Modeling fatigue conditions?

[ay8tb]

Hello,

How can I model fatigue conditions in pyMAPDL with conditions such as R, loading, sinusoidal loading, number of cycles, and frequency?

[germa89]

Hi @ay8tb

I converted the issue to a discussion because I feel this format is better suited for this kind of questions.

I believe that you can do it. If it can be done in MAPDL, it can be done in PyMAPDL. Maybe you can give more details on the model?

[mikerife]

Hi @ay8tb @germa89
ay8tb there are several answsers which depend, like germa89 said, on the details of what you really need to do. Generally speaking:

Answer 1 MAPDL, and so by extension PyMAPDL, is a general purpose FEA tool with features/functions that can be used to post-process as you need.

Answer 2 Please see the Ansys Help, Mechanical APDL Feature Archive. Archived features are those that still exist in the code but are not actively developed; often due to the feature being replaced or offered elsewhere. Anyway MAPDL post-processing of fatigue still exists, but it is based on a very specific ASME Code which may or may not be appropriate for your needs. If it is you can still access the APDL commands via the PyMAPDL "RUN" command. There are examples in that feature guide.

Answer 3 Workbench Mechanical has a built-in Fatigue post-processing tool. Have you ever used this? PyMechanical was recently released.

Answer 4 Do you use Ansys nCode? If so nCode is a 3rd party tool but has native WB Mechanical access now (a few releases ago it was accessed by its own WB Component System and not Mechanical based). Again I think PyMechanical may be an option.

Sort of Answer 5 Search 'fatigue' on ansys.net. ansys.net was started by Sheldon I was back before he started at Ansys Inc as a project for him to learn html etc. Anyway it still exists and has a lot of MAPDL 'stuff'. A few people have written fatigue macros that may help you and/or some papers on fatigue+mapdl+specific model that may be of use.

Mike

[ay8tb]

HI @mikerife @germa89,
For more details, it's a for a specimen undergoing fatigue (modeled based on an MTS 810) with x Hz, a sinusoidal load with R = -1 and k number of cycles.

Answer 2 - Thank you, I'll take a look at it
Answer 3 - I haven't used this before, but my intent for using pyMAPDL is to keep the environment purely in Python.
Answer 4 - I haven't heard of nCode before, but if it can be used in Python, I'd appreciate more details on it.
Answer 5 - I'll take a look, thanks!