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Compliance increase in the optimization

Hello,

I have been performing an optimization of carbon fiber monocoque. I set up the compliance as an objective to minimize to maximize the stiffness.

However, I have realized that compliance increase as the optimization progresses. I have checked the tutorials of optimization and the same happened. Should this value not be decreased?

Thank you

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Adriano_Koga

what is your optimization setup??

Just check if your design constraints are not violated from the beginning.

Objective being Minimize means achieving the least possible WHILE RESPECTING CONSTRAINTS.

Not necessarily minimize will reduce your objective, if your constraint are not respected in the initial iteration.

Dani_20

Yes, constraint violation is 0 in freesize and also in size optimization. Moreover at the end of the simulation appear the message: Feasible design (all constraints satisfied) what let me think the process is correct.

Is this output value what you refer with design constraint violating?

Adriano_Koga

do you have the .out file of the model that you see this happening??

Dani_20

Yes, I have it, I have checked it there

I attached both files, freesize and size .out

Unable to find an attachment - read this blog

Adriano_Koga

from freesize .out, there's a decrease, AS THE CONSTRAINTS ARE OK.

Iter 0

Objective Function (Minimize WCOMP) = 2.31275E+05

Iter 12

Objective Function (Minimize WCOMP) = 8.63265E+04 % change = -0.44

For Size, there's an increase AS THE CONSTRAINT HAS 9.4% VIOLATION:

Iter 0

Objective Function (Minimize WCOMP) = 1.03702E+05
Maximum Constraint Violation % = 0.93882E+01

Iter 6

Objective Function (Minimize WCOMP) = 3.51606E+05 % change = 0.00
Maximum Constraint Violation % = 0.00000E+00

Adriano_Koga

RETAINED RESPONSES TABLE
------------------------------------------------------------------------------------
Response Type Response Subcase Grid/ DOF/ Response Objective Viol.
User-ID Label /RANDPS Element/ Comp Value Reference/ %
/Model MID/PID/ /Reg Constraint
+Frqncy Mode No. Bound
/Times
------------------------------------------------------------------------------------
2 WCOMP Wcomp -- -- -- 1.037E+05 MIN
1 MASS Mass -- -- TOTL 2.665E+01 < 2.436E+01 9.4 V
------------------------------------------------------------------------------------

Dani_20

Thank you for the clarification, now I understand the concept