Compliance increase in the optimization

User: "Dani_20"
Altair Community Member
Updated by Dani_20

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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    User: "Adriano_Koga"
    Altair Employee
    Updated by 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.

    User: "Dani_20"
    Altair Community Member
    OP
    Updated by 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?

    User: "Adriano_Koga"
    Altair Employee
    Updated by Adriano_Koga

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

     

    User: "Dani_20"
    Altair Community Member
    OP
    Updated by 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

    User: "Adriano_Koga"
    Altair Employee
    Updated by 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

     

    User: "Adriano_Koga"
    Altair Employee
    Updated by 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
    ------------------------------------------------------------------------------------

    User: "Dani_20"
    Altair Community Member
    OP
    Updated by Dani_20

    Thank you for the clarification, now I understand the concept