Altair EHTC
Topology Optimization of a Steel-Aluminium-Hybrid for an Automotive Body Structure
Speaker: D. Funke (Imperia GmbH)
November 4th, 2009Ludwigsburg
Page 211/04/2009
Agenda
1. Common Hybrid Structures in today‘s Automotive Industry
2. The Steel-Aluminium-Hybrid: VarioStruct
3. Principle of Hybrid Structures
4. Loadcases
5. Dimensioning of the Sheet Metal Profile
6. Analogous Model for Rib Optimization
7. Dimensioning of Rib Structure with Submodel
8. Dimensioning of Rib Structure with Component Model
9. The VarioStruct Roof Crossmember
10. Mechanical Properties of the VarioStruct Roof Crossmember
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1. Common Hybrid Structures in today‘s Automotive Industry
Thin-walled steel-lightmetal-hybrids for automotive body structures
Application of metal-plastic-hybrid in an automotive body
Steel-lightmetal-composite castingin motor manufacture
• Roof crossmember with master-formed plastic reinforcement
• Form closure
• Engine block with cast-in cylinder liners
• Form closure• Metallic continuity
Source: Lanxess Source: Honda
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2. The Steel-Aluminium-Hybrid: VarioStruct
• Aluminium rib structure casted in steel sheet profile
• Advantage of both material will be taken
• Connection steel ↔ casting
• Complex cast structures with sheetmetals possible
• High potential of integration
• Possible to combine other materials
master forming
Material 1 (Sheet)• property profile 1
Material 2 (Cast)• property profile 2
Steel-Aluminium-Hybrid+
metallic continuity
form closure
frictional connection
extrusion joint
continued sheet metal
cast cantilever
assembly attachment
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3. Principle of Hybrid Structures
Conventionalsheet metal structure
F
Hybridstructure
F
Hybrid structure
Conventional sheet metal structure
• Prevention of local buckling• Limitation of plastic hinges
less weighthigher energyabsorption
Maximum supporting effect:Optimal dimensioning of cast ribsDesign proposal: topology optimization with OptiStruct
supportingeffect
cross section height
cross section height
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4. Loadcases
Example of Submodel
• 3-point-bending, centric
• Torsion
• Roof impact
• Pole impact
Component Model
• 3-point-bending, excentric
FF
Combination of all loadcases
F
F
Combination of all loadcases
• Axial compression
F
F
F
Design space
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5. Dimensioning of the Sheetmetal Profile
Result of topology optimization Derived profile of sheetmetal
• Topology optimization (solids)
• Submodel
• Combination of all loadcases
Next step: dimensioning of rib structure
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6. Analogous Model for Rib Optimization• Application of volume elements
Elements ↑, calculation time ↑Maximum rib thickness ↔ element size (Maxdim = 6 * lc)
• Remedial action with approach by Hartzheim [1]• Design space: shell elements• Approximation of volume: rigid bars
Elements ↓High resolution with small elements
thin ribs
[1] HARTZHEIM, Lothar: Strukturoptimierung, Verlag Harri Deutsch, Frankfurt, 2008
shell layer 1, design space
shell layer 2, sheetmetal, nondesign space
rigid bar
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7. Dimensioning of Rib Structure with Submodel
• Topology optimization (shells)
• Submodel
• Combination of all loadcases
• Suitable for outer rib structures
Next step: dimensioning of rib structure in crossmember‘s middle area
design space
Iteration 10
Iteration 20
Iteration 30
derived structure
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8. Dimensioning of Rib Structure with Component Modelribs derived from first optimization
Iteration 15
Iteration 25
Iteration 36
design space
• Topology optimization (shells)
• Component model
• Combination of all loadcases
• Suitable for inner rib structures
Next step: derive initial rib structure for nonlinear optimization
F
FF
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9. The VarioStruct Roof Crossmember
loadcases, constrains, designspace, ...
component model
initial design
nonlinear optimization (crash loadcases)
final design
submodel
topology optimization, solids
topology optimization, shells
derive rib structure
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10. Mechanical Properties of the VarioStruct Roof Crossmember
Hybrid structure Conventional sheetmetal structure
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11. Mechanical Properties of the VarioStruct Roof Crossmember
75% 106% 112%0%
20%
40%
60%
80%
100%
120%
Mass MaximumForce
AbsorbedEnergy
• 3-point-bending test
0.0
0.5
1.0
1.5
0 50 100Displacement [mm]
Forc
e [-]
OriginalVarioStruct
ConventionalVarioStruct
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Thanks to BMBF
Thanks to project partners
Thanks for support in research project from
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Dipl.-Ing. (FH) David FunkeTel.: +49 - (0)2 41 - 6 08 33-15Fax: +49 - (0)2 41 - 6 08 33-20Mail: [email protected]
Imperia GmbHAutomotive Engineering Soerser Weg 9D-52070 Aachen
Imperia GmbHAutomotive Engineering Soerser Weg 9D-52070 Aachen
Dipl.-Ing. Niels NowackTel.: +49 - (0)2 41 - 6 08 33-14Fax: +49 - (0)2 41 - 6 08 33-20Mail: [email protected]
Thank you for your attention!