Werkstoffmodellierung und eigenschaftsberechnung auf Basis von CT-Aufnahmen

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Elijah Bell
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1 Werkstoffmodellierung und eigenschaftsberechnung auf Basis von CT-Aufnahmen Fachtagung Computertomografie, Erik Glatt, Jürgen Becker, Stefan Rief und Andreas Wiegmann Fraunhofer Institut Techno und Wirtschaftsmathematik, Kaiserslautern 1

2 Computer Aided Material Engineering with GeoDict Lab Porous Media Composite Material image CT Image Model filter & segment generate manufacture next material measure Voxel Mesh compute Properties Properties 2

3 Computer Aided Material Engineering with GeoDict Lab Tomograph Porous Media Composite Material image CT Image Model filter & segment generate manufacture next material measure Voxel Mesh compute Properties Properties 3

4 Computer Aided Material Engineering with GeoDict Lab Tomograph Porous Media Composite Material image CT Image Model filter & segment generate manufacture next material measure Voxel Mesh try next set of parameters compute Properties Properties 4

5 Computer Aided Material Engineering with GeoDict Lab Tomograph Porous Media Composite Material image CT Image Model filter & segment generate measure Voxel Mesh compute Properties Properties engineer next material 5

6 Computation of permeability Darcy-Law: u 1 = K p L Generalized: u = κ p Permeability tensor:k k = k k k k k k k k Find anisotropic material behavior 6

7 Knitted Wire Meshes: Geometry-Based Property Analyses (a): CT-scan of a knitted wire mesh. (b): Largest through pore. (c): Bubble point pressure in dependency of the contact angle. (d): Pore size distribution. 7

8 Use PSD for solids to get fiber diameters 8

9 Knitted Wire Meshes: Partial-Differential-Equation-Based Property Analysis (a): Magnitude of velocity in a CT-scan of a knitted wire mesh. (b): Mean velocity as function of pressure drop for three knitted wire meshes. 9

10 Woven Metal Wire Meshes: Geometric Validation (a): CT of a twill Dutch-weave. (b): Geometry model. (c)-(d): Geometric validation. Microscopy Courtesy M. Knefel, Gebr. Kufferath AG. 10

11 Woven Metal Wire Meshes: Geometric Validation (a): CT of a twill Dutch-weave. (b): Geometry model. (c)-(d): Geometric validation. Microscopy Courtesy M. Knefel, Gebr. Kufferath AG. 11

12 Woven Metal Wire Meshes: Measurement and Simulation Velocity dependent pressure drop: Comparison between measurements and simulations on corresponding geometry models. 12

Model: Curved Fibers with inder Process: fibers consist of straight segments start with one segment, then add segments direction of added segment:

13 Model: Curved Fibers with inder Process: fibers consist of straight segments start with one segment, then add segments direction of added segment: direction of prev. segment + random disturbance direction of first segment + random disturbance keep current curvature + random disturbance add binder 13

14 Relative Permeability Two-step approach: 14

15 Relative Permeability Two-step approach: 1. Use pore morphology method (Hilpert, 2001) to determine distribution of air and water phase. Idea: a pore is filled with the non-wetting fluid (=water), if non-wetting fluid r β wetting fluid 15

16 Relative Permeability Two-step approach: 1. Use pore morphology method (Hilpert, 2001) to determine distribution of air and water phase. Idea: a pore is filled with the non-wetting fluid (=water), if 2. Solve Stokes equation on the remaining pore space to determine wetting phase (=air) permebility 16

17 Simulated mercury Distribution at Bubble Point in tomography pc= 10.6 kpa (r=10.5 µm) 17

18 Comparison of two compression models uncompressed 18

19 Comparison of two compression models Geometric Algorithm: (Schulz, Becker, Wiegmann, Mukherjee, Wang, J. Electrochem Soc. 154, 2007) compression in z-direction handles each z-column separately mass is kept by shifting solid blocks No knowledge about applied forces uncompressed compressed (20%, red. model) computation time: 0.25 s 19

20 Comparison of two compression models uncompressed compressed (20%, FE model) computation time: 5 days 20

21 Comparison of two compression models uncompressed compressed (20%, comparison) 21

Compression Effect on Permeability calculated for 0%, 10%, 20%, 30% compression 20 18

22 Compression Effect on Permeability calculated for 0%, 10%, 20%, 30% compression Permeability [1e-12 m²] Porosity [%] In-plane Through-plane 22

23 Compression Effect on Relative Permeability Gas Permeability [1e-12 m²] % compr uncompressed Water Saturation 23

24 Tomography and Models of felts Forming fabric and dewatering felt 10m Papiermaschine 1mm Tomographie 24

25 Binarized SEM (top) and virtual sintered ceramics (bottom) 25

26 Computed vs measured porosities and permeabilities simulation measurement 26

27 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 27

28 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 28

29 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 29

30 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 30

31 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 31

32 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 32

33 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 33

34 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 34

35 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 35

36 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 36

37 Pressure and Velocity in Clogging Simulation Filtration is multiple physics! 37

38 Thank You! Geometry and property predict dictor 38

Pore Scale Modelling of Porous Layers Used in Fuel Cells

Pore Scale Modelling of Porous Layers Used in Fuel Cells Special Semester RICAM Linz 05.10.2011 Jürgen Becker Fraunhofer Institute for Industrial Mathematics ITWM Kaiserslautern, Germany 1 Pore Scale Modelling