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History MSE

In this example time history curves are used to calibrate directly experiment vs. simulation curves.

Solution with LS-OPTui

Solution with LS-OPTui

Strategy

Strategy

Open LS-OPTui

  1. Select the Strategy panel.strategy1.png
  2. Switch the radio button of the section “Strategy for Metamodel-based Optimization” to "Sequential with Domain Reduction (SRSM)".
  3. Select a tolerance of 1% to be satisfied by both the design and objective changes.

 

 

 

 

 

 

 

 

 

Solvers

Solvers

Solvers Panel

 

  1. Select the Solvers panel.
  2. For Command specify the LS-DYNA executable ls971_R4_2 (This name can be different on your computer).
  3. For Input File browse the file foam1.k.
  4. Enter a name for Name of Analysis Case, e.g. Case1.
  5. Push the Add button.
solver1.png

 

Variables

Variables

Define the Variables

 

  1. Select the Variables panel. The variables are already defined in the input file foam1.k using *PARAMETER (see below) and therefore cannot be deleted.
  2. Switch the YMod Type from Constant to Variable.
  3. Enter 500000 for the Minimum.
  4. Enter 2000000 for the Maximum.

 

 var_ymod1.png
  1. Switch the Yield Type from Constant to Variable.
  2. Enter 500 for the Minimum.
  3. Enter 2000 for the Maximum.

 

 var_yield1.png
  keywordfile1.png

Histories

Histories

Define Response Histories

 

Define z-displacement of node 296

  1. Select the Histories panel.
  2. From the possible histories select NODOUT.
  3. Type in the node ID: 296.
  4. For Component select Displacement.
  5. For Direction select Z Component.
  6. Type in Disp1 for the History Name.
  7. Push the Add button.

 

 

history_disp1.png

Define z-slave-force on interface 1

  1. From the possible histories select RCFORC.
  2. Type in for Interface ID: 1.
  3. For Component select Z slave force.
  4. Type in Force1 for the History Name.
  5. Push the Add button.
history_force1.png

Define crossplot for -Disp1 and Force1

  1. From the possible histories select Crossplot.
  2. For z(t) type in -Disp1 (negative Disp1).
  3. For F(t) type in Force1.
  4. Type in F_vs_d as History Name.
  5. Push the Add button to create a new history.
history_f-vs-d1.png
Define a history through a text file
  1. From the possible histories select File.
  2. Push the Browse button to find the file Test1.txt from your main directory.
  3. Type in FILE1 as History Name.
  4. Push the Add button to create a new history.
 		history_test-file1.png

Responses

Responses

Define the Responses

 

  1. Select the Responses panel.
  2. From the possible response types select: MeanSqErr.
  3. For Target curve select FILE1.
  4. For Computed curve select F_vs_d.
  5. Type in the label MSE for Response Name.
  6. Push the Add button.
response_mse1.png

Objective

Objective

Objective

 

  1. Select the Objective panel.
  2. Select MSE from Response as the objective function.
  3. Leave the default 1.0 for Weight. If you have several objective functions, you may assign weight to each one according to their importance.
objective_mse1.png

Run

Run

Run the Optimization

 

  1. Select the Run panel.
  2. For Number of iterations enter 3.
  3. Push the Run button to start the optimization. (Save the project as com.mse_history)
run1.png

Com-file

Com-file

The created command file may look like this:

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Command file "com.mse_history"
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$ Generated using LS-OPT Version 4.1
$
"Optimization Problem"
$
$ Created on Fri Jan 21 14:10:59 2011
solvers 1
$
$ WARNING -- NO RESPONSES ARE DEFINED
$
histories 4
$
$ DESIGN VARIABLES
$
variables 2
 Variable 'YMod' 7.e5
  Lower bound variable 'YMod' 5.e5
  Upper bound variable 'YMod' 2.e6
 Variable 'Yield' 1500.
  Lower bound variable 'Yield' 500.
  Upper bound variable 'Yield' 2.e3

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$      OPTIMIZATION METHOD   
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$
Optimization Method SRSM

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$      SOLVER "Case1"
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$
$ DEFINITION OF SOLVER "Case1"
$
 solver dyna960 'Case1'
  solver command "ls971_R4_2"
  solver input file "foam1.k"
  solver check output on 
  solver compress d3plot off 
$ ------ Pre-processor --------
$   NO PREPROCESSOR SPECIFIED
$ ------ Post-processor --------
$   NO POSTPROCESSOR SPECIFIED
$ ------ Metamodeling ---------
  solver order linear
  solver experiment design dopt
  solver approximate history linear
$ ------ Job information ------
$
$ WARNING - NO RESPONSES DEFINED FOR SOLVER "Case1"
$
$
$ HISTORIES FOR SOLVER "Case1"
$
 history 'Disp1' "BinoutHistory -res_type nodout  -cmp z_displacement -id 296"
 history 'Force1' "BinoutHistory -res_type RCForc -cmp z_force  -id 1  -side SLAVE"
$
$ HISTORY EXPRESSIONS FOR SOLVER "Case1"
$
 history 'F_vs_d' expression {Crossplot("-Disp1","Force1")}

$
$ HISTORIES FROM FILES
$
 history 'FILE1' file "Test1.txt"
composites 1
$
$ COMPOSITE EXPRESSIONS
$
 composite 'MSE' {MeanSqErr(FILE1,F_vs_d)}
$
$ OBJECTIVE FUNCTIONS
$
 objectives 1
 objective 'MSE' 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
  Use GSA
$
$ JOB INFO
$
 iterate 3
STOP

Results

Results

Histories

Histories

Start the LS-OPT Viewer by selecting the View tab and

 

  1. Select under Simulations the item Histories.

new_plot1.png

Set up the panel

 

  1. Select the last iteration.
  2. Set time as x-coordinate.
  3. Choose history response F_vs_d as y-coordinate.
  4. Add FILE1 to y-coordinate, so that we can compare its plot with F_vs_d 's.
  5. For the third coordinate, whose quantity is displayed by means of colors, we choose variable YMod. (Or other interesting entities)

 

 history_panel1.png

→ The green curve shows the predicted crossplot of Force1 and -Disp1. The crosses mark out the "experiamental" result stored in FILE1 in order to compare themself with the predicted result. We can see, they are well-matched.

history_plot1.png

 

Confidence Intervals

Confidence Intervals

The Confidence Intervals can be found in the lsopt_report file.

  1. From the main menu bar select View → Summary Report.

 

The Confidence Intervals are located at the end of the file.

view_summary1.png

Alternatively, we can directly open the lsopt_report file from the main directory with an editor and scroll to the end to find the Confidence Intervals of YMod and Yield.

 

→ YMod is rather insignificant and Yield is significant.

conf_interval1.png

Download

Download

The complete data set (input and command files) is available for download:

For Linux

For Windows