No material is around pretension bolt

Altair Forum User

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

 

 

 

Altair Forum User

HI,

 

What are the optimization conditions used for this simulation?

Altair Forum User

@Prakash Pagadala  

 

At this time my object in min volume and I have set the stress constraint in design variable.

Altair Forum User

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...?

Altair Forum User

@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?

Altair Forum User

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

Altair Forum User

@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 10-3(30% original model)=7 kg .

 

the two situation is different. Do I describe right?

Altair Forum User

Hi,

 

So when we say 30% this means we let the solver use a minimum of 30% material out of 100% to start with.