Inquiry about rotational control (RX, RY, RZ) in flex3d.mph

[zyjGraphein]

Hello,

I'm new to COMSOL and was very excited to find your open-source project. Thank you for sharing your work!

I'm trying to implement rotational constraints (RX, RY, RZ) in the comsol/flex3d.mph model, but I'm running into some trouble. The model currently only seems to have controls for translational movement (UX, UY, UZ).

I attempted to add the rotational degrees of freedom (e.g., RX) myself, but my changes either resulted in errors or did not produce the expected behavior.

Could you please provide some guidance on the correct way to set up these rotational constraints? Is there a specific method I should be using?

Alternatively, I was wondering if the current file is an intermediate version. Do you have a version of the model that already includes rotational controls?

Any help you could offer would be greatly appreciated. Thank you!

[artofscience]

Hi! Thanks gor your message. You can add rotational DOFs by imposing linear rotation on the top surface (or both top and bottom). For example in 2D consider coordinate system in the centre of the flexure and dimensions lx and ly of the flexure. Then to impose a unit linearized rotation of top surface prescribe:
ux = 1/ly and uy = -coord.x/lx.

That is, eg for lx=ly=1, the top surface moves a unit in the right direction and y dispaces as function of x coordinate.

Hope this helps. Otherwise also check the matlab implementation.

As you mention, this is just a minimum working example.

Kind regards,

Stijn

[zyjGraphein]

Thank you very much for your patient reply. I will try this method.
I wish you all the best.
Yujie