Constraint formulated by combination of responses from multiple models in MMO

Minsik Seo
Minsik Seo Altair Community Member
edited June 2023 in Community Q&A

Hi, I'm working on a multi-model optimization (MMO) in OptiStruct.

I'd like to solve an optimization problem with contraints defined by entire responses from multiple models.

For example, I have two input files model1.fem and model2.fem as below:

$ model1.fem DESOBJ(MIN)=1 SUBCASE        1   LABEL LINEAR STATIC ANALYSIS STATICS   SPC =        1   LOAD =        2   DESSUB =       2 BEGIN BULK DESVAR,1,Thickness,1.0,1.0,5.0,, DVPREL1,1,PSHELL,1,4,,,0.0, +,1,1.0, DRESP1,1,Mass,MASS,PSHELL,,,SUM,1, DRESP1,2,dMax1,DISP,,,TY,,21, ...
$ model2.fem DESOBJ(MIN)=1 SUBCASE        1   LABEL LINEAR STATIC ANALYSIS STATICS   SPC =        1   LOAD =        2   DESSUB =       2 BEGIN BULK DESVAR,1,Thickness,1.0,1.0,5.0,, DVPREL1,1,PSHELL,1,4,,,0.0, +,1,1.0, DRESP1,1,Mass,MASS,PSHELL,,,SUM,1, DRESP1,2,dMax2,DISP,,,TY,,21, ...

And MMO master input file master.fem

$ master.fem SCREEN OUT RESPRINT ASSIGN,MMO,Model1,model1.fem ASSIGN,MMO,Model2,model2.fem BEGIN BULK ENDDATA

In this case, for example, I can define a constraint by summing up the response 2 in model1.fem (dMax1) and response 2 in model2.fem (dMax2), that is

dMax1 + dMax2 >= target

In this constraint, the responses are not independent. How do I use this type of constraint? Or is it even possible?

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Answers

  • Robert Hoglund
    Robert Hoglund
    Altair Employee
    edited June 2023

    Hi Minsik,

    Please have a look at the DRESPM continuation line on the DRESP2 card for a combined optimization response for MMO models.

    https://help.altair.com/hwsolvers/os/topics/solvers/os/dresp2_bulk_r.htm

    This allows you to reference MMO responses for MMO models by the model tags in the ASSIGN statement in the master .fem file and the response ID in each file.  You can also use DRESP2 to sum the responses together with the SUM option.

    Thanks,

    Rob H.

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