Retrieve applied loads on FE model

[derne058]

Hi all,

I am interested in retrieving all the loads applied on an FE model in Pymapdl. Is there a command that returns nodal loads, surface loads, surface element loads and so on?

[mikerife]

Hi @derne058
What do you mean by retrieving? Or rather, what is the purpose in retrieving the loads? Each APDL command that defines a load has a load list counterpart. For example to define a surface load of a set of node SF can be use; then to list the nodes and the applied surface load we can use SFLIST. The same naming convention holds for many load types; SFE and SFELIST, BF and BFLIST etc.

In the "Enriched Command Output" section of the PyMAPDL Documentation Page listing of the D (boundary conditions on nodes) and F (forces applied to nodes) have an extra method in their listing. To create a Python list of the node IDs and values, or a dataframe. It would be nice if this idea was extended to the other types of loads (hint @germa89).

The CDBWRITE command has a "Load" option to write just the loading information.

So answer could change depending on what you need to do.

Mike

[derne058]

I am writing an optimization code where I need to compute an adjoint model, then I need to remove the “original” applied loads and, after solving the adjoint model, I want to “resume” and apply the “original loads”. Since I am trying to write something that is as general as possible, I wanted to know if it is possible to use some command to have a list/array of all applied loads (type of loads and associated node or element depending on the load used).
I hope I have clarified my question.

[mikerife]

@derne058 well if you are resuming the original model it could have the original loads so you would not need to reapply them. Or write out the loads with cdwrite then read them in as needed with cdread (assuming here that the FEM is not changing including IDs).

[germa89]

This is probably the easiest approach.. save the model with no loads as a different CDB file.

The other alternative is more complex, because you will have to store the nodes/elements/kp/lines/... where the loads are applied and then iterate over there to remove the applied loads.