Centrifugal load and deloading

Hello everybody,

I’m quite new at Calculcix and I’m performing an analysis of a rotor under centrifugal load.

I’m using the time step command to ramp up the load in defined steps, and so far the results are as expected.
Now I would like to expand my model and to reduce the rotation speed again in the same simulation, but I have not yet found a proper way to do this. I have tried:

  • adjusting the time points to go “back” in time
  • adding a second time point card
    but both do not work.

If somebody can point me to an example or reference for a similar problem this would be great.

Thank you

Are you using *AMPLITUDE to control the centrifugal load? If so, you can extend that to bring it back down after the maximum like:

0, 0
1, 1000
2, 0

for a linear load ramp from 0 to a factor of 1000 then back to 0 at time 2.

If you’re not using *AMPLITUDE and maybe relying on the automatic ramping, then I’d recommend using *AMPLITUDE instead because it gives you simple and full control over how loads change with time.

Hello Victor,

thank you for your suggestion.
I was using the *TIME POINT card.

But this options seems to be one way only. I will try to use the amplitude card.
Can you access the results at any given time with amplitude as you would with time points (like *node print, nset=mypoint, time points= tp and then for example u for displacement)

I don’t use *TIME POINTS but I’m pretty sure it still works if you also use *AMPLITUDE.

I wanted to update this post with the solution that worked for me.

The *AMPLITUDE command is indeed the way to go to simulate a loading and deloading.
It can be mixed with *TIME POINTS. Initially this did not work, because I had defined the keyword “direct” in the step command. This is not compatible with *TIME POINTS as it seems, so get rid of it.