Failure models for plastics - material characterization for *MAT …€¦ · PPT20 PC/ABS 0 20 40 60 80 100 120 140 160 180 200 1 Mittelwert F max PCABS PPT20 0 500 1000 1500 2000

© 4a engineering GmbH, all rights reserved

Failure models for plastics - material characterization

for *MAT_ADD_EROSION (DIEM)

A. Fertschej, B. Hirschmann, P. Reithofer, M. Rollant

Seite: 1 / 23

Autor: Artur Fertschej, Peter Reithofer

Datum: 170509

Titel: rep_17050901_afer_pr_gga_FailureModelsForPlastics.ppt

4a engineering GmbH

Industriepark 1

A-8772 Traboch

[email protected]

++43 (0) 664 80106 619

http://impetus.4a.co.at/en

11th European LS-DYNA Conference

9th – 11th May 2017, Salzburg, Austria


Introduction

Failure models

Measurement possibilities using 4a impetus

Material modeling

Validation

Summary

Content

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Plastics in automotive pedestrian protection show different deformation

and fracture behavior Energy absorption

Failure is a function of load type, time, temperature, processing, …

Introduction

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[1] H. Staack, D. Seibert, H. Baier - Application oriented failure modeling and characterization for polymers in

automotive pedestrian protection, COMPLAS 2015, Barcelona

[1]


constant plastic strain

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constant plastic strain + damage evolution

Plastic strain as function of strain rate Failure as function of triaxiality and strain rate

Failure Models in LS-Dyna

[2] M. Basaran, S. Wölkerling,

F. Neukamm, M. Feucht, D.

Weichert – An extension of

the GISSMO damage model

based on Lode angle

dependence, LS-Dyna

Developer Forum 2010,

Bamberg

Standard – simple None standard - simple

None standard - simple Advanced

[2]


Many well known failure criteria for ductile materials [3]

Failure Models for Metals

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Tresca or maximum shear stress criterion

von Mises yield criterion

Gurson yield criterion for pressure-

dependent metals

Hosford yield criterion

Hill yield criteria

various criteria based on the invariants of

the Cauchy stress tensor

[4] F. Neukamm, M. Feucht, A. Haufe, P. DuBois – GISSMO – Material modeling with a sophisticated failure

criteria, LS-Dyna Developer Forum 2011, Stuttgart

[3] https://en.wikipedia.org/wiki/Material_failure_theory

[4] [2]


Failure surface in dependence of triaxiality and strain rate

Failure Models for Plastics DIEM-Model

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Datum: 170509


[1] H. Staack, D. Seibert, H. Baier - Application oriented failure modeling and

characterization for polymers in automotive pedestrian protection, COMPLAS 2015,

Barcelona

[1]


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4a impetus Reverse engineering

[5] https://www.carhs.de/en/companion-poster/product/caecompanion-print.html

[5]


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(Failure) Measurement Possibilities using 4a impetus Test specimens, test setup

3-point bending 0.1 mm/s - 4.5 m/s Clamped bending - 4.5 m/s

T-specimen (rib) 0.1 mm/s - 4.5 m/s Puncture test 0.1 mm/s - 4.5 m/s


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Simulation Possibilities using 4a impetus Test specimens, test setup

3-point bending 0.1 mm/s - 4.5 m/s Clamped bending - 4.5 m/s

T-specimen (rib) 0.1 mm/s - 4.5 m/s Puncture test 0.1 mm/s - 4.5 m/s


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Visualization of dynamic failure behavior of the material during

test (crack initiation and propagation)

Easy view, different angles possible

Trigger signal from 4a impetus synchronizing

Measurement Possibilities using 4a impetus High-speed camera


Material Modeling for Plastics Complex yield surface + failure

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Load cases

Plasticity

Complex yield surface

Failure

static,

dynamic (2x)

Classical approach

Should be done with DIC

(difficult at high strains !)

static Typical no failure for

plastics

static Typical failure under

tension

static (2x),

dynamic (3x) Strain rate dependency

Only brittle materials, no

failure for ductile materials

dynamic

4a impetus

approach

reverse engineering

4a impetus

approach

reverse engineering

static,

dynamic

static,

dynamic

[6]


Material Modeling – Plasticity + Hardening Workflow for *MAT_SAMP-1

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--- lw 50 mm / 1 mm/s

˗˗˗ simulation

··· mean value curve of the tests

normalized displacement

no

rmaliz

ed

fo

rce

static behavior - yield

˗˗˗ simulation



no

rmaliz

ed

fo

rce

3 point bending0.1 mm/s

1 m/s

2.5 m/s4 m/s

dynamic behavior – strain rate


no

rmaliz

ed

fo

rce

˗˗˗ simulation


Clamped bending 4 m/s


no

rmaliz

ed

fo

rce

˗˗˗ simulation


--- clamped bending 4 m/s

check compression/tension behavior fit compression/tension behavior

Reverse engineering process with 4a impetus [7]

3-point-bending

3-point-bending clamped


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Validation on further tests (*MAT_SAMP-1) [7]


no

rma

lize

d fo

rce

Tensile test static

T-specimen 2 m/sClamped bending 4 m/s

˗˗˗ simulation

··· mean value test curves

Material Modeling – Validation Validation for *MAT_SAMP-1


DIEM: Damage Initiation and Evolution Model [6]

Base: Standard material model (e.g. *MAT_SAMP-1)

3 individual criteria can be used:

Ductile criterion:

Shear criterion:

Instability criterion:

After initiation the damage evolution occurs:

),( pP

D

P

D

),( pP

D

P

D

),( pP

D

P

D

P

P

D

P

D

d

0

P

major

P

or

min

P

D

P

D

max

:)1( epCD

Failure Models for Plastics DIEM-Model

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[6] LS-DYNA© KEYWORD USER'S MANUAL - VOLUME II - Material Models


4a impetus Test data for *MAT_ADD_EROSION (DIEM)

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Evaluation of the failure strains


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4a impetus Failure models

GUI – different possibilities to setup failure models

Strain rate

dependency

Post failure

Triaxiality


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4a impetus Failure models

GUI – different possibilities to setup failure models

Strain rate

dependency

Post failure

Triaxiality


Failure Modeling - Validation *MAT_SAMP-1 with *MAT_ADD_EROSION

3-point-bending, 4 m/s, unfiltered curves

The test curves are matched very well [7]

no

rma

lize

d f

orc

e


Colored: Test curves

Black: Simulation

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no

rma

lize

d f

orc

e


Dynamic puncture test, 6.3 m/s


Colored: Test curves

Black: Simulation


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0

300

600

900

1,200

1,500

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007

Kra

ft [

N]

Zeit [s]

Kraft [N] DSP06

Kraft [N] DSP07

Kraft [N] DSP08

Kraft [N] DSP09

Kraft [N] DSP10

Simulation


no

rma

lize

d fo

rce

Simulation


[7] A. Fertschej, P. Reithofer, M. Rollant - Failure of thermoplastics - PART 2, Material modeling and simulation, LS-

DYNA Konferenz 2015, Würzburg

Dynamic puncture test with the part, 4.3 m/s



Example: 30 measurements for both materials (30 users)

Displacement [mm]

Fo

rce

[N

]

PPT20

PC/ABS

0

20

40

60

80

100

120

140

160

180

200

1

Mittelwert Fmax

PCABS PPT20

0

500

1000

1500

2000

2500

3000

3500

1

Mittelwert E-ModulPCABS PPT20

Mean value Fmax

Mean value Young‘s Modulus

Failure Modeling - Validation Statistical evaluation in 4a impetus

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Failure probability: 20% and 80%

PPT20

Fo

rce

[N

]

Displacement [mm]

20% 80%

Failure Modeling - Validation Statistical evaluation in 4a impetus

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Material behavior of plastics depends on load type, time, temperature,

processing, …

Easy evaluation of failure at high strain rates Clamped 3-point-bending

tests and puncture tests on 4a impetus

*MAT_SAMP-1 + *MAT_ADD_EROSION material can be reproduced

best possible and close to reality

The reverse engineering process to determine the material parameters

using 4a impetus works properly

The latest software release of 4a impetus includes up to date failure

modeling accurate material modeling

Summary

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15th

28th February – 1st March 2018

in Schladming, Austria

„Plastics – Testing and Simulation” further information: http://technologietag.4a.co.at/

Thank you for your attention!

Wednesday, 8:30: Workshop: MPIP – Material Parameter Identification Process

with 4a impetus

Thursday, 8:55: *MAT_4A_MICROMEC – Theory and Application Notes

Thursday, 11:30: Biotex BigBag Simulation – LS-Dyna Airbag Tool – Unusual

Application

Documents

Failure models for plastics - material characterization for *MAT …€¦ · PPT20 PC/ABS 0 20 40 60 80 100 120 140 160 180 200 1 Mittelwert F max PCABS PPT20 0 500 1000 1500 2000