18th Inter-Institute Seminar, 23-25 September 2011, Budapest, Hungary 1 J. Lógó, D. B. Merczel and...
Transcript of 18th Inter-Institute Seminar, 23-25 September 2011, Budapest, Hungary 1 J. Lógó, D. B. Merczel and...
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J. Lógó, D. B. Merczel and L. Nagy
Department of Structural Mechanics
Budapest University of Technology and Economics
Hungary
Robust Optimal Topology Design with Uncertain Load Positions
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Introduction, Motivation Assumptions, Mechanical Model Numerical Examples
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Introduction, Motivation
Lógó J., Ghaemi M. and. Vásárhelyi A., Stochastic compliance constrained topology
optimization based on optimality criteria method, Periodica Polytechnica-Civil Engineering, 51, 2, pp. 5-10, 2007.
Lógó J., New Type of Optimality Criteria Method in Case of Probabilistic Loading Conditions, Mechanics Based Design of Structures and Machines, Vol.35, No.2, 2007, pp.147-162 .
Lógó, J., Ghaemi, M. and Movahedi Rad M., Optimal topologies in case of probabilistic loading: The influence of load correlation, Mechanics Based Design of Structures and Machines, 37, 3, pp. 327-348, 2009.
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Mechanical Models, Assumptions
1
1
min!G
pg g g
g
W A t
min
max
0;
0; 1,..., ,
0; 1,..., .
g
g
C
t t for g G
t t for g G
Tu F
(3.a)
subject to
(3.b-d)
P(2 0 ) (4.c)T T C q u F u F
Stochastically linearized form:
2 (4.b)T T T u F u F u F
P( 0 ) (4.a)T C q u F
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Probabilistic Compliance Constraint
Deterministic constraint:
1 2 1 1 1, ,..., , , , 1,..., ; ( ) 1;n n i i n nf f f f f E f i n f E f TF
1, , 1; 1,..., , 1,..., : given and 0; 0;ij n i i ni n j n
1 2 1, ,..., nx x x Tx
1 1 2 2 1 1 2 2P 2 ... ... 0 4.cn n n nu f u f u f u f u f u f C q
n+1
-1ov
i=1
2 +2 0 (4.e)Ti ix f q x K x
1 1 1 2 2, 1,..., ; ... / 2i i n n nx u i n x u f u f u f C 1
1
P(2 0 ) (4.d)n
i ii
x f q
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Minimum Weight Design with Stochastically Calculated Compliance
1
1
min!G
pg g g
g
W A t
(6.a)
subject to
(6.b-d)
-1ov
min
max
+2 0;
0; 1,..., ,
0; 1,..., .
T T
g
g
C q
t t for g G
t t for g G
u Ku x K x
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if 1
p
pg g
gg g
p R Bt
A
Determination of the Active and Passive Sets
min maxgt t t
1
min
p
pg g
g g
p R Bt
A
if
if
g A
g P
g P
1
max
p
pg g
g g
p R Bt
A
mingt t
maxgt t
Iterative Formula
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Probabilistic Compliance Design in the Case of Uncertain Loading Positions: Adjoint Design
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1 1 1
, n n n
i iy i i y i
i i i
x xA f f B f
w w
2
2 2 2
1
ni
A B ii
f
w
Adjoint Design
1 1 1 2 2 2 1 1 1 2 2 2
2 2 2 2 21 1 1 2 2 2 1 1 2 2
M a b a b a M b a M b
D a b a b a D a D
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Adjoint Design
Table 1: Data of the symmetric case
Original structure adjoint structure
M(x_1) M(x_2) %1 %2 D(x_1) D(x_2) F1 F2 w M(A) D(A) M(B) D(B)
30 90 0 0 0 0 100 100 120 100 0 100 0
30 90 5 5 1,5 1,5 100 100 120 100 0,88388 100 0,88388
30 90 10 10 3 3 100 100 120 100 1,76776 100 1,76776
Table 2: Data of the asymmetric case
Original structure adjoint structure
M(x_1) M(x_2) %1 %2 D(x_1) D(x_2) F1 F2 w M(A) D(A) M(B) D(B)
30 90 0 0 0 0
100 50 120 87,5 0 62,5 0
30 90 5 5 1,5 1,5
100 50 120 87,5 1,39754 62,5 1,39754
30 90 10 10 3 3
100 50 120 87,5 2,79508 62,5 2,79508
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Probabilistic Compliance Design in the Case of Uncertain Loading Positions: Load Distribution
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Load Distribution
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Numerical Example
20160 FEs, Poisson’s ratio is 0. The compliance limit is C=410000. q=0.9
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Analytical Solution of the Deterministic Problem
Rozvany, Lewinski
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Numerically Obtained Optimal Topology of the Deterministic Problem
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Probabilistic Topologies by Adjoint Design
2 21,1 0.88A 2 2
2,2 0.88B 21,2 0.0 2
2,1 0.0
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Probabilistic Topologies by Adjoint Design
22,1 0.0
2 21,1 1,76A 2 2
2,2 1.76B
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Probabilistic Topologies by Adjoint Design
21,2 0.0 2
2,1 0.0
2 21,1 3,53A 2 2
2,2 3.53B
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Numerically Obtained Optimal Topology of the Deterministic Problem in the Case of Asymmetrical Magnitudes
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Numerically Obtained Optimal Topology of the Stochastic Problem in the Case of Asymmetrical Magnitudes
21,2 0.0 2
2,1 0.0
2 21,1 1,39A 2 2
2,2 1,39B
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Numerically Obtained Optimal Topology of the Stochastic Problem in the Case of Asymmetrical Magnitudes
21,2 0.0 2
2,1 0.0
2 21,1 2,79A 2 2
2,2 2,79B
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Numerical Example II.
25600 FEs, Poisson’s ratio is 0. The compliance limit is C=220000. q=0.75
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Analytical Solution
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Numerical Solution for Deterministic Design
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Adjoint Design
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Distributed Load
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The probabilistically constrained topology optimization problem was solved
The introduced algorithm provides an iterative tool which allows to use thousands of design variables
The algorithm is rather stable and provides the convergence to reach the optimum.
Needs rather simple computer programming The covariance values have significant effect for the
optimal topology The asymmetry of the deviations is lost
Conclusions