Lightweight Chassis Development at Ford Motor Company

Xiaoming Chen, John Uicker and David Wagner Overview • Lightweight Design Strategies • Magnesium Subframe Development • Carbon Fiber Composite Subframe Design • F-150 aluminum Cross Members • Lightweight Coil Springs • Summary Lightweight Chassis Design Strategies • Eﬃcient structure design – Knowledge database – CAE driven opmizaons • Lightweight material applicaons – Aluminum – Magnesium – Carbon ﬁber composite • Cost esmates – Variable cost – Tooling cost Magnesium Subframe Development High pressure die cast magnesium subframe Supplier partner : Meridian Magnesium

CAE Driven Design Met all sﬀness targets Met durability and strength requirements Analyzed strain caused by bolt proof loads Magnesium Prototype 4.8 kg (30%) weight saved

Tests Planned Corrosion migaon Component fague Component strength Bolt load retenon Proving ground durability, corrosion and special events Magnesium Subframe Development

Design Iteration start with stiffness requirements

Package investigation Design block for topology optimization

Topology contour of material distribution Part geometry Magnesium Subframe Development

Other Design Attributes

Strain contour under extreme loads

Durability life contour

Strain contour under bolt proof loads CMM for dimension and tolerance control Carbon Fiber Composite Subframe Concepts Compression molded composite and UD laminates Supplier partner : Cosma Internaonal and Magna Exteriors

Steel front subframe Steel rear subframe

CF front subframe CF and Al rear subframe Carbon Fiber Composite Subframe Concepts

CAE Driven Design Met all sﬀness targets Met durability and strength requirements Analyzed strain caused by bolt proof loads Front subframe 6.6 kg (25%) weight saved Rear subframe 12 kg (43%) weight saved

Other Key Deliverables Package Manufacturing feasible for high volume producon Safety aributes Cost esmates Risks and unknown idenﬁcaons for future test and invesgaon Carbon Fiber Composite Subframe Concepts

Challenges of CF Subframe Design Package space Sﬀness design Joining Thermal eﬀects

Test Planned Corrosion mitigation Component fatigue Component strength Bolt load retention Proving ground durability, corrosion and special events F-150 Lightweight Frame Cross Members

Tailor rolled steel cross member

Aluminum cross member Al Cross Member and Spare Tire Carrier

Steel sleeves

Steel assembly Aluminum assembly proposal

Steel sleeves are introduced accommodating current production frame assembly process Al Cross Member and Spare Tire Carrier

Aluminum Cross Member to Steel Sleeve Joint

A combination of structure adhesive and mechanical interlock

Investigation Conducted Distance of welds to adhesive Adhesive selection Number of mechanical interlocks Al Cross Member and Spare Tire Carrier

Cross Member Temperature Measurements During Welding Using Thermocouples

Aluminum Crossmember/Frame Rail Welding Study

700 600 TC#1 TC#2 500 TC#3 400 TC#4 300 TC#5 TC#6

200

(F) Temperature TC#7 100 Aluminum assembly concept TC#8 0 00:00.0 00:10.0 00:20.0 00:30.0 00:40.0 00:50.0 01:00.0 01:10.0 01:20.0 01:30.0 01:40.0 01:50.0 02:00.0 02:10.0 02:20.0 Time Al Cross Member and Spare Tire Carrier

Aluminum Cross Member and Steel Sleeve Assembly

Pre-crimped steel sleeves Apply adhesive Assemble cross member and sleeve

Crimp to create 1st pair of interlock 2nd crimp to complete Al Cross Member and Spare Tire Carrier

Load Carrying Capacity Tests

load

Tension

Torsion

Bending Al Cross Member and Spare Tire Carrier

Corrosion Tests (3 adhesives and 6 surface treatments) Lightweight Coil Springs (CD Car) • Composite Front Spring – Supplier partner: Sogefi Group – 1.2 kg/spring – 1.6 kg (57%) weight saving • Hollow Steel Rear Spring – Supplier partner: NHK Spring Group – 2.7 kg/spring – 1.6 kg (37%) weight saving • Titanium Rear Spring – Supplier: Renton Coil Spring – 2.0 kg/spring – 2.3 kg (54%) weight saving Lightweight Coil Springs (CD Car) • All springs met performance requirements in component tests – Rate/load – Dry fague – Key life • Composite FRT spring and hollow steel RR spring were tested at proving ground – Durability – Corrosion

Lightweight Coil Springs (CD Car)

Additional Tests on Composite Springs

• Dry Fatigue at 80ºC – Cyclic fatigue to requirement, then… – Accelerated fatigue to break • Relaxation Test – Relaxation < 4% – Height loss < 8 mm Lightweight Coil Springs (CD Car)

Addional Tests on Composite Springs

• Under Water with Alternating Temperature Fatigue Test – Alternating temperature – Cyclic fatigue to requirement – Same life cycles as dry fatigue – Height loss within tolerance • Chemical Resistance Fatigue Test – Liquid spray periodically – Cyclic fatigue to requirement – Same life cycles as dry fatigue Lightweight Coil Springs (CD Car)

Vehicle Proving Ground Durability Test • No issue During Test – Perform well in vehicle • Observation – < 4mm ride height change (composite) – No visible damage – No dirt/grits buildup • Marks on coils (post test) – Possible touching Summary

• Ford is commied to lightweight chassis development • Lightweight materials have great potenal for weight reducon • Effecve structure design is a key factor for efficient weight saving • Lightweight chassis component applicaons rely on – More affordable material price – Improved manufacturing process – Adequate package space for alternave designs Acknowledgements • Ford Research – Michael Azzouz, Jeff Wallace, Allen Li, Guosong, li and Alberto Girelli Consolaro • Ford Product Development – Sanjay Mehta, Paul Mayer, Dan McCarthy, John Kniel, Eric Barre, Mark Wlotkowski, Elaine Kelley, Hua Lu, Jon Watson, Sunil Kasaragod, Joe Buchwitz and Rao Pothuraju • Ford Central Lab – Kim Lazarz and Andrew Wedepohl • Supplier Partners – Sogefi Group, NHK Spring, Renton Coil Spring – Meridian Magnesium, Magna Internaonal