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bird strike post-process

Hi, my analysis show some problems. the blades stretch in radial direction as you can see in the photo below(difference between t start and t finish) . i think it is due to centrifugal effects, am i right ? if so, can you help me to delete them ?

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Altair Forum User

Hi,

what type of load is it?

Altair Forum User

i applied only angular velocity and this is the results of analysis. i didn't apply any load. this is the displacement field

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Altair Forum User

Hi,

Yeah, I noticed it. Let me check on a sample model and I will get back to you.

Altair Forum User

Hi @nicola.andreini

Centrifugal is a physical phenomenon,

Is there a reason you want to counter this?

Altair Forum User

yes for 2 reason first of all the centrifugal forces change the geometry of the blade (not realistic effect) after that the stress and strain due to CF obscure the stress and strain due to bird impact. do you know how can i see the effect of bird strike clearly ?

Altair Forum User

Hi Nicola,

Yes, it is a physical phenomenon.

You can review the results of the bird alone. In contour select only bird component contour for it alone.

You can also hide the blade component in the Results browser

Altair Forum User

Thank you Prakash, is it possible to view only forces due to interaction between blades and bird and obscure centrifugal forces?

Altair Forum User

Thank you Prakash, is it possible to view only forces due to interaction between blades and bird and obscure centrifugal forces?

You can view contact forces as HG plot using TH/INTER

Altair Forum User

Thank you, and how can i make a rotational system of reference integral to blades to view the displacement?

Altair Forum User

I don't understand why this centrifugal forces are so hight, Are correct use rigids (rbody) to connect blade at the centre ? there is another way to model the joint between blades anda case ?

Altair Forum User

HI,

There are two methods to correctly account for the centrifugal force. The first method would be to use an imposed velocity starting at zero and increase the speed to the final value. I would recommend using a smooth curve

The second method is to do the preload using /LOAD/CENTRI. Included are example files.

With either method you can use *.sta state files to save the preload in the blades and reuse it in other simulations assuming you do not change the rotating blades between simulations

Unable to find an attachment - read this blog

Altair Forum User

thank you Prakash, in last model i use ' initial velocity around an axis' is this wrong ? now i do as you say but i'm a starter with radioss and i can't do it. if i send you the file with transfer link, Can you please help me to add imposed velocity ?

Altair Forum User

Yeah sure,

Altair Forum User

i send you the model. thanks a lot

Altair Forum User

Ok, thank you.

I will work on this as time allows.

Altair Forum User

thank you very much, Prakash.