Mathematical modeling of dislocation dynamics · 2007-12-19 · explored by computer simulations....
Transcript of Mathematical modeling of dislocation dynamics · 2007-12-19 · explored by computer simulations....
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Mathematical modelingof dislocation dynamics
Régis Monneau
Thursday 13th, December 2007 CERMICS-ENPC
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Plan of the talkIntroduction to dislocationsSharp interface modelingMathematical results for the dynamicsLink with MCM
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Introduction to dislocations
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Traction of a sample
F−F
l
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Plasticity
Y
F
F
l−l0
0l
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Persistent plastic strain
Y
F
F
l−l0
0l
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Persistent plastic strain
l0
l > l 0
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Scenario 1
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Scenario 1
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Scenario 1
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Scenario 1
IMPOSSIBLE !!
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Scenario 2
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Scenario 2
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Scenario 2
Concept of dislocation (1934): Orowan; Polanyi; Taylor
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Scenario 2
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Scenario 2
POSSIBLE !!
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Description of dislocations
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Observation of dislocationsDislocations in metallic alloys Al-Mg
Definition: a dislocation is a line of crystal defects.Length = 10−6m, Thickness = 10−9m.
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Observation of dislocationsDislocations in metallic alloys Al-Mg
Definition: a dislocation is a line of crystal defects.
Length = 10−6m, Thickness = 10−9m.
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Observation of dislocationsDislocations in metallic alloys Al-Mg
Definition: a dislocation is a line of crystal defects.Length = 10−6m, Thickness = 10−9m.
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A very brief summary of the history
1934: introdution of the concept of dislocationto explain plasticity [Orowan / Polanyi / Taylor]
1956: first observation of dislocations
∼ 1970: treatises on dislocations equilibrium[Nabarro / Hirth &Lothe, ...]
Since 1990: dislocations dynamicsexplored by computer simulations
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A very brief summary of the history
1934: introdution of the concept of dislocationto explain plasticity [Orowan / Polanyi / Taylor]
1956: first observation of dislocations
∼ 1970: treatises on dislocations equilibrium[Nabarro / Hirth &Lothe, ...]
Since 1990: dislocations dynamicsexplored by computer simulations
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A very brief summary of the history
1934: introdution of the concept of dislocationto explain plasticity [Orowan / Polanyi / Taylor]
1956: first observation of dislocations
∼ 1970: treatises on dislocations equilibrium[Nabarro / Hirth &Lothe, ...]
Since 1990: dislocations dynamicsexplored by computer simulations
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A very brief summary of the history
1934: introdution of the concept of dislocationto explain plasticity [Orowan / Polanyi / Taylor]
1956: first observation of dislocations
∼ 1970: treatises on dislocations equilibrium[Nabarro / Hirth &Lothe, ...]
Since 1990: dislocations dynamicsexplored by computer simulations
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3D continuous model
elastic medium
dislocation line
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2D continuous model
defect
elastic medium
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2D atomic model
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Perfect crystal
=⇒ elasticity at large scale
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Perfect crystal
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Singular deformation of the crystal
dislocation = topological defect
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Singular deformation of the crystal
dislocation = topological defect
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How do dislocations move ?
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A sharp interface modelingof dislocation dynamics
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3D continuous model
elastic medium
dislocation line
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2D-3D coupled system
R \3
3D elastic field2D dislocation
Γ Γ
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Computation of the stress
Σ
div σ = 0 with [u] = b on Σ
b : Burgers vectorσ : stress[Volterra 1905]
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Computation of the stress
Σ
div σ = 0 with [u] = b on Σ
σ = Λ : e with e = (e(u) − δΣ · (b ⊗ e3)sym)
e(u) = (∇u)sym =1
2
(
∇u + t∇u)
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Dislocation dynamics
We define E(Γ) =∫
R3
12e : Λ : e with e = e(Γ)
c ∆t n Γt
ΓtΓt+ ∆t
dΓt
dt= c nΓt
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Dislocation dynamics
We define E(Γ) =∫
R3
12e : Λ : e with e = e(Γ)
c ∆t nΓt
ΓtΓt+ ∆t
dΓt
dt= c nΓt
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Dislocation dynamics
We define E(Γ) =∫
R3
12e : Λ : e with e = e(Γ)
c ∆t nΓt
ΓtΓt+ ∆t
dΓt
dt= c nΓt
with c = “ −∇ΓE(Γt)′′ = σ : (b ⊗ e3)
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A sharp interface modeling
Ωt
ρ(t, x1, x2) =
1 if (x1, x2) ∈ Ωt
0 otherwise
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A sharp interface modeling
dΓt
dt= c nΓt
with c = c(ρ) = −(−∆)1
2ρ
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A difficulty of the classical theory
σ ∼ 1r
r
dislocation line
stress
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Regularization
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Peierls-Nabarro modelReplace the energy by
E(ρ) +
∫
R2
W (ρ)
with
W
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Notion of core function
x
xχ( )
We consider
regularized stress = χ ? (classical stress)
c = c0 ? ρ with c0 = −(−∆)1
2χ
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Notion of core function
x
xχ( )
We consider
regularized stress = χ ? (classical stress)
c = c0 ? ρ with c0 = −(−∆)1
2χ. – p.39/62
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Core functionFor the Peierls-Nabarro model we have
W (ρ) =1
ζ(1 − cos(2πρ))
withχ(ξ1, ξ2) = e−ζ
√ξ2
1+ξ2
2
ζ > 0 : Peierls-Nabarro parameter
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Dynamics of a single dislocation
dΓt
dt= c nΓt
with c = c(ρ) = c0 ? ρ
where c0(x1, x2) is a fixed kernel
⇐⇒ ∂ρ
∂t= (c0 ? ρ) |∇ρ| on R
2
Under an exterior stress field c1, we get
∂ρ
∂t= (c1 + c0 ? ρ) |∇ρ| on R
2
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Dynamics of a single dislocation
dΓt
dt= c nΓt
with c = c(ρ) = c0 ? ρ
where c0(x1, x2) is a fixed kernel
⇐⇒ ∂ρ
∂t= (c0 ? ρ) |∇ρ| on R
2
Under an exterior stress field c1, we get
∂ρ
∂t= (c1 + c0 ? ρ) |∇ρ| on R
2
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Dynamics of a single dislocation
dΓt
dt= c nΓt
with c = c(ρ) = c0 ? ρ
where c0(x1, x2) is a fixed kernel
⇐⇒ ∂ρ
∂t= (c0 ? ρ) |∇ρ| on R
2
Under an exterior stress field c1, we get
∂ρ
∂t= (c1 + c0 ? ρ) |∇ρ| on R
2
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Mathematical studiesof the dynamics
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Mathematical difficulty
How to define the evolutionwith the change of topology ?
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Mathematical difficulty !
Change of topology = you can be affraid !
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Level Sets method
Front in the plan xyFront = intersection of the surface with the plan xy
Level Sets equation:∂f
∂t= c(x, t)|∇f |
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Level Sets method
Front in the plan xyFront = intersection of the surface with the plan xy
Level Sets equation:∂f
∂t= c(x, t)|∇f |
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Notion of solution
∂ρ
∂t= (c1 + c0 ? ρ) |∇ρ| on R
2
Viscosity solutions (introduced by Crandall and Lions)for Hamilton-Jacobi equations.
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Notion of solution
∂ρ
∂t= (c1 + c0 ? ρ) |∇ρ| on R
2
Viscosity solutions (introduced by Crandall and Lions)for Hamilton-Jacobi equations.
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Known results (general c0)
Short time existence, uniqueness[Alvarez, Hoch, Le Bouar, M.], [Forcadel]Convergent schemes[Alvarez, Carlini, M., Rouy], [Ghorbel, M.]Fast Marching schemes[Carlini, Cristiani, Forcadel], [Carlini, Falcone,Forcadel, M.]
Long time (c ≥ 0)[Alvarez, Cardaliaguet, M.], [Barles, Ley],[Cardaliaguet, Marchi], [Cannarsa, Cardaliaguet]Long time (general c)[Barles, Cardaliaguet, Ley, Monneau]
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Known results (general c0)
Short time existence, uniqueness[Alvarez, Hoch, Le Bouar, M.], [Forcadel]Convergent schemes[Alvarez, Carlini, M., Rouy], [Ghorbel, M.]Fast Marching schemes[Carlini, Cristiani, Forcadel], [Carlini, Falcone,Forcadel, M.]Long time (c ≥ 0)[Alvarez, Cardaliaguet, M.], [Barles, Ley],[Cardaliaguet, Marchi], [Cannarsa, Cardaliaguet]
Long time (general c)[Barles, Cardaliaguet, Ley, Monneau]
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Known results (general c0)
Short time existence, uniqueness[Alvarez, Hoch, Le Bouar, M.], [Forcadel]Convergent schemes[Alvarez, Carlini, M., Rouy], [Ghorbel, M.]Fast Marching schemes[Carlini, Cristiani, Forcadel], [Carlini, Falcone,Forcadel, M.]Long time (c ≥ 0)[Alvarez, Cardaliaguet, M.], [Barles, Ley],[Cardaliaguet, Marchi], [Cannarsa, Cardaliaguet]Long time (general c)[Barles, Cardaliaguet, Ley, Monneau]
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Main difficulty
Physics =⇒∫
R2 c0 = 0 and c0(−x) = c0(x).
=⇒ no inclusion principle
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Main difficulty
Physics =⇒∫
R2 c0 = 0 and c0(−x) = c0(x).
=⇒ no inclusion principle
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Loosing the graph in finite time
−2 −1 0 1 2−2
0
10
0
X−Axis
Y−A
xis
−2 −1 0 1 2−2
0
10
−2 −1 0 1 2−2
0
10
0.000974359
X−Axis
Y−A
xis
−2 −1 0 1 2−2
0
10
−2 −1 0 1 2−2
0
10
0.00194872
X−Axis
Y−A
xis
−2 −1 0 1 2−2
0
10
−2 −1 0 1 2−2
0
10
0.00292308
X−Axis
Y−A
xis
−2 −1 0 1 2−2
0
10
−2 −1 0 1 2−2
0
10
0.00389744
X−Axis
Y−A
xis
−2 −1 0 1 2−2
0
10
−2 −1 0 1 2−2
0
10
0.00487179
X−Axis
Y−A
xis
−2 −1 0 1 2−2
0
10
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Link with MCM
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particular kernels
Let x ∈ Rn, and
J(−x) = J(x) =1
|x|n+1g
(
x
|x|
)
1|x|≥1 ≥ 0
We define
c0 = J −(∫
Rn
J
)
δ0
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particular kernels
Let x ∈ Rn, and
J(−x) = J(x) =1
|x|n+1g
(
x
|x|
)
1|x|≥1 ≥ 0
We define
c0 = J −(∫
Rn
J
)
δ0
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Rescaling
∂ρ
∂t= (c0 ? ρ) |∇ρ| on R
n
For ε > 0, we define
ρε(x, t) = ρ
(
x
ε,
t
ε2| ln ε|
)
=⇒
∂ρε
∂t= (cε
0 ? ρε) |∇ρε| on Rn
with
cε0(x) =
1
εn+1| ln ε|c0
(x
ε
)
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Rescaling
∂ρ
∂t= (c0 ? ρ) |∇ρ| on R
n
For ε > 0, we define
ρε(x, t) = ρ
(
x
ε,
t
ε2| ln ε|
)
=⇒
∂ρε
∂t= (cε
0 ? ρε) |∇ρε| on Rn
with
cε0(x) =
1
εn+1| ln ε|c0
(x
ε
)
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At large scale
ε
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Slepcev level sets formulation
∂ρ
∂t= (c0 ? ρ) |∇ρ| on R
n with ρ ∈ 0, 1
is replaced for ρ continuous by
∂ρ
∂t=
(
c0 ? 1ρ(·,t)≥ρ(x,t))
(x)
|∇ρ| on Rn
with≥ for subsolutions> for supersolutions
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Convergence to anisotropic MCM
Theorem 1 [Da Lio, Forcadel, M.]In the Slepcev formulation, and under certain regularityassumptions, as ε goes to zero, ρε converges to ρ0
solution of∂ρ0
∂t= Fg(D
2ρ0,∇ρ0)
where
Fg(M, p) = trace(
M · Ag
(
p
|p|
))
Ag
(
p
|p|
)
=
∫
Sn−1∩p⊥
(
1
2g(θ)θ ⊗ θ
)
dθ
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Similar results[Garroni, Muller] (Gamma limit, stationnary pb)[Merriman, Bence, Osher] algorithm[Evans], [Barles, Georgelin], [Ishii], [Ishii, Pires,Souganidis], ...
[Forcadel] : error estimate for a scheme for MCM
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Similar results[Garroni, Muller] (Gamma limit, stationnary pb)[Merriman, Bence, Osher] algorithm[Evans], [Barles, Georgelin], [Ishii], [Ishii, Pires,Souganidis], ...[Forcadel] : error estimate for a scheme for MCM
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Identification of the limit MCMTheorem 2 [Da Lio, Forcadel, M.]If u is smooth, then
Ag(p) = D2G(p), Fg(D2u,∇u) = |∇u| div ((∇G) (∇u))
derives from the energy∫
G(∇u) with
G = − 1
2πLg
Lg = pv
g(
x|x|
)
|x|n+1
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Identification of the limit MCMTheorem 2 [Da Lio, Forcadel, M.]If u is smooth, then
Ag(p) = D2G(p), Fg(D2u,∇u) = |∇u| div ((∇G) (∇u))
derives from the energy∫
G(∇u) with
G = − 1
2πLg
Lg = pv
g(
x|x|
)
|x|n+1
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More properties
Theorem 3 [Da Lio, Forcadel, M.]
n = 2 : g ≥ 0 ⇐⇒ G convexn ≥ 3 : ∃G convex and g 6≥ 0
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An example in 2D
G(x1, x2) = γx21 + x2
2 with
γ = 11−ν
∈(
12 , 2
)
ν = Poisson ratio
g(x1, x2) = (2γ − 1)x21 + (2 − γ)x2
2
(for x21 + x2
2 = 1).
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Anisotropic evolution of a circle
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O. Alvarez (Univ. Rouen)G. Barles (Univ. Tours)A. Briani (Univ. Pise)P. Cardaliaguet (Univ. Brest)E. Carlini (post-doc Univ. Roma))F. Da Lio (Univ. Padoue)A. El Hajj (Post-doc Univ. orleans)M. Falcone (Univ. Roma)
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A. Finel (ONERA)N. Forcadel (Post-doc INRIA)A. Ghorbel (Univ. Sfax)P. Hoch (CEA)H. Ibrahim (PhD student CERMICS)C. Imbert (Univ. Dauphine)O. Ley (Univ. Tours)Y. Le Bouar (ONERA)R. Monneau (CERMICS)E. Rouy (Centrale Lyon)
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