Frequency Response Optimization Optistruct
Hi, I have been trying to optimize the frequency of a basic plate with a hole, the plate is fixed on two ends for all 6 DOF's and a normal modal analysis is being run. The Dimensions for the plate are 550 mm x 550 mm with a thickness of 10 mm. E = 70000, p = 0.33, density = 2.75e-6, wtmass conversion of .001.
The first mode is coming at 204 Hz.
Now after I add my design variable with the default base thickness in the optimization>topology menu. I proceed to add Volume fraction, and Frequency as my responses.
As my aim is to constrain the frequency I add a lower bound of 300 with the objective of minimizing frequency.
now after i run the optimization on obstructionist and attach the s1.h3d file to see what the optimized results frequency are they are lower then the original not optimized plate at 195 Hz.
I do not understand what I am doing wrong here. Any help would be greatly appreciated.
Thank You.
Answers
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do you have the .out file for your run?
usually a good starting point is to go through the .,out file and try to understand what is going on, if the optimization was feasible, or not.
If the baseline, with full material was not fullfilling your constraint, it raises a yellow flag here.
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just run your model, and Ive got a 477HZ frequency at the last iteration, while respecting all the constraints.:
------------------------------------------------------------------------------------
2 FREQ freq 1 1 -- 4.773E+02 MAX
1 VOLFR vf -- -- TOTL 5.838E-01 > 5.000E-01 0.0
1 VOLFR vf -- -- TOTL 5.838E-01 < 6.000E-01 0.0
------------------------------------------------------------------------------------
************************************************************************OPTIMIZATION HAS CONVERGED.
FEASIBLE DESIGN (ALL CONSTRAINTS SATISFIED).
Looking at the _S1.H3D file, make sure you're looking at the Last iteration, and NOT iteration 0 in the browser.
<?xml version="1.0" encoding="UTF-8"?>
0
Altair Employee