Robust Parameter Design
Solution with LS-OPTui
Solution with LS-OPTui
Task
Task
Open the file com.2bar.rbdo.start.
RBDO Task
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Solvers
Solvers
Define the solver (Linux version) 
- Select the Solvers panel.
- For Command type in echo N o r m a l. This signals LS-OPT a normal termination of the solver.
- For Name of Analysis Case enter SOLVER_1.
- Push the Add button.
Define the solver (Windows version) 
- A direct call of the command echo N o r m a l doesn't work for the Windows version. We have to save the command line type N o r m a l in a .bat file and take it as the solver. NOTE: It's necessary to give the complete path of the solver command.
Distribution
Distribution
Normal Distribution
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Variable
Variable
Noise Variable
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Sampling
Sampling
Sampling Panel
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Responses
Responses
Response Panel
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Objective
Objective
Objective Panel
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Constraints
Constraints
Constraints Panel
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Run
Run
Run Panel
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Com-file
Com-file
The created command file may look like this:
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Command file "com.2bar.robust.correct"
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$ Generated using LS-OPT Version 4.1
$
"Two-bar Truss"
$
$ Created on Fri Feb 25 12:41:39 2011
solvers 1
responses 2
$
$ NO HISTORIES ARE DEFINED
$
$
$ PROBABILISTIC DISTRIBUTIONS
$
distribution 1
distribution 'area' NORMAL 2 0.1
$
$ DESIGN VARIABLES
$
variables 2
Noise variable 'Area' distribution 'area'
Variable 'Base' .8
Lower bound variable 'Base' .1
Upper bound variable 'Base' 1.6
Range 'Base' 1.6
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$ SOLVER "SOLVER_1"
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$
$ DEFINITION OF SOLVER "SOLVER_1"
$
solver own 'SOLVER_1'
solver command "echo N o r m a l"
$ ------ Pre-processor --------
$ NO PREPROCESSOR SPECIFIED
$ ------ Post-processor --------
$ NO POSTPROCESSOR SPECIFIED
$ ------ Metamodeling ---------
solver order interaction
solver experiment design 3toK
$ ------ Job information ------
solver concurrent jobs 1
$
$ WARNING - NO RESPONSES DEFINED FOR SOLVER "SOLVER_1"
$
$
$ RESPONSE EXPRESSIONS FOR SOLVER "SOLVER_1"
$
response 'Weight' expression { Area * sqrt(1+Base*Base) }
response 'Stress' expression { 0.124 * sqrt(1+Base*Base) * (8/Area + 1./Area/Base) }
composites 1
$
$ STD DEV COMPOSITES
$
composite 'StandardDeviation3' noise 'Stress'
$
$ OBJECTIVE FUNCTIONS
$
objectives 1
objective 'StandardDeviation3' 1
$
$ THERE ARE NO CONSTRAINTS!!!
$
constraints 0
$
$ PARAMETERS FOR METAMODEL OPTIMIZATION
$
Metamodel Optimization Strategy DOMAINREDUCTION
$
iterate param design 0.01
iterate param objective 0.01
iterate param stoppingtype and
$
$ OPTIMIZATION ALGORITHM
$
Optimization Algorithm hybrid simulated annealing
$
$ JOB INFO
$
iterate 10
STOP
Results
Results
Optimization Histories
Optimization Histories
Variable History
→ The Area noise variable remains unchanged during the optimization process.
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Variable History
→ The deployment of the variable value (red) and the bounds of the region of interest (blue) during the optimization process.
→ The optimum value of the variable Base is computed as 0.50489.
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Composite History
→ The standard deviation has converged during the optimization process. | ![]() |
Metamodel
Metamodel
Metamodel
Set up the panels
→ Using the metamodel facility you can investigate that a higher value of the variable Base goes together with a lower value of the stress standard deviation. |
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Download
Download
The complete data set (input and command files) is available for download:
For Linux
For Windows
















