🎉Community Raffle - Win $25

An exclusive raffle opportunity for active members like you! Complete your profile, answer questions and get your first accepted badge to enter the raffle.

Join and Win

Topology optimization after Response Spectrum Analysis

Altair Forum User

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!

Find more posts tagged with

English

OptiStruct

Accepted answers

All comments

Altair Forum User

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

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

Altair Forum User

Hi Tim_

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

Altair Forum User

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

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

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