writing DRESP3-Card (here: Tresca-Stress)

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hello,

 

as suggested in another thread in this Forum, i tried the usage of dresp3-Card.

 

What i want to do:

- let excel calculate the tresca-stress (Input: max principle, min principle, output: stress (=difference between both input variables).

- get the tresca stress back and use it for an 'minmax-' or 'min-objective' in optimisation

 

What i wrote until today:

 


LOADLIB DRESP3  GR01    tresca.xlsx


$solid

DRESP1  1       MAX_PR1 STRESS  PSOLID          SMAP
DRESP1  1       MAX_PR3 STRESS  PSOLID          SMIP

 

DRESP3  20      TRESCA  GR01    MYFUNC  1       2
+       DRESP1  1       2
+       CELLIN  C2      C3 
+       CELOUT  D1

 

I also use a small excel-file, which calculates the difference beween 'cell C2' and 'cell C3' in 'cell D1'.

 

Questions:

- would it work like that ? (I can't test it at the moment)

- What do I get with the DRESP1 / DRESP3 ? When using DRESP1 with 'ELEM' and enter an element-ID, it would give ONE value to the excel-file, which seems to be pretty clear. But when I use PSOLID as the PTYPE, there might be hundrets or thousands of values (here: principal stresses). At that point I do not understand my own programmed code..

 

Maybe someone can help?

I read the Tutorial OS-4095 and also a lot of manual pages.

 

Thanks a lot 

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2016

    I got a running Model now, but I didn't use dresp3 but dresp2 with dequation. With dreport I get the right values now in my outputfile.

    But i can't use these values for constraints / objectives. Optistruct unfortunately understands, that an equation with two stresses as input always results in a stress, so my resp2 is a stress-response (even though it is a 'formula'-response..). Due to this fact i get error 1800, which tells me to use the stress-constraints in the desvar-panel instead...

     

    Any thoughts?

     

    What i want to do is to reduce the maximum stress (=objective). That means I only need the greatest stress as ONE response and not as many responses as myy number of elements... Any help on this point?

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited November 2020

    Hi,

    Just want to share information on stress response using DRESP1 is possible from 14.0 version and it is not only limited to vonmises stress.I hope max shear & tresca stress both are same. Attached is the same model using DRESP1.

     

    Regards

    Rahul R

    <?xml version="1.0" encoding="UTF-8"?>Stress Response.JPG

    Unable to find an attachment - read this blog

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