Modal analysis

[virtuamechanica]

Hello

Is it possible to make a linear modal analysis , for computing free frequencies of structure (no boundary conditions) , with the library ?
If yes, could i have an example ?

Thanks

[FrozenWinterheart]

Hi,
sorry for the late response. I'm currently working on implementing modal and buckling analysis. I think at the end of february the next release will be ready, so stay tuned.
At the meantime, there is a possibility for modal analysis. You can create a frequency step by using the universal keyword class.
Here is a small example

# Make new step and add to model
step = sk.Step() 
model.add_steps(step) 
# add keywords to the step
step.add_step_keywords(
    mk.Universal("*FREQUENCY\n10"), # use Universal keyword to set up a frequency step and ask for 10 frequencies
    sk.NodeFile([enums.ENodeFileResults.U]), # request deformations in frd file
    sk.ElFile([enums.EElFileResults.S]), # request stresses in frd file
)

model.solve()
model.show_results_in_cgx()

The problem atm is reading the results for post processing. The current frd reader will read the frd file without errors, but quering the created result object may be tricky. Because step time is now frequency and there may be some equal frequencies in one step (esp. the rigid body motions with a frequency of 0). So you have to look at the result sets in the result object to figure out which one is the one you need for further processing.

Kind regards,
Matthias

[virtuamechanica]

Thank you for your reply Matthias.
I will test your workaround and wait for the next upgrade.

Thank you again for sharing your very nice library ! Great job.