Crystalmechanics Introduction
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Transcript of Crystalmechanics Introduction
Multiscale Models of Crystals
D. Raabe, F. Roters, S. Zaefferer, P. Eisenlohr
Department of Microstructure Physics and Metal Forming
WWW.MPIE.DE
02. May 2010
2
Scientific Board
Shareholder:
Max-Planck-Society, German Steel Institute
Scientific Board Trustees Board
MPIE
Strategy Board
MPIE Departments
Microstructure
Physics
and Metal
Forming
Dierk
Raabe
Interface
Chemistry
and
Surface
Engineering
Martin
Stratmann
Administration
Herbert
Wilk
Computational
Materials
Design
Jörg
Neugebauer
Multiscale Crystal Plasticity FEM
Overview
Raabe: Adv. Mater. 14 (2002), Roters et al. Acta Materi.58 (2010)
4Raabe, Zhao, Park, Roters: Acta Mater. 50 (2002) 421
Multiscale crystal plasticity FEM
5
dyadic flow law based on dislocation rate theorydyadic flow law based on dislocation rate theory
Physics-based constitutive laws: mean field theory
plastic gradients, size scale and orientation gradients (implicit)
plastic gradients, size scale and orientation gradients (implicit)
1
1. set internalvariables
2
grain boundariesgrain boundaries3
2. set internalvariables
3. set internalvariables
T
T
T
T
T
T
T
T
Taylor, Kocks, Mecking, Estrin, Kubin,...
Nye, Ashby, Kröner,....
activation concept:energy of formation upon slip penetration: conservation law
Ma, Roters, Raabe: Acta Mater. 54 (2006) 2169; Ma, Roters, Raabe: Acta Mater. 54 (2006) 2181; Ma, Roters, Raabe: Intern. J Sol. Struct. 43 (2006) 7287
Roters et al.: Acta Mater. (2010)
6
From local misorientations to GNDs
misorientation
orientation gradient(spacing d from EBSD scan)
Demir, Raabe, Zaafarani, Zaefferer: Acta Mater. 57 (2009) 559
orientation difference
misorientation angle
0°
20°
7
From local misorientations to GNDs
distortion(sym, a-sym)
dislocation tensor (GND)
J. F. Nye. Some geometrical relations in dislocated crystals. Acta Metall. 1:153, 1953.E. Kröner. Kontinuumstheorie der Versetzungen und Eigenspannungen (in German). Springer, Berlin, 1958.E. Kröner. Physics of defects, chapter Continuum theory of defects, p.217. North-Holland Publishing, Amsterdam, Netherlands, 1981.
Demir, Raabe, Zaafarani, Zaefferer: Acta Mater. 57 (2009) 559
8
From local misorientations to GNDs
Frank loop through area r
DDT in terms of 18 b,t combinations
DDT in terms of 9 b,t combinations
Demir, Raabe, Zaafarani, Zaefferer: Acta Mater. 57 (2009) 559
9
Extract geometrically necessary dislocations
Demir, Raabe, Zaafarani, Zaefferer: Acta Mater. 57 (2009) 559
10
Size effect sas a mean-field break down phenomenon
11
SSD
experiment
CPFEM:viscoplasticphenomen.model
CPFEM:dislocation-based model;g.b. model
von Misesstrain [1]
10% 20% 30% 40% 50%
Ma, Roters, Raabe: Acta Mater. 54 (2006) 2169 and 2181
10% 20% 30% 40% 50%
Al Bicrystals, low angle g.b. [112] 7.4°, v Mises strain
12
3% 8%
15%Sachtleber, Zhao, Raabe: Mater. Sc. Engin. A 336 (2002) 81
Homogeneity and boundary conditions at grain scale
Raabe et al. Acta Mater. 49 (2001) 3433
13
1mm
21mm
8mm
5mm
5mm
FE mesh
exp., grain orientation, side A exp., grain orientation, side B
equivalent strain
equivalent strain
Zhao, Rameshwaran, Radovitzky, Cuitino, Roters, Raabe : Intern. J. Plast. 24 (2008)
Crystal plasticity FEM, grain scale mechanics (3D Al)
14
T
T
Texture component crystal plasticity FEM for large scale forming
Zhao, Mao, Roters, Raabe: Acta Mater. 52 (2004) 1003
0 15 30 45 60 75 900,95
0,96
0,97
0,98
0,99
1,00
1,01
1,02
1,03
1,04
1,05
Simulation
Experiment
rela
tive e
ar
hig
ht
[1]
angle to rolling direction [°]
Texture component crystal plasticity FEM for large scale forming
D. Raabe and F. Roters: Intern. J. Plast. 20 (2004) 339 15
Numerical Laboratory: From CPFEM to yield surface (engineering)
Kraska, Doig, Tikhomirov, Raabe, Roters, Comp. Mater. Sc. 46 (2009) 383 16
Multiscale crystal plasticity FEM for large scale forming
DC04 study with Mercedes, Volkswagen, Audi, Inpro