Altair RISE

A program to recognize and reward our most engaged community members

Nominate Yourself Now!

Doubts regarding topology optimization

Altair Forum User

Hello,

I have been working on Topology optimization on a solid cylindrical structure of thickness 20mm.(trial)

Objective: To minimise mass

Contraint: deflection < 20mm

responses: mass and deflection.

Is it possible to carry out topology optimization ? An error shown on the output file.Screen shot of output file is attached here. Please help me.

Unable to find an attachment - read this blog

Find more posts tagged with

English

OptiStruct

Accepted answers

All comments

GirishM

Hi Meera,

As the error mentioned, please check for any RBM. Make sure you constrained all degrees of freedom.

Altair Forum User

Ok. Also after optimization my structure has no continuity.How to force a constant cross section along a given direction in optistruct

Altair Forum User

Hi @meera

An image would help to understand your question.

Anyways, you can play with ISO value for better design. If this did not help, you can add manufacturing constraints like minimum and maximum membersize, grouping patterns, etc...

Altair Forum User

Hai,

In my output file, error -topology optimization cannot be performed due to possible rigid body mode. Please help me to solve the problem. Here i attached the screenshot of my model.

Unable to find an attachment - read this blog

Altair Forum User

Meera,

Kindly provide the .fem file or .hm file which has all optimization and analysis setup instead of raw geometry file.

Altair Forum User

Here attached .fem file. Please help me.

Unable to find an attachment - read this blog

Altair Forum User

Hai, in my outputfile error: In static load case 1 ,the compliance is negative or large 3.33976e+008.
Optimization/buckling analysis cannot be performed due to possible rigid body mode.
FEASIBLE DESIGN (ALL CONSTRAINTS SATISFIED). What is the reason? Please help me

Altair Forum User

helloo...

Altair Forum User

Hi Meera,

Sorry for a late reply, the model is taking long time to run on my local machine.

I think some how the bottom material from the designable component is removed and this is what make it too compliance to the applied load.

Maybe you can try with adding minimum and maximum member size constraints to your model and try again.

Altair Forum User

K . Thank you. I will try.

Altair Forum User

Hai, in my outputfile, error: In static load case 1 ,the compliance is negative or large 3.33976e+008.
Optimization/buckling analysis cannot be performed due to possible rigid body mode.
FEASIBLE DESIGN (ALL CONSTRAINTS SATISFIED). What is the reason? Please help me .

Altair Forum User

Hi meera,

I tried to have a look but it's too much for my laptop.

In such a simple model you should reduce drasticly the element count, it would be easier to troubleshoot and then if needed increase the number of elements.

In a topology optimization you only going to get an ideia where to put material so the element count should be much much lower, and the goal is to use as few elements as possible to achieve faster runs. Even 2D shell would give a good estimation. Then for the final static analysis increase the element count but still not that much.

Best regards,

Gonçalo

Altair Forum User

Thank you for your reply.