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Great Designs in Steel
2011 Grand Cherokee
Doug Smith
May 18, 2011
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Body Structure Outline
Body Functional Objectives: Essence of the Grand CherokeeMandates:
Improve performance, increase size & lower weight
Body Stiffness/Torsion/Bending
Durability
NVH
Impact Performance:
3rd Party Rating including Top Safety Pick (4x SWR Roof Crush)
Trail Rated Performance
Body Design Body Topology Evaluation
Section / Connection / Continuity
Structural Front End Module (FEM)
Steel Gage and Grade Selection
Resultant Components Chart
Development Welding Structural Adhesive
Multi - Disciplinary Optimization (MDO)
Structural Efficiency Calculation
Structural Adhesive Application
Body Static Stiffness
Body Modes
NVH
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Body Structure Outline
Development - Continued Tow Hooks
Water Fording
Performance Confirmation Road Test Simulator (RTS) Validation
Proving Grounds Duty Cycles
Impact Performance: 3rd Party Rating including Top Safety Pick (4x SWR Roof Crush)
Trail Rated and Rubicon Performance
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Body Functional Objectives:
Durability & Capability Driver Confidence Global Body Functional Objectives: Essence of the Grand Cherokee
Mandates:
Body Stiffness/Torsion/Bending
Durability
Impact Performance:
3rd Party Rating including Top Safety Pick (4x SWR Roof Crush)
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WK Load Cases & Functional Requirements
Roof Crush
Platen angle
4 X GVW
Side Impact
FMVSS 214
IIHS Side impact
Euro NCAP
Front Impact FMVSS 301
40% offset direct push on Rail
Full Flat Frontal
Euro NCAP
Front & Rear Durability & Fatigue Loads
(with and without max payload)
Vertical 3G load at Susp mount(In phase & Out of phase)
Cornering Load2G Lateral load
Rear Impact FMVSS 301
70% offset direct push on Rail
Liftgate LoadingProp Rod Loads
Hinge loading
1st & 2nd Row Seat FMVSS 207 / 210 Belt
Torsional/Bending Stiffness
Sill loads Wheel Input
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Body Design:
Experienced Engineers / State-of-the-Art Tools
Body Design Body Topology Evaluation
Section / Connection / Continuity
Structural Front End Module (FEM)
Steel Grade Selection
Resultant Components Chart
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Topology:
Mass and Geometry Optimized to ObjectivesTypical Topology Process
Packaging Volume
Holistic Forces:
Safety
Refinement
Durability
Topology Results
Spatial load image
Beam Model
Load paths
Body Design
Detailed Components
Optimization
Steel Gauge & Materials
Toe Board
Crossmember
Shock tower
Upper Load
Path
Component Topology Design Application
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Section / Connection / Continuity:
Energy Management Strategy and Execution
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Structural Front End Module:
Functional System and Plant Build Optimization
Hood Slam
Torsion
Tow Hook
Push / Pull
Tow Hook
Push / Pull
Lo Speed Impact No-Fire Threshold & 16 mph
Hi Speed Impact 20-40 mph
Front-to-Front Compatibility
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High Strength Steel Usage:
Weight Reduction and Impact Performance
50% HighStrength
Steel
47%
42%
4%4% 3%
2011 Grand Cherokee MaterialUsage
Mild Steel
HS Steel
AHS Steel
Hot Stamp
Other
High Strength Steel: YS > 200 MPa
Hi h S h S l U
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Previous Grand Cherokee
2011 Grand Cherokee
New Vehicles
29%
High Strength
50%High Strength
70%
High Strength
High Strength Steel:
YS > 200 MPa
High Strength Steel Usage:
Weight Reduction and Impact Performance
WK B d C t Ch t
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WK Body Components Chart:
Body Shop Build Strategy
B d D l t
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Body Development:
Body Complete -- Jeep
Development Welding
Structural Adhesive
Multi - Disciplinary Optimization (MDO)
Structural Efficiency Performance Factor (PF)
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WK U d b d S t W ldi
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3308 Spot Welds in Underbody Shell
WK Underbody Spot Welding:
Connecting the Structure for Jeep Capability
WK Upperbod Spot Welding
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2069 Spot Welds in Upperbody Shell
WK Upperbody Spot Welding:
Connecting the Structure for Jeep Capability
WK MIG welding:
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112 Mig Welds in Body Shell (Total mig weld length of 3494mm)
WK MIG welding:
Connecting the Structure for Jeep Capability
WK Welding Complete:
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5489 Total Welds in Body-in-White Complete
WK Welding Complete:
Connecting the Structure for Jeep Capability
WK Body Adhesive & Anti Flutter:
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Structural Adhesive (3mm bead) 108.6m total length
Anti-Flutter (5mm bead or gum drop) 8.3m total length
WK Body Adhesive & Anti-Flutter:
Finalization of Body Build Construction
WK Multi Disciplinary Optimization (MDO):
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Gages maintained for critical impact and
durability parts
Total Weight Savings = 23 kg
No change in bending and torsion modes
No degradation in mobility responses
Maintained overall BIW NVH responses
COLOR KEY
Downgaged
Upgaged
No Gage Change
WK Multi - Disciplinary Optimization (MDO):
Wt. Optimization with no Functional Degradation
Resultant Body:
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Resultant Body:
To Be Classified as a Jeep
Development Body Static Stiffness
Body Modes
NVH
WK BIW Static Stiffness:
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WK BIW Static Stiffness:
Solid / Confident Driving Experience
Bending Stiffness = 10200 N/mm (CAE)Torsional Stiffness = 23000 N-m/deg (CAE)
Torsional Stiffness Setup Bending Stiffness Setup
11WK BIW Normal Modes:
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11WK BIW Normal Modes:
Solid / Confident Driving Experience
First Torsion Mode 43 Hz First Bending Mode 51 Hz
11WK Mobility Responses to Inputs @ Body
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11WK Mobility Responses to Inputs @ Body
Attachments to Cradles: NVH Achieved
Front Cradle Front Body Attachment Front Cradle Rear Body Attachment
Rear Cradle Front Body Attachment Rear Cradle Rear Body Attachment
TARGET TARGET
TARGET TARGET
Target Met: < 0.2 mm/sec/N
11WK Acoustic Responses to Input @ Body
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11WK Acoustic Responses to Input @ Body
Attachment to Cradles: Driver Delight
Front Cradle Front Body AttachmentTARGET TARGET
TARGET TARGET
Front Cradle Rear Body Attachment
Rear Cradle Front Body Attachment Rear Cradle Rear Body Attachment
Target Met: < 55 dB
Tow Hooks:
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Tow Hooks:
Rugged Performance and Capability
Development Tow Hook Development
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Tow Hooks:
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A Jeep Queue
Front Tow Hooks (Two per Vehicle RT and LT) / Rear Tow Hook (one per Vehicle LT)
1. Design for Impact Requirements
1. Requires pulse separation between low speed threshold vs. 16 FF.2. Common calibration with and without tow hooks.
2. Design for durability Requirements
1. 1.0 /1.5 GVW pull.
2. 2.0 GVW pull with no separation.
3. 0.9 GVW 90 deg outboard pull no separation.
4. 0.5 GVW push/pull (BUX).
Tow Hooks:
Complex and Punishing Requirements
Tow Hook Design:
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Tow Hook Design:Engineered Geometry for Multi-Purpose Objectives
Front Tow Hook Development:
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Front Tow Hook Development:
System Level Confirmation Testing
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Tow Hook Development - Rear
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Rear Tow Hook Development:
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Rear Tow Hook Development:
System Level Confirmation Testing
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Water Fording:
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Water Fording:
Trail Rated Requirement
Development Body Sealing - 20 Water Fording Define P/1/P2 Sealing
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Water Fording Requirements:
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20 inches water
fording line
Water Fording
69.4 meters of sealer on BIW
76.4 meters including closures and hem sealing
Water Fording Requirements:20 inches of Water Submersion Performance
Water Fording:
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Water Fording:Body Sealer Robust Joints
Water Fording:
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Robotically Applied Sealants - 76.4m total length
Water Fording:Body Sealer Robust Joints
WK Water Fording:
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WK Water Fording:Capable Results Achieved!
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Performance Confirmation:
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Performance Confirmation:Legendary Jeep Performance
Confirmation Road Test Simulator (RTS) Validation
Proving Grounds Duty Cycles
Impact Performance:
3rd Party Rating including Top Safety Pick (4x SWR Roof Crush)
Trail Rated and Rubicon Performance
WK Road Test Simulator Testing:
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gAccelerated Discovery and Durability Results
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2011 WK on Road Test Simulator Rig
SUV Body/Chassis PG Durability Duty Cycle
Represents 95th Percentile Usage Customer 150K Customer Equivalent Miles
Testing Performed to 2x Life
WK Pro ing Gro nds Testing
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WK Proving Grounds Testing
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WK NCAP Results
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WK NCAP Results
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Driver
Passenger
Front MDB
Rear MDB
Front Pole
Overall Vehicle Rating
Mode
Rating
Rollover
2011 WK NEW US NCAP RATINGS
Frontal
New NCAP Mode
Side
WK IIHS Offset:
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All Injury Criteria in Green Zone
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0% 25% 50% 75% 100%125%150%175%200%225%
HIC
Nij - Tension-Extension
Nij - Tension-Flexion
Nij - Compression-Extension
Nij - Compression-Flexion
Neck axial compression
Neck axial tension
Chest acceleration (3ms clip)
Chest compression
Sternum deflection rate
Viscous criteria
Left knee displacement
Left upper tibia index
Left lower tibia index
Left tibia axial force
Left foot acceleration
Left femur force
Right knee displacement
Right upper tibia index
Right lower tibia index
Right tibia axial force
Right foot acceleration
Right femur force
Poor Marginal Ac ceptable Goo d Meas ured V alues
2011 Jeep Grand Cherokee
IIHS Side Impact:
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pAll Injury Criteria in Green Zone
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WK IIHS Side Crush:
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After-test Geometry in Green Zone
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Table From IIHS website:
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Model Overall ratingCurb weight(lb)
Peak force(lb)
Strength-to-weight ratio
Jeep Liberty
2008-10
models
Dodge Nitro
2007-10
models
4,245 21,073 4.96
Toyota
Highlander
2008-10
models
4,325 20,511 4.74
Toyota Venza
2009-10
models
4,037 18,977 4.70
Jeep Grand
Cherokee
2011 models
4,655 21,545 4.63
Dodge
Journey
2009-10
models
4,318 19,649 4.55
Good Acceptable Marginal Poor | Vehicles are listed in order of performance
Roof Crush Rating : Good
IIHS Classification: Roof Crush Rating Good
2011 Jeep Grand Cherokee:
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pTrail Rated Performance
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Questions & Answers
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Questions & Answers
Q & A
Making Of The 2011 Jeep Grand Cherokee
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Making Of The 2011 Jeep Grand Cherokee
Thank You for Your Attention!