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How to properly create rotation

Iwona Wyrębska_20318

Hi Everyone,

my project is to model a planetary ball mill, and I have some big problem with the rotation of the disk and cylinders.

These elements should rotate in the opposite direction (as in the picture); however, if the speeds of the disk and cylinders are close to each other, the movement of the cylinders slows down or stops altogether. 
This problem does not occur when I change the rotation to the same direction. I think there's something wrong with the reference system but I can't find the error.

I will be grateful for help.

Iwona

1.png

2.png

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Stephen Cole

Hi Iwona, it looks like you have the kinematics setup as 'parent child' where the child geometry will follow the parent then also apply it's own kinematics. The setup looks OK however it's difficult to tell from the images.

I would recommend trying to setup the rotation of the cylinders as two kinematics and removing the parent - child relationship. For the cylinders you can setup 1 motion to rotate around the centre of the domain, and a second kinematic setup to rotate around the CoM of the cylinder. For this second kinematic you'll need 'moves with body' to be selected to ensure that you are always rotating around the CoM of the cylinder, even though this is moving.

Regards

Stephen

Iwona Wyrębska_20318

Dear Stephen,

Thank you very much for your reply; I appreciate it.

I did what you advised, but it's the same result; in this case, there is a problem with rotating around the centre of the domain. When I set it (just this one move), it also begins to turn around its own axis in the same direction. I see two vectors, but the gray one is generated automatically, and I can't remove it.

Best regards

Iwona

3.png

650.wmv

Stephen Cole

Dear Stephen,

Thank you very much for your reply; I appreciate it.

I did what you advised, but it's the same result; in this case, there is a problem with rotating around the centre of the domain. When I set it (just this one move), it also begins to turn around its own axis in the same direction. I see two vectors, but the gray one is generated automatically, and I can't remove it.

Best regards

Iwona

Hi Iwona, could you share the input files? if you zip them at time = 0 s and include the simulation_data folder we can review the settings.

Regards

Stephen

Iwona Wyrębska_20318

Dear Stephen,

The file is attached; thank you for your time.

Best regards

Iwona

multi_400.zip

Stephen Cole

Dear Stephen,

The file is attached; thank you for your time.

Best regards

Iwona

Hi Iwona,

Is this the motion you were looking for (Attached). I created a new square geometry to just rotate around the centre point while maintaining it's original orientation. Then as a child of this rotating the rectangle and associate disks around their own axis. I checked the rotations first then linked them together.

Regards

Stephen

multi_400_data.zip

Rotation.mp4

Iwona Wyrębska_20318

Dear Stephen,

that's the motion!:)

You helped me a lot, I fought it for a long time... Thank you!

Regards

Iwona