How to get internal force inside 3D model

[mQmichelle]

Hi,

I am modeling a steel composite frame in 3D as shown in the picture, on the top left is the pin support and on the right is the roller support, uniform distributed load on the mid beam, after solving the model, I would like to know the axial compression or tension force on the beam. How should I get the force???

Thank you

Michelle

 

[StefCon]

Hi,
The field variable NFORC gives you nodal forces. In the viewer, you can create a model cut (on element faces). In the settings for that you can show force components and bending moment components.

Hope it helps!

 

[mQmichelle]

Thanks for your reply. I tried this method before I post my question. However, this calculate forces at the nodes of the element caused by the stress in the element, but I would like to get the effective total force acting on that surface.

For example, I create a 100*100*100 cube, then I applied 100Pa (pressure load) on the top of the cube in the 1st second, then applied -100Pa on the top of the cube in the 2nd second, and the cube is supported vertically. After solving the model, in the visualization module, I create a free body cut with 3D element face, and plot the force components of the cut as shown in the picture.

For the 1st second, the cube is in compression with compression force equal to 100*100*100=1000000N, and for the 2nd second, the cube is in tension (1000000N). However, this is not the forces that I get from the NFORC command.

Is there a way I can get the compression or tension force acting on the cut surface or can it be worked out from the NFORC result?

 

[StefCon]

Hello,
For your cube example you could maybe create a coupling at the side where you constrain it. Then you move your boundary condition to the coupling. Later on, you can view reaction force (RF) in the constrained coupling. I do think it will give you the same result as the sum of the nodal forces in the cross section. It could be worth a shot.

Good luck!