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SPRING2N and RBODY Connection

Dear all,

I have a problem defining the right connection between a rigid and a spring (please find a picture attached).

I want to design a simultaneous movement of a Part by rotation around global zero and translation along a spring (translational KJOINT).

My Problem is how to connect SPRING2N and RBODY to ensure no relative movement in the connection point.

Also attached is a test-model of the problem.

Thanks so much!

Best regards

Kerschten

<?xml version="1.0" encoding="UTF-8"?>

Unable to find an attachment - read this blog

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Altair Forum User

Hi Kerschten,

We are working on your query and will update the progress very soon.

gopal_rathore

Hi,

I think you need to use coincident node option for connecting same node of spring to the rbody.

Altair Forum User

Hi gopal_rathore,

thanks for reply!

There are no coincident nodes in the model. Slave node of RBODY equals first node of SPRING2N. Connection between spring and rigid is working well but spring has rotational dof around slave node of RBODY which is what I have to avoid.

Altair Forum User

Hi George P,

Thanks for your files. I worked on your deck and changed the masses. Attached you find the new version. This time, the movement I want to realize nearly seems to work with few oscillation's (although I want to avoid oscillations and damping increases calculation time).

My problem is the displacement in X direction of the spring (between nodes 3 and 5). This is not intended. Original value is 100 mm before movement. After rotation displacement of the spring is around 115 mm despite the movement in x direction has to be 0 mm ('no_translation' curve).

Centrifugal force is really low and translational stiffness is really high. I don't know why there is a displacement in X direction. Doesn't make sense to me. Can you please look at the deck? Is there any other connection like a translational joint ideally having rigid behavior in every direction?

Thanks and best regards

Kerschten

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Unable to find an attachment - read this blog

Altair Forum User

Hi George P,

please have a look at the distance (magnitude) between nodes 3 and 5 in the video attached made from your 'model.h3d'. Distance is starting with 100 mm and ending with approx. 117 mm. There was no additional movement applied. Where does it come from?

Unable to find an attachment - read this blog

Altair Forum User

Hi Kerschten,

This is because of the translational load applied on the component. If the transaltional load is removed the distance between the nodes is consistent, that is 100mm.

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Altair Forum User

Hi George P,

I'm wondering because there is no translational load applied, see pictures attached.

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi Kerschten,

This seems bit strange, Will check and update you.

Altair Forum User

Hi George P,

anything new on this topic?

Altair Forum User

Hi Kerschten,

This /IMPVEL loading condition is acting as a boundary condition in X direction. At every point listed in the function user is imposing 0 movement in X direction.

Altair Forum User

Hi George P,

you're right, this is like it should be. Unfortunately it is not working, since the part is moving in x direction??

Altair Forum User

Hi Kerschten,

This movement is because of rotation provided in ZZ direction. You can try imposing the same /IMPVEL condition in ZZ direction for the component and review the distance between the nodes.

Altair Forum User

Hi George P,

thanks for the suggestion! I don't know if I understood right but what I did is not working :-(

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Altair Forum User

Hi Kerschten,

Please check the files attached.

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Altair Forum User

Hi George P,

in this case, spring and rigid beam do not stay rectangular to each other :-(

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Altair Forum User

Hi Kerschten,

Then I hope this model may suit the need. These are the possible workarounds for this model.

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