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Hello,

 

I am running a topology optimisation using Optistruct. I am trying to look at the key structural members of an aerospace component.

I am attempting to use a low volume fraction of ~3-6%.

When the volume fraction is particularly low does this effect the solver's ability to converge?

 

Thank you in advance

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Hi,

 

I think with lower volume fraction constraint solver has the freedom to use more volume for optimization. 

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Meaning you are allowing more material to use for optimization, this may end up with a slightly heavier structure 

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Hi @Prakash Pagadala,

 

I think I understand.

So rather than inspecting the topology of results with variable volume fractions with the same density cut off, is it more appropriate to inspect the results for a specific volume fraction optimisation with the same corresponding density value.

 

I.e. If the volume fraction is 0.3, the density cut off for iso should also be 0.3?

 

Thanks

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1 hour ago, exx077 said:

I.e. If the volume fraction is 0.3, the density cut off for iso should also be 0.3?

 

So it is arriving at the best design. But relating ISO with Volume Fraction may not help always. 

 

Looking at the results and judging the design or it should be based on experience. 

 

I have gone through the model and I see you have used a VF with upper bound of 0.5 and no lower bound. Is there a reason?

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@Prakash Pagadala,

 

8 minutes ago, Prakash Pagadala said:

I see you have used a VF with upper bound of 0.5 and no lower bound. Is there a reason?

There is no particular reason for doing this.

My understanding was that you set the upper limit of the volume fraction and the optimiser will be constrained to this value.

I thought that if i set a upper and lower limit, then the simulation would just work to the upper limit of the volume fraction as this would enable it to minimise the compliance better.

 

Thanks

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