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Rotordynamic Analysis Problem

Hi everyone,

i simulate vibrations of rotating systems. Therefore i start to build a model with only a vertical straight shaft with an unbalance (rigid body) on top. I simulate with a constant rotational acceleration up to 8500 1/min.

Even with gravity the shaft is elongating along z-axis with more than 10% strain. Hourglass is already prevented.Any idea?

Thanks in advance.

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Rahul Rajan_21763

Hi,

Altair Optistruct 13.0 latest version support Rotor Dynamics.

Please refer attached thumbnail for reference.

Regards

Rahul R

Unable to find an attachment - read this blog

Altair Forum User

Hi LoHo,

The reason could be because of the weight of the rigid body defined on the top of the shaft and the constraints applied to the shaft.

could you please check the constraints on the shaft?

Altair Forum User

Hello Prakash Pagadala,

thanks for replying. Translational DOFs are fixed via RBE2 element at the bottom of the shaft.

Altair Forum User

Hi LoHo,

Sorry for a late reply,

Not sure whether the elongation is elastic or in plastic.Can you check the unit consistency to confirm the material is OK for the shaft?

If you still see similar result, please share the model with us. You can use the secured dropbox link in my signature below.

Altair Forum User

Hi Prakash Pagadala,

it seems to be all right with my parameters and settings. I already shared the model with my professor, consequently with Altair technical support. So model is shared with developer, we still wait for an answer. Anyway thanks.