No material is around pretension bolt
At bolt hole I set a bolt to contact freeze with the bolt hole.
then set the pretension on the bolt, like the photo.
and this just a part of loading condition of all model.
I want to ask why my topology result pretension at here didn't need any material.
I have seen the result of pretension, bolts are subjected pretension and aslo have contact force.
This is my result then reduce 10% material
Answers

HI,
What are the optimization conditions used for this simulation?
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At this time my object in min volume and I have set the stress constraint in design variable.
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Hi @LKZ
Using stress constraint may not be a good idea for topology optimization.
Consider something else. To start off with, try compliance and volume fraction...?
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@Prakash Pagadala Thanks to your suggestion
I will try both.
At here, I have read about volume fraction, but I still confused.
How do you explain about the volume fraction by yourself?
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Hi,
for volume fraction, When the lower bound is set to 30% the solver takes minimum 30% of the original volume to optimize. If no upper bound is provided, the solver may remove all material depending on design objective and constraints
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@Prakash Pagadala Thanks to your apply.
So it means the volume, not about the situation if my part's weight is 10kg.
if I set volume fraction is 30% off is will be 103(30% original model)=7 kg .
the two situation is different. Do I describe right?
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Hi,
So when we say 30% this means we let the solver use a minimum of 30% material out of 100% to start with.
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