Consideration of uncertainties in forming simulation using HyperWorks

WWW.DTE-ONLINE.DE p.1

WWW.DTE-ONLINE.DE DTE

2013 European Altair Technology Conference

Consideration of uncertainties in forming simulation using

HyperWorks

Markus Reinert, DTE-Verfahrenstechnik

ENGINEERING SIMULATION

METHOD PLANNING DESIGN

KINEMATICS

WWW.DTE-ONLINE.DE p.2 DTE Verfahrenstechnik Gmbh&Co.KG • In der Trift 57 • D-57462 Olpe • Telefon: +49(0)2761 9024-61 • Telefax: +49(0)2761 9024-69

1. Introduction

2. Problem Definition

3. Discussion

4. Conclusion

5. Acknowledgements

6. References

Agenda


1. Introduction

•DTE was founded in 2000

•24 employees in two locations Olpe and

Hamburg in Germany

•Complete service in the field of sheet metal

forming tools, mainly automotive

•Only software not hardware:

• Engineering

simulation; process planning;

feasibility studies; kinematical studies

• Tool designing

transfer tools; progressive tools

DTE Werkzeug and Verfahrenstechnik GmbH&Co. KG

Design Tool Engineering


Manufacturing Process

1. Introduction

(Drawing) (Cutting)

(Cutting)

(Calibrating) (Punching)

Drawing and Springback Simulation with help of

•How to get a ready automotive sheet metal part out of a flat coil

•Create a Manufacturing Process with the help of CAD

•Simulation (FEM) is a helpful tool to ensure the feasibility of your Process


1. Introduction Drawing Simulation (FEM)

Die geometries out of CAD

Preprocessing of the Simulation with HyperForm

Simulation with Radioss-Solver

Forming Parameters

•Sheet material data

•Friction

•Forces

•Velocities

•Drawing Clearance

•Etc.


Drawing Simulation in engineering phase

Put results and information out of

the simulation into the Processplan

Put changed Forming-Geometries

and -Paramters into the simulation Springback

FLD

Thinning

1. Introduction

Postprocessing of the Simulation with HyperView:

Change Geometries in CAD:

•Drawing radius

•Die design

•Blank geometries

•Whole process

Change Forming Parameters in

Preprocessing :

•Forces

•Meshing Parameters

•Draw beads



Lightweight with high strength steels and aluminum

In the automotive industry, the lightweight is

an increasingly important issue. This leads

to the increased use of high strength steels

and aluminum. These materials decrease

the process capability of forming of many

automotive components than conventional

materials. It becomes more difficult to

predict the feasibility of CAE methods.

The feasibility region is getting smaller


2. Problem Definition Simulation (CAE) is a Model of reality

There are many influential parameters

material quality

•Material data and flow curve (tensile

strength, yield strength, modulus of

elasticity, …)

•Anisotropy (rollingdirection, r-values)

•Thickness

•Tribology (surface of the sheet)

•Blank geometry

•Trim lines hardening

•etc.

Influenz on feasibility

Influenz on springback


2. Problem Definition Simulation (CAE) is a Model of reality

There are many influential parameters

physical parameters

•Friction (die, binder)

•Binder force

•Forming geometries

(Drawing radius, clearance, …)

•Press parameters

(drawing velocity, pressing force during time,

tilting and deflection of press ram)

•Temperature

•Lubrication

•Drawbeads

•etc.

Influenz on feasibility

Influenz on springback


More Problems


Material change

• From Plate-Material to Coil-Material

• From one Material batch to another batch

Press change

• From Tryout Press to Serial Press

• From Serial Press to Replacement Press

Trim lines hardening on aluminum

• After cutting process there is a second

forming process

•Crack failure on bending trim line

Fluctuation on material quality

Fluctuation on physical parameters


2. Problem Definition Simulation (FEM) is a model of reality

Reality Simulation FEM

Problem

•Simulation is OK

•First tryout is OK

•After changing the coil in real process there

are cracks!

•Why there are cracks? How we will be able

to make the process safety?


How to deal with the uncertainties

Look critically on your Simulation Results

• are the results plausible

• compare your results with reality (ex post analysis)

Look at other results than Thinning and FLD

• plastic strain

• look at results over forming time

Integrate other Failure Model into Simulation

• Johnson Cook Failure

Sensitivity Analysis

• Study of the fluctuation of Forming Parameters using HyperStudy,

Design of Experiments (DoE)

3. Discussion


3. Discussion

Other results (Plastic Strain along thickness)

Detect significant areas:

•It mustn't means there is a Crack or Failure

•Have a look at detected Elements at the rest

of Simulation-Analysis


3. Discussion

Results over forming time (FLD)

At the end of

Simulation:

•Tensile

At the beginning of

Simulation:

•Compression


Failure Model Johnson Cook

3. Discussion

Crack like reality

No cracks in reality

(>> use this Failure

Model carefully!)

How to determine D1, D2, D3 Parameters

(Excel List by Altair):

•Method of least squares to fit the rupture strain given by

function to experimental data (tension, compression, shear)


HyperStudy; Design of Experiments (DoE)

3. Discussion

Fluctuating Parameter

(Design variables):

• Blank Thickness: ±10%

• Flow Curve: ±10%

• Binder Force: ±30%

• Die/Binder Friction: ±50%

HyperStudy at the end of Engineering and Simulation Process!

Detect critical nodes out of HyperView

(Responses):

• Response 1-5: max. plastic Strain or five nodes

• Response 6-10: min. thickness for same five nodes

Full Factorial DoE class:

• Each min. and max. Design variable with each other

>> 32 runs


4. Conclusion

•Safety and robust manufacturing processes

•Reduction of Tryout Time and Tryout Problems

•Less waste in manufacturing processes

•Better Part Quality

•Less Costs in later product life cycle

Simulation by using HyperWorks and spend more time, knowhow and money in CAE brings benefits


Thanks to ALTAIR Germany for Software and Problem Support

I especially thank Mr. Trickov for his personal

commitment

5. Acknowledgements


ALTAIR, ”Reference Guide”, Altair 2012 V. Trikov, “Johnson Cook Failure”, Altair 2012

C. Held, R. Schleich, M. Sindel, M. Liewald, “Untersuchungen zum

Einfluss der Verfestigung von schergeschnittenen Kanten auf

folgende Umformprozesse,“ UTFscience 2/2009

6. References


Thank You for Your attention!

Q & A