sol200; fit accPSD response to test results

I have a 2 mass and 2 spring system which has test response specified in DABLED1. I would like to find spring stiffneses to match the test result. How to define the objective function in such case?

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opt_fresp_02.dat

0 Martin MSC Nastran over 6 years ago

See attached PDF. Slide S30 shows a setup. For your model you could use the table constraints on your response shown in S37.

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psd_sol200.pdf
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0 adam.narozniak over 6 years ago

It does not work. If I make it like this:

DCONSTR 800   801     17            20.    2000.

DRESP1  801   PSDpar  PSDACCL 1000             3     MAX   2

TABLED1 17     log    log

+      20.    0.16   21.33  0.17   23.28  0.19   27.18  0.23   +

+      72.37  2.41   84.49  7.71   92.24  34.09  98.36  237.82 +

+      102.26 66.3   107.83 14.6   118.4  3.4    213.95 0.32   +

+      234.92 0.65   247.71 1.91   257.52 5.02   279.72 0.24   +

+      313.17 0.02   382.18 0.01   1347.62 0.01   1644.6 0.01   +

+      1841.28 0.01   2000.  0.01   ENDT

I got an error:

    "DCONSTR ASSOCIATED WITH DRESP1     801, AN IMPLIED DRESP2, CAN NOT REFERENCE TABLEDx ID IN LALLOW AND/OR UALLOW FIELDS.

    USER ACTION: SPECIFIC ALLOWABLES IN REAL NUMBER MUST BE PROVIDED ON DCONSTR FOR AN IMPLIED DRESP2."

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opt_rms_01.dat
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0 Hrishikesh Phadke over 6 years ago

Attached modified file.

DRESP1 801 PSDpar PSDACCL 1000 3 10. 2

This will work.

-------------------

DRESP1 801 PSDpar PSDACCL 1000 3 MAX 2

MAX is not allowed. It can take input at specific freq only.

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opt_rms_01.dat
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