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w w w . a u t o s t e e l . o r g
The LX BIW StructureA
Great “Steel” DesignThomas N. Seel
DaimlerChrysler
w w w . a u t o s t e e l . o r g
LX BIW StructureA
Great “Steel” Design
Co-Authors/ AcknowledgementsShan Haq CAE
Mike Mihelich BIWPaul Belanger & J. P Singh MaterialsPamela Larson Vehicle Development
Subhas Shetty CAEChristie Brusha Manufacturing
Larry Brookes BIWLX BIW Engineering Department
DaimlerChrysler
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What Defines a “Great BIW Design”
• Looks (Styling)• Light Weight (materials/construction)• Structural Performance• Flexible Manufacturing Process• Low Cost ($)
w w w . a u t o s t e e l . o r g
What Defines a “Great BIW Design”
• Looks (Styling)• Light Weight (materials/construction)• Structural Performance• Flexible Manufacturing Process• Low Cost ($)
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Looks (Styling) : The all new Chrysler 300
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Looks (Styling) : The all new Chrysler 300
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• Looks (Styling)
A new Classic Proportion for Chrysler
1955 C300 2005 300C50 years
300 C 5.7L Hemi V8 (340hp) 300 Touring 3.5L V6300 2.7L V6Start of Production: February 2004, in showroom: April 2004
Looks (Styling) : The all new Chrysler 300
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What Defines a “Great BIW Design”
• Looks (Styling)• Light Weight (Materials/Construction)• Structural Performance• Flexible Manufacturing Process• Low Cost ($)
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What Defines a “Great BIW Design”
• Light Weight (Materials/ Construction)– HSS Steel
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• Near Double Parts with High Strength Steel (HSS)– ’98 20% HSS– ’05 37% HSS
• Dual Phase Steel for Front Rails
0%10%20%30%40%50%60%70%80%90%
100%
'98300M
'05300C
>= 550Mpa>= 340Mpa>= 280Mpa
Light Weight : Materials / Construction
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05 LX HSS Part <= 280 MPa Yield
Light Weight : Materials / Construction
0%10%20%30%40%50%60%70%80%90%
100%
'98300M
'05300C
>= 550Mpa>= 340Mpa>= 280Mpa
w w w . a u t o s t e e l . o r g
Light Weight : Materials / Construction
05 LX HSS Parts >= 340 MPa Yield
0%10%20%30%40%50%60%70%80%90%
100%
'98300M
'05300C
>= 550Mpa>= 340Mpa>= 280Mpa
w w w . a u t o s t e e l . o r g
Light Weight : Materials / Construction
0%10%20%30%40%50%60%70%80%90%
100%
'98300M
'05300C
>= 550Mpa>= 340Mpa>= 280Mpa
05 LX HSS Parts >= 550 MPa Yield
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What Defines a “Great BIW Design”
Light Weight (Materials/ Construction)– HSS Steel– Construction : Section Design
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Delta %Ip1: 7.2%Ip2: 8.0 %A: 8.0%
NominalIp1:2.299 X106 mm4
Ip2:1.351 X106 mm4
A :888 mm2
EffectiveIp1: 2.132 X106 mm4
Ip2:1.243 X106 mm4
A: 817 mm2
ASPPCARS/GAS
Light Weight : Materials / Construction
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Variable Section Kick-Up C/M
Octagon Shape Front Rail
Double C-Section Rear Rails
Light Weight : Materials / Construction
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Light Weight : Materials / Construction
Load BearingRoof Bow
3 Layer Body Side Sections
Constant Moment B-Pillar Internal Shear Plate Sill
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What Defines a “Great BIW Design”
• Light Weight (Materials/ Construction)– HSS Steel– Construction : Section Design– New Technology
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05LX Headlamp Mounting Crossmember (HMC)
Metal / Plastic HybridWeight = 16 lbs. savings
Variable cost neutralInvestment = $6.8M savingsImproved Build Tolerances
Light Weight : Materials / Construction
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What Defines a “Great BIW Design”
• Light Weight (Materials/ Construction)– Bottom line ?
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LX 300C vs LH 300M
DE
D
EXTERIOR Chrysler ChryslerHARD PTS mm (in) 300C 300MLength. . . . . . . . . . 5,001 (196.9) 5,023 (197.8)Width . . . . . . . . . . 1,881 (74.1) 1,892 (74.5)Height . . . . . . . . . . 1,483 (58.4) 1,422 (56.0)Wheel Base . . . . . . 3,048 (120.0) 2,870 (113.0)Frt Track . . . . . . . . 1,600 (63.0) 1,573 (61.9)Rr Track . . . . . . . . 1,603 (63.1) 1,565 (61.6)Frt Over Hang . . . . . 876 (34.5) 1,054 (41.5)Rr Over Hang . . . . 1,078 (42.4) 1,100 (43.3)
Light Weight : Materials / Construction
7” longer WB1.5” wider trackRWD vs. FWDImproved Safety CageUpgraded NVH
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7.57.77.7Weight/Interior Volume
110114.8118.8Interior Volume ft^3
829.0880.0914.8Body Shell Weight lbs.
Benchmark#2 FWD
Benchmark#1 RWD
LX
Light Weight : Materials / Construction
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What Defines a “Great BIW Design”
• Looks (Styling)• Light Weight (Materials/Construction)• Structural Performance
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What Defines a "great BIW Design”
• Structural Performance– Torsional Stiffness
w w w . a u t o s t e e l . o r g Gregory M. Goetchius, A. Akanda APC/NVH LABApril 4, 2000
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
22000
400 500 600 700 800 900 1000 1100 1200 1300
Mass (lbs)
Ct/M = 35 Ct/M = 25 Ct/M = 17
Ct/M = 11
Ct/M = 494 Accord*
JA
ULSAB
BMW 5 Series
93LH
98 Accord*
JR
98LH
LX
E-Class
*Estimated BIW Mass
14000 lb-ft/deg
830 lbs
Proposed LX Target Zone
LX Sedan 13,200 ft. lbs/degLH Sedan 12,500 ft. lbs/deg12% Increased stiffness
Structural Performance: Torsional Stiffness
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What Defines a "great BIW Design”
• Structural Performance– Torsional Stiffness– React Chassis Inputs
w w w . a u t o s t e e l . o r gStu Eddy
Design Tools•FEA: Finite Element Analysis•Lab & Shaker Testing: Components & Assembly tests•Proving Grounds: On Road Testing•RTS: Road Test Simulation
Structural Performance: React Chassis Inputs
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What Defines a "great BIW Design”
• Structural Performance– Torsional Stiffness– React Chassis Inputs– Noise Attenuation / Shake Control
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Front Floor AssemblyRail Extensions
Front Rail AssemblyBulk heads
Chris Kennedy
Structural Performance: NVH
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Double ShearSuspension Attachments
Tuned Exhaust Attachments
Structural Performance: NVH
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0
20
40
60
80
100
120
140
Vehi
cle
Spee
d, m
ph
0 5 10 15 20 25 30 35 40 45 50
Frequency, HzHigh Speed
Fan #2(43.7 hz)
High SpeedFan #1
(39.7 hz)
Low SpeedFan #2
(23.3 hz)
0
200
400
600
800
1000
1200
1400
Engi
ne S
peed
, rpm
V-8 WarmIdle Range4th Order
500-650 rpm
1st Order17” Tire
1.5 Order (V6)500-650 rpm
(12.5-16.25 hz)
V-6 WarmIdle Range3rd Order
500-650 rpm
1st AcousticCavity Mode
(48.3 hz)
Low SpeedFan #1
(19.8 hz)La
t = (3
3.8H
z
Driv
er =
16.
8Hz
Vert
= (3
6.4H
z
P as s
= 1
5.7 H
z
5.7L four cylinder mode
2nd order excitation
Mode Shape Test Pre-Test CAEFrequency Prediction Mode Shape
Global Torsion 40.1 Hz 40.0 Hz 91%
Global Bending 48.8 Hz 49.2 Hz 84%
Structural Performance: NVH
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CAE Optimization for Low Frequency NVH Performance
• Four Bolt Bumper Attachment• Radiator Xmbr • HMC to Rail & Load Beam Joints• Bulk heads in the Toe board Xmbr• IP Center Stack
• Shelf Panels• Shelf Gussets• Beading of the Rear Floor Pan & battery Tray design
Structural Performance: NVH
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What Defines a “Great BIW Design”
• Structural Performance– Torsional Stiffness React Chassis Inputs– React Chassis Inputs– Noise Attenuation / Shake / Control– Superior Occupant Safety Cage
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Safety Cage: Enginebox•Dual phase DP 590 octagon shape front rails with defined crush zones•Dash panel toe-board crossmember, end rail extensions and rail extension to sill to limit intrusion
Structural Performance: Safety Cage
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35 mph Flat FrontalRail Tip Multiple fold / crushLow Intrusion
Structural Performance: Safety Cage
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40 mph Front OffsetMid Rail Body/Chassis CrushLow Intrusion
Structural Performance: Safety Cage
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Safety Cage: Body Sides- Cross car load bearing roof bow- C pillar reinforcement rear occupant protection - A pillar reinforcement for structural integrity for offset events - Occupant friendly B pillar deformation zones
Structural Performance: Safety Cage
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Structural Performance: Safety Cage
38.5 mph Crabbed SideSill / B pillar EngagementLow Intrusion
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Safety Cage : Rear Underbody• Double C section rear rail crush zones balance to rear cradle• Rear tire tub with designed crush zones
Structural Performance: Safety Cage
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Structural Performance: Safety Cage
50 mph Rear OffsetMultiple Crush ZonesProtected Zone
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What Defines a “Great BIW Design”
• Looks (Styling)• Light Weight (Materials/Construction)• Structural Performance• Flexible Manufacturing Process
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Assembly Plant Welds 2592Purchase Sub Welds 1685
Total Spot Welds 4277Adhesive C(mm) 22366Drawn Arc Studs 23Projection Weld 7
LX BIW Process
Flexible Manufacturing Process
0
1000
2000
3000
4000
5000
6000
7000
Spot Welds
LX#1#2
Underbody – 3 Sub AssembliesBody Sides – Robot Framed
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What Defines a “Great BIW Design”
• Looks (Styling)• Light Weight (materials/construction)• Structural Performance• Flexible Manufacturing Process• Low Cost ($)
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• 15% reduction in equalized variable costs
• 40 % reduction in capital tooling
0
0.2
0 .4
0 .6
0 .8
1
1 .2
1 .4
1 .6
1 .8
'98 300M '05 300C
Variable Investment
Low Cost $
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What Defines a “Great BIW Design”
• Looks (Styling)– Wow!
• Light Weight (materials/construction)– Increased HSS Utilization/ Efficient
Design Engineering • Structural Performance
– Stiffer / Stronger /Safe• Flexible Manufacturing Process
– Strategic use of sub-assemblies• Low Cost ($)
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The LX Sedan BIW StructureJust The Beginning!
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