1st European HyperWorks Technology Conference … European HyperWorks Technology Conference. Copyright © 2006 Altair Engineering, Inc. All rights reserved. 2 1-ALE Multi-phase Material

Copyright © 2006 Altair Engineering, Inc. All rights reserved. 122/10/2007

Non homogeneous material and material failure

Gérard WinkelmullerDirector Radioss Development

1st European HyperWorksTechnology Conference

Copyright © 2006 Altair Engineering, Inc. All rights reserved. 2

1-ALE Multi-phase Material2-Austenitic steel3-Honeycomb4-Fabric5-Foam & polymer6-Failure models

Copyright © 2006 Altair Engineering, Inc. All rights reserved. 3Copyright © 2006 Altair Engineering, Inc. All rights reserved. 3

Law 37

� Two phases liquid gas mixture• Gas liquid interaction• Cavitation in liquid

� Presentation of the test• Interaction between a ship hull and fluid.• Euler Lagrange Contact interface type 18• Law 37: two phases air and water

Lagrangian

mesh

AIR fluid mesh

WATER fluid

mesh


Law 51

� 3 phases Mïe Grüneisen EOS• Non diffusive material boundary option• Each phase can be:

– liquid or gas– Elastic solid – Elastoplastic solid (v 9.0),

• Explosive material can be added as 4th phases (new in version 9.0)

• Optional thermal conduction (v 9.0)

Law 37 Fuel tank sloshing Law 51 (non diffusive ON)

Underwater explosion


LAW51 TESTS

Inlet (burn gases)

Cold gases

Water

Outlet

Metal plate

• This test presents a typical problem of burn gases interaction with cold gases and water

– Phase 1: Burn gases ( γ=1.2 )

– Phase 2: Air ( γ=1.4 )

– Phase 3: Water


Austenitic steel

� Full Coupling of three factors : • Microstructure (martensite transformation)• Temperature• Work Hardening model

� Two Laws• Hänsel• U&A

� Thermal conduction (in Radioss 9.0)� In collaboration with NGV consortium

Martensite rate equation

∫ ∂∂∂=

p

p

p

mm

VV

ε

εε0

Martensite fraction

( )

( )( )TDCVV

VT

QA

BV Pm

BB

m

m

p

m ⋅+−

−

=

∂∂

+

tanh12

11exp

1

ε

VolumeC

ETT

pi ρ

int+=

Coupled thermal analysis

Mechanical behavior( ) ( )( )( )( ) m

n

pHSHSHSy VHTKKmABB αγεεσ ′→∆+++−−−= 210exp

Hänsel law

0

1000

2000

3000

4000

5000

6000

7000

0 50 100 150 200

Displacement (mm)

For

ce (

N)

Test 1 - 5m/s

Test 2 - 5m/s

Test 3 - 0.001m/s

LAW63


Deep Drawing with thermal conduction

� Blank Temperature : 70 °°°°C

� Tools Temperature : 19 °°°°C

� Holder Force : 480 KN

� Estimated Material : 1.4301

� Constant temperature in tools

Benchmark 1Deep Drawing Single Pass

Punch

Holder

Blank

Die

Plastic strain

Temperature


Honeycomb:Special solid elementand material law (law 58)

� Main limitation of simple homogenization approach• Crushing

• Shear behaviour

� Solution• New element with additional nodal variable

• Cosserat elasticity

Honeycomb


Honeycomb� Compression

• With classical formulation it is not possible to take into account the initial crushing peak

Stress strain input Force output

Honeycomb


Honeycomb� Compression

• New formulation with enriched nodal variables

– An additional nodal scalar is used to transmit the buckling information from one element to his neighbours

Honeycomb

Stress strain input Force output


Honeycomb� Shear behaviour� Apart from the peak problem global honeycomb compre ssion is

easy to describe with a classical orthotropic mater ial. And thisfor the 1, 2 and 3 direction

� But a partial compression with some punching effect need some additional calibration.

• A partial compression in direction 1 can be adjusted with the 12 shear

• A partial compression in direction 2 can also be adjusted with the 21 shear

• But 12 shear and 21 shear are the same, and if one direction is adjusted, the other one isn’t

• What we need is a model with different shear behaviour in 12 and 21 direction. But this is impossible with classical FEM for equilibrium reasons

Cosserat elasticity


0

0

0

≠

=

≠

z

yx

xy

m

ττ

0

0

0

≠

≠

=

z

yx

xy

m

ττ

Cosserat elasticity


Honeycomb


� FABRIC • Anisotropic

– Variable warp/weft angle• Physical fiber Coupling

– Nominal stretch modelization– True Poisson’s effect

— Initial Poisson’s value = 1.— Final value = 0.

• Non linear shear with lock angle• Non linear elastic fiber

Fφα warpweft

Fabric

αt π/2

αt


δ weft δ warp

Warp force

δ warp δ weft

Weft force

Weft force

Warp force

δ warp

Fabric tension


Law 58 Law 19

Fabric

Airbagexample


Fabric forming


� LAW 65� New in Radioss 9.0� Non linear elasto-plastic law� Non linear elastic loading and non linear elastic unloading� Stress-strain functions depending on strain rate� Elastic loading : stress < yield(strain rate)� Plastic loading : stress > yield(strain rate)� Unloading : follows unloading curve shifted by plastic strain value

�

YieldstressUnloadingcurveLoading curve

Strainrate 2

Strainrate 1

Strainrate 1

Polymer Material Law

YieldstressUnloadingcurveLoading curve

Constant strainrate


Nonlinear ‘visco’ elastic law 70

eqeqeq εεσ &,,

Law Theory :Estimate stress Tensor

),(max eqeqloadfyld εε &=Load yield stress

),(min eqequnloadfyld εε &=Unload yield stress

We use a spherical criteria for

[ ] εσσ ~~0 ∆+= D

3loadε&

1loadε&

ε

σ

1unloadε&

maxσ

minσ

⇒≤≤⇒≤≤

unloading

loading

unloadequnload

loadeqload

21

32

εεεεεε&&&

&&&


Front rail impact

Courtesy of PSA

� Without failure


Front rail impact

Courtesy of PSA

� With failure model


Hyper velocity impact

� Ductile tensile rupture


Concrete law

� Impact on ceramic

Courtesy of Eurocopter


Composite Law 25

� Tsai Wu yield surface and hardening� Tsai Wu or Chang Chang failure criteron

resσσσσ

PW

maxσσσσ

1PW 2

PW Courtesy of Eurocopter


Failure modelization

� New Failure models• Can be used with different material law• /FAIL/fail_model/mat_id

– Fail_model: —JOHNSON : Johnson Cook failure criteria—TULERB : Tuler Butcher criteria—WILKINS : Wilkins Failure criteria—FLD : forming limit diagram—Chang Chang : composite—BAO-XUE-WIERZBICKI failure model—USER1,2,3: user failure model

� Future improvement• Damage model improvement• X-Fem for failure propagation


Tuler Butcher

� Tuler Butcher• Based on the concept of cumulative damage• Use for dynamic fracture.

� General criterion:

ft

fσK;λ

Courtesy of LALP

( ) Kft

f ≥−∫λ

σσ0

ft Fracture time

fσ Static stress for fracture

K;λ Material constants


Johnson Cook

� Johnson Cook failure criterion• Derived from the following cummulative

damage law:

• Where

∑∆=

f

Dε

ε

]1)][ln(1)][exp([ *5

*4

*321 TDDDDDf +++= εεεεσσσσεεεε &

vm

m

σσσσσσσσσσσσ =*

0

*

εεεεεεεεεεεε&

&& =

0

0*

TT

TTT

melt −−=

Rivet failure


Bao Xue Wierzbicki

-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Round Bar Tensile Tests

Upsetting Tests

_

_

76

9

5

8

3

2

1

0.8

0.4

experiment (plane stress) experiment (axial symmetry)

Al2024-T351

σσσσm

/σσσσ

εεεεf

� failure criterion

: Equivalent strainε

σ : Equivalent stress

mσ : Mean stress

σση m= : Stress triaxiality

J3 : Third invariant of stress deviator

33

2

27

σξ J

= : Deviatoric state parameter


Bao Xue Wierzbicki

Axial symmetry

Plane strain

Plane stress

fε

plane stress

failure criterion


Soccer simulation with Radioss








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1st European HyperWorks Technology Conference … European HyperWorks Technology Conference. Copyright © 2006 Altair Engineering, Inc. All rights reserved. 2 1-ALE Multi-phase Material