Selecting only 3d elements

[manarshhjot]

I have a mesh file that contains both 3D volume elements and some contact elements. I require arrays containing strain energy density and volumes of the 3d elements.

[akaszynski]

@mikerife, I'm going to leave this to you, but tentatively @manarshhjot I would recommend selecting by the solid element types using esel with:

mapdl.esel('S', 'TYPE', vmin=1)
# or mapdl.esel('S', 'TYPE', '', 1)

Where 1 is the element type that you're selecting.

[manarshhjot]

@akaszynski Thank you for your answer. The selection worked. My main query is how can I extract the values from element table for the selected elements. Or how can I pass the selected elements to create an element table containing only these selected elements.

[pmaroneh]

HI @manarshhjot , the element table command operates on the selected elements only. So once the elements are selected through: mapdl.esel('S', 'TYPE', '', 1)
You can use a command similar to mapdl.etable('s1_table','s','1') to create the element table that you want.

[pmaroneh]

Once this is done, if you want to manipulate the table as a pythonic array, you can use the following workflow:

1. Create an APDL table with the results:

• instanciate the APDL array: mapdl.dim('my_results','array',40000,1) Note - the dimensions of the table array need to be adapted to your case
• fill the array with the ETABLE values: mapdl.starvget('my_results','elem',1,'etab','s1_table')

2. Transform the MAPDL table array into a Python array: mapdl.parameters['my_results']

[mikerife]

Hi @manarshhjot @pmaroneh @akaszynski
The PRETAB command allows the use of the extra method .to_array so we don't need to dump the element table to a MAPDL array.

Also we can create a function to unselect all the contact/target element types. Or maybe on to select all the 3D structural element types. Which to use will often be situationally dependent. Unselecting would be easier since we only need one selection type, whereas the other would have one selection and several also select.

Here is an example:

def no_contact(mapdl):
    contact = [169, 170, 172, 174, 175, 177, 178]
    for type in contact:
        mapdl.esel('u','ename','',type)
    return

mapdl.etable('volume','volu')

mapdl.allsel()
no_contact(mapdl)
vol = mapdl.pretab('volume').to_array()
print(vol)

Running a very simple 2 solid element model with symmetric contact (so 2 each contact and target elements) results in this:

Mike

[pmaroneh]

@mikerife much less convoluted than my initial suggestion, I should have thought of this.

[akaszynski]

Thanks @mikerife! You're starting to become a real python programmer!

One nitpick:

def no_contact(mapdl):
    contact = [169, 170, 172, 174, 175, 177, 178]
    for type in contact:
        mapdl.esel('u','ename','',type)

There's no need for a return up above since Python functions automatically exit on completion.

[mikerife]

Thanks @akaszynski !! I was a unsure if it was good/bad practice to include that return or not so I played it safe. Mike

[manarshhjot]

@akaszynski @pmaroneh @mikerife Thanks