Cost-benefit conflict in material modeling€¦ · Microalloyed steel grades EN 10149 SAE J2340...

of 30/30
1 Technical perfection, automotive passion. Cost-benefit conflict in material modeling Dr.-Ing. Birgit Reichert
  • date post

    29-Jan-2021
  • Category

    Documents

  • view

    4
  • download

    0

Embed Size (px)

Transcript of Cost-benefit conflict in material modeling€¦ · Microalloyed steel grades EN 10149 SAE J2340...

  • 1

    Technical perfection, automotive passion.

    Cost-benefit conflict in material modeling

    Dr.-Ing. Birgit Reichert

  • 2

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Content

    • Introduction

    • Modelling philosophies

    • Material testing for data input FEM

    • Questions

    -300

    -200

    -100

    0

    100

    200

    300

    -300 -200 -100 0 100 200 300

    σ1, N/mm²

    σ2,

    N/m

    str

    ess

    strain

  • 3

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Faurecia Seating GroupFrames

    Safety and comfort

    modules

    Foam and covers

    Mechanisms

    Complete seat

  • 4

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Faurecia as global player

    710

    4

    58

    12

  • 2008 Faurecia Group Presentation 5

    Others

    60 PSA

    % of sales

    18

    11

    74

    Daimler

    Renault

    VW

    1997

    * Excluding monoliths

    Leading commercial position & successful customer diversification

    2

    PSA PSA PSA PSA

    VAGVAGVAGVAG

    RenaultRenaultRenaultRenault----NissanNissanNissanNissan

    BMWBMWBMWBMW

    GMGMGMGM

    ChryslerChryslerChryslerChrysler

    FordFordFordFord

    28 %28 %28 %28 %

    26 %26 %26 %26 %

    13 %13 %13 %13 %

    13 %13 %13 %13 %

    8 %8 %8 %8 %

    4 %4 %4 %4 %

    2 %2 %2 %2 %3 %3 %3 %3 %

    Others Others Others Others 2 %2 %2 %2 %

    DaimlerDaimlerDaimlerDaimler1 %1 %1 %1 %

    ToyotaToyotaToyotaToyota

    2008

  • 6

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    The complex material landscape (steel sheet)

    JIS, JFS- focus on tensile strength- TS steps: no system- specimen’s length: 50mm

    SAE, ASTM- focus on yield strength- YS steps: no system- specimen’s length: 50mm

    EMS.ME- focus on yield strength- YS steps: 40MPa- specimen’s length: 50mm

    EN- focus on yield strength- YS steps: 40MPa- specimen’s length: 80mm

  • 7

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Best equivalence of sheet steel by norms • Often old short names in

    use

    • In Europe EN standards obligatory

    • In general only ‘best equivalence’ to other

    standards possible (JIS,

    SAE, ASTM, JFS,…)

    • For the newest steel developments standards

    do not exist, only

    companies’ information

    can be cited

    Grade classes Europe Europe China IndiaDeep drawing steel grades EN 10130 SAE J2329 ASTM A 1008M-07a JIS G 3141 JFS A 2001 GB/T 5213 IS 513

    cold rolled DC01 - CS SPCC JSC270C DC01 CR1

    cold rolled DC03 CR3 DS SPCD JSC270D DC03 CR3

    cold rolled DC04 CR4 DDS SPCE JSC270E DC04 CR4

    cold rolled DC06 CR5 EDDS SPCG JSC260G DC06 CR5

    Deep drawing steel grades EN 10111 SAE J2329 ASTM 1011M-07 JIS G 3131 JFS A 1001 GB 710-91/ GB 711-88 IS 1079

    hot rolled DD11 - - SPHC - 08 D

    hot rolled DD12 HR2 HR CS Type B SPHD JSH270C - DD

    hot rolled DD13 - - SPHE JSH270D 08A1 EDD

    hot rolled DD14 HR3 HR DS Type B SPHF JSH270E - -

    High strength IF steel grades EN 10268 SAE J2340 ASTM A 1008M-07 JIS G 3135 JFS A 2001 GB/T 20564-3 India

    HC180Y CR 180AT - SPFC340 JSC340W CR180IF

    HC260Y CR 280AT - SPFC390 JSC390W CR260IF

    Microalloyed steel grades EN 10268 SAE J2340 ASTM A 1008M-07a JIS G 3135 JFS A 2001 China IS 14491

    HC260LA - CR SS275 - - 260Y

    HC300LA CR 300XF CR HSLAS310 Class 2 - - 300Y

    HC340LA CR 340XF CR HSLAS340 Class 2 - JSC440R 340Y

    HC380LA CR 380XF CR HSLAS380 Class 2 - - 380Y

    HC420LA CR 420XF CR HSLAS410 Class 2 - - 420Y

    Microalloyed steel grades EN 10149 SAE J2340 ASTM 1011M-07 JIS G 3134 JFS A 1001 GB/T 20887-1 IS 5986

    S315MC HR 300XF HR HSLAS310 Class 2 - JSH440R HR315F -

    S355MC HR 340XF HR HSLAS340 Class 2 - JSH490R HR355F Fe 490

    S420MC HR 420XF HR HSLAS410 Class 2 - JSH540R HR420F -

    S460MC - HR HSLAS450 Class 2 - JSH590R HR460F -

    S500MC HR 490XF HR HSLAS480 Class 2 - - HR500F -

    S550MC HR 550XF HR HSLAS-F550 - - HR550F -

    S600MC - HR UHSS 620 - - HR600F -

    S650MC - - - - HR650F -

    S700MC - HR UHSS 690 - - HR700F -

    Dual phase steel grades draft EN 10338 SAE J2745 ASTM A 1008M-07a JIS G 3135 JFS A 2001 GB/T 20564-2 India

    HCT450X CR DP440T/250Y - SPFC440 JSC440W CR260/450DP -

    HCT500X CR DP490T/290Y - SPFC490 - CR300/500DP -

    HCT600X CR DP590T/340Y - SPFC590 JSC590Y CR340/590DP -

    HCT780X CR DP780T/420Y - SPFC780Y JSC780Y CR420/780DP -

    HCT980X CR DP980T/550Y - SPFC980Y JSC980Y CR550/980DP -

    Dual phase steel grades draft EN 10338 SAE J2745 - JIS G 3134 JFS A 1001 China -

    hot rolled HDT580X HR DP590T/300Y - SPFH590Y JSH590Y - -

    Complex phase steel grades draft EN 10338 SAE J2745 ASTM A 1008M-007a JIS G 3135 JFS A 2001 China India

    HCT600C - - - - - -

    HCT780C - - - - - -

    HCT980C - - - - - -

    Complex phase steel grades draft EN 10338 SAE J2745 ASTM 1011M-07 JIS G 3134 JFS A 1001 China India

    HDT750C - - - - - -

    HDT780C - - - JSH780R - -

    HDT950C - - - - - -

    Martensite phase steel grades draft EN 10338 SAE J2745 ASTM 1011M-07 JIS G 3134 JFS A 1001 China India

    hot rolled HDT1200M - - - - - -

    America Japan

    cold rolled

    cold rolled

    cold rolled

    cold rolled

    hot rolled

    hot rolled

  • 8

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Modeling philosophiesExperimental data• using the unprocessed experimental data

    (materials database)

    • extrapolation by mathematical trend

    Empirical derived models• e.g. flow stress functions• parameter without physical meaning• determination of parameters by fitting to

    experimental data of material

    Continuum mechanics models• physical interpretable parameters• fitting of model parameters to experimental data

    of material

    Microstructurally based models• involving microstructure-related internal variables.• determination of model parameter by certain set of

    experiments

    Ab initio modeling• applying quantum mechanics• parameter-free determination

    Models represent

    macroscopic

    behaviour

    Models represent

    metal-physical

    mechanisms

    str

    ess

    strain

    str

    ess

    strain

    DATEN

    ZEIT ; KRAFT ; WEG ;BREITENAENDERUNG ;

    0.0; 1.062636e+002; 0.0; 0.0

    0.0; 1.015853e+002; 0.0; 0.0

    0.0; 1.015853e+002; 0.0; 0.0

    0.0; 1.973226e+002; 0.0; 0.0

    0.0; 1.916418e+002; 0.0; 0.0

    0.0; 1.857940e+002; 0.0; 0.0

    1.953125e-002; 1.849586e+002; 4.952637e-005; 3.607978e-004

    5.953125e-002; 1.839561e+002; 1.481264e-004;-6.943555e-005

    9.595312e-001; 1.904723e+002;-7.475736e-004;-4.480221e-005

    1.059531e+000; 1.914748e+002;-8.966403e-004; 3.460645e-004

    1.679531e+000; 1.948164e+002;-1.920274e-003; 2.654394e-004

  • 9

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    0.01

    0.10

    1.00

    10.00

    100.00

    1 10 100 1000 10000 100000 1000000 10000000

    cycle to failure Ni

    str

    ain

    am

    plit

    ud

    e,

    %

    h

    elastic portion

    plastic portion

    total strain S-N line

    Manson-Coffin S-N line

    Manson-Coffin elastic portion

    Manson-Coffin plastic portion

    HX340LAD

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    1000

    0 0.1 0.2 0.3 0.4

    true plastic strain, -

    tru

    e s

    tre

    ss, N

    /mm

    ²

    H

    0.004s-1 at 296K

    1s-1 at 296K

    20s-1 at 296K

    200s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    0.0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5

    minor strain, -

    majo

    r str

    ain

    , -

    HX420LAD, 1.0mm

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    0,00 0,20 0,40 0,60 0,80 1,00

    true plastic strain, -

    tru

    e s

    tress,

    N/m

    h

    Experiment

    Input for FEM

    Estrin-Mecking

    Formingflow curve (quasi-static)forming limit diagramyield locus

    Crashflow curves

    (dynamic)

    Fatigue strain S-N curves

    friction, spring back,

    fracture

    bake hardening, fracture

    fracture

    Youngs-Modulus

    Poisson ratio

    anisotropy coefficient

    friction coefficient

    specific weight

    specific heat capacity

    -300

    -200

    -100

    0

    100

    200

    300

    -300 -200 -100 0 100 200 300

    σ1, N/mm²

    σ2,

    N/m

  • 10

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    180

    230

    280

    330

    380

    430

    480

    530

    580

    630

    680

    0.00 0.20 0.40 0.60 0.80 1.00

    true plastic strain, -

    true

    str

    ess,

    N/m

    h

    tensile testHollomon (2 Parameter)

    Swift (3 Parameter)Gosh (4 Parameter)Voce (3 Parameter)

    Hockett-Sherby (4 Parameter)Estrin-Mecking (3 Parameter)

    Empirical derived models for flow curvestensile test quasi-static ( )

    ( )

    ( ) ( )

    ( ) ( )

    ( ) ( )

    ( )

    ( ) ( )

    −⋅−+=−

    ⋅−⋅−−=−

    −⋅−+=

    −+=

    +=

    ⋅=

    ⋅+=

    *

    exp:

    exp)(:

    exp:

    :

    :

    :

    :

    222

    122

    0

    r

    SiSf

    HS

    HSf

    r

    SiSf

    n

    iSf

    n

    iSf

    n

    Hf

    n

    Lf

    kMeckingEstrin

    n

    mCCCkSherbyHockett

    kVoce

    DCkGosh

    CkSwift

    CkHollomon

    CkLudwik

    S

    S

    H

    L

    ϕ

    ϕσσσϕ

    ϕϕ

    ϕ

    ϕσσσϕ

    ϕϕϕ

    ϕϕϕ

    ϕϕ

    ϕσϕ

    microstructural interpretation of Voce for fine grain or

    precipitation hardened single phase microstructure

    (1909)

    (1948)

    microstructurally interpreted by Kocks-Mecking for coarse

    grain and single phase microstructure (1981)

    (1945)

    (1952)

    (1977)

    (1975)

    (1984)

    180

    230

    280

    330

    380

    430

    480

    530

    580

    630

    680

    0.00 0.20 0.40 0.60 0.80 1.00

    true plastic strain, -

    tru

    e s

    tre

    ss,

    N/m

    h

    Kocks-Mecking (Voce) and Estrin-Mecking are presented currently as modules of the One Internal Variable Model (OIVM)

  • 11

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Application of fitting functions to HX180YD

    2

    __

    1

    )( ModelliExperimenti

    n

    i

    yy −Σ=

    Minimising sum of flow curve and hardening rate:

    Constraints: - experimental tensile curve is

    of priority- stress at true plastic strain 0

    is not lower than Rp0.2 (205MPa)

    Differential quotient of tensile flow curve dσ/dε versus σ

    0

    100

    200

    300

    400

    500

    600

    0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

    true plastic strain, -

    tru

    e s

    tress, M

    Pa

    0

    100

    200

    300

    400

    500

    600

    0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

    true plastic strain, -

    tru

    e s

    tress, M

    Pa

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    200 300 400 500 600

    true stress, MPa

    ha

    rde

    nin

    g r

    ate

    , M

    Pa

    HX180YD tensile

    HX180YD bulge

    Hollomon

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    200 300 400 500 600

    true stress, MPa

    ha

    rde

    nin

    g r

    ate

    , M

    Pa

    HX180YD tensile

    HX180YD bulge

    Sw ift

  • 12

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Application of fitting functions to HX180YD

    0

    100

    200

    300

    400

    500

    600

    0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

    true plastic strain, -

    tru

    e s

    tress, M

    Pa

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    200 300 400 500 600

    true stress, MPa

    ha

    rde

    nin

    g r

    ate

    , M

    Pa

    HX180YD Zug

    HX180YD Bulge

    Ludw ik

    0

    100

    200

    300

    400

    500

    600

    0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

    true plastic strain, -

    tru

    e s

    tress, M

    Pa

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    200 300 400 500 600

    true stress, MPa

    ha

    rde

    nin

    g r

    ate

    , M

    Pa

    HX180YD Zug

    HX180YD Bulge

    Voce

    0

    100

    200

    300

    400

    500

    600

    0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

    true plastic strain, -

    tru

    e s

    tress, M

    Pa

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    200 300 400 500 600

    true stress, MPa

    ha

    rde

    nin

    g r

    ate

    , M

    Pa

    HX180YD Zug

    HX180YD Bulge

    Gosh

  • 13

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Application of fitting functions to HX180YD

    0

    100

    200

    300

    400

    500

    600

    0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

    true plastic strain, -

    tru

    e s

    tre

    ss

    , M

    Pa

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    200 300 400 500 600

    true stress, MPa

    ha

    rde

    nin

    g r

    ate

    , M

    Pa

    HX180YD tensile

    HX180YD bulge

    Hockett-Sherby

    0

    100

    200

    300

    400

    500

    600

    0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

    true plastic strain, -

    tru

    e s

    tre

    ss

    , M

    Pa

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    200 300 400 500 600

    true stress, MPa

    hard

    en

    ing

    rate

    , M

    Pa

    HX180YD tensile

    HX180YD bulge

    Estrin-Mecking

    Comments: - best simultaneous fit to flow curve

    and hardening rate for models with 4 parameters (Hockett-Sherby or Gosh)

    - best model working with 3 parameters is Estrin-Mecking; superior to Swift or Ludwik and similar to Gosh due to minimising criteria

    - application of model using two parameters is difficult (Hollomon)

    - if it comes to parameterise models for application of stochastic analysis then one may care for as less model parameters as possible

  • 14

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Cost assessment for basic testing

    • Chemical composition• Metallography• Tensile tests on sheet specimens

    - longitudinal, transversal, diagonal

    - statistically reliable (e.g. according to SEP 1240)

    • Flow curve up to high strains

    ⇒⇒⇒⇒ 1000 - 1250€ for one material

  • 15

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Yield criteria familiesYield criteria

    Hill's family σ0 σ30 σ45 σ75 σ90 σb τ r0 r30 r45 r75 r90 rb A1 A2Hill48 X X X X

    Hill79 X X X X

    Hill90 X X X X X X

    Hill93 X X X X X X X X

    Chu95 X X X X X X

    Lin, Ding96 X X X X X X X X

    Hu2005 X X X X X X X X

    Hosford's family σ0 σ30 σ45 σ75 σ90 σb τ r0 r30 r45 r75 r90 rb A1 A2

    Hosford79 X X X X

    Barlat89 X X X X X

    Barlat91 X X X X X

    Karafillis, Boyce93 X X X X X X X X

    Barlat96 X X X X X X X X X

    BBC2000 X X X X X X X X X

    Bron-Besson2003 X X X X X X X X X

    Barlat2003 X X X X X X X X X X

    BBC2003 X X X X X X X X X X

    Aretz-Barlat2004 X X X X X X X X X X

    A1: anomalous behavior of first kind

    A2: anomalous behavior of second kind

  • 16

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Other yield criteria approaches

    • Budiansky (polar coordinates)• Ferron (polar coordinates)• Vegter (Bézier interpolation)• …

    σ 1 /σ f

    σ 2 /σ f

    reference point

    hinge point

    equi bi-axial

    plane strain

    uni-axial

    pure shear

    σ

    σλ

    σ

    σλ λ

    σ

    σλ

    σ

    σ

    1

    2

    1

    2

    1

    2

    1

    2 1

    ⋅ ⋅ ⋅

    +

    = (1- ) + 2 (1- ) + 2

    i

    r

    i

    h

    2

    i

    r

    Second order interpolation between the reference points i and i+1 (here i= 1, 2, 3, 4).

    Hinge points are the intersectionpoints from the known slopes inthese reference points.

    Orientation dependency described via cosine interpolation.

  • 17

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Experimental data for describing yield loci

    1

    6

    5 4 32

    Uniaxial tension 0°

    Uniaxial tension 90°

    Strain plane 0°

    Strain plane 90°

    Equibiaxial tension

    Pure shear tension

    σ1

    σ2

    Point 1: σ0Point 2: σ1 = 2σ2 (ε2 = 0)

    Point 3: σ1 = σ2 = σbPoint 4: σ1 = σ2/2 (ε2 = 0)

    Point 5: σ90Point 6: σ1 = -σ2 = τ

    yiel

    d st

    ress

    angle to rolling direction0 15 30 45 60 75 90

    Lank

    ford

    val

    ue

    angle to rolling direction0 15 30 45 60 75 90

    Tensile tests with different angle to rolling direction

    Tensile tests: r0, r90, r45, (r15, r30, r60, r75)

    σ0, σ90, σ45, (σ15, σ30, σ60, σ75)

    Hydraulic bulge test: σb

    Biaxial tensile tests: σb, further biaxial stress combinations (σ1 = x⋅σ2)

    Shear test: τ

  • 18

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Determination of FLC

    • Uniaxial tensile test (3)• Hydraulic bulge test (5)• Punch stretching test• Keeler test (4)• Hecker test• Marciniak test• Nakajima test (2)• Hasek test (1)

    -0.4 -0.2 0.2 0.4

    0.6

    0.4

    0.2

    ε2

    ε1

    0.0

    12

    34

    5

    -0.4 -0.2 0.2 0.4

    0.6

    0.4

    0.2

    ε2

    ε1

    0.0

    12

    34

    5

  • 19

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Forming seat tracks

    • Bending (bending limit curve, …)• Spring back (Chaboche, Backhaus, Yoshida, …)• Failure (Gurson, EWK, CrachFEM, …)

    grain boundaries

    failure in deep drawing

    failure in bending

  • 20

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Cost assessment for advanced testing

    • Chemical composition• Metallography• Tensile tests on sheet specimens

    - longitudinal, transversal, diagonal- statistically reliable (e.g. according to SEP 1240)

    • Flow curve up to high strains• Plane strain and shear• Forming limits • Hole expansion and bending

    ⇒⇒⇒⇒ 5000 - 7000€ for one material

  • 21

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Dynamic tensile testing for crash

    Typical ranges of strain rate covered by conventional load frames, servo-hydraulic machines and bar

    testing systems

    Schematic of tensile Split Hopkinson Bar System

    Schematic of Servo-hydraulic System

    Specific requirements needed for load measurement,

    direct measurement of strain and specimen geometry

  • 22

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Johnson-Cook

    ( ) )1983(1ln10

    210

    −−

    ++=

    m

    roommelt

    roomn

    TT

    TTCC

    ε

    εεσσ

    &

    &

    0

    100

    200

    300

    400

    500

    600

    0 0.05 0.1 0.15 0.2 0.25 0.3

    true plastic strain, -

    true

    str

    ess, N

    /mm

    ²

    H

    0.004s-1 at 296K

    1s-1 at 296K

    20s-1 at 296K

    250s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    350

    400

    450

    500

    550

    600

    650

    700

    750

    800

    850

    0 0.05 0.1 0.15 0.2

    true plastic strain, -

    tru

    e s

    tre

    ss, N

    /mm

    ²

    H

    0.008s-1 at 296K

    0.91s-1 at 296K

    13.14s-1 at 296K

    81.7s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    DC06 HCT600X

  • 23

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Tanimura

    ( ) ( ) ( ) )1992(log0

    kmnEDCBA ε

    ε

    εεεσ &

    &

    &+

    −+⋅+=

    0

    100

    200

    300

    400

    500

    600

    0 0.05 0.1 0.15 0.2 0.25 0.3

    true plastic strain, -

    true

    str

    ess, N

    /mm

    ²

    H

    0.004s-1 at 296K

    1s-1 at 296K

    20s-1 at 296K

    250s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    350

    400

    450

    500

    550

    600

    650

    700

    750

    800

    850

    0 0.05 0.1 0.15 0.2

    true plastic strain, -

    true

    str

    ess, N

    /mm

    ²

    H

    0.008s-1 at 296K

    0.91s-1 at 296K

    13.14s-1 at 296K

    81.7s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    350

    400

    450

    500

    550

    600

    650

    700

    750

    800

    850

    0 0.05 0.1 0.15 0.2

    true plastic strain, -

    tru

    e s

    tre

    ss,

    N/m

    H

    0.008s-1 at 296K

    0.91s-1 at 296K

    13.14s-1 at 296K

    81.7s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    suggested fit by steel supplier

    DC06

    HCT600X

  • 24

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    One Internal Variable Models (OIVM)

    0

    100

    200

    300

    400

    500

    600

    0 0.1 0.2 0.3 0.4

    true plastic strain, -

    true

    str

    ess, N

    /mm

    ²

    H

    0.004s-1at 296K1s-1at 296K

    20s-1at 296K250s-1at 296K500s-1at 296K

    experimentexperimentexperiment

    experimentexperiment

    Estrin-Mecking

    extended by heat effects

    350

    450

    550

    650

    750

    850

    950

    0 0.05 0.1 0.15 0.2

    true plastic strain, -tr

    ue s

    tress, N

    /mm

    ²

    H

    0,008s-1 at 296K

    0,91s-1 at 296K

    13,14s-1 at 296K

    81,7s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    Hybrid model extended by

    dislocation self organisation,

    two-phase description and

    heat effects

  • 25

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    200

    250

    300

    350

    400

    450

    500

    550

    600

    650

    700

    0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

    true plastic strain, -

    tru

    e s

    tress,

    MP

    a

    HX260YD tensile

    HX260YD bulge

    HX260YD model

    Identifying family parameters for OIVM

    200

    250

    300

    350

    400

    450

    500

    550

    600

    650

    700

    0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

    true plastic strain, -

    tru

    e s

    tress,

    MP

    a

    HX220YD tensile

    HX220YD bulge

    HX220YD model

    200

    250

    300

    350

    400

    450

    500

    550

    600

    650

    700

    0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

    true plastic strain, -

    tru

    e s

    tress,

    MP

    a

    HX180YD tensile

    HX180YD bulge

    HX180YD model

    Model constants:

    Taylor factor M: 3

    Numerical constant α: 0.5

    Shear modulus G: 80769 MPa

    Burgers vector b: 2.5 x10-10m

    Normalising strain rate ε0: 1000s-1

    Material parameters to adjust:

    Grain size d

    Recovery factor k20

    Exponent n

    Exponent m

    Family parameters determined:

    a and b for d

    c and d for k20

    e and f for n

    g and h for m

    and use of yield strength for each alloy·

    HX180YD, HX220YD and HX260YD by Estrin-Mecking:

    HX180YD HX220YD HX260YD

  • 26

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Application of family parameters

    100

    200

    300

    400

    500

    600

    700

    0 0.1 0.2 0.3 0.4

    true plastic strain, -

    true

    str

    ess, N

    /mm

    ²

    H

    0,004s-1 at 296K

    1s-1 at 296K

    20s-1 at 296K

    200s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    100

    200

    300

    400

    500

    600

    700

    0 0.1 0.2 0.3 0.4

    true plastic strain, -

    true

    str

    ess, N

    /mm

    ²

    H

    0,004s-1 at 296K

    1s-1 at 296K

    20s-1 at 296K

    250s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    100

    200

    300

    400

    500

    600

    700

    0 0.1 0.2 0.3 0.4

    true plastic strain, -

    true

    str

    ess, N

    /mm

    ²

    H

    0,004s-1 at 296K

    1s-1 at 296K

    20s-1 at 296K

    200s-1 at 296K

    experiment

    experiment

    experiment

    experiment

    HX180YD HX220YD HX260YD

    Family parameters determined:

    a and b for d

    c and for k20

    e and f for n

    g and h for m

    and use of yield strengths for each alloy

    Heat conduction parameters:

    Heat transfer parameter β: 0.018s-1

    Specific heat capacity cspec: 477 Nmkg-1K-1

    Material density ddens: 7800 kgm-3

    Heat dissipation factor χ: 1

  • 27

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Other models for strain rate dependence

    • Extended Hollomon• Cowper-Symonds• 10 Parameter model• Bergström• Zerilli-Armstrong• Mechanical Threshold (MTS)• …

  • 28

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Cost assessment complete process chain

    • Formability testing: 5000 – 7000€• Strain rate dependence of material

    ⇒⇒⇒⇒ 10.000 – 15.000€ for one material

    (plus joinability testing and evt. fatigue testing)

  • 29

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    General questions

    • How to come from the material testing to the models of choice?

    • How to ensure reliable FEM input data worldwide?

    • How to deal with the customer diversification?

  • 30

    Technical perfection, automotive passion.Cost-benefit conflict in material modeling

    Potential criteria for model choice

    • Accuracy of model prediction proved by simulating standard material tests by FEM

    • Number of model parameters

    • Financial efforts for the material tests to determine the model parameters

    • Number of materials the model chosen is applicable to

    • Modular character of model

    • Level of commercialisation

    • …