adding volumes of fiber assembly 1

[rvallabh]

I started working on ansys a few months back and I am stuck now with a problem. I would greatly appreciate your suggestions and help.

Here's the problem I'm facing.
I want to find the length of connected air channels (free spaces) in a fiber assembly, so I made a layered assembly of cylinders, where in each layer has a group of cylinders (lying in X-Z plane) which are oriented in random directions. Some of these cylinders intersect with other, while some do not. The layers are stacked in the Y-direction. I tried to convert the empty spaces to solid by subtract the volumes (cylinders) from a solid volume, but the operation failed and I got the BTOL error. I tried to change the BTOL setting, but the operation still failed. I even tried adding the volumes before subtracting. Please suggest, how to overcome this?

Is there a different approach, you can suggest to find the length of the connected air channels.

thanks
Rahul

 

[cbrn]

Hi,
the only thing I can suggest is to execute several booleans in sequence, each time subtracting a single cylinder, instead of trying and subtract all the cylinders in the same time.
After that, you may know that ANSYS-Classical's booleans are almost the worst ones which exist nowadays among the solid modelers... If you have the license for DesignModeler, don't hesitate and go with it!!!

Regards

 

[rvallabh]

Thanks cbrn.

I tried subtracting single cylinder at a time, but I was not able to subtract all of them. Gave the same BTOL error for while subtracting some of the cylinders.

Is there another approach I can employ. I was wondering if I could export the model into some image analysis software which is capable of 3D connected component analysis.

Can someone suggest?

thanks.
Rahul

 

[meshparts]

Try to find out, why those cylinders cannot be substracted. They must have something special. Then try to correct this problem.

Regards,
Alex

 

[Mech151]

I would recommend a 3d cad package (solidworks, invnetor, ProE, or whatever). These have very robust cavity features. You could then import the cad geometry into ansys.

 

[rvallabh]

Thanks for your suggestions.
I changed the geometry of the volume to be subtacted from and it works. But, since I have a large number of cylinders and layers, I need to write a code for the operations.

I will also look into other packges. Thanks Mech151

 

[rvallabh]

Hello again.

When I run the code for subtracting volumes, new volume(s) are created. I want to store these newly created volumes in an array after each subtraction operation. I want to use these newly created volumes for subsequent substraction operations.

Can you suggest please.

Thanks

 

[meshparts]

After boolean operations volume numbering can change. So you will never be shure, that the volume numbers that you once saved are still the same.

In some case it works, but that depends on the type of geometry and and othe factors. If you stil want do do it, the you can use an APDL code to save the actual volume numbers in an array parameter

*get,vcount,volu,,count
*if,vcount,ge,1,then
   *dim,vnum,array,,vcount
   vnum(1)=vlnext(0)
   *if,vcount,ge,2,then
      *do,i,2,vcount
         vnum(i)=vlnext(vnum(i-1))
      *enddo
   *endif
*endif

Regards,
Alex

 

[cbrn]

Hi,
just like Mihaiupb says, this storing operation can be very dangerous in Ansys, unless you think just like Ansys does and find the "future" numbers depending on the "current" ones. This may involve some *GET queries and possibly some criteria based upon the position in space...

Regards

 

[rvallabh]

Thank you all for your suggestions. Thay have been very helpful. I working on the codes to execute the operations.

Thanks once again.