# Centrifugal load and deloading

**URL:** <https://calculix.discourse.group/t/centrifugal-load-and-deloading/417>\
**Category:** Uncategorized\
**Created:** [February 2, 2021, 4:00pm UTC](https://calculix.discourse.group/t/centrifugal-load-and-deloading/417 "2021-02-02T16:00:54Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Yannick](https://avatars.discourse-cdn.com/v4/letter/y/b782af/32.png) [@Yannick](https://calculix.discourse.group/u/Yannick)\
**Post date:** [February 2, 2021, 4:00pm UTC](https://calculix.discourse.group/t/centrifugal-load-and-deloading/417/1 "2021-02-02T16:00:54Z")

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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  
Yannick

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**Author:** ![vicmw](https://avatars.discourse-cdn.com/v4/letter/v/6de8d8/32.png) [@vicmw](https://calculix.discourse.group/u/vicmw)\
**Post date:** [February 2, 2021, 10:30pm UTC](https://calculix.discourse.group/t/centrifugal-load-and-deloading/417/2 "2021-02-02T22:30:39Z")

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

\*AMPLITUDE,NAME=myamplitude  
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.

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**Author:** ![Yannick](https://avatars.discourse-cdn.com/v4/letter/y/b782af/32.png) [@Yannick](https://calculix.discourse.group/u/Yannick)\
**Post date:** [February 3, 2021, 7:35am UTC](https://calculix.discourse.group/t/centrifugal-load-and-deloading/417/3 "2021-02-03T07:35:57Z")

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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)

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**Author:** ![vicmw](https://avatars.discourse-cdn.com/v4/letter/v/6de8d8/32.png) [@vicmw](https://calculix.discourse.group/u/vicmw)\
**Post date:** [February 3, 2021, 11:40pm UTC](https://calculix.discourse.group/t/centrifugal-load-and-deloading/417/4 "2021-02-03T23:40:55Z")

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

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**Author:** ![Yannick](https://avatars.discourse-cdn.com/v4/letter/y/b782af/32.png) [@Yannick](https://calculix.discourse.group/u/Yannick)\
**Post date:** [February 24, 2021, 9:27am UTC](https://calculix.discourse.group/t/centrifugal-load-and-deloading/417/5 "2021-02-24T09:27:45Z")

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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.