Extract internal forces in shell model to apply as external loads

SOFiSTiK
1

Hi,
I have two quad models, model A and model B, where model B is a cut-out section of model A.
In model A I calculate internal forces. Now I want to apply these internal forces at the cutting planes as external loads in model B.

My first idea was to get the nodal forces in model A and then apply nodal loads in model B. It would be a clear and comprehensible approach but unfortunately I can’t find nodal loads as results in the database. There’s membrane forces per node but then I need geometry information from the neighbouring quads to calculate the resultant forces.

grafik
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The picture shows external loads and the resulting membrane forces per node. I can calculate the nodal forces for the edge nodes with 800 kN/m x 0,005m=4 kN and for the inner nodes with 800 x 0,01m=8 kN but my actual model is of course more complicated and 3D.

Does anyone have an idea what would be the best approach for this?

Best regards
Joachim

4

If anybody is still interested here’s what I did in the end: I read the membrane and shear forces in the nodes at a section using the Python API to read CDBs and then manually integrate the forces assuming linear distribution between the nodes. From that I get global forces in X,Y,Z per node. To get started with the Python API I recommend this video: https://www.youtube.com/watch?v=l8lc1vV3Tto Best regards Joachim

2

Hi,
In fact you can get nodal forces for quad elements:

image
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3

Okay, I see. Here’s an idea: For the support nodes of Model B, extract the displacements and rotations from Model A and apply them as as support displacements and rotations in Model B.
In more scientific words apply Dirichlet boundary conditions instead of Neumann, if I use English terms correctly.