Constraint formulated by combination of responses from multiple models in MMO

Minsik Seo

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?

master.fem

model1.fem

model2.fem

RobHoglund

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.