Basic Relations
Figure 1 The Forces Action on the Shell r(x) – distance of rotation axis
h(x)-thickness of shel (design variable)
r
1- meridional and r
2- circumferential curvature
q-internal pressure R – resultant load
2
Basic Relations
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Basic Relations
Figure 2 Geometric Terminology for the Shell
4
Basic Relations
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Ν
θΝ
φ− normal membrane forces per unit length
σ
φσ
θ− Normal membrane stresses
Fatigue Crack Growth under Cyclic Loading
Safety condition, K1-stress intensity K1C-given quasi-brittle strength constant
n
cr-number of cycles, l
cr- critical crack length before fracture
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Safety Condition n
*- given number of cycles
Optimized Functional (volume of material)
geometrical constraints
Shape Optimization under Structural Longevity
Analysis of the Longevity Constraint
Integration
Minimum of n
crwith respect to l
iMinimum of n
crwith respect to α
where
Transformed longivity constraint
8
Analysis of the Longevity Constraint
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n
cris the root of the equation
if
than
For m=4 we have solution
Analysis of the Longevity Constraint Non-dimensional functional and constraints
parameter
Figure 4 The Shell Loaded by Axisimmetrical Forces
Applied to the Free Ends
Genetic Algorithm
Modification:
cyclic probability of crossover and mutation, nodes fixation for process axelleration(c)2006 http://www.ipmnet.ru/
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Dependence Shell of Iteration Step
Computational Results with Genetic Algorithm
Types of Optimal Shapes
Computational Results with Genetic Algorithm
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D 1 =2 D 2 =0.1 L=5
Computational Results with Genetic Algorithm
D 1 =2 D 2 =1 L=5
Computational Results with Genetic Algorithm
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D 1 =2 D 2 =2 L=5
Computational Results with Genetic Algorithm
D 1 =1.5 D 2 =0.1 L=5
Computational Results with Genetic Algorithm
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D 1 =1.5 D 2 =0.75 L=5
Computational Results with Genetic Algorithm
D 1 =1.5 D 2 =1.5 D 1 L=5
Computational Results with Genetic Algorithm
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D 1 =1 D 2 =0.1 L=5
Computational Results with Genetic Algorithm
D 1 =1 D 2 =0.5 L=5
Computational Results with Genetic Algorithm
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Prospect Vernadskogo 101, 117526 Moscow, Russia
D 1 =1 D 2 =1 L=5
Computational Results with Genetic Algorithm
D 1 =0.5 D 2 =0.1 L=5
Computational Results with Genetic Algorithm
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Prospect Vernadskogo 101, 117526 Moscow, Russia
D 1 =0.5 D 2 =0.25 L=5
Computational Results with Genetic Algorithm
D 1 =0.5 D 2 =0.5 L=5
Computational Results with Genetic Algorithm
(c)2006 http://www.ipmnet.ru/
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Prospect Vernadskogo 101, 117526 Moscow, Russia