Lightweighting Using Composites: Rise, Fall and Now “Enlightenment” Srikanth Pilla, Department of Automotive Engineering 1
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Lightweighting Using Composites: Rise, Fall and Now “Enlightenment”
Srikanth Pilla, Department of Automotive Engineering
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Contents
• Motivation • Understanding the importance of lightweigthing
• Effects on fuel economy • Inversion of the mass spiral • Lightweight case study
• Understanding Amara’s law• Composites ‘s: Amara’s law
• Composites at Clemson: Clemson Composite Center • What’s next?
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Motivation
• CAFE2025– Fueleconomytargets
• CO2 Emissions2007/46/EC– CO2 emissionstargets
• End-oflifevehicledirective2000/53/EC– 95%reuseandrecoveryfrom1stJanuary2015.
• Highestmasscontributionisfromtheloadbearingstructure.(15%to30%)
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Importance of lightweigthing
Plottingdatafrom400passengercarswithgasolinepowertrainbetween1990-2014
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R²=0.7227
0
50
100
150
200
250
0 10 20 30 40 50
Powerinhp
MPG
PowervsMPG
R²=0.67314
0
2
4
6
8
10
12
0 10 20 30 40 50
No.ofcylinde
rs
MPG
No.ofcylindersvsMPG
Wecaninferthatweighthasthemostsignificanteffectonfuelefficiency.
R²=0.7647
0
1000
2000
3000
4000
5000
6000
0 10 20 30 40 50
Weightinlbs
MPG
CurbweightvsMPG
Understanding fuel economy for electric car
Plottingdatafromsevencarswecanclearlyseehowweighteffectstherangeofthecar.
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R²=0.73932
0
500
1000
1500
2000
2500
0 2 4 6 8 10 12
CurbW
eightinKg
Rangeperunitenergyfromthebatteryinkm
WeightvsRangeperunitenergy
• AvgcostforeachKwhofthebatteryis$700.
• Withthishighcostforbatteries,lightweightingisveryimportant.
Inversion of the mass spiral
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Intelligentstructurewithadvancedmaterials
LighterchassisDownsizedengineandelectricmotor
Reducedfueltankandbattery
- kg
The benefits of lightweigthing are often multi-
faceted. Lightweigthing has a positive impact
on vehicle performance, cost and efficiency.
Substantial lightweigthing can often trigger
mass inversion, which is desirable during
vehicle development.
Weight distribution in passenger vehicles
Closures contribute ~20% to 40% of the total structure
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Closures25%
Frame
68% Fenders1%
Bumpers6%
Closures28%
Frame
66% Fenders
1%
Bumpers5%
2017Hondacivic 2017AcuraMDX 2016BMWi3
Closures31%
Frame
60% Fenders2%
Bumpers7%
Current state-of-the-art for BiW
Body in white structures that are commercially produced today can broadly be categorized into 3 groups.
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SteelBiW
• 45k- 150kunitsperyear• ~290to~430partspercar• Lightweightindex:>3.5
Aluminumspaceframe
• 45kunitsperyear• ~350partspercar• Lightweightindex:2<X<3.5
Carboncell
• 30kunitsperyear• ~160partspercar• Lightweightindex:1.5<x<2
Future for automotive structures
Fiber reinforced thermoplastics are a viable material choice for primary structural applications.Re-processability and recyclability are major motivation for the push towards thermoplastics matrix.
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Steel Aluminum ThermosetComposites
ThermoplasticComposites
Light weightpotential Medium High VeryHigh VeryHigh
Material cost Moderate Medium High High
Reprocessing/ recyclability Good Good Not Good
Partmanufacturing Very Fast VeryFast Slow Fast
Structuraljoiningspeed Fast Moderate Very Slow VerySlow
Numberofpartspervehicle 290-430 350 160 Tbd
Annual productionvolume(in1000s) 45-90 45 30 Tbd
Averagetakttimepervehicle 55-100sec 120-200sec 480sec Tbd
Diversity in composites
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Anisotropicmaterialhardtomodelandpredictperformance
Microcells(GasBubbles)
Fiberlengthsupto~5mm Fiberlengthsabove~10mm Continuousfiber
ScF FoamedPolymer PurePolymerShortFiberReinforced
PolymerLongFiberReinforced
PolymerEndlessFiberReinforced
Polymer
0
1
2
3
4
5Strength
toughness
stiffness
shearstrength
Ligthweigth
Ecconomy
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1
2
3
4
5Strength
toughness
stiffness
shearstrength
Ligthweigth
Ecconomy
0
1
2
3
4
5Strength
toughness
stiffness
shearstrength
Ligthweigth
Ecconomy
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1
2
3
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5Strength
toughness
stiffness
shearstrength
Ligthweigth
Ecconomy
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1
2
3
4
5Strength
toughness
stiffness
shearstrength
Ligthweigth
Ecconomy
IsotropicmaterialEasytomodelandpredictperformance
Technology portfolio for efficiency
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High
High
Low
Low Efficiencygains– Miles/GramsofCO2
CostofV
ehicle$
Lowrollingresistancetires
BetterAerodynamics
CNG
Diesel
DesignOptimization
Enginedownsizing
Hybrids
Plug-inHybrid
FullElectric
Hydrogen
HCCIAluminumBiW
CFRPBiW
LargeBolt-onCompositeparts
TurboCharging
LowHangingFruits
Lightweigthing technologies Powertraintechnologies General&miscellaneous
UltraLightweightClosuressystems?
Case study, lightweighting vs powertrain
Efficiency gains per dollar is a good indicator for fair comparison of lightweight technologies. In this case study, the efficiency gained for dollar spent is calculated between two vehicles with similar performances.
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2017BMW330i$38,7501606.17kg
29.8MPGcombined
Vs
2017BMW330e$43,700
1769.01kg38.41MPGcombined
(inhybridmodewithzeroelectricrange)
Body– 302kgDoors(4)– 101kg
Body– 328kgDoors(4)– 101kg
Case study, lightweighting vs powertrain
Calculating fuel economy for a hypothetical car
From experience in developing ultra-lightweight doors, 42.5% mass reduction with no performance compromise, while noticing a cost increase of $5 per pound saved is achievable.
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Compositedoor
Body– 302kgDoors(4)– 101kgTotalcarweight– 1606.17Kg
Body– 302kgDoors(4)– 58.07kgTotalcarweight– 1563.24KgNetcostincrease($5/pound)–$214.65
Case study, lightweighting vs powertrain
Calculating fuel economy
• A simple drive cycle energy model iscalibrated to match the performance of thebaseline and hybrid vehicles.
• This model take into consideration the effectof mass, aerodynamics and rolling resistanceon fuel economy, as shown below. All theterms highlighted in green are vehicledependent and yellow are drive cycledependent.
• Fuel economy during city and highway drivecycles are calculated to compare the EPAreported fuel economy for all the abovementioned cases above.
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Drivecycle
Vehicle
ICEonly Hybrid ICE+ULWDCityfueleconomy 24.9 35.1 26.4
Highwayfueleconomy 32.42 37.46 33.72EPAreported 27.8 36.11 29.26
Costincreasepermpg n/a $595.7 $146.6
Case study, lightweighting vs powertrain
Comparing cost vs efficiency improvement
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BMW330i+LightweightDoors
BMW330e(Hybrid)
WhatwegetULWD
Amara’s law
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We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run
Expe
ctation
Time
Technologytrigger
Technologytrigger
Troughofdisillusionment
Plateauofproductivity
SlopeofEnlightenmentHype
1 23
1. Trigger point and hype
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Trigger point – Aerospace • First applications started in the aerospace industry. • Cost penalty for weight are so high, this forced innovation in
composites.
Windecker Eagle,1969Fiberglassandfoamsandwich
Boeing787,2011FirstlargeCarbonfiberfuselage
1. Trigger point and hype
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Trigger point – Automotive • Mclearn formula one, was the first to use carbon fiber as primary
structural material for its race car in 1981 grand prix.• Mclearn F1 was the first road car to use carbon fiber monocoque.
Mclearn f1
Mclaren MP4/1,1981Carbonfibertub.
Mclaren F1,1992ProductioncarwithCarbonfibertub.
2. Peak and fall
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Rise and hype of carbon fiber in automobiles:2014, BMW starts manufacturing the first carbon fiber mass production vehicles, BMW i3 and BMW i8.
2. Trough of disillusionment
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High expectation from technologies, often leads to disappointment. Without giving the technology time for maturity.
3. Slope of enlightenment
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With the knowledge and infrastructure generated during the peak of technologies, slowly more companies adopt these technologies.• E.g.: Components in multi material body structures.
Clemson Composites Center
What is Clemson Composites Center?
VisionTo be the premier and preferred innovation center in the country in transforming composites through the development of cost-effective and efficient yet sustainable technologies that benefit the four key sectors of education, industry, society and the environment.
Mission To conduct basic and translational research, transform, develop, and rapidly transfer technologies and innovations so as to promote economic development in the state and support the vision of Greenville Technical College’s Center for Manufacturing Innovation (CMI) to educate a highly skilled workforce.
What is C3?An investigative hub for fundamental ResearchAn engineering center for technology InnovationA prototyping center for composites application DevelopmentA teaching hub for distinctive workforce training and Education
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Research areas
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Advance Materials• Advanced Fibers• CFRP Composites & Foams• Sustainable Materials• Nanomaterials• Energy Materials• Accelerated Materials Discovery
Advanced Manufacturing• Polylemma of Production Technologies• Hybrid Production Systems• Advanced Manufacturing Simulations• Dissimilar Materials Joining• IIoT-enabled Composites 4.0
C3’s pathway: science to commercializationFundamentalresearch• Atomiclevel• Polymerscience,fibertechnology
Compositesprocessing• Extrusion• Injectionmolding,• HP-RTM,GI- andC-RTM• PIFandScFTechnologies• Polylemmaofproduction
Researchandcollaboration• AutomotiveOEM’S• Federalagencies• Othereducationalintuitions
Applicationresearch• Innovativeproblemsolving• Conceptdevelopment
Prototypingandtesting• Manufacturingfunctional
prototypes• Performingindustry
standardtestingforvalidation.
Commercialimplementation
Seriesproductionvalidation• Virtualplantsimulations• Qualitycontrolprocess
design
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Green Car• Lighter• Recyclable• Environmentally friendly• Economical• Efficient
Infrastructure at C3
o Twin-screw extrusion line for compounding and manufacturing films and foams
o Thermoplastics pultrusion manufacturing Line
o 1000 ton HP-RTM line with bolt-on injection molding unit and ScF (MuCell®) technology
o Bolt-on injection molding unit
o Workspace
o Storage
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Infrastructure at C3
*Thispictureillustratesequipmentsimilartotheonethat’sgoingtobecommissionedatC3
One of kind equipment that enables manufacturing of thermoset, thermoplastic or hybrid parts.
• HP-RTM• C-RTM• Wet compression molding• Prepreg compression molding• Injection molding • Insert/outsert molding• Sheet/bulk molding compound• Polymer-metal hybrid molding
1000 ton HP-RTM line with bolt-on injection molding unit and ScF technology
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Infrastructure at C3
Thermoplastics pultrusion manufacturing line* Twin-screw extrusion line for compounding and manufacturing films and foams
*plannedforfuture
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Manufacturing capabilities at C3
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Manual processes
• Hand layup• Vacuum infusion
• Low and High Pressure RTM• Wet compression molding • Thermoforming • Compression molding : Sheet and Bulk
• Injection molding with Mucell®• Over molding: insert/outsert molding
• Co-rotating twin screw extrusion• Custom thermoplastics pultrusion
Compressionprocesses
Injection processes
Continuous processes
Product development capabilities at C3
Services offered to industry partners and clients
Product development with systems approach CAE simulation Market survey Plant layout simulationLight-weighting support Collaboration and R&D supportTooling design and development
Mold trialsFull scale functional prototypingWorkforce training Themed workshops/seminarsTechnology transferIn-house production cell
Research Design Development Virtual Validation Prototype Manufacturing
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Industry partnership
CUICAR has a vast network (partnership/engagement) of over 100 companiesranging form automotive OEMs to tiered manufacturers. Below are few examplesof these companies:
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AutomotiveOEMsSuppliersGovernmentagencies
Education enabled by C3
C3 will engage in a statewide initiative to improve education capacity in STEM fields. This institution embodies a model to engage universities, 2-year colleges, K-12 institutions, statewide industries and federal agencies to deliver highly skilled workforce.
K-12 Technical college Undergrad Graduate Workforce training
Engagement & outreach programs
Training for advanced
manufacturing
Early exposure to research in STEM
fields
Courses, research and practical experience
Interactive training for professionals and
executives for advanced technologies
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Engage Academic Core
Center’s growth philosophy
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2018 2023 2028
SC USA
Over the next 10 years, achieve excellence to be the flagship center in the world for composites R&D and full-scale prototyping.
What’s next?
Current trends for composites in automotive industry
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CostProductionvolumesRecyclability
Thermoplasticsresins Lowcostcarbonfibers
Discontinuousfibercomposites Longfiberinjectionmolding
Compressionmolding
Wetcompressionmolding ThermoplasticspultrusionThermosetresins
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