COMSOL Forums: boundary integration in podtprocessing

Re: boundary integration in podtprocessing

Wed, 11 Aug 2010 04:26:51 +0000

Hi Ivar:

I am having a similar issue, I was wondering if you can help me. I am modeling the insertion of a probe into the a cube. The probe I am having in post processing is that using point evaluation on vertices or boundary integration on the probe boundaries, the reaction force is always zero (in the z-direction of insertion).

I am looking for the resistance force that the probe is experiencing during the insertion - this is the reaction force right?
Also, for those points on the surface of the cube that are not part of the geometry, I cannot do point evaluation of any parameters on those points, any idea why?

I am attaching a simple version of this simulation.

Thank you,

Joe

Re: boundary integration in podtprocessing

Tue, 10 Aug 2010 19:14:51 +0000

Hi Alex:

I am having a similar issue, I was wondering if you can help me. I am modeling the insertion of a probe into the a cube. The probe I am having in post processing is that using point evaluation on vertices or boundary integration on the probe boundaries, the reaction force is always zero (in the z-direction of insertion).

I am looking for the resistance force that the probe is experiencing during the insertion - this is the reaction force right?
Also, for those points on the surface of the cube that are not part of the geometry, I cannot do point evaluation of any parameters on those points, any idea why?

I am attaching a simple version of this simulation.

Thank you,

Joe

Re: boundary integration in podtprocessing

Mon, 15 Mar 2010 09:18:38 +0000

Hi Ivar,

of course it is but the problem is that in my case it works only in x and z directions.
It should be that reaction force directed according axes but this rule works only in x and z directions...
in y direction(where my prescribed displacement applied) it works in opposite way...

Thank you in advance,
Alex

Re: boundary integration in podtprocessing

Sun, 14 Mar 2010 16:24:44 +0000

Hi

I would expect that the reaction force sign is defined with respect to the surface normal = direction pointing "outwards" of the volume.

Therefore I find the signs rather coherent that way, but I agree it's a convention issue

Do you agree ?

Good luck
Ivar

boundary integration in podtprocessing

Wed, 10 Mar 2010 15:14:39 +0000

Dear all,

I have a simple question about comression simulation.

I have a cube in mechanical module.
I applied a prescribed displacement(in -y direction)as a boundary settings for upper boundary.
bottom boundary is fixed.

In Postprocessing/boundary integration I clicked on upper boundary and chose reaction force in y direction.

This reaction force has negative value!!!!!!!

How it can be that I press on cube and cube's reaction force is negative?

Thanks in advance,
Alex