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Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 1 Altair Product Design Dmitri Fokin Airbag Folding with Radioss Pre- Simulation 3 November 2009 European HTC Ludwigsburg, Germany [email protected] +49 711 6208184
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Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

May 01, 2018

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Page 1: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 1

Altair Product Design

Dmitri Fokin

Airbag Folding with Radioss Pre- Simulation

3 November 2009European HTC Ludwigsburg, Germany

[email protected]+49 711 6208184

Page 2: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 2

FE Airbag model

Geometrical folder

Folding pre-simulation with Radioss

Conclusions

Content

Page 3: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 3

FE Airbag model

Page 4: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 4

- Airbag geometry (closed volume)- Meshed airbag surface with account of folding- Fabric material and FE property- Internal airbag contacts- Method for airbag simulation (uniform pressure, ALE, finite volume method)

FE Airbag model: general

300 mm

99 mm

straps

Fold 5

Fold 8

Fold 1

Fold 2

border of the airbag (gas

leakage)Fold 7

Fold 6

Fold 4

Fold 3

99 mm

102 mm

Page 5: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 5

Definition of airbag model is Material definition for the airbag fabric (orthotropic, elasto- plastic materials, no resistance by compression)

/MAT/FABR_A/1MAT_FABRIC # Init. dens. Ref. dens.6.83000000000000E-07 0.0

0.47 0.0 0.47 0.0 0.050.002 0.002 10.00.2 0.2

1 1 0.05 0.05

FE Airbag model: fabric materials and properties

Page 6: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 6

Definition of airbag model is Material definition for the airbag fabric (orthotropic, elasto- plasticmaterials, no resistance by compression)

/MAT/FABR_A/1MAT_FABRIC # Init. dens. Ref. dens.6.83000000000000E-07 0.0

0.47 0.0 0.47 0.0 0.050.002 0.002 10.00.2 0.2

1 1 0.05 0.05

Property definition for the airbag fabric (membrane, no bending stiffness)

/PROP/SH_FABR/1airbag_thickness # Ishell Ismstr

4 0 0.1 0.1 0.1 0.1

1 0 0.3 0.0 00.0 1.0 0.0 0 00.0 90.0 0.3 0.0 1

FE Airbag model: fabric materials and properties

Page 7: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 7

Internal contact for airbag fabric components (prescribed contact gap and contact stiffness)

/INTER/TYPE7/2Internal Contact

8 7 1 0 25 0 0 00.0 0.00.0 0.00.1 0.0 0.3 0.0 0.0

000 0 0.0 0.0 0 0 0.0 0

/INTER/TYPE11/1Internal Contact EE

10 10 1 0 25 00.1 0.0 0.203 0.0 0.0

000 0 0.0 0.0 0.0

FE Airbag model: internal contact

Page 8: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 8

Inflator model: position of injectors, jet directions, gas consistence, massflow rates, gas temperature, time to fire, airbag solver (uniform pressure, finite volume)

/MONVOL/AIRBAG/1Airbag# Isur

7# Scal_T Scal_P Scal_S Scal_A Scal_D

0 0 0 0 0# Mu Pext Tphi

0 1.013E-4 295.0# Gammai cpai cpbi cpci

1.4 926 0 0# Njet

1# Gamma cpa cpb cpc

1.325 1168 .4274 0# Imass Iflow Smass Itemp Stemp Isensor

77 1 .001 84 1 1# Ijet N1 N2 N3

0 0 0 0# Nvent

0

FE Airbag model: solver and inflator

Page 9: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 9

Unfolded FE airbag (reference geometry)

FE Airbag model: airbag folding

Page 10: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 10

FE Airbag model: airbag folding

Unfolded FE airbag (reference geometry)

Black box= Airbag Folder

Transformation of airbag geometry

Page 11: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 11

FE Airbag model: airbag folding

Unfolded FE airbag (reference geometry)

Black box= Airbag Folder

Folded FE airbag

Transformation of airbag geometry

Page 12: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 12

FE Airbag model: airbag folding

Unfolded FE airbag (reference geometry)

Black box= Airbag Folder

Folded FE airbag

Geometrical folder

- Translate

- Rotate

- Scale

- Non-linear transformation

Transformation of airbag geometry

Page 13: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 13

FE Airbag model: airbag folding

Unfolded FE airbag (reference geometry)

Black box= Airbag Folder

Folded FE airbag

Geometrical folder

- Translate

- Rotate

- Scale

- Non-linear transformation

Transformation of airbag geometry

Pre- simulation of the folding process using an explicit solver (Radioss)

-Exact simulation of the folding process

-Simulation of a simplified folding process

Page 14: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 14

FE Airbag model: airbag folding

Unfolded FE airbag (reference geometry)

Black box= Airbag Folder

Folded FE airbag

Geometrical folder

- Translate

- Rotate

- Scale

- Non-linear transformation

Transformation of airbag geometry

Com

bine

d fo

lder Pre- simulation of the folding process

using an explicit solver (Radioss)

-Exact simulation of the folding process

-Simulation of a simplified folding process

Page 15: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 15

Element sizes, fold thickness and fold layout must be adjustedsuch that certain requirements are met: i.e.

• Package space requirements (final size of folded airbag)

• Requirements for numerical stability (element quality, time step, intersection and penetration free)

• Requirements for model validity (reliable folding deformation)

FE Airbag model: folding requirements

Page 16: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 16

Geometrical folder

Page 17: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 17

Simple fold consist of:

Non-knick elements (regions BCD and B´C´D´)

Knick elements (regions AB, A´B´, DE, ´D´E´)

Following rules are important by airbag meshing for further simple folding

1. Only one element should lie in the knick regions AB, A´B´, DE, ´D´E´

2. Elements in the knick and non-knick region should have approximately same size

A B

C

DE

A´ B´C´

D´E´f O

BA C D E

A´ B´ C´ D´ E´d

OBefore folding

After folding

Geometrical folder: simple fold

Page 18: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 18

Initial data:

Distance between layers, d

Fold height, f

Element size to knick

Elliptic elongation

Thickness increase coefficient

Output data:

Average distance between layers on the knick

Node displacements for corresponding folding step

Calculation of fold parameters ( 3 variants)

Geometrical folder: simple fold

Page 19: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 19

Step 1

BA C D E

A´ B´ C´ D´ E´d

Direction of displacement

Geometrical folder: four step algorithm

Page 20: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 20

Move nodes CC´ vertically by the value of “node

displacement for step 2”

BA

C

D E

A´ B´

D´ E´

Step 2

Direction of displacement

Geometrical folder: four step algorithm

Page 21: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 21

Step 3

Result of rotation:

BA

C

DE

A´ B´C´

D´E´

Rotate all these nodes over node C by 180 grad

BAC

D E

A´ B´

D´ E´

Center of rotation is the node on the lower surface of the airbag

Geometrical folder: four step algorithm

Page 22: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 22

Step 4

BA

C

DE

A´ B´C´

D´E´Rotate node C´ about node C by 90 grad

BA

C

DE

A´ B´C´

D´E´

Result of rotation

Geometrical folder: four step algorithm

Page 23: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 23

Geometrical folder: four step algorithm

Elements deform during folding

A B

C

DE

A´ B´C´

D´E´f O

D

BA C D E

A´ B´ C´ D´ E´d

OBefore folding

After folding

Inside elements (B‘C‘, C‘D‘) will be shorter

Outside elements (BC, CD) will be longer

Volume of the folded airbag has changed

Page 24: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 24

Geometrical folder: reference geometry

Unfolded FE airbag (reference geometry)

Initial strains in the folded airbag fabric

Folded FE airbag

/REFSTA# reference geometryAIRBAG02.ref

Page 25: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 25

300 mm

99 mm

straps

Fold 5

Fold 8

Fold 1

Fold 2

border of the airbag (gas

leakage)Fold 7

Fold 6

Fold 4

Fold 3

99 mm

102 mm

Geometrical folder: fold planning

Geometrical folder requires exact „planning“ of the airbag geometry: fold lines should be present in the geometry before meshing

Page 26: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 26

Fold plan for „Branch“ programm

Provides a detailed airbag “fold plan” for further manual airbag folding. Allows to control important characteristics of the airbag: minimal element size, thickness of the folded airbag etc. (Branch programm L.Fredriksson)

Geometrical folder: fold planing

Page 27: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 27

Airbag folder is a part of the Hyperworks

Types of fold:

- Simple fold

- Open fold

- Tuck folds

- Rolling

Important feature:

Airbag geometry is folded and then meshed!

Geometrical folder: Hypercrash folder

Page 28: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 28

Folding pre-simulation with Radioss

Page 29: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 29

Radioss runnable inputdeck with unfolded airbag, materials, contacts etc. but w/o airbag card

Folding pre-simulation with Radioss

Page 30: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 30

Fold planFOLD 2

0.0 10.0-1000.0 1000.0 0.0 1000.0

0.0 297.864 0.0 296.864-10.7 6.0 1.2 -0.0005 0

FOLD 3 (sym to 2)0.0 10.0

-1000.0 1000.0 -1000.0 0.00.0 -297.864 0.0 -296.864-10.7 6.0 1.2 -0.0005 0

Radioss runnable inputdeck with unfolded airbag, materials, contacts etc. but w/o airbag card

Folding pre-simulation with Radioss

Page 31: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 31

Fold planFOLD 2

0.0 10.0-1000.0 1000.0 0.0 1000.0

0.0 297.864 0.0 296.864-10.7 6.0 1.2 -0.0005 0

FOLD 3 (sym to 2)0.0 10.0

-1000.0 1000.0 -1000.0 0.00.0 -297.864 0.0 -296.864-10.7 6.0 1.2 -0.0005 0

Fold script generates Radioss inputdeck for folding

Radioss runnable inputdeck with unfolded airbag, materials, contacts etc. but w/o airbag card

Folding pre-simulation with Radioss

Page 32: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 32

Fold planFOLD 2

0.0 10.0-1000.0 1000.0 0.0 1000.0

0.0 297.864 0.0 296.864-10.7 6.0 1.2 -0.0005 0

FOLD 3 (sym to 2)0.0 10.0

-1000.0 1000.0 -1000.0 0.00.0 -297.864 0.0 -296.864-10.7 6.0 1.2 -0.0005 0

Fold script generates Radioss inputdeck for folding

Radioss runnable inputdeck with unfolded airbag, materials, contacts etc. but w/o airbag card

Folding pre-simulation with Radioss

Radioss simulation

Page 33: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 33

Folding pre-simulation: principal scheme

Rotated nodes Fixed nodes

Oo

Fold (deformable nodes)

Rotation center

Page 34: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 34

Folding pre-simulation: principal scheme

Rotated nodes Fixed nodes

Fixed nodes

Rotated nodes

Oo

90o

Fold (deformable nodes)

Rotation center

Page 35: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 35

Folding pre-simulation: principal scheme

Rotated nodes Fixed nodes

Fold (deformable nodes)

Fixed nodes

Rotated nodes

Rotated nodes

Fixed nodes

Oo

90o

180o

Fold (deformable nodes)

Rotation center

Page 36: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 36

Folding pre-simulation: principal scheme (video)

Page 37: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 37

Folding pre-simulation: blade scheme (video)

Rotated elements are deformable and trapped between two rigid blades by a contact

Page 38: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 38

Folding pre-simulation: knife scheme (video)

All airbag elements are deformable. Folding is carried out by moving rigid knives

Page 39: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 39

Altair training airbagElement edges follow folding lines4 symmetrical folds

Folding pre-simulation: complete run

Page 40: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 40

Mesh rotated by 30 grad. Fold lines are parallel to mesh direction

Element edges follow folding lines Arbitrary fine mesh

Folding is mesh independent

Folding pre-simulation: three different meshes

Page 41: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 41

Fold lines introduced in the mesh Arbitrary fine mesh

Folding pre-simulation: airbag deployment

The airbags have same shape and fold plan but different mesh. Airbag deployment is similar

Page 42: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 42

- Radioss model for folding is generated automatically

- No intersections and minor penetrations in folded airbag due to sensitive Radioss contacts

- Final size of airbag is predicted before folding starts

- Transfer from unfolded state (reference geometry) to folded is physically consistent (internal material forces and contact forces provide physically reliable strains in the airbag fabric during the folding)

- Folding method is mesh independent

- Folded mesh can be used for any solver (RADIOSS, DYNA)

Folding pre-simulation: some notes

Page 43: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 43

Example: passenger airbag folding

Page 44: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 44

Example: description

Mesh 100000 elementsAverage element size 5mmSimulation time 2h

Upper view

Lower view

Side view

Inflator

Housing

Airbag surface- typical 3D T-shape form

Page 45: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 45

Example: fold plan

Page 46: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

Dmitri Fokin , EHTC 2009, Copyright © 2008 Altair Engineering, Inc. All rights reserved. 46

Example: fold plan

First step: symmetrical zig zag side folds

Page 47: Airbag Folding with Radioss Pre- Simulationaltairatc.com/.../Session_02/ALTAIR_Airbag_Folding_ehtc_003b.pdf · FE Airbag model: airbag folding Unfolded FE airbag (reference geometry)

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Example: fold plan

First step: symmetrical zig zag side folds

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Example: fold plan

Second: lower rolls

Second step: lower rolls

First step: symmetrical zig zag side folds

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Example: fold plan

Second: lower rolls

Second step: lower rolls

Third step: upper roll

First step: symmetrical zig zag side folds

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Example: fold plan

Second: lower rolls

Second step: lower rolls

Third step: upper roll

Fourth step: press in housing

First step: symmetrical zig zag side folds

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Example: inputdecks

#RADIOSS STARTER/BEGINAIRBAG01

51 0/MAT/FABR_A/1MAT_FABRIC ……/PROP/SH_FABR/1airbag_thickness……/INTER/TYPE7/2Internal Contact……/INTER/TYPE11/1Internal Contact EE ……/END

Model of unfolded airbag

FOLD 20.0 10.0

-1000.0 1000.0 0.0 1000.00.0 270.000 0.0 269.0001

1.0 6.0 1.2 -0.00101 0FOLD 3 (sym to 2)

0.0 10.0……FOLD 15

70.0 80.0-1000.0 1000.0 -1000.0 1000.0-21.0 0.0 -20.0 0.0

11.0 6.0 1.2 -0.00101 1

END

Fold plan

FOLD SCRIPT

#RADIOSS STARTER/BEGINAIRBAG01

51 0###include FOLD00_0000.inc#include FOLD01_0000.inc##

/MAT/FABR_A/1MAT_FABRIC ……/PROP/SH_FABR/1airbag_thickness……/INTER/TYPE7/2Internal Contact……/INTER/TYPE11/1Internal Contact EE ……/END

Model of unfolded airbag with folding includes

# FOLD 2 START/SENSOR/TIME/ 200000T= 0.000

0.000…….#enddata

Fold includes

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Example: folding of a passenger airbag (video)

Mesh 100000 elementsAverage element size 5mmSimulation time 2h

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Example: fit passenger airbag in housing (video)

Mesh 100000 elementsAverage element size 5mmSimulation time 15min

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Example: deployment of the passenger airbag (v)

Mesh 100000 elementsAverage element size 5mmUniform pressure, Simulation time 0.5h

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Promising technology for numerical airbag folding

Easy to implement in HW

No need of additional explicit solver for folding simulation

Radioss model for folding is generated automatically

Simulation delivers a reliable strains in the folded airbag

Folded mesh can be used for any solver (RADIOSS, DYNA)

Conclusions

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Thank you for the attention!