Strain at midside nodes?

[a-s-yehia]

Hi,
Currently running a model meshed with SOLID186 where midside nodes return NaN for strain values. In Ansys Workbench, the same midside nodes return a value for strain. How can this be coded into pyMAPDL? I know the documentation mentions result.nodal_elastic_strain will return NaN if there are no strain values (e.g. midside nodes), but is there a line in the code that can calculate these strains (such as averaging them from corner nodes)? How does ANSYS Workbench currently calculate strain at midside nodes? Thanks!

[mikerife]

Hi @a-s-yehia
Mechanical and MAPDL calculate the mid-side node quantities "on the fly"...that is, they are calculated when needed to plot. What do you need the mid-side node values for? For example, and it's been a while so I may have this wrong, but PyVista can interpolate mid-side node values given corner node values. Or do you need a list of the values to work with? Something else?
MIke

[a-s-yehia]

Hi @mikerife, I would need the values to work with in another application. Currently calling result.nodal_elastic_strain() only populates corner nodes with strain values and mid-side nodes with N/A. In ANSYS Workbench, when the strain results are extracted as a text file, all nodal strain results are calculated.

[mikerife]

@a-s-yehia yes like I said, Mechanical and Mechanical APDL calculate the mid-side node results during post-processing as they need them. So you would need to do the same. PyDPF does have an extend to mid-side nodes operator. Go here and search for the word extend. Why does the application need the results? To plot? To use in some other calculation? Some other reason?

[a-s-yehia]

@mikerife I need the strains at all nodes including midsides stored in a numpy array or pandas DataFrame for numerical post-processing and comparison against experimental measurements. I've been trying to get DPF working but I keep getting 'Operator does not exist in the registry' errors. I've checked that the dpf version matches the ANSYS version but haven't had any luck yet.
Is there a recommended approach for extracting midside node elastic strains programmatically with Ansys 2022 R2 and PyMAPDL? Or is DPF the only reliable path and I need to troubleshoot the installation further?

[germa89]

@mikerife can we use post_processing module for that?

[a-s-yehia]

Hi @germa89 and @mikerife, any chance you have additional information on whether midside node strain extraction is possible using post_processing? I just want to make sure I've explored all potential avenues before resorting to manual calculations.