sheet metal forming ii - rwth aachen · pdf filesheet metal forming ii ... planning tool...

Seite 1© WZL / IPT

SheetSheet Metal Metal FormingForming IIII

Prof. Dr.-Ing. F. Klocke

Simulation Techniques in Manufacturing

Seite 2© WZL / IPT

Sheet Metal Forming - Contents

� Modeling

� Reasons for modeling

� Connection: process modelling - process chain

� Simulation of Sheet Metal forming

� Commercial FE codes for sheet metal forming

� Case Study

� Part Evaluation: Step by step

� Process optimisation by improved tool design

� Evaluation of wrinkling

� Economical aspects of process modelling

Seite 3© WZL / IPT

Why process modelling?

Car Body

Time Cost

Quality

Increase quality

Apply new materials(Al, Mg, …)

Use material moreefficiently

Reduction of toolcost

Reduction of leadtime

Reduction of timerequired for training

Increase reliabilityof production

Manufacture complex parts

Reduction of pre production trials

Source: BMW

Seite 4© WZL / IPT

Integration of process modelling into the process chain

Source: BMW

Designof car

exterior

Part design

Partproduction

Means of production Tool manu-facturingand testingTool designPlanning

Sheet metal forming simulation

Part evaluation Process optimisation

So

ftw

are

so

luti

on

Ap

pli

cati

on

Pro

cess c

hain

Methods applied:- 2D modelling- one-step modelling- modelling with membrane elementsShort computation time with sufficientprecision

Methods applied:- Simulation with membrane elements- Simulation with shell elements

High Precision within acceptablecomputation times

Seite 5© WZL / IPT

Sheet Metal Forming II - Contents

� Modeling





� Case Study





Seite 6© WZL / IPT

Commercial FE codes for sheet metal forming

2D Modelling of selected cross sections:• Abaqus www.abaqus.com

• Ansys www.ansys.com

• Autoform 2D www.autoform.ch

• Deform 2D www.deform.com

• Marc www.marc.com

•...

Advantages:

• reduced computation time

• less sensitive to quality of input

data

• usually less input data required

Disadvantages:

• difficult selection of cross sections

to be modelled

• less accurate results

Source: BMW / Fontana Pietro SPA

Seite 7© WZL / IPT

One-step simulation:

• Isopunch

• SIMEX

• Corps

• AutoForm Onestep

• ...

Advantages:

• reduced computation time

• usually less input data required

• suitable tool for part evaluation

Disadvantages:

• decreasing significance due to

increasing computing power

• still not very accurate

Source: BMW


Seite 8© WZL / IPT

Model with membrane elements:

• AutoForm Incremental

• Abaqus

• ...

Advantages:

• acceptable computation time

• suitable tool for part evaluation

• suitable for process optimisation

• basically accurate results

Disadvantages:

• long computation time

• problems when severe bending

occurs

• not accurate enough in predicting

wrinkles

• requires high quality input dataSource: BMW


Seite 9© WZL / IPT

Model with shell elements:

• PAM-STAMP

• Optris

• DYNA-Form

• Indeed

• ...

Advantages:

• state of the art tools for process

optimisation

• very accurate results

Disadvantages:

• long computation time leads to

long response time

• requires high quality input data

Source: BMW


Seite 10© WZL / IPT


� Modeling





� Case Study






Part Evaluation: One step method

Steps:

1) Create mesh from 3D

CAD model

2) create blank holder

3) simplified add-on

4) computation

5) interpretation of results

Source: BMW



Source: BMW

Steps:


CAD model



4) computation



Source: BMW

Steps:


CAD model



4) computation




Source: BMW

Steps:


CAD model



4) computation





� Modeling





� Case Study






Case study: Process optimisation by improved tool design

Source: BMW


Process optimisation: Tool design

Source: BMW



Source: BMW



Source: BMW


Process optimisation: Material data

Source: BMW


Process optimisation: Process parameters

Source: BMW


Process optimisation: Numerical parameters

Source: BMW


Process optimisation: Forming process

CAD-datatool

& blank

Meshing

Process dataNumerical

data

GENERIS

Material-data

PAM-STAMP Input fileSource: BMW


Process optimisation: Forming sequence

Source: BMW



Source: BMW


Source: BMW



Source: BMW



Source: BMW




� Modeling





� Case Study






Case study: Evaluation of wrinkling

distribution of effective strain during and after the drawing process

Source: BMW


Process optimisation: Evaluation of wrinkling

Source: BMW

distribution of effective stress during and after the drawing process


Process optimisation: Comparision between simulation and real part

Source: BMW

wrinkling


Process optimisation: Comparision between simulation and real part

Source: BMW

rupturing



� Modeling





� Case Study






Modelling sheet metal forming: Quality of the computed results

0+springback

++++wrinkles

+++rupture

Quality

qualitatively quantitatively

Result

Source: BMW


Flow chart of a modelling project

Partgeometry

no

yes

Part design Process development Simulation all

Materialselection

tools(CAD)

Processparameters

Simulation Start tooldesign

Source: BMW


Effort for a sheet metal modelling project

Change of responsible effort CAD effort Simulation

Process parameters

(friction, beads, ...)Process design ---- 1h --3h

die setup (blank holder,

etc. ...)Process design 1d -- 1w 3h -- 1d

Material quality and

thicknessBody design ---- 1h -- 3h

Part geometry Body design 1d --1w 3h -- 1d

Total effort for a medium sized part: Usually 2 weeks

Source: BMW


Preprocessing effort for a modelling project in sheet metal forming

1993 2000

1W

2 W

3 W

Effort for preprocessingSource: BMW


Development of computing power and computation time

100%

1993 2000

20%

Increase of computing power

1993 2000

50h

15h

Reduction of computationtime for a large car body

partSource: BMW


Development of hardware cost

1993

Hardware cost

2000

100 %

< 1 %

Source: BMW


Prerequisits for the industrial application of process modelling

Time: Cost: Quality:

Short responsetimes

Low projectcost

Reliable results

Integration into the process chain of a car body

Source: BMW


Simulation of crashworthiness for the Ford Explorer (LS-Dyna)

Source: Livermore Software Technology

sheet metal forming ii - rwth aachen · pdf filesheet metal forming ii ... planning tool...

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