reaction, cooling
o Injection Mouldingo Blow Moulding o Thermoformingo Vacuum Formingo Rotational Mouldingo Extrusion
o Castingo Encapsulation o Reaction Injection
Moulding
Manchester Engineering Association, March 15, 2011
Thermoset Composite Processes
o Irreversibleo Heating, metering, fibre impregnation, reaction, cooling
o Contact Mouldingo Spray Moulding o Resin Transfer Mouldingo Resin Infusiono Tape Layingo Fibre Placement
o Compression Mouldingo Transfer Mouldingo Wet Mouldingo Filament Windingo Pultrusiono Autoclave Moulding
Manchester Engineering Association, March 15, 2011
Which Process? – Breakeven Analysis
o Breakeven analysis used to quantify a typical “run length” for different manufacturing routes according to the amortisation of the tooling cost
o The approach is less useful than it was 20-30 years ago particularly as a result of “cheap” tooling and increasing levels of imports
o Even injection moulding is “viable” over a run length of a few hundred mouldings
Start-up Cost B
Start-up Cost A
These costs must be amortised over the number of mouldings made
Manchester Engineering Association, March 15, 2011
Shape Classification
Manchester Engineering Association, March 15, 2011
SHAPE DESCRIPTION
Panel/Plate Solid section of predominantly constant thickness and which is predominantly flat or only slightly curved
Hollow Shell having a solid skin which bounds a cavity such as a bottle, bucket, bin, etc.
Half-Shell Shape that comprises a predominantly open, plane base and a more or less complex bounding wall. Two make a clam-shell
3D Solid section of some complexity, typically incorporating features such as ribs, bosses, changes in thickness, etc.
Film Thin (less than say 200µm). Membrane-like (cannot support a bending stress)
Sheet Solid material, constant thickness (200µm-10mm)
Profile Solid (constant thickness) material bounding a number of open or closed channels
Preferred Process (Thermoplastics)
Manchester Engineering Association, March 15, 2011
SHAPE DESCRIPTION
Panel/Plate Compression moulding, Injection Moulding
Hollow Rotational Moulding, Blow Moulding
Half-Shell Injection Moulding, Vacuum Forming, Thermoforming
3D Injection Moulding
Film Blown Film Extrusion
Sheet Sheet Extrusion
Profile Extrusion
Note that all these shapes, apart from film, can be made in glass-filled or mineral-filled thermoplastics. For these materials the only viable processes are compression moulding, injection moulding and extrusion
Preferred Process (Composite Materials)
Manchester Engineering Association, March 15, 2011
SHAPE DESCRIPTION
Panel/Plate Compression Moulding, Pultrusion, Contact Moulding, Spray-Up, Resin Transfer Moulding, Resin Infusion, Autoclave Moulding
Hollow Compression Moulding, Pultrusion, Filament Winding
Half-Shell Compression Moulding, Injection Moulding, Resin Transfer Moulding, Resin Infusion, Reaction Injection Moulding
3D Compression Moulding, Resin Transfer Moulding, Injection Moulding, Resin Infusion, Reaction Injection Moulding, Autoclave Moulding
Profile Pultrusion
Rough Cycle Times
Manchester Engineering Association, March 15, 2011
Method Cycle Time, s (unless stated) Method Cycle Time, s (unless stated)
Injection Moulding 30-60 Tape Laying Depends on part geometry and complexity. Anticipate typical cycle times in the order of tens of minutesBlow Moulding 20-60 Fibre Placement
Thermoforming 40-80 Compression Moulding 60-180
Vacuum Forming 40-100 Wet Moulding 60-180
Rotational Moulding 1500-2400 Filament Winding 10kg/h
Extrusion (Line Speed) 15m/min Pultrusion (Line Speed) 1m/min
Casting 300-1200 Autoclave Moulding 30min -24h
Encapsulation 60-300
Reaction Injection Moulding 60-180
Contact Moulding 60s per ply per m2
Spray Moulding 10s per ply per m2
Resin Transfer 10-60s per m2
Resin Infusion 20-120s per m2
Some Examples
o Thermoformingo Microwave Pultrusion
o Re-Barso Hinged Profileso Microwave Effecto Sintering
o SAFIRE and Bra-Wireso Composite Springso Foam Filled Boardo Pultrusion on a Spaceshipo Solid State Lighting
Manchester Engineering Association, March 15, 2011
NERCOR
o DTI/Industry Fast-Track Award Reference J350B
Partners
o The University of Manchester o Haywood Rotomoulding, Rochdale o Tecni-Form, Stone
Manchester Engineering Association, March 15, 2011
Rotational Moulding
o Hollow aluminium or steel mould charged with plastics powder and rotated at between 2 and 10rpm in 2 orthogonal directions in a gas-fired oven
o Typical oven has volume in the range 5m3 to 50m3 and a gas burner delivering energy in the range 200,000BTU/h to over 3x106 BTU/h (106BTU/h=~293kW). The oven temperature is set in the range 220oC-350oC.
o Powder fuses to a consolidated skin on the inner surface of the mould over roughly 25 minutes. Once the powder is consolidated, the mould is indexed to a cooling station and after another 20minutes or so the material is sufficiently cool to be de-moulded.
o Heat transfer is extremely energy inefficient since it depends on low velocity air flow and, as a result, the process has a Specific Energy Consumption (SEC) of about 6.5 kWh/kg of product. This compares with less than 2kWh/kg for injection moulding.
o Project Target is to reduce the SEC of the process
Manchester Engineering Association, March 15, 2011
Outcomes
o Intensification of heat transfer was effected by making a number of modifications includingn incorporation of heat transfer pinsn heat pipesn oven modification (baffles)n process modification (Temperature cycle)
o All resulted in minor improvements of around 5% saving in energy
Sump mould with Al heat transfer pins attached. The inclusion of the pins
roughly doubles the surface are a of the mould
Manchester Engineering Association, March 15, 2011
Radical Change to the Process
o Redesign the process around the use of a mould which is heated directly through slip-rings
Box Mould 175mm x 175mm x 75mm – Manufactured by CNC machining of Aluminium with heaters attached by means of strangle bands
Mould in place in the lab moulder made as part of the project
One of the slip-rings through which the heaters are supplied with power and the data are collected from thermocouples in and on the mould
Manchester Engineering Association, March 15, 2011
Uniformity of Heating
For direct heating, the uniformity of the temperature of the aluminium mould is important. Here this is measured and modelled using an aluminium plate. Note the witness to the heater locations
Manchester Engineering Association, March 15, 2011
Successful Outcome
o The SEC for the new process is in the order of 1.2kWh/kg, that is to say a nominal energy saving of more than 80%
o A second (larger) lab machine is under construction
o Partner companies are considering full-scale implementation
0
50
100
150
200
250
300
0 500 1000 1500 2000 2500 3000
Time (s)
Mouldings produced by the lab moulder
Time –temperature curves for the new process (The temperature label from the ordinate has been omitted in error)
Manchester Engineering Association, March 15, 2011
Electroheat – Overview
Microwave Radio-Frequency (RF) Induction
General
Typical Frequency 915MHz, 2450Mhz 13MHz, 27.1MHz, 40MHz 50Hz-200kHz
Source Magnetron ‘C’-Class oscillator Inverter
Applicator Conductive box Electrodes Helical or spiral (pancake) conducting coil
Equipment
Power (CfM Labs) 1.5kW, 2450MHz 12kW, 27.1MHz 7.5kW, Self-Tuning (200kHz max)
Manufacturer Sairem, France Relco, UK Inducto-Heat Banyard (Lepel, USA)
Load
Material Dielectric Dielectric Conductor
Heating Effect Polarisation Polarisation Eddy current. Magnetic hysteresis
Heating Characteristics
Volumetric Yes Yes Heating depth increases with decreasing frequency
Instantaneous Yes Yes Yes
Non-Contacting Yes Selectable Selectable
Selective Yes Yes No?
Manchester Engineering Association, March 15, 2011
Characteristics of Electromagnetic Heating
o Instantaneouso Volumetric or Surfaceo Non-Contactingo Selective
These unique characteristics are key to the implementation of a commercially viable electromagnetic heating system
One source of the “microwave effect”?
Manchester Engineering Association, March 15, 2011
MAP Line : TM010 Cavity
Pyrex Die
Brass Cylinder, 5mm wall
ID=83mm
138mm
ResinSpeed m/min
PowerW
Epoxy 0.7 340
Polyester 2.0 590
Modar 4-5 700
Vinyl Ester 7 10005mm Diameterφf = 0.62
Precursor
Manchester Engineering Association, March 15, 2011
Summary (Modar 865 Composites)Area,mm2
Speed.m/min
Power.W
Efficiency
19.6 4.5 700 1
60 1 755 0.63
78.5 0.8 1.5 0.33(95 0.7 1.2 0.44)
proprietary resin system
Manchester Engineering Association, March 15, 2011
Re-Bars: Corrosion of RC
Migration of De-Icing Fluid(Chloride ions)
Rust Formation on Steel Rebar
Expansion and Cracking
Spalling – Accelerated Corrosion
STEELGRP
EUROCRETE DATAo Rebars subjected to a saturated solution of
Calcium Hydroxide (pH=13) at 80oC for 28 days
o Equivalent to 50 years "service"o 25% reduction in tensile strengtho 4% reduction in modulus of elasticity
Manchester Engineering Association, March 15, 2011
Rebar - Form
o Since the form of a rebar is that of a long, thin profile, the immediately obvious (continuous) process for manufacture of a fibre-reinforced rebar is pultrusion
o The surface of a rebar must incorporate undercuts transverse to its axis so that it is mechanically keyed into the concrete matrix.
o Provision of undercuts precludes conventional pultrusion since they will lock the profile into a rigid pultrusion die.
Manchester Engineering Association, March 15, 2011
Peel-Ply Process
Textured Fabric
Textured FabricFabric “peeled off” thecrosslinked profile
SmoothPrecursor
TexturedProfile
Pultrusion Die
o Reduced heat transfero Reduced Line Speedo Cost of the material
o Loss of resino Cost is estimated to be about 4x that of an
equivalent “smooth” profile
Manchester Engineering Association, March 15, 2011
Overwinding
o Provision of mechanical keying is accomplished by overwinding the rebar profile before crosslinking so that the composite rebar incorporates a helical undercut along its entire length.
o By exploiting the non-contacting nature of microwave heating there is no need for a rigid pultrusion die. This is an example of “die-less” pultrusion
Manchester Engineering Association, March 15, 2011
Overwinder
Safety cage
Winding arm with glass bobbin
Manchester Engineering Association, March 15, 2011
Travelling Wave Applicator (TWA)
96,000 tex E-glass core9mm φ
Pitch is determined by the line (pulling) speed and the speed of rotation of the overwinder
1m length of WR340 waveguide
Microwave Power in(2450MHz)
Pulling Direction
Core from Overwinder
Dummy Water Load
WaterExcess Power Out
up to 3 ends of 2400 tex
CrosslinkedProfile(to Haul-Off)
Manchester Engineering Association, March 15, 2011
TWA - Electrical
4gXY
λ=
o5.22=φ
E-Bend
X
Y
E-Field Decay
TE-Mode
ChokeChoke
E H
Microwave Power in(2450MHz)Water
Load
Excess Power Out
Manchester Engineering Association, March 15, 2011
Re-Bar Line: Applicator End
B
C
A
Microwave Generator
Overwinder
Overwound Core
Applicator
C
A
B
D
D
Manchester Engineering Association, March 15, 2011
Manchester Engineering Association, March 15, 2011
Re-Bar Line: Haul-Off
Microwave Generator
Overwinder
Applicator
Haul-Off
Re-Bar
D
A
B
E
AB
D
E
F
F
Manchester Engineering Association, March 15, 2011
Overwinding Control
Flow of resin generatedby overwinding
Should be matched to theline speed and permeability
Acceptable profileLinear Density 135g/m
“Corkscrew” profile produced as a result of excessive overwinding tension
Consolidation
Manchester Engineering Association, March 15, 2011
Beam Testing
o Three 9mm rebars incorporated into the tensile face of a rectangular beam 125mm (H) x 75mm (W) x 1000mm (L) at a centreline depth of 100mm
o Beam subjected to 4-Point bending with a minor span of 250mm and a major span of 900mm
250mm
900mm
P
NmPM2
325.0×=
Manchester Engineering Association, March 15, 2011
ACI 440 Design
Composite rebar Elastic to failure and exhibits no yielding. Design is based on failure by concrete crushing (ACI-440). The level of composite required is GREATER than the balance ratio and the beam is said to be OVER-REINFORCED
Balance Failure SIMULTANEOUS failure of the rebar in tension and the concrete matrix in compression
Mild steel rebar Failure by yielding of the steel rebar (ACI-318). The level of steel required for yielding is LESS than the balance ratio and the beam is said to be UNDER-REINFORCED.
cf ′
bafc′85.0
cf ′
ff
c
f Afff
b
d
cu
AfNA
a = 1c
ffu
c
fu
Afffu
b
d
cu
AfNA
a = 1c
Balance Failure
Over-Reinforcement
bafc′85.0
Manchester Engineering Association, March 15, 2011
Rebar Properties
Parameter Value Concrete Strength,MPa 41 Concrete Factor 1 Concrete Design Strength, MPa 41 FRP Modulus, GPa 41 FRP Strength, MPa 1056 FRP Factor 1 FRP Design Strength 1056 ρ fb 0.00292 1.4ρ fb 0.0041 Bars Required for 1.4ρ fb 0.64 Bars Used 3 ρ Used 0.0192 K = ρ /ρ fb 6.57 Predicted Ultimate Moment, Nm 4884 Predicted Failure Load, KN 30
2'59.01 bdff
fMc
ffffn
−=
ρρ
cufcuff
ccuff EE
fEf εε
ρβε
5.085.0
4)( '
12
−+=
Maximum stress in rebar
Nominal Moment Capacity
Manchester Engineering Association, March 15, 2011
Design Data
0
1000
2000
3000
4000
5000
6000
0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 0.022
Reinforcement Ratio
Ben
ding
Mom
ent,
kNm
0
200
400
600
800
1000
1200
1400
1600
1800
2000
GR
P S
tres
s, M
Pa
BalanceRatio
1.4* Ratio at Balance
Ratio Used 0.0192
Manchester Engineering Association, March 15, 2011
Test Data
0
5
10
15
20
25
30
35
0 2 4 6 8 10 12 14Deflection, mm
Instrument Noise
Onset of Cracking
Manchester Engineering Association, March 15, 2011
Testing to Failure
Testing Rig
Ultimate Failure
Failure Load, kN
Measured 32Calculated 30
GOOD AGREEMENT!
But …
Manchester Engineering Association, March 15, 2011
Economics and Market
o This bar weighs 150g/mo Realises about £20/houro Must be made faster or multi-streamed
THERE IS POTENTIALn 946,000 tonnes of rebar used in the UK (1999)n 4% is Corrosion Resistant (Stainless, Epoxy Coated) n Say half could be GRP – Equivalent to 5000tn Equivalent to 10% of the Total EU Pultrusion Market
Manchester Engineering Association, March 15, 2011
Conclusions
o Process is technically viable o Consolidation may be enhanced by overwinding with a
shrinkable fibreo Improved coupling and hence faster line speeds by
incorporating a susceptor in the core resino Multi-streaming by using 915MHz or Radio Frequency (27MHz)o Magnetron Lifetime?
Manchester Engineering Association, March 15, 2011
Selectivity of Microwave Heating
Moisture levelling (drying of paper or carpets)
Substrate (low loss)
Water (high loss)
Bonding of Ceramics
Alumina phase(low loss)
Grain Boundary phase(high loss)
Mince Pies
Manchester Engineering Association, March 15, 2011
In General ...
o All industrial processes involve mixtures of materials
o The components in the mixture will have different loss factors
o The component with the greatest loss factor will heat preferentially in a microwave cavity
o The temperature of the mixture is non-equilibrated
Manchester Engineering Association, March 15, 2011
Now ...
o If the “hot” species is engaged in a chemical reaction ANDo If the rate of this reaction is of the same order as the rate of
temperature re-equilibrationTHEN o The non equilibrated temperature WILL influence the reaction kinetics,
the reaction path (yield) and the morphology of the material
THIS IS POSSIBLE ONLY WITH MICROWAVE HEATING
o Examplesn Lewis (Imidization)n MAP (High Loss factor of peroxide – High rate of initiationn Difficult to “prove” – Gedeye, Mingoes and othersn BUT – Hamelin – “inverse microwave effect”
Manchester Engineering Association, March 15, 2011
Potential
o In systems in which temperature re-equilibration is relatively slow. Perhaps where interfaces are encountered - such as
o Heterogeneous Catalysiso Interfacial Bondingo Emulsionso Sinteringo Foamso Rubber Toughening
OR
o Add a susceptor to achieve selectivity as in sintering of UHMWPE
Coat the surfaceWith a susceptor
… and preserve the morphology of the bulk
Heat this and, by conduction, a shallow depth of the granule
Manchester Engineering Association, March 15, 2011
Sintering of PE using Susceptors
0 20 40 60 80 100
Trigonox C
Trigonox 21
Ethylene Glycol
Diethylene Glycol
Propylene Glycol
DiPropylene Glycol
Polyalkylene Glycol
Sunflower Oil
20g samples, 10 minutes at 900W, 6% by weight
Manchester Engineering Association, March 15, 2011
DASS Cable
Distribution Plate
To cylindrical TM010 Cavity
Borosilicate Die
Rovings from Impregnation Bath
Core from Storage Reel
Product
2.5mm GRPannulus
Interstitial Jelly
Optical Fibre
PET Tape
PET Tube
Core6mm OD
Linear Density 122g/m
Transients
Manchester Engineering Association, March 15, 2011
Power ON
Modar 865, 3m/minute 50mm is equivalent to 1s
DieEntrance
DieExit
89.25
114.25
50.2
71.8
Power OFFcrosslinkednot crosslinked
Transients offer Hinged Pultrusions
o Turning the power on an off in a prescribed sequence results in cured straight regions and partly (or uncured) regions which can be shaped and cured after pultrusion
o This offers the prospect of making artefact such ads space-frames
o The curvature of the uncured regions invariably results in local buckling which can be mitigated by hoop winding the entire profile
Manchester Engineering Association, March 15, 2011
Power Off
Manchester Engineering Association, March 15, 2011
Induction Heating: Materials
Property Mix 1 Mix 2
Thermal Conductivity, W/m/K 0.77 2.5
Specific Heat Capacity, kJ/kg/K 0.94 0.81
Density, kg/m3 2220 2650
Weight of sample, g 120 140
Proprietary Rubber/Resin compositions incorporating metal fibres and metal fillers
Manchester Engineering Association, March 15, 2011
Typical Oven Cycle
0
50
100
150
200
250
0 30 60 90 120 150 180 210 240 270 300 330 360
Time, minutes
Tem
pera
ture
, C
Transfer toCooler 216 mins
Oven Off211 mins
3-hour hold at 200C
3.3 [degrees/min]
2.1 [degrees/min]} Linear Region only
Manchester Engineering Association, March 15, 2011
Pancake Coil – Unconstrained
Pancake coil above specimen
Infra-Redpyrometer
Data logger
Coil
123.4
s
Manchester Engineering Association, March 15, 2011
Mixes 1-3: Backface Temperatures 60s Exposure
0
50
100
150
200
250
0 50 100 150 200 250 300 350 400
Time, s
Tem
pera
ture
, oC
Mix 1
Mix 2
Mix 3
60s Exposure
Manufacture of Bra Wires
o Marks and Spencer – replacement policy of electrical goodso “Loose” steel bra wires ruin washing machineso Thicker and hence stiffer regions of fabric to replace wires made by
computer aided embroidery and other methods slow and expensiveo Desire for a “plastic” replacement but cannot contain glass fibres …
and by the way the steel ones cost 2p
o The function of a bra wire is a mystery – a quasi-encastré fixing of the bra to the chest wall so that the bosom becomes a supported cantilever
o Simple enough to “replace” the steel with a composite material in principle but how to mould it bearing in mind the large number of sizes required – dedicated tooling would be prohibitively expensive
Manchester Engineering Association, March 15, 2011
The Solution
o Use two reinforcing fibres: one thermally stable and the other having a controllable thermal shrinkage
o Use a cross-head extruder to impregnate a combination of the fibres with a simple thermoplastic such as polypropylene and produce a “straight wire”
o Cut the wire into appropriate lengthso Heat the wires in a simple jig which represents the target profile
o It worked – Field testing was extremely popular o Too expensive in the long run (10p) and not quite stiff enough for the
larger sizes
Manchester Engineering Association, March 15, 2011
Temperature Response
Manchester Engineering Association, March 15, 2011
Cross-section A-A
Profile bends to give a
U-shaped curve in the horizontal
plane
1-7 minutes at 160oC
A A
Polyester (PET) fibres Cotton Fibres
SAFIRE (Self Assembling Fibre Reinforcement)
o Reinforcement of thermoplastic polymer products by long glass fibres ( 5–10 mm) at low fibre volume fraction (3%-5%)
o Assembly is created during processing by means of a proprietary fibre separating device followed by a fibre lacing device
o Key is the creation of a robust “mat”
Manchester Engineering Association, March 15, 2011
0
10
20
30
40
50
60
70
0 2 4 6 8 10
Tensile strength (MPa)
Percentage of glass fibre v/v
20 deg C
60 deg C
85 deg C
120 deg
Composite Springs
o Leaf-Spring by pull-forming – Pultrusion followed by Compression Moulding (1970s). Ford Econoline Van
o Sulcated Spring by layup or compression moulding (1970s) RAE/TBAo Post-buckled pultruded spring (MACE 2010)
Manchester Engineering Association, March 15, 2011
Post-Buckled Springs
Manchester Engineering Association, March 15, 2011
Section Rigidity (EI)
Stiffer Springs – Lost Wax
o Curved hollow tubeso Lost Wax Method
Manchester Engineering Association, March 15, 2011
R
Section Rigidity (EI)
R3
Stiffness
Stiffer Springs - Braiding
o Bladder Moulding using a braided sock
Manchester Engineering Association, March 15, 2011
o Solar Panels up to 18m longo Supporting struts are simple profiles – readily identified with
manufacture by pultrusiono In a spacecraft, power and space are at a premium
o Re-examine the process in the light of these constraintso No power available to heat a rigid steel die (No rigid steel
die)o No prospect of using an impregnation bath
Manufacture in Outer Space
Manchester Engineering Association, March 15, 2011
Space-Ship Pultrusion
o Transport only the raw materials and, maybe a pump
o Pull the fibre through a heat-shrinkable sleeve (a) before leaving
o Pump resin in the tube and move it by hand, peristalsis-style along the length of the tube (b)
o Attach the far end of the tube to something and stretch taut
o Run a heater along the stretched tube – to crosslink the resin and at the same time to consolidate the profile as a result of the shrinking of the sleeve (c)
Manchester Engineering Association, March 15, 2011
(a) (b)
(c)
o Target is to fill an 8 foot by 4 foot corrugated board with low density PU foam
o Consortium plan is to sell the filled boards a pre-packed furniture
Foam-Filled Boards (CRAFT G5ST-CT-2002-50374)
Manchester Engineering Association, March 15, 2011
o A typical board consists of paper skins between which are glued layers of flutes created by a crenulated roller. The whole thing is held together by an adhesive
o Free expansion from a “crushable” mould was unsatisfactory (3 foot rise, 2 foot width)
o A bespoke “porcupine” of needles to inject into each flute was too expensive
Foam Filled Boards – Finally
Manchester Engineering Association, March 15, 2011
o Create a pillar box slot in an oversized board and insert a sacrificial runner
o Close the faces of the slot with PE film and support the board in a large clamp
o Inject the PU mixture through the runner
o Success. The first full board
Acknowledgements
o Professor Stephen Busho Dr David Blackburno Dr Reza Ghaffariyano Dr Zainal Abidino Dr James Myerso Dr Madhu Athinarayanan o Annette Neuendorffo Karl Jamiesono David Rigby
Manchester Engineering Association, March 15, 2011
o It is predicated on the high efficacy of a typical high brighness LED (HBLED) of around 100 lumens per Watt (lm/W) compared with that of a CFL (80lm/W) and that of a tungsten (GLS) lamp (12lm/W)
o The project is concerned with the efficiency of the power driver and the management of heat transfer within the HBLEDs. In practice, this has required the group to consider the design of complete lighting units (luminaires)
Luminaires
Manchester Engineering Association, March 15, 2011
Measurements and Analysis
Clockwise : • Photo-goniometer, Sackville A18,6• Finite Element Heat Transfer Analysis
of torus luminaire• LightTools® illuminance simulation of
“Open” LED array • Open LED array
Manchester Engineering Association, March 15, 2011
Desk Lamp
Manchester Engineering Association, March 15, 2011
o A smaller desk version of this design is based on a hexagonal plate that houses 1, 1W LED on each edge
o This generates around 2500 lux for an input power of 10W, compared with around 1600 lux for a pearl 40W GLS bulb
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