GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH...
Transcript of GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH...
![Page 1: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/1.jpg)
GRONBACH
GRON BACH GermanyDipl.-Ing. Stephan Manuel Dörfler
Advanced Modeling of Friction Stir Welding – Improved MaterialModel for Aluminum Alloys and Modeling of Different Materialswith Different Properties by Using the Level Set Method
• Introduction to Friction Stir Welding
• Motivation and target of presented work
• Model setup• Metallic material modeling in CFD – empirical material model
for Aluminum Alloys and it´s implementation• Introduction of the level set method to FSW-Modelling
• Results Modelling FSW
• Results Modelling Extrusion Process
• Conclusion
Presented at the COMSOL Conference 2008 Hannover
![Page 2: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/2.jpg)
GRONBACH Process Principle - Friction Stir Welding
![Page 3: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/3.jpg)
GRONBACH
FSWFSW
Motivation and target of this work
? ?
![Page 4: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/4.jpg)
GRONBACH Modelling challanges
FSW properties:
• Very high plastic strains within the weld nugget
• Great variety of strain rates, strains and temperature
• Ususally joining two different materials with different properties
Use of CFD – Model Extension of the State of the Art by
• Adapted material model for Aluminium alloys (modelling temperatureand strain rate dependency of yield stress)
• Using level-set method for integration of two different material models
![Page 5: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/5.jpg)
GRONBACH Yielding behavior of Aluminium alloys at high strains and elevated temperatures
[Akeret78]
plastic strain
yiel
dst
ress
![Page 6: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/6.jpg)
GRONBACH Material model
)ln()(),( 22 TcTbabTaTcTbaTk cccbbaaaf ⋅+⋅++⋅−⋅−⋅+⋅+= ϕϕ &&
To cope with specific behavior of aluminum alloys at elevated temperaturesand high strains, a new, empirical material model is proposed:
)ln()( cbaTk f +⋅−= ϕ&
a b c
Basic concept:
Introducing temperature dependency of a, b and c:2TcTbaa aaa ⋅+⋅+=
)( bb bTab −⋅=2TcTbac ccc ⋅+⋅+=
Results in empirical material model [Doerfler08]:
![Page 7: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/7.jpg)
GRONBACH Model factors for different alloys
Model factor Unit EN-AW 3103 EN-AW 6060aa MPa 624,16 401,53ba MPa K-1 -1,4096 -0,8465ca MPa K-2 8,20E-04 4,60E-04ab MPa K-1 0,02872 3,97E-03bb K 958,3 2041,3ac s-1 0,084 2,62bc s-1 K-1 -6,02E-05 -7,86E-03cc s-1 K-2 1,44E-07 5,97E-06
![Page 8: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/8.jpg)
GRONBACH Material model quality I
Material model in comparison to Johnson-Cook (best fit) andexperimental results (from Akeret) – EN-AW 6060
![Page 9: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/9.jpg)
GRONBACH Material model quality II
Material model (Doerfler) in comparison to Johnson-Cook (best fit) andexperimental results (from Akeret) – EN-AW 3103
![Page 10: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/10.jpg)
GRONBACH Model concept
• CFD-Model (non-newtonian fluid dynamicsmode from Comsol Chemical Engineering Module)
• Material flow through model domain• Thermal boundary conditions in conformity to experimental
measurements (tool and material boundaries)• Constant material speed at inlet• No slip condition at tool pin
![Page 11: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/11.jpg)
GRONBACH Material model implementation in momentum equations
⎪⎪⎩
⎪⎪⎨
⎧
γ⋅η+γτ
=ττ≥τ
=γτ<τ
&&
&
)(:
0:
00
0
γ⋅η+γ−τ
=τγ−
&&
&
))1(
( 0me
γ⋅γ
−γτ=τ
γ−
&&
& &
))1)(,(
(m
kf eT
Bingham-Fluid-> you`d need to know, whereyield stress is reached and wherenot
Solution from Papanastasiou forabove problem (approximation)
Modification for strain rate and temperature sensitive materialsthat won´t converge
γ⋅+γ
γτ=τ &
&
&)
)(),(
( m
mkf
hT Own, converging approach
using the convergence parameterm together with a small constant h
![Page 12: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/12.jpg)
GRONBACH Material model implementation in momentum equations
⎪⎪
⎩
⎪⎪
⎨
⎧
τ=γ
γ
γτ≈
+γ
γτ>γ
=τ
))(
),0((:0
))(
),(()
)(),(
(:0
m
mkf
m
mkf
m
mkf
hT
ThT
&
&
&
&
&&
h is used to prevent instabilitydue to shear rates near or equalzero (h<<1)
m is increased from 0 to 1 using the parametric solver to determine plastisicedand solid areas within the domain
Newtonian fluid s.th. in between yielding material
![Page 13: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/13.jpg)
GRONBACH Introduction of level set approach to FSW-model
• Introduction of convection and diffusion equations to the model (level-set-method)
• Sign of virtual concentration c‘ determines, where which material is
Implementation:
))'(,,( csignTkk ff ϕ= &
)())'(1(21
121 ffff kkcsignkk −⋅++=
Convergence is reached by using smoothing function and anotherconvergence factor:
fAl
m
fAl
fAlfAlfKern
f kk
kkkcsignk
c
⋅
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡ +−+=
)))('(1(21
![Page 14: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/14.jpg)
GRONBACH Results: Determination of the material division on retr. and adv. side
![Page 15: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/15.jpg)
GRONBACH Results: Particle tracing
![Page 16: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/16.jpg)
GRONBACH Results: Particle tracing II
![Page 17: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/17.jpg)
GRONBACH Verification experiment - simulation
[LFT06]
![Page 18: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/18.jpg)
GRONBACH Resulting material distribution of twodifferent alloys due to welding process
![Page 19: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/19.jpg)
GRONBACH Material distribution for specialaluminum material AFS
![Page 20: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/20.jpg)
GRONBACH Results: Modeling of extrusion process
Speed Streamlines Particle tracing
![Page 21: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/21.jpg)
GRONBACH Simulation of material distribution for the coextrusion process
coordinate x
coor
dina
tey
![Page 22: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/22.jpg)
GRONBACH Summary and conclusion
• Modelling of aluminum alloys by empirical material model leads to improved implementation of material behavior for high temperaturesand strain rates
• Special measures for the implementation of the constitutive law arenecessary
• Implementation of the level set method features two improvements– Different properties of different materials can be implemented– Prediction of material distribution after welding becomes possible
• With the improved modeling it becomes possible not only to simulatefriction stir welding, but also similar processes (extrusion/ coextrusion)
![Page 23: GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany · GRON Dipl.-Ing. Stephan Manuel DörflerBACH Germany Advanced Modeling of Friction Stir Welding – Improved Material Model for](https://reader033.fdocuments.in/reader033/viewer/2022042212/5eb4d0c5ab4c1f4916337c23/html5/thumbnails/23.jpg)
GRONBACH Acknowledgements
Results of this work have been elaborated in collaboration with
• Gronbach Group• University of Erlangen-Nuremberg (Dr. Otto, Prof.
Geiger)• Comsol Multiphysics
Many thanks for this kind support…
… and many thanks for your kind attention!