Topology optimization after Response Spectrum Analysis

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

I did a response spectrum analysis of a structure following the methodology of this tutorial. As a next step, I want to optimize my structure using volfrac as an objective, and or maximum displacement at a node (or overall) as a constraint. 

One of my responses is volfrac, the other one is frf displacement, but that gets me following error:

 

'DRESP1 2 is not referenced from within a dynamic SUBCASE.

This type of response must be specified from within a dynamic SUBCASE.

This error occurs in DESSUB 2.'

 

I tried optimizing for compliance and displacement as well, but nothing runs. Thanks a lot in advance and an optimized 2015 for whoever helps me further on this!

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2015

    Hi TIm,

     

    Have you requested for FRF displacements in your model?

     

    Please request displacements (refer OS-2095: Frequency Response Optimization of a Rectangular Plate) and use FRF displacement as a response and check if you are able to run the model without errors.

     

    if you still face the error, please share the model with us using the dropbox link in the below signature.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2015

    Thanks for the reply Prakash, it still doesn't work using FRF displacement so I've sent the file.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2015

    Hi  Tim_

     

    Thanks for sharing the file. I will look into this and will get back to you ASAP!! image/emoticons/default_smile.png' alt=':)' srcset='/emoticons/smile@2x.png 2x' width='20' height='20'>

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2015

    HI,

     

    Instead of FRF displacement can you use RMS displacement as a response or change the analysis type to FRF if you want to use FRF displacement?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2015
    Altair Forum User said:

    HI,

     

    Instead of FRF displacement can you use RMS displacement as a response or change the analysis type to FRF if you want to use FRF displacement?

     

    Thanks for the help. Yes I can chance the analysis type to FRF and run an analysis but that doesn't permit me to get out the peak response as a response spectrum analysis does.

     

    In terms of the RMS displacement, I would need a randps load collector but it's unclear to me what that does. The Bulk data section is not very helpful to find that out, could you explain a bit more how this would work?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2015

    Hi TIm,

     

    RANDPS should point to TABRND1 which contains the PSD (load Vs frequency). Please refer to the tutorial OS-1325: Random Response Analysis of a Flat Plate

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