How to use "mapdl.secread",File of.SECT,Runs successfully in ansys, But fails in python

[bismarck1943]

Python:3.8 Ansys:2021R1
I've defined a custom section called "MESH".I used the mapdl.secwrite command to generate a CFST.SECT file, which can be read by secread in ansys, and generate beam units. But it cannot be read in python.
The error message is:
Beam section has zero or negative cross sectional area. Input data for
section ID 1 is ignored.

Here is the python code:

from ansys.mapdl.core import launch_mapdl


# start MAPDL and enter the pre-processing routine
mapdl = launch_mapdl()
mapdl.clear()
mapdl.prep7()


deck = 0.30
tside = 0.04
tmid = 0.02
widths = 1.5
widthm = 0.6


mapdl.et(1, "PLANE82")
mapdl.mp("EX", 1, 3.5E7)
mapdl.mp("PRXY", 1, 0.167)
mapdl.et(2, "BEAM189")
mapdl.mp("EX", 2, 2E8)
mapdl.mp("PRXY", 2, 0.3)


mapdl.rectng(-11, 11, -deck, 0)
mapdl.wpoffs(-10, 0)
mapdl.rectng(-widths/2, widths/2, -(deck+tside), 0)
mapdl.rectng(-tside/2, tside/2, -2.5, 0)
mapdl.rectng(-widths/2, widths/2, -2.5, -2.5+tside)
mapdl.asel("S", "LOC", "X", -11, -9)
mapdl.wpoffs(5, 0)
mapdl.rectng(-widthm/2, widthm/2, -(deck+tmid), 0)
mapdl.rectng(-tmid/2, tmid/2, -1.3, 0)
mapdl.rectng(-widthm/2, widthm/2, -1.3, -1.3+tmid)
mapdl.asel("S", "LOC", "X", -6, -4)
mapdl.wpave(0, 0, 0)
mapdl.asel("ALL")
mapdl.aptn("ALL")

mapdl.pnum("AREA", 1)
mapdl.numcmp("AREA")
mapdl.asel("S", "LOC", "Y", -deck, 0)
mapdl.aplot()
mapdl.aatt(1, "", 1)
mapdl.asel("INVE")
mapdl.aplot()
mapdl.aatt(2, "", 1)
mapdl.asel("ALL")
mapdl.aglue("ALL")
mapdl.aplot()
mapdl.esize(0.1)
mapdl.mshape(0, '2D')
mapdl.mshkey(1)
mapdl.amesh("ALL")
mapdl.nummrg("NODE", "", "", "", "LOW")
mapdl.secwrite("CFST", "SECT", 1)
mapdl.sectype(1, "BEAM", "MESH")
mapdl.secoffset("CENT")
mapdl.secread("CFST", "SECT", "MESH")

mapdl.asel("ALL")
mapdl.aclear("ALL")
mapdl.adele("ALL", "", "", 1)
mapdl.secplot(1,0)



mapdl.n(1, 0, 0, 0)
mapdl.n(2, 16, 0, 0)
mapdl.n(3, 32, 0, 0)

# Define one node for the orientation of the beam cross-section.
orient_node = mapdl.n(4, 8, 1)

# Print the list of the created nodes.
print(mapdl.nlist())

mapdl.et(3, "BEAM188")

mapdl.type(3)
mapdl.secnum(1)


mapdl.e(1, 2, orient_node)
mapdl.e(2, 3, orient_node)
# Print the list of the created elements.

print(mapdl.elist())

# Display elements with their nodes numbers.
mapdl.eplot(show_node_numbering=True, line_width=5, cpos="xy", font_size=40,vtk=False)

---

This image shows a successful run in ansys

[mikerife]

Hi @bismarck1943 Do you happen to have a newer version of MAPDL installed? I tried this using 2022R2 and it works as expected. Just my luck that I do not have 2021 R1 installed. I can install to test if you have to use 21R1. Mike

[mikerife]

Hi @bismarck1943
I've run the model with Python 3.9, MAPDL 2021R1, PyMAPDL 0.64 within Jupyter Lab and did not receive any error. Can you post pictures of the error.

[bismarck1943]

Thanks a lot. I later ran the model with python3.8 and ansys2021R1, ansys.mapdl Version: 0.63.2 successfully.

But when I want to display the beam element section in python, I use the following code :
mapdl.eplot(show_node_numbering=True, line_width=5, cpos="xy")
It just shows the units, not the sections.

So I use the "mapdl.shape(1)"and "vtk=Falese", code:
mapdl.eshape(1)
mapdl.eplot(vtk=False, cpos="yz")
It only shows the side view and can't switch angles.It cannot display a 3D graph like ansys.

And then there's the warning:
UserWarning: pymapdl does not support /ESHAPE when plotting in Python using mapdl.eplot(). Use mapdl.eplot(vtk=False)
warnings.warn
I would like to know whether it is because python cannot use "eshape" to display the section shape like ansys. And if python can display the section, what should I do

[mikerife]

Hi @bismarck1943 right, the PyMAPDL plotting does not yet support beam cross-sections on element plots. You can use the PyMAPDL 'view' command to change the view of the MAPDL plot. For example

mapdl.view(1,1,1,1)

Will result in a ISO plot of the section (add command before plotting). Should look something like:

Or you can use the mapdl.open_gui() to open MAPDL interactively and double check the beam section. Then exit out of MAPDL and continue on with PyMAPDL.

Mike

[bismarck1943]

Thank you very much for your help! ：）
It is very satisfying for me to display the 3D graphics effect after meshing through the "view" command.