1. No category

Body-in-White technology in the new:
Saturn Outlook
GMC Acadia &
Buick Enclave
Terry Swartzell and Don Kolis
General Motors North America
March 7, 2007
Swartzell
www.autosteel.org
Outline
• Vehicle architecture
• High level body-in-white strategy
• Underbody steel strategy
• Uppers steel strategy
• Construction
• Performance
• Questions
Swartzell
www.autosteel.org
Outlook, Acadia & Enclave
architecture
• All new BFI crossover utility
platform for GM.
• Spacious accommodations for 7
or 8 passenger.
• 3.6L transverse V6 and sixspeed transmission.
• Offered in both AWD and FWD
versions.
• Built in new Delta Township
plant near Lansing, Michigan.
• EPA estimated 26 MPG highway
(FWD).
Swartzell
www.autosteel.org
Market trends
(selected vehicles)
Chev Suburban
Ford Expedition
Nissan Armada
Chev Tahoe
Toyota Sequoia
Outlook & Acadia
Dodge Durango
Mercedes GL
Hyundai Veracruz
Chrysler Pacifica
Audi Q7
Chev Trailblazer
06 Acura MDX
Mazda CX-9
Honda Pilot
BMW X5
Ford Freesytle
VW Toureg
Cadillac SRX
Ford Edge
Chevrolet Equinox
04 Lexus RX
Nissan Murano
Highlander
Mazda CX-7
BMW X3
Increasing
Saturn VUE
Vehicle Honda Element
Ford Escape
size
07 Hyundai Sante
07 Honda CR-V
Jeep Compass
06 Toyota RAV 4
Saturn Outlook,
GMC Acadia &
Buick Enclave
• Market is demanding larger
BFI crossover vehicles with
accommodations similar to
full size BOF SUV’s.
• Steel technology remains key
in satisfying the performance
requirements of the larger
BFI entries at a competitive
mass.
Body-on-Frame (BOF) sport utilities
OAL x OAW x OAH
Body-Frame-Integral (BFI) crossovers
Swartzell
www.autosteel.org
BIW high level strategy
World class BIW performance
across platform bandwidth.
Enable competitive mass
with effective geometry, steel
selection and optimization.
Configure BIW to
achieve best-inclass interior
spaciousness
Maximize re-use
for future variants.
Aggressively leverage
AHSS, UHSS & HSLA’s in
cost effective applications.
Advance GM
common product and
process strategies.
Swartzell
Develop enablers to achieve world class quality:
- gap and flushness of fits
- “jewel effect” features on panels
- secondary surfaces appearance
www.autosteel.org
BIW structure features
Open front end
facilitates vehicle
assembly.
Straight rails
tuned for high
crush efficiency.
Laminated
steel
plenum.
Pumpable foam
acoustic cavity
treatments.
Cost effective usage of
martensitic, D-P, and HSLA
steels in primary load paths.
Rear HVAC
duct integrated
inside section.
Layered framing allows
welding prior to outer
panels closing section.
Sub-assembly of structure
surrounding lift-gate provides
high torsional stiffness.
Swartzell
www.autosteel.org
UHSS straight C/C
tube manages side
impact load.
Steel selection strategy
Steel specification strategy
Tensile
Strength
Grades
used
Typical usages
Mild steel
Low
Carbon
Large underbody closeout panels,
highest quality outer panels.
260 - 270
Bake
hardenable
180-210-300
Stiffness dominant parts and
formability restricted parts.
300 - 390
HSLA
340-410-550
Strength dominant parts with
minimal energy absorption.
440 - 650
Strength dominant energy
absorption parts and high
strain parts.
590 - 980
Dual Phase
DP600
DP800
DP1000
Martensitic
Grade 9
Grade 13
(mPa)
Parts requiring highest ultimate
strength.
Swartzell
www.autosteel.org
900 - 1300
Steel grade usage
percent by mass
Martensitic 7%
Grade 9 – Grade 13
Low Carbon 26%
Dual Phase 7%
600 - 800 - 1000
HSLA 34%
340 - 410 - 550
Bake Hardenable 26%
180B - 210B - 300B
Swartzell
www.autosteel.org
Underbody steel applications Steel grade usage
(underbody)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
Martensite applications
• Used where maximum strength is required
for crash (rockers and cross-members).
• Constant sections provide structural
continuity and allows roll form processing .
• Both Grade 9 and Grade 13 used based on
optimum weldability.
Cross-car
tube
Rocker Inner
panels
Swartzell
www.autosteel.org
Underbody steel applications Steel grade usage
(underbody)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
Dual-Phase applications
• Used in crush zones for improved energy
absorption.
• Also used in high strain areas.
• Use DP 600 and DP 800 grades in
underbody based on manufacturability.
Swartzell
www.autosteel.org
Underbody steel applications Steel grade usage
(underbody)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
HSLA applications
• Used as complement to Dual Phase to
facilitate weldability.
• Used where high yield strength is
required but with minimal energy
absorption need.
• Use 340, 410 and 550 grades based
on formability.
Swartzell
www.autosteel.org
Underbody steel applications Steel grade usage
(underbody)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
Bake Hardenable
applications
• Used in stiffness dominant parts
and formability restricted parts.
• 180, 210 and 300 grades of bake
hardenable used.
Swartzell
www.autosteel.org
Steel grade usage
(underbody)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
Low Carbon
applications
• Used to close out underbody.
• Not treated as primary load
path.
• Thickness minimized for mass
and cost efficiency.
Swartzell
www.autosteel.org
Steel grade usage
Upper structure steel applications
(upper structure)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
Martensite applications
• Used in rocker outer as well as
underbody.
• Creates fully closed martensitic
rocker section.
• Section stabilized with bulkheads.
Rocker Outer
panels
• Maximizes structural efficiency for
front, rear and side crash events.
Kolis
www.autosteel.org
Steel grade usage
(upper structure)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
Dual-Phase applications
• Used in “B” pillar for side impact
and roof crush loading events.
• DP 800 and DP 1000 grades used.
Kolis
www.autosteel.org
Steel grade usage
(upper structure)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
HSLA applications
• Used selectively for reinforcements.
Kolis
www.autosteel.org
Steel grade usage
Upper structure steel applications
(upper structure)
Martensitic
F.O.C.
Dual Phase
HSLA
Bake
Mild
Bake Hardenable
applications
• Used in stiffness dominant parts
and formability restricted parts.
• 180, 210 and 300 grades of bake
hardenable used.
• Grades specified based on
manufacturability and strength
balance.
Kolis
www.autosteel.org
Steel grade usage
(upper structure)
Martensitic
Dual Phase
HSLA
Bake
Mild
Low carbon applications
• Used in one-piece body side outer
panel and roof.
• Selected to enable crisp features in
styled panels for highest possible
quality.
• Mild steel panels not treated as load
carrying primary structure.
Kolis
www.autosteel.org
Dual Phase considerations
• Develop part geometry with features to control spring back and side wall curl.
• Provide greater open wall angles for spring-back compensation.
• Provide constant section height to maximize shape set & strain.
• Shorten overall part length to minimize twist end to end.
• Plan for additional binder tonnage and try-out time to compensate die for spring back.
• Reduced trim and pierce angles and use hardened/coated tool steels.
• Flanging possible in non work hardened areas from draw or form dies.
• Develop part to minimize compression and stretch flanges and edge splitting
• Develop robust processes for weld verification.
Kolis
www.autosteel.org
Layered
framing
BOP framing sequence / construction
strategy
facilitates weld access
1) Inner panels loaded.
2) Inner panels welded to
underbody with full access.
3) Outer panels loaded.
Benefits:
- reduced need to weld through access holes.
- has demonstrated high dimensional capability.
- allows optimal welding for improved mass efficiency.
Kolis
www.autosteel.org
Stiff back body opening
built as sub-assembly
Traditional back body build
Sub-assembled back body build
GM Framing
Process
Benefits:
- structural continuity through corners.
- effective corner reinforcement.
- allows integration of HVAC duct which
maximizes enclosed area of section.
Results:
- 25.9 N-m / deg torsional stiffness.
- 24 hz first bending mode (fully trimmed)
- 28 hz first torsion mode (fully trimmed)
Kolis
www.autosteel.org
HVAC duct
integrated
inside
welded
section
Lightweight design coefficient*
Lightweight design coefficient used to
evaluate construction and joint efficiency
Results vs benchmark crossover’s
More efficient
Benchmark
vehicle #1
6
5
Outlook, Acadia
& Enclave
4
Benchmark
vehicle #2
Projected Area
3
Lightweight
design
=
coefficient
2
Benchmark vehicle #4
1
Benchmark vehicle #5
Body-in-white mass (kg)
2
Area (m ) x Torsional stiffness (N-m/deg)
0.00
Kolis
Benchmark vehicle #3
2.00
* Described in SAE paper 2006 - 01-1405
www.autosteel.org
4.00
6.00
8.00
10.00
BIW noise strategy
Laminated steel plenum
reduces structure borne noise
Extensive mobility development
at isolated chassis interfaces
Best practices executed to
minimize wind noise at source
Liquid applied sound deadener
tuned for optimum performance
Sealing strategy achieved
aggressive body leakage targets
Pumpable foam acoustic cavity
treatments provide robust noise
barrier and sealing.
Kolis
www.autosteel.org
Crash Performance
Overall crash performance:
Competitive!
Kolis
www.autosteel.org
Crash Test Results*
Frontal Crash
Driver
Passenger
Side Crash
Driver
Passenger
Not yet released
Not yet released
* Source: National Highway Traffic Safety Administration
www.autosteel.org
Questions & Answers:
Acknowledgements: Andy White, Bushan Dandekar, Marcel Cannon, Curt Horvath, Gary Telleck, Greg Warden
www.autosteel.org