How to remove rigid body motion from an XYZ displacement data?

[ash267]

Hello, I have XYZ displacement results for few cylinders. Is there a way I could remove any rigid body motion from the data.
By rigid body motion I mean - Rigid shift of the cylinder axis with respect to the nominal axis.
normally what I would do is fourier transform the data and remove first order coefficients to remove rigid body motion.
I want to look at the possibilities of doing this directly with the XYZ data avoiding the fourier step.
Thanks in advance!

 

[rb1957]

trying to wrap my mind around using a model with rigid body motion ?

or are you saying that you want deflections in terms of some local CID (not global CID) ?

another day in paradise, or is paradise one day closer ?

 

[ash267]

By rigid body motion I mean - Rigid shift of the cylinder axis with respect to the nominal axis.

 

[IRstuff]

If these are engine cylinders, then the rigid body motion is ostensibly determined by the motion of the center of the piston shaft bearing. But, I'm unclear from your posting what other motion you are implying, whether it's deflection or deformation?

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[ash267]

Deformation. Ths shift of cylinder axis is the result of the deformation between top and bottom part of adjacent cylinders.

 

[IRstuff]

OK, so somewhere in your model, you are commanding the bulk motion of the cylinder, so you already know what that is?

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[ash267]

I only the have the XYZ displacement from the customer. if I could just calculate the first order A and B from xyz displacement using equation y=A0 +(An * Cos n*Φ + Bn* Sin n*Φ) . That would be enough too.
Thanks