Volume Fraction OSSmooth Iso_surface

Altair Forum User

Hi,

 

I am establishing a topology optimization, the aim is to attend 50% of the original masse of my mechanical part.

I used this formula to calculate volume fraction:

Volume fraction = (total volume at current iteration – initial non-design volume)/initial design volume= 0.082

I put 0.082 as upper bound for volume fraction constraint and for Isosuface threshold parameter in Ossmooth when I export this file.

The problem that I am not getting a 50% masse of the original solid at the end.

Should I put 0.082 or 0.5 threshold parameter in Ossmooth?

I am I doing something wrong?

 

Thank you.

Altair Forum User

Any response please

Altair Forum User

Hi,

 

Sorry for a late reply.

 

First, let us understand how upper and lower bounds for volume fraction works:

Lower bound set to 0,4: the solver takes minimum 40% of the original volume to optimize. If you do not constraint an upper bound as well it might go to 100% if it is structurally necessary

 

Upper Bound set to 0,4: The solver is allowed to take maximum 40% or less material for the optimized design.

 

Now, if you are giving 0.082 as upper bound that means you are allowing to only take up to that percentage. 

Altair Forum User

Thank you for the reply.

Supposing like you said the upper bound is 40%, I am talking now about the value of threshold in OSSmooth, should it be 0.4 or other value??

Because for my case, my upper bound is 0.82, so I putted also 0.82 in threshold for OSSmooth and it didn’t give the good reduction percentage, I tried 0.5 and it gave me very close results to a total mass reduction.Thank.

Altair Forum User

HI,

 

if your threshold is 0.82 on OSSmooth, meaning you are asking for a model with 82% less material, is that correct?

 

For example, If you key in 0 you will see a complete model without any material removed. If you provide say 0.3, this means the material whose density is less than 30% is removed. 

Altair Forum User

Thank you.