Displacement reading issue with nodal_displacement

[raphael-31]

Hi,
I am using pymapdl-reader to read an rst file from a simulation to analyse the displacement of a modal analysis.
There is no probleme when I take directly from the displacement list of the APDL gui, but when I am trying to read it with the method : result.nodal_displacement(mode), I have the following problem : all my displacement or either huge, either null :
[-1.00111706e+172 0.00000000e+000 0.00000000e+000]
[0. 0. 0.]
[0. 0. 0.]
[0. 0. 0.]
[0. 0. 0.]
...
[0. 0. 0.]
[0.00000000e+00 0.00000000e+00 5.78486458e+15]
[0. 0. 0.]
[0. 0. 0.]
[0. 0. 0.]
[0. 0. 0.]

Also, I work on plane element so I should not have any displacement in the Z-axis. It seems to not be the case.

The link to the files used for the analysis : link

Thank you,
Raphaël

[FredAns]

Hi Raphael,

It may be because records in the RST Files are compressed must of time, and I think the pymapdl-reader module is not compatible with the last evolutions of this compression algorithm ( @akaszynski, this is a 22.1 RST File, and I worked again on that during this last release).

You can use an alternative way to read these quantities, especially the one described in this example:

(https://mapdldocs.pyansys.com/examples/01-apdlmath-examples/explore_mapdl_files.html#sphx-glr-examples-01-apdlmath-examples-explore-mapdl-files-py

See where we extract the first nodal solution of the RST File here:

Thanks
Fred

[raphael-31]

Thanks, merci beaucoup !

Raphaël.

[raphael-31]

Hello,

One last question the displacement at 1.267e30 are huge compared to the others, is-it also a mistake with the format when I am reading ?

Thanks,
Raphaël.

[FredAns]

Hi Raphael, no mistake here.
These huge values are used to flag some dofs values. You can replace these values by zeros.
That's how the MAPDL GUI or DPF handle these special values. Perhaps we should automatize (least optionally) this operation in PyMapdl.
Regards
Fred

[akaszynski]

Thanks @FredAns!

Since it's not really possible for pymapdl-reader to keep up with changes upstream, this should be another reminder to use ansys-dpf-core or the MAPDL Database Explorer.

[akaszynski]

We can leave this open as an issue and potentially fix compression if it's necessary to maintain/update for 22.1