Learning Forum

[Murilo Granato]

Hello everyone.

I did this beam and created a mesh with one element, but statistics of mesh show 3 nodes ad can't select the third node that should not exist because it does not appear in the beam. I tried to solve this problem by apdl commands but nothing turns right.
I need two nodes in the mesh, because I am taking the K matrix to compare with other analysis.

Can someone help me? 

[Kaushal Vadnere]

Hi Murilo, 

In Ansys mechanical, when you create a mesh with one element, it's common to see three nodes in the mesh statistics. This is because linear line elements in Ansys have three nodes, with the third node defining the orientation of the cross section. It does not contribute to the solution. If you're having trouble selecting the third node, it might be because it doesn't contribute to the solution and is used for orientation purposes.
See this post on forum on similar discussion: Why do the mesh stats show 6 nodes here instead of 3? (Truss Elements) (ansys.com)

Thanks,
Kaushal.

[Murilo Granato]

Hi, Kaushal. 

Yes, understood. But when I get the stiffness matrix from the model, this third node appears on it, and I don't want that this happens. So, this fact shows that the third node might be contributing to the solution.

Thanks for your support.

Murilo.

 

[Kaushal Vadnere]

Can you share the stiffness matrix which you are getting and the method through which you have retrieved the stiffness matrix?

[Murilo Granato]

The method is in this link:

The matrix is this one below. I constrained the external nodes in UX, UZ, ROTX, ROTY, so I should have a 4x4 matrix, but with the third node I got a 10x10. And one thing weird is happening as well. When I get the Mass matrix, the are values equal to zero, what should not happen. If you have any suggestions about this too, would be great.