Stress readout: +/- signs API vs RFEM

API & Interfaces
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1

I am working with the RFEM API in Visual Studio Code and am trying to retrieve the different stress components. I would like to retrieve σx+, but this does not appear to be available as a separate option. Therefore, I am using the basic stress results at the bottom, middle and top of the surface.

I noticed that the values in the generated tables differ depending on the orientation of the local coordinate system defined in the base data. When the z-axis is oriented downward, the results correspond correctly to the values shown in RFEM. However, when the z-axis is oriented upward, the values generated by the API do not correspond to the results displayed in RFEM.

I have prepared a file containing several comparisons.

In conclusion, my question is: Is there an issue with the API when generating these tables, or am I interpreting the results incorrectly?

Comparison different axes systems.pdf (1.5 MB)

Thanks! Kind regards Bart

3

Hi BartR,

welcome to the Community!

Did you ensure, that you compare the same values (grid vs. FE results)?

Best regards
Stefan Hoffmann

4

Hi Stefan,

Yes, I compared the same values. It looks like the table from the API flips the bottom and top rows or something like that. Or i totally misunderstand something.

5

Hi BartR,

thanks for your response!

To analyse the problem more precisely, the model file would be very helpful:

:right_arrow: Click on File → Save as and choose the following settings to reduce the file size:

image
image467×393 7.53 KB

:right_arrow: Then upload the file here (e.g. *.rf6, *.rs9) – this way, the community can also contribute to the solution.

:owl: Prefer not to share the file publicly? No problem – send it to me via direct message: click on my profile picture or user name → Message.

Best regards
Stefan Hoffmann

6

Question_API_stress_readout.rf6 (1.0 MB)

It is just a file for testing.

8

Hi BartR,

I will check the issue with the layered results. In the meantime, as this was your initial wish. You should be able to get also sigma_x_plus results:

from dlubal.api import rfem, common

with rfem.Application() as rfem_app:

    result_table:common.Table = rfem_app.get_result_table(
        table = rfem.results.ResultTable.STATIC_ANALYSIS_SURFACES_BASIC_STRESSES_MESH_NODES_TABLE,
        loading= rfem.ObjectId(
            no=1,
            object_type=rfem.OBJECT_TYPE_LOAD_CASE
        )
    )
    print(f"\nResult Table:\n{result_table.data}"),

Best regards
Stefan Hoffmann

10

Hi BartR,

RFEM 6.15.0013 is supposed to include the fix regarding TOP/ BOTTOM stresses as well.

Best regards
Stefan Hoffmann