Lightweighting and steel technologies in the all-new

2016 Chevrolet Malibu 2017 Buick LaCrosse

Terry A. Swartzell Underbody System Architect

General Motors Company May 11, 2016

v2

AGENDA

The new sedans

Mass reduction hierarchy

Part sharing

Steel technologies

Crash examples

THE NEW SEDANS

2016 Chevrolet Malibu

• 9th generation

• 111” wheelbase

• Sold in 18 countries around the world

• 3 assembly sites (Fairfax, China, Korea)

2017 Buick LaCrosse

• 3rd generation

• 114” wheelbase

• Sold in US, Canada and China

• 2 assembly sites (Detroit Hamtramck & China)

EFFICIENTLY POWERFUL

All-New 1.5L Turbo

• 6-speed auto transmission

• 160 hp / 184 ft-lb of torque

2.0L Turbo

• 8-speed auto trans

• 250 hp / 258 ft-lb of torque

1.8L Hybrid

• 60 cell / 1.5 kWh Li-Ion battery

• Leverages Volt technology

2017 BUICK LACROSSE

• 3.6L V6

• Quiet-Tuning

• Stronger, longer, stiffer & lighter

STRONGER, LONGER, STIFFER & LIGHTER

2016 Malibu BIW: ~331 kg*

• 2.3” longer OAL vs predecessor

• 3.6” longer W/B vs predecessor

2017 Lacrosse BIW: ~343 kg*

• 0.5” longer OAL vs predecessor

• 2.7” longer W/B vs predecessor

Body structure ~ 100 lbs lighter than previous generation

(Vehicle ~ 300 lbs lighter)

* BIW structure, paint, sealer, adhesive, bolt-on braces, etc

2016 Malibu BIW: ~331 kg* 2017 Lacrosse BIW: ~343 kg*

GM’S BODY MASS REDUCTION HIERARCHY

• Efficient integration of systems

• Aggressive CAE iteration & optimization

• The right performance targets

• Efficient design fundamentals

• The right steel grades

Lower

Higher

Influence on body

mass

kg

• Efficient integration of systems

• Aggressive CAE iteration & optimization

• The right performance targets

• Efficient design fundamentals

• The right steel grades

• Control of architectural bandwidth • Control of architectural bandwidth

• Execution excellence (short flanges, scallops, lightening holes, etc)

• Execution excellence (short flanges, scallops, lightening holes, etc)

GM’S BODY MASS REDUCTION HIERARCHY

• Control of architectural bandwidth

• Efficient integration of systems

• The right performance targets

• Aggressive CAE iteration & optimization

• Efficient design fundamentals

• The right steel grades

• Execution excellence (short flanges, scallops, lightening holes, etc)

ARCHITECTURE BANDWIDTH

2016 FWD

Malibu

LaCrosse AWD

long W/B

GM OLD APPROACH: “ONE UNDERBODY FITS ALL”

Scar Mass

Possible future Derivatives and variants (Bubble size indicates global volume)

GVM

(kg)

Illustrative only not to scale

Possible future derivatives & variants

ARCHITECTURE BANDWIDTH

2016 FWD

Malibu

LaCrosse AWD

long W/B

GM NEW APPROACH: “MANAGED BANDWIDTH”

Possible future Derivatives and variants (Bubble size indicates global volume)

GVM

(kg)

Illustrative only not to scale

Possible future derivatives & variants

Higher mass optimization point

High volume low mass

optimization point

ARCHITECTURE BANDWIDTH

• 4 cylinder only • FWD only • Base FWD tunnel • Base W/B • 4-link rear suspension • Base strut front suspension • Lower GVM’s

• V6 engine • FWD & AWD • Larger AWD tunnel • Longer W/B & ROH • 5-link rear suspension • HiPer strut front suspension • Higher GVM’s

2016 Malibu optimized for: 2017 Lacrosse optimized for:

Higher mass optimization point Low mass optimization point

• Minimum scar mass

BODY STRUCTURE SHARING STRATEGY COMMON SOLUTIONS – UNIQUE PARTS

Low mass optimization point

2016 Chevrolet Malibu

Higher mass optimization point

2017 Buick LaCrosse (NA)

Malibu base parts Common w/Malibu

Trim change only

Unique to LaCrosse

GM’S BODY MASS REDUCTION HIERARCHY

• Control of architectural bandwidth

• Efficient integration of systems

• The right performance targets

• Aggressive CAE iteration & optimization

• Efficient design fundamentals

• The right steel grades

• Execution excellence (short flanges, scallops, lightening holes, etc)

AGGRESSIVE VIRTUAL DEVELOPMENT

Optimization iterations

Visualization & interpretation iterations

Concept design iterations

Optimization iterations

Visualization & interpretation iterations

Concept design iterations

• 6 virtual gates per model

• 2832 standard loadcases

• 10 million CPU hours

• 6 virtual gates per model

• 2832 standard loadcases

• 10 million CPU hours

FULLY OPTIMIZED FINAL ITERATION

Planar & parallel faces

Extended seatback beam

Multi-piece gusset

Integrated right-sized sections

1

2

3

4

Extended seatback beam 1

Planar & parallel faces 2

Multi-piece gusset 3

Upper seatback

section

Max

Ixx

Integrated right-sized sections 4

RESULTS: STIFFER PERFORMANCE

Global Static Torsion (kN-m/deg)

New Malibu Predecessor Malibu

Base roof: 23.0

21.6

28.4

23.6

+23%

+9% Sunroof:

HIGH EFFICIENCY FRONT TOPOLOGY CONCEPTS

Upper rail flows

into cradle standoff

Hoop structure between struts 3

5

Stiff powertrain mount loadpaths 2

Drag section tubes & stampings 4 Drag section tubes & stampings 4

Strut tower - A pillar loadpath 1

Upper rail flows

into cradle standoff 5

Strut tower - A pillar loadpath 1

Hoop structure between struts 3

2 Stiff powertrain mount loadpaths

Unit load

PERFORMANCE RESULTS: STIFF CONTINUOUS HIGH QUALITY DEFORMED MODES

Upper rail flow into

cradle standoff 5

N&V IS KEY DRIVER OF TOPOLOGY

Structure Goals: Maximize mount isolation.

Minimize vibration sensitivity.

Source Powertrain and road

Path Structure

Receiver Cabin noise and vibration

Example: engine pulse response optimization

Example: Cradle mount dynamic stiffness development.

2

2 Minimize vibration sensitivity.

1

1

Maximize mount isolation.

Structure Goals:

GM’S BODY MASS REDUCTION HIERARCHY

• Control of architectural bandwidth

• Efficient integration of systems

• The right performance targets

• Aggressive CAE iteration & optimization

• Efficient design fundamentals

• The right steel grades

• Execution excellence (short flanges, scallops, lightening holes, etc)

EFFICIENT DESIGN FUNDAMENTALS

• Thin skins • Stable sections • Bulkheads • Local reinforcement • Bolt-in struts

EFFICIENT FUNDAMENTALS EXAMPLE BOLT-IN N&V STIFFENER

Achieves key target for dynamic stiffness

Low mass - very effective

Allows lean “down-rigger” structure

Unit load

EFFICIENT DESIGN FUNDAMENTALS

54 meters of structure adhesive

Supplements spot welds

Improved durability at thin gauges

Enhances stiffness

Arc welding/brazing

Used in high value areas

Allows single sided joining

Allows smaller, stiffer sub-assemblies

GM’S BODY MASS RED’ N HIERARCHY

• Control of architectural bandwidth

• Efficient integration of systems

• The right performance targets

• Aggressive CAE iteration & optimization

• Efficient design fundamentals

• The right steel grades

• Execution excellence (short flanges, scallops, lightening holes, etc)

THE RIGHT STEEL GRADES

Mild PHS &

martensite

Dual phase & multi-phase

HSLA Bake hardenable

7%

34% 24%

9%

27%

•Thicker at max bending moment

•Long thickness transitions

Variable thickness blank

Side view of part

Thin Thin Thick

HIGH THICKNESS ONLY WHERE REQUIRED

transitions

Thickness profile*

* Thickness profile optimized for Malibu. Reinforcement added for higher GVM LaCrosse.

Co-formed patch blank utilization

Co-formed dash & constrained layer doubler

Co-formed PHS B-pillar and reinforcement

• PHS patch on PHS pillar • Avoids dimensional issues • Maximizes weld flats

• Steel-viscoelastic-steel sandwich in key N&V area

• Net vehicle mass savings (lower acoustic mass)

HIGH THICKNESS ONLY WHERE REQUIRED

HIGH THICKNESS ONLY WHERE REQUIRED

Laser welded rail blanks

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```

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Front rail inner

Front rail reinf

Front rail outer

Varying thickness &

grade

Varying thickness

Varying thickness &

grade

Varying thickness & grade

Rear rail lower

Front rail rear extension

Varying thickness & grade

LASER WELDED RAIL BLANK

Example: China NCAP rigid moving barrier

TUNING EXAMPLE

Gauge and grade in each zone optimized for performance

Zone

C A Zone

B Zone

Crush Fold Backup

CRASH EXAMPLE

SMALL OVERLAP PERFORMANCE

Vehicle deflection Strong back-up structure

• Bolt-on body parts • Cradle deflector

• High part strength • High weld strength

Vehicle Deflection Strong backup structure

SMALL OVERLAP ANALYTICAL DEFORMATION

THANK YOU FOR YOUR ATTENTION!