HOW TO READ NAMED SELECTION NODES USING mapdl.cmsel

[viks4mech]

Hi All, i have a python script to read 2d stress tensor of a node which is a named selection geometry.

However, when i try to read this using the mapdl.cmsel option, it says the geometry doesn´t exist, does anyone know why i get this error?

[mikerife]

Hi @viks4mech Well nodes are not geometry. And Named Selection is a WB Mechanical term; Named Selections are converted to element or node components for the MAPDL input file as Mechanical does not write out the (CAD) geometry to the input file.

Maybe double check the components by using print(mapdl.cmlist())

[viks4mech]

Thanks @mikerife , i'm calling the named selection and not the geometry itself. i checked print command and the print commmand does show the node i'm looking for as an option. Not sure why i gives an error still.

[mikerife]

@viks4mech can you post sample code with a test model? Also maybe a screen shot of the error.

[viks4mech]

here is a part of the script:

# Open output file for writing
with open(output_file, 'w') as f:
    # Loop through load cases
    for lcase in range(0, 2 * len(casenames_array) - 1):  # Adjusted loop range
        if lcase < len(casenames_array)-1:  # Corrected the condition
            mapdl.post1()
            mapdl.set(lcase)  # Select the load case
            mapdl.prep7()

            for ns in range(0, len(ncomps_array)):  # Corrected the loop range
                mapdl.allsel()
                print(ncomps_array[ns])
                print(mapdl.cmlist())
                mapdl.cmsel('S', ncomps_array[ns]) #Selects a subset of components and assemblies(like named selection).

                mapdl.esln('S', 0, 'ACTIVE') 
                mapdl.esel('R', 'ENAME', '', 181) 
                nodelist = mapdl.get(0, param_name='NODE', entity='', item1='NLIST')
                nnodes = mapdl.get_param(nodelist, 'DIM', 'NODE', 1)
                rsys_index = csysdata_array[ns][0]  # Corrected indexing
                cylcat_index = cylcatdata_array[ns][0]  # Corrected indexing
                bb = rsys_index

                mapdl.rsys(bb)
                aa = cylcat_index
                cc = nnodes

                node = nodelist[0]

                mapdl.shell('BOT')

[germa89]

This script does not help since it does not allow us to replicate the model.

[mikerife]

Hi @viks4mech & @germa89
viks4mech, parameter names must start with a letter. So this:

nodelist = mapdl.get(0, param_name='NODE', entity='', item1='NLIST')

is an error. Instead of getting the list why not use:

nodelist = mapdl.mesh.nnum

Also what is "get_param"? I'm not familiar with that PyMAPDL command (maybe in development?). Why not just get the length of the nodelist?

nnodes = len(nodelist)

Mike

[viks4mech]

I get the same error, with these changes. Does, ansys customer care help with PyMAPDL ?, cause i can´t share further info here as its confidential.

[mikerife]

@viks4mech normally no. Can you post a screen shot of the error. If the model is not ITAR then go ahead and open a technical support case and ask that I take a look (mike rife is my real name). Mike

[mikerife]

In case anyone is following this; just needed to change

mapdl.cmsel('S', ncomps_array[ns])

To

mapdl.cmsel('S', ncomps_array[ns][0])

[viks4mech]

Thanks Mike for your answer. really helpful.

i get this error saying that RSYS can't be used. is that correct?

[mikerife]

That is correct - RSYS is not a preprocessing command. Comment out or don't use the mapdl.prep7() after the mapdl.set(lcase).