topology optimization of a steel-aluminium-hybrid … · topology optimization of a...

Altair EHTC

Topology Optimization of a Steel-Aluminium-Hybrid for an Automotive Body Structure

Speaker: D. Funke (Imperia GmbH)

November 4th, 2009Ludwigsburg

11/04/2009

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


• 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


• 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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Hybrid structure Conventional sheetmetal structure

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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!

topology optimization of a steel-aluminium-hybrid … · topology optimization of a...

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