Obtaining mapping of mass and stiffness matrix

[shs18]

Hi all,

I am trying to obtain the mass and stiffness matrix from a modal analysis along with the mapping of nodes and DOF in order to rearrange the matrices to a specific pattern. Obtaining the matrices works perfectly fine using:

k = mapdl.math.stiff()
m = mapdl.math.mass()

I have though not been able to obtain the mapping. I have tried using the mapdl.hbmat function to obtain both matrix and mapping, however I experience issues with finding the full file containing the information when using this function.
When I run:

mapdl.aux2()
mapdl.file(fname=file.full)
mapdl.hbmat('K_Plate', matrix='stiff', mapping='yes')

I get an error message "FileNotFoundError: Unable to locate file.full"

As far as I understand the same file is used to find the matrices in the math functions which works perfectly fine.
I am rather new at python and pymapdl, so I hope anyone can help me if there is another way of obtaining the mapping or if I do something wrong since I cannot locate the file using one function when it works using the other?

Thanks!

[germa89]

Hi @shs18,

Could you upload a minimum working example I can have a loot at?

Kind regards!

[shs18]

Hi @germa89

Thank you very much!

I have tried with just a very simple model to get the program up running and understand what is going on along.
Here is my code:

from ansys.mapdl.core import launch_mapdl
import numpy as np

mapdl = launch_mapdl()
mapdl.clear()
mapdl.prep7()
Plate = mapdl.blc5(0, 0, 2e-3, 4e-3, 1e-3)
mapdl.vplot(vtk=True, show_axes=True)

mapdl.et(1, "Solid185", KOP=2)
mapdl.mshape(0, "3D")
mapdl.esize(1e-3)
mapdl.vmesh("all")
mapdl.eplot(vtk=True, show_edges=True, show_axes=True, show_node_numbering=True)

mapdl.mp("EX", 1, 210e9)
mapdl.mp("Dens", 1, 7850)
mapdl.mp("PRXY", 1, 0.3)
mapdl.finish()

mapdl.slashsolu()
mapdl.antype(2)
mapdl.eqslv("spar")
mapdl.mxpand(10)
mapdl.modopt("lanb", 10, 0, 1000)

mapdl.solve()
mapdl.finish()

k = mapdl.math.stiff()
m = mapdl.math.mass()

mapdl.aux2()
mapdl.file(fname='file.full')
mapdl.hbmat('k_plate', matrx="stiff", mapping='yes')

k = np.asarray(k)
m = np.asarray(m)

mapdl.exit()

[germa89]

for future references, you can highlight code using triple `.

https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/creating-and-highlighting-code-blocks#syntax-highlighting

[mikerife]

Hi @shs18 & @germa89
The /AUX2 processor does not use the FILE command, it has its own command to set the binary file FILEAUX2. So try:

mapdl.aux2()
mapdl.fileaux2(fname='file', ident='full')
mapdl.hbmat('k_plate', matrx="stiff", mapping='yes')

What happens then?
Mike

[shs18]

It works! Thank you very much :-D