External Response by HyperMath to Access Individual Compliance in Weighted Compliance Topology Optimization

Altair Forum User

I am doing topology optimization using Optistruct. I set up the problem in the form of minimizing the Weighted Compliance with volume constraint, since I have several loadsteps. Right now, I am trying to do some manipulations on each of the individual Compliance to set up the new objective function using external response by HyperMath. I use the DRESP3 card to achieve that. The problem is that I can only get access to the summation of all the Weighted Compliance instead of each of them individually. Is there any way to get access to the individual Compliance? 

 

 

For example, I want to get the individual Compliance of Subcase 1 and 2 and do some manipulations as the objective function, such as C1^2+C2^2, not the summation of them. 

 

 

ITERATION   4

 

Objective Function (Minimize EXTER) =  3.32436E+06   % change =        15.66

Maximum Constraint Violation %      =  0.54462E-03

Design Volume Fraction              =  3.00002E-01   Mass     =  0.00000E+00

 

 

 Subcase  Weight     Compliance                            Weight*Comp.

       1  1.000E+00  1.478572E+06                          1.478572E+06

       2  1.000E+00  1.835716E+05                          1.835716E+05

       3  1.000E+00  1.478658E+06                          1.478658E+06

       4  1.000E+00  1.835621E+05                          1.835621E+05

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

Sum of Weight*Compliance                                   3.324364E+06

 

 

                           RETAINED RESPONSES TABLE

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

Response Type  Response     Subcase Grid/     DOF/   Response     Objective    Viol.

User-ID          Label      /RANDPS Element/  Comp     Value      Reference/     %  

                            +Frqncy MID/PID/  /Reg                Constraint

                                    Mode No.                        Bound   

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

      11 EXTER SUMH              --       --     1   3.324E+06 MIN

       1 VOLFR VF                --       --  TOTL   3.000E-01  <  3.000E-01    0.0 A

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

 

 

Altair Forum User

Hello,

 

For the exact function you specified in your post, you don't need to go to an external function (DRESP3), you could use the internal function (DRESP2).  In either case, the card structure is virtually identical.

 

You need to setup a response of type compliance, not weighted compliance.  Then pass this response along with the subcase number through the DRESP2/3 card.

 

For example:

DRESP1  2       comp    COMP              

DEQATN  1       z(x,y)=x**2+y**2  

DRESP2  3       myValue        1        
+       DRESP1L        2       1       2       2