IGA Solver¥雪峰.pdf · Immersed methods and non-body fitted methods IGA-based immersed methods...
Transcript of IGA Solver¥雪峰.pdf · Immersed methods and non-body fitted methods IGA-based immersed methods...
IGA Solver
6ȸ
ënóÆðó§Æ
IGA Solver–Xuefeng Zhu ënóÆ
SN0
1 IGA for Linear Elastic Problems
2 Isogeometric Shell Analysis
3 Trimmed Isogeometric Analysis
4 B++ Splines with Applications to IGA
IGA Solver–Xuefeng Zhu ënóÆ
kÚAÛ©Û¦)ìuЧ
1 1943c§CourantuL1¦^n/«õª¼ê5
¦)Û=¯KØ©"
2 1956 cÅÑúiTurner§Clough§Martin ÚTopp 3©ÛÅ
(XÚïÄlÑ\!ù!n/üfÝLª
3 1960 cClough 3?n²¡5¯K§1gJÑ¿¦^/k
0(finite element method)¶¡"
4 1967 cZienkiewicz ÚCheung Ñ1k'k©Û
;Í"
5 1970 c±§km©A^u?n5ÚC/¯
K"ͶÆöXTed BelytschkoÚThomas Hughes.
6 2005c§Thomas HughesÇJÑAÛ©Û.
IGA Solver–Xuefeng Zhu ënóÆ
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IGA Solver–Xuefeng Zhu ënóÆ
¥mïK
e¡±¥mò¡AC¯K~§505
¯KAÛ©Û
Ù)Û)µ
σr ,r (r , θ) =Tx
2(1− R2
r2 ) +Tx
2(1− 4
R2
r2 + 3R4
r4 )cos2θ (1)
σθ,θ(r , θ) =Tx
2(1 +
R2
r2 )− Tx
2(1− 3
R4
r4 )cos2θ (2)
σr ,θ(r , θ) =Tx
2(1 + 2
R2
r2 − 3R4
r4 )sin2θ (3)
IGA Solver–Xuefeng Zhu ënóÆ
5¯KAÛ©ÛÄÚ½
5¯KAÛ©ÛÄÚ½8B±eÚ½µ
(AÛëêz
ü©Û-üf
N©Û-of
\Dirichlet>.^Ú1Ö>.^
¦) £|
?n
IGA Solver–Xuefeng Zhu ënóÆ
I(AÛëêz-Volumetric parameterizations
Jessica Zhang, Gang Xu, Xin Li, Na Lei et al.
IGA Solver–Xuefeng Zhu ënóÆ
I(AÛëêz-Surface parameterizations
Xianfeng Gu, Xin Li, Jessica Zhang, Gang Xu et al.
IGA Solver–Xuefeng Zhu ënóÆ
I(AÛëêz-²¡¯K
IGA Solver–Xuefeng Zhu ënóÆ
I(AÛëêz-²¡¯K
IGA Solver–Xuefeng Zhu ënóÆ
IIü©Û
IGA Solver–Xuefeng Zhu ënóÆ
IIü©Û
ÀJ £¼ê(ë)
S =n∑i
Ri (ξ, η)Pi
u =n∑i
Ri (ξ, η)di
IGA Solver–Xuefeng Zhu ënóÆ
IIü©Û
∏=
∫Ω
12εσdΩ−
∫Ω uT fdΩ−
∫∂Ω uT TdΓ
þ㼪=zzüþ¼ªÚµ∏=
∑e∏e =
∑e(∫Ωe
12ε
TeσedΩ−
∫Ωe
ueT fedΩ−
∫∂Ωe
uTe TdΓ)
Ù¥
σe =
σxx
σyy
τxy
= Dεe εe =
εxx
εyy
γxy
= Lue
ue =
u
v
L =
∂∂x 0
0 ∂∂y
∂∂y
∂∂x
IGA Solver–Xuefeng Zhu ënóÆ
IIü©Û
bneq´,ü':ê8
ue =
u
v
=
R1 0 · · · Ri 0 · · · Rneq 0
0 R1 · · · 0 Ri · · · 0 Rneq
dx1
dy1...
dxi
dyi
...
dxneq
dyneq
IGA Solver–Xuefeng Zhu ënóÆ
IIü©Û-2
∏e =∑
e dTe∫Ωe
12 BT DBdΩdT
e−deT ∫
ΩRT fedΩ−dT
e∫∂Ωe
RT Td∂Ω
³U¼égdݦ
∂∏∂d
= 0
éuzü¼aq¦Xeª
∂∏∂d
=∑
e
(
∫Ωe
12
BT DBdΩdTe −
∫Ω
RT fedΩ−∫∂Ωe
RT TdS) = 0
üfݧª
Kede = fe
Ù¥ke´üfÝݧde´ü!:gdݧfe´ü1Öþ"
IGA Solver–Xuefeng Zhu ënóÆ
IIü©Û
K eij =
∫Ωe
BTi DBjdΩe =
∫Ωe
D0
∂Ri∂x 0 ∂Ri
∂y
0 ∂Ri∂y
∂Ri∂x
1 ν 0
ν 1 0
0 0 1-ν2
∂Rj∂x 0
0 ∂Rj∂y
∂Rj∂y
∂Rj∂x
∂Ri
∂ξ
∂Ri
∂η
=
∂x∂ξ
∂y∂ξ
∂x∂η
∂y∂η
∂Ri
∂x∂Ri
∂y
= J
∂Ri
∂x∂Ri
∂y
IGA Solver–Xuefeng Zhu ënóÆ
IIü©Û
IGA Solver–Xuefeng Zhu ënóÆ
IIIN©Û
IGA Solver–Xuefeng Zhu ënóÆ
IIIN©Û
IGA Solver–Xuefeng Zhu ënóÆ
IIIN©Û
N²ï§µ
Kd = f
ª¥§kNfÝݶdN!: £þ¶fN1
Öþ"
§¦)3Ú\>.^c§N²ï§´Ûɧ=
N§Ø)"3Ú\>.^§§)"
IGA Solver–Xuefeng Zhu ënóÆ
III\ £>.^Ú1Ö
NURBSØ÷vKronecker delta5§ÏdÃ\ £>.
^§ÀÀÇ)ûù¯K"¦ò £>.':=z
>.:§KN:gdÝÚ>.:gdݱïáéXµ
d = Td∗
KKd = fCµ
TT KTd∗ = TT f
IGA Solver–Xuefeng Zhu ënóÆ
IV?n(J
IGA Solver–Xuefeng Zhu ënóÆ
SN0
1 IGA for Linear Elastic Problems
2 Isogeometric Shell Analysis
3 Trimmed Isogeometric Analysis
4 B++ Splines with Applications to IGA
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
~^NnØ)Reissner-MindlinnØ
Úkirchhoff-LovenØ"ö¦%CAÛC1ëY§ cö
KØI"
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
NAÛ¼êµ
x(ξ, η, ς) = xN(ξ, η) + ςh(ξ, η)
2f(ξ, η)
âëg§ÑN £¼ê
u
v
w
=∑
i
Ni (ξ, η)
ui
vi
wi
+12ςhi
[V1i −V2i
] αi
βi
þ/ª:
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
u
v
w
= Nae; ae =
ae
i...
aej
with aei =
ui
vi
wi
αi
βi
(4)
N =
N1 N2 · · · N9
ae =
u1 v1 w1 ϕ1 ψ1 · · · u9 v9 w9 ϕ9 ψ9
(5)
Ù¥
Ni =
Ni (ξ, η) 0 0 ζ
2 hi l1iNi (ξ, η) − ζ2 hi l2iNi (ξ, η)
0 Ni (ξ, η) 0 ζ2 him1iNi (ξ, η) − ζ2 him2iNi (ξ, η)
0 0 Ni (ξ, η) ζ2 hin1iNi (ξ, η) − ζ2 hin2iNi (ξ, η)
(6)
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
ÛIÚÛÜIm'Xµ
X = θX′
Ù¥
X =[
x y z]T
X′ =[
x ′ y ′ z ′]T
θ =[
V1 V2 V3
]=
l1 l2 l3
m1 m2 m3
n1 n2 n3
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
ÛÜIXeÛÜAåÛÜACµ
ε′ =[εx ′ εy ′ γx ′y ′ γy ′z′ γz′x ′
]T
=[
∂u′
∂x ′∂v ′
∂y ′∂u′
∂y ′ + ∂v ′
∂x ′∂v ′
∂z′ + ∂w ′
∂y ′∂u′
∂z′ + ∂w ′
∂x ′
]T
σ′ =[σx ′ σy ′ τx ′y ′ τy ′z′ τz′x ′
]T= Dε′
Ù¥
D =E
1− ν2
1 ν 0 0 0
ν 1 0 0 0
0 0 1−ν2 0 0
0 0 0 1−ν2k 0
0 0 0 0 1−ν2k
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
ÛIXÚÛÜIX £ê'Xµ∂u′
∂x ′∂v ′
∂x ′∂w ′
∂x ′
∂u′
∂y ′∂v ′
∂y ′∂w ′
∂y ′
∂u′
∂z′∂v ′
∂z′∂w ′
∂z′
= θT
∂u∂x
∂v∂x
∂w∂x
∂u∂y
∂v∂y
∂w∂y
∂u∂z
∂v∂z
∂w∂z
θÙ¥
θ =[
V1 V2 V3
]=
l1 l2 l3
m1 m2 m3
n1 n2 n3
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
ÛÚÛÜêfm'Xµ
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
ÛACL«
ε = Lgug = Lgug = LgNae
Ù¥
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
ÛIXÚÛÜIXAC'Xµ
ε′ = Qgεg = QgLgug = QgLgNae = Bae
zNURBSfÝL«µ
Ke =
∫V e
Hdxdydz =
∫ 1
0
∫ 1
0
∫ 1
0BT DB |J|dξdηdζ
IGA Solver–Xuefeng Zhu ënóÆ
Isogeometric Shell Analysis
gÌïuçôge(AÛ©Û£)182N¤
IGA Solver–Xuefeng Zhu ënóÆ
SN0
1 IGA for Linear Elastic Problems
2 Isogeometric Shell Analysis
3 Trimmed Isogeometric Analysis
4 B++ Splines with Applications to IGA
IGA Solver–Xuefeng Zhu ënóÆ
Trimmed Isogeometric Analysis
IGA Solver–Xuefeng Zhu ënóÆ
Trimmed Isogeometric Analysis
IGA Solver–Xuefeng Zhu ënóÆ
Trimmed Isogeometric Analysis
IGA Solver–Xuefeng Zhu ënóÆ
Trimmed Isogeometric Analysis
IGA Solver–Xuefeng Zhu ënóÆ
Trimmed Isogeometric Analysis
IGA Solver–Xuefeng Zhu ënóÆ
SN0
1 IGA for linear elastic problems
2 Isogeometric Shell Analysis
3 Trimmed Isogeometric Analysis
4 B++ Splines with Applications to IGA
IGA Solver–Xuefeng Zhu ënóÆ
Immersed methods and non-body fitted methods
IGA-based immersed methods include immersed IGA, FCM,
XIGA et al.
Traditional non-body fitted methods include such as IBM,
XFEM, EFGM, RBF-based meshless method et al.
Issue IIt is difficult for these methods to strongly impose Dirichlet boundary
conditions because they do not satisfy Kronecker delta property.
IGA Solver–Xuefeng Zhu ënóÆ
Incorporating boundary collocation points or boundary curves/surfaces
Issue IIAnother disadvantage of immersed methods is that they are
difficult to incorporate boundary collocation points or boundary
curves/surfaces as boundary representation.
IGA Solver–Xuefeng Zhu ënóÆ
Analysis-suitable volume parameterization is still a big challenge
Issue IIIVolume parameterization for isogeometric analysis is still a big
challenge, especially for the CSG models with complex topology
structures. Stress functions are usually discontinuous!
IGA Solver–Xuefeng Zhu ënóÆ
B++ spline method
B++ Splines = Boundary Plus Plus Splines
Advantages of B++ splinesStrongly impose Dirichlet boundary conditions
Incorporate boundary collocation points as the boundary
representation.
Say bye to multi-blocks and stress functions are continuous.
IGA Solver–Xuefeng Zhu ënóÆ
B++ splines
Its idea is replacing the control points of the background
spline mesh using the boundary collocation points or the
boundary spline curves/surfaces.
IGA Solver–Xuefeng Zhu ënóÆ
B++ spline basis functions
B++ spline basis functions satisfy the Kronecker delta property,
build the partition of unity. They are also linearly independent.
IGA Solver–Xuefeng Zhu ënóÆ
Mutually orthogonal components
By BPB = PC , we can rewrite PPPB, in terms of two mutually
orthogonal components, one in the row space of B and the other in
the null space of B, that is
PB = BTΦΦΦ + Z = BTΦΦΦ + RΨΨΨ (7)
where
BR = 0 (8)
Combining these equations, we get
PB = BT (BBT )−1PC + RPE (9)
IGA Solver–Xuefeng Zhu ënóÆ
Hierarchical B++ spline representation of a trimmed spline surface
Thus, S is reformulated
S = NAPA + NBBT (BBT )−1PC + NBRPE (10)
For simplicity
S = NAPA + NCPC + NEPE (11)
PA Control points with complete basis functions.
PC Boundary collocation points or the control points of trim
curves.
PE Enriched control points.
NA Complete basis functions.
NC Basis functions of the boundary collocation points or the
control points of trim curves.
NE Basis functions of enriched control points.IGA Solver–Xuefeng Zhu ënóÆ
T
The matrix T is
T = [T1 T2] =[
BT (BBT )−1 R]. (12)
where T1 = BT (BBT )−1 and T2 = R.
Advantages
Linear independence. Yes
Kronecker delta property. Yes
Partition of unity. Yes.
IGA Solver–Xuefeng Zhu ënóÆ
Applications-Structural analysis
IGA Solver–Xuefeng Zhu ënóÆ
Applications-Structural analysis
IGA Solver–Xuefeng Zhu ënóÆ
Applications-XIGA
IGA Solver–Xuefeng Zhu ënóÆ
Applications-Topology optimization
IGA Solver–Xuefeng Zhu ënóÆ
Applications-Onestep inverse isogeometric analysis
IGA Solver–Xuefeng Zhu ënóÆ
Processing and potential applications on B++ splines
In processing:
Fluid-solid interactions using B++ splines.
Topology optimization using B++ spline-based isogeometric
analysis.
B++ spline-based XIGA.
Potential applications:
Simulations of failure and crack using B++ spline-based XIGA.
Multigrid method using B++ splines
Hierarchical B++ splines with applications to adaptive iso-
geometric analysis.
IGA Solver–Xuefeng Zhu ënóÆ
IGA Solver–Xuefeng Zhu ënóÆ