FENET_Zurich_June2002_PSO_Allinger_ (1).pdf

2001 FE-Design GmbH www.fe-design.de

The TOSCA-Topology Optimisation -Mesh Adaption and Manufacturing

Restrictions

© FE-Design GmbH 2002

Peter Allinger


The TOSCA-Topology Optimisation -Mesh Adaption and Manufacturing

Restrictions

• Who is FE-Design?

• What is TOSCA?

• Manufacturing restrictions for topology

optimisation

• Mesh adaption for topology optimisation

• Conclusions


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• FE structural analyses

• Structural optimisation

• CDF calculations• Computation• Consulting• Training

Engineering Service

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Research & Development

Software Development• TOSCA• MSC.Construct...• ASPNational & International research projects• HiPOP• iViP• Elano

Software Products

• TOSCA.topology, TOSCA.shapeTOSCA.smooth

• OEM-Products:MSC.ConstructCATopo visualNastran Desktop FEA

• Support


Automotive industry

Aerospace industry

Universities &Research

Supply industry

ETH ZürichETH Zürich

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• Structural optimisation system• Stable and fast algorithms• Interfaces to MSC.NASTRAN, ABAQUS, ANSYS, IDEAS• UNIX and NT• Optimisation of nearly every FE-model• Unlimited number of load cases• Efficient handling of very large models (> 4,5 Mio. DOF)

Fields of application

• Domestic appliances • Machine tools • Automotive- and aerospace-industry• …

Basic Technology of


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Topology Optimization with

Optimal design from a given design space

• Shorter development time• Economic use of material

Shape Optimization with

Load homogenization by modification of the component‘s surface• Increase of durability• Reduction of stress concentration

By courtesy of AUDI AG


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Optional: Shape Optimization

Design Space Topology Optimization

Smoothing, Data Reduction, Remeshing,

Remodelling

Transfer to CAD(STL, IGES)

Analysis ModelOptimization and

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„The topology and the shape of a component has to be determined in such a way, that its mechanical behaviour is an optimum for the

specified design criteria. Only the available boundary conditions, the forces and the design area for the component has to be defined. “

[Maute 98]

Design area Iteration loop Design proposal


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Motivation• Bending and torsion load

lead to a hollow body� Results of the topology

optimisation cannot be transferred into real components because of the costs for producing.

� The manual transfer of the results into a castablecomponent needs a lot of time and of leads to sub-optimal components.


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• Pull direction / removable components• No undercuts or hollow structures• Removal angle• No conglomeration of material (problems during cooling

process)• No thin structures or supports• ...

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F F F F


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4961 Nodes; 4000 Hexaeder elements


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Side view

Front view

Pull direction sideways

Pull direction backwards

Side view

Front view


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93854 Nodes; 495158 Tetraeder-elements

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By courtesy of AUDI AG


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Advantage:+ more detailed solution + better material distribution

Disadvantage:- increase of design variables- dramatic increase of computational time

Adaptive mesh refinement during topology optimization

-> refinement of result without big influences of disadvantages

Coarse mesh

Fine mesh


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Selective refinement Necessary areas: refined mesh

Unnecessary areas: mesh of start model

When should the refinement be performed? start criteria

Where should the refinement take place? location criteria

How should the refinement been done? refinement algorithms


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2) Coupling of nodal displacement

1) refinement with templates

)(2

1213

iii XXX +∗=

displaced mesh

initial mesh

3

2

1

Multi Point Constraint (MPC)


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How to ensure the mesh consistency ?

Templates for QUAD elements

Element to be refined

= Nodes marked for refinement

Select template No. 2aand rotate clockwise 90°

Select template No. 4

2D and 3D refinement is possible


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• Permanent mesh refinement / coarsening

• Error estimator as indicator for the mesh refinement area

• Refinement in areas of high error indicator values

• Coarsening in areas of high error indicator values

• Definition of a limit volume of elements to be refined

• Error criteria enables the system to refine in more than one level (multi level refinement)


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6 min 15 sec

9 min 48 sec

17 min 50 sec

26 min 1 sec

time

24,0 %

37,6 %

68,5 %

100%

percentage

Without refinement

Refinement with displacement conditions (each element border is divided into two new borders)

Template refinement(each element border is divided intothree new borders)

complete refinement

model

PC 866 MHz with 512 MB RAM


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Coarse mesh

CPU-Time=9,6%

DOF= 22 000

Fine mesh

CPU-Time=100 %

DOF= 151 000

Adaptive mesh refinement

CPU-Time=60,9%

DOF=100 000


Maximize stiffness

obj. Function:

210000Youngs modul [N/mm2 ]

0,3Poisson ratio

Material: Steel

Mesh type: Pave

9252tetraeder elements(3D)

2924nodes

944shell elements (2D)

Optimization task:

55%constraint volume:

mixed mesh: 2D-3D elementsLocation criteria: errror indicator distribution

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Without refinement

adaptive mesh refinement

Complete refinement

Results of the tetraeder mesh are smoothed


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• Manufacturing restrictions– Difficult to transfer solutions of non restricted optimization– Manufacturing process has to be included in the early stages of

the product development

• Adaptive refinement during topology optimization – Error indicator distribution is used as location criteria– Permanent mesh refinement and coarsening during iteration

process– Results of the adaptive topology optimization are comparable to

the optimization with the fine mesh

• Optimization system TOSCA– integrated solution for structural optimization of real-world

problems– wide acceptance in industry

Documents

FENET_Zurich_June2002_PSO_Allinger_ (1).pdf