State of the art in lightweight materials

1. Loose weight - win money
Materials Day 2011
Markus Kaufmann

2. Loose weight - win money
Introduction

3. The iceberg problem
ACQUISITION COST Poor Design
(Research, Design, Test,
Production, Construction)
OPERATION COST
PRODUCT DISTRIBUTION COST
SOFTWARE COST TEST AND SUPPORT
MAINTENANCE COST EQUIPMENT COST
TECHNICAL DATA
TRAINING COST COST
SUPPLY SUPPORT COST
RETIREMENT AND
DISPOSAL COST

4. What happened?
Cost benefit of lightweighting
is 100 to 1,000 per kg
Figure: DLR Braunschweig

5. What happened?
Source: Eurocopter

6. What happens?
In space sector cost benefits of
lightweighting are > 10,000/kg
Image: Nasa

7. • Procurement is currently
dominated by initial costs.
• Cost benefits of lightweighting
are ca 10/kg
• Suggested cost benefit
for lightweighting is ca
2 /kg
composiTn: a thematic network on the future use of composites in transport

8. • Procurement is currently
2,4 dominated by initial costs.
• Cost benefits of lightweighting
average weight [tons]
2,2
are ca 10/kg
2,0
1,8
1,6
1,4
Trucks
1,2 Suggested cost benefit
• Cars
for lightweighting is ca
1,0 2 /kg
1970 1980 1990 2000 2010
Source: U.S. Environmental Protection Agency,
Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2006, Appendix D, July 2006.

9. Towards Lightweight Materials
Opportunities and Threats

10. Towards Lightweight Materials
Opportunities Threats
• higher performance • unknown materials,
• lower energy consumption unknown processes
• lower transport cost • higher development cost
• optimized use of raw material • higher material cost
• legislation • other issues are
– repair
– design and structural
simulations
– crashworthiness
– recycling
– fire safety

11. Material Evolution for bicycles
Period Material system
70ies: Columbus SL or Reynolds 531
80ies: Titanium bike frame
1982: Unreinforced plastics bike
90ies: Aluminum
90ies: Carbon fibers
1993: Beryllium frame
2010: Flax/carbon frame

12. Material Evolution for bicycles
Figure: Ashby M. Materials selection in mechanical design

13. Material Evolution for bicycles
Comparison of Materials Used in Bicycles
STEEL TITANIUM
Pros Cons Pros Cons
• Inexpensive • Heavy • Light • Expensive
• Strong • Corrosive • Strong • Designs limited by
• Stiff • Designs limited by • Resilient and available tubes
• Resilient and available tubes and • Not easily repaired
lugs • Shock absorbing • Bad welds are easily
• Easy to work with • Brazing/welding  • Non-corrosive hidden
and repair weaker, heat- • Stiffness vs.
affected zones lightweight
ALUMINUM CARBON FIBER
Pros Cons Pros Cons
• Inexpensive • Fatigue risk reqs • Lightest • Expensive
• Light overbuilding • Strongest • Technology still
• Adequately strong • Lacks resilience • Best shock evolving
• Very stiff for the absorption • Strength and stiffness
weight • Not easily repaired • Unlimited design are design dependent
• Non-corrosive in • Bonded joints applications • Fully molded styles
non-salty prone to failure • Non-corrosive have very limited sizes
environments • Heat treatment can • Material has high
be inconsistent fatigue resistance
http://www.calfeedesign.com/tech-papers/technical-white-paper/

14. Steel and metallic alloys

15. Steel and alloys for bicycle frames
Material specific specific Weight
E-modulus strength
Carbon steel 25.6 30 140%
Cr-Mo steel 25.6 85 100%
AA-6061-T6 25.9 95 55%
Ti-3Al-2.5V 24.4 156 46%
• carbon steel is corrosive, heavy, strength loss by brazing
• Cr-Mo steel is lighter and more fatigue resistant, weldable
• Aluminum is welded or bonded, very stiff, risks for fatigue
• Titanium is light, strong, but expensive
tube sources are aircraft hydraulic lines
http://www.calfeedesign.com/tech-papers/technical-white-paper/

16. ABM Beryllium Frame
• Beryllium alloy
• aluminum lugs
• adhesive bonded
• 1.1 kg frame weight
•
• 2 ex were built
Source: http://mombat.org/1992AmericanBe1.jpg

17. Alloys at turbine inlets
T1 T2
Efficiency
T1
Turbine inlet temperature for a selection of Rolls-Royce turbines
thanks to major material developments
Source: Aviation and the Environment 03/09

18. Alloys at turbine inlets
T1 T2
Efficiency
T1
Turbine inlet temperature for a selection of Rolls-Royce turbines
thanks to major material developments
Image: Nikon Metrology Blog

19. Trends in cast alloys (i)
• Hybrid structures
– MnE21 (Magnesium/Manganese/Cerim)
– casted on aluminum or steel sheet
• Thin-walled ductile cast iron
– carbide-free production
– 2-3 mm wall thicknesses
• Aluminium Lithium alloys
– higher specific strength
– better corrosion resistance
Images: Lightweight-Design.de / Alcan Airware

20. Trends in cast alloys (ii)
• Solution strengthened nodular cast iron
– higher silicon content
– higher yield strength and higher elongations
• Compacted graphite iron
– narrow process window
– combination of strength and thermal conductivity
– engine blocks
• Thixomolding
– high-speed, net-shape injection molding
– semisolid magnesium slurry
– low porosity, complex parts
– reduces risk of burning magnesium
Sources: Thixomat / GoCycle

21. Plastics

22. Plastics
Source: lassecollin.se

23. Plastics
Ultra Polymers
HDT > 150
High-Performance
Polymers
Engineering
Polymers 100 HDT < 150
Commodity
Polymers HDT < 100
Source: SpecialChem (12/08)

24. Trends in plastics (i)
• Towards the top of the pyramid
– Self-reinforced plastics
e.g. PrimoSpire from Solvay Advanced Polymers
– PEEK and PPS
in order to increase the heat deflection temperature (HDT)
  (PP  PPS  PEEK)
• Fillers and reinforcements
– add 30% glass fibers to PA66 (230260
– increase both static properties and HDT
• Hybrid designs
– overmoulding of inserts
and metal components
• Increased toughness
Sources: SolvayPlastics, SpecialChem (12/08) and Lightweight-Design

25. Trends in plastics (ii)
Increased Toughness:
Dyneema and Spectra
• UHMwPE fibers with high tensile strength
• better light/UV stability than Aramid/Kevlar
• similar applications as Kevlar, including
personal protective equipment, speaker cones,
high-performance ropes and cables
Innegra
• high modulus PP fiber
• low-cost
• similar applications as above
Source: Xtreme Degreez Sports Magazine

26. Example: Innegra reinforced concrete
Source: Wikinnegra.com

27. Trends in plastics: Self-reinforced
• Curv is self-reinforced polypropylene
PP Curv
Density kg/m3 900 920
Notched Izod impact kJ/m2 4 400
Tensile strength MPa 27 120
Tensile modulus GPa 1.12 4.2
Sources: Materials World, Vol. 6 No. 10 pp. 608-09 ,1998 / Samsonite / curvonline / matweb

28. Composites

29. Example: Composite Bike Frame
Images: www.lotustalk.com

30. Case study: Optimization of C-Spar
• milled aluminum AA7010-T73651
• resin transfer molded carbon/epoxy
– RTM6
– non-crimp fabric
• autoclave carbon/epoxy prepreg
– M21/T800
– Plain Weave
Kaufmann, Zenkert, Åkermo. Journal of Aircraft (0021-8669) 2011 vol. 48 no. 3

31. Case study: Optimization of C-Spar
weight [kg]
cost [€]
RTM i
RTM ii
RTM iii
Prepreg i
Prepreg ii
Alu
RTM iv
Kaufmann, Zenkert, Åkermo. Journal of Aircraft (0021-8669) 2011 vol. 48 no. 3

32. Trends in Composites (i)
• shorter cycle time
– through automation
– fast curing thermosets
– thermoplastics
 enables cost reduction
for automotive and aerospace
• cost-effective processes
– hybrid processes
– out-of-autoclave
• new material systems
– tougher
– cheaper
– greener
Images: Coriolis Composites, BMW

33. Trends in Composites (ii)
Images: Roltex, FiberShell, GreenCore, Museeuwbikes, Innobat, Huntsman Advanced Materials

34. Message
Design with
Opportunities
ACQUISITION COST
(Research, Design, Test,
Production, Construction)
OPERATION COST
PRODUCT DISTRIBUTION COST
SOFTWARE COST TEST AND SUPPORT
MAINTENANCE COST EQUIPMENT COST
TECHNICAL DATA
TRAINING COST COST
SUPPLY SUPPORT COST
RETIREMENT AND
DISPOSAL COST

35. Questions?