Learning Forum

[Christopher Hernandez]

I need to measure the translations and rotations of a specific surface on an assembly during random vibration. I have the mass and CG location of the assembly only. I don't have, and cannot get, the detailed assembly model. I figured the next best thing is to define a point mass at the assembly CG scoped to the mounting points of the mating part. Then define another point mass of nearly zero mass at the centroid of the surface of interest and connect the two points with a nearly weighless and extremely stiff beam. The top point is the surface of interest. The bottom point is the CG. 

 

After building the model I put in a remote rotation about a single axis at the CG to see if the second remote point behaves as expected. It doesn't. The beam appears to length as the CG rotates so the vertical component remains unchanged. This is confirmed using the deformation probe to output the measurements.

What's going on here?

Is there a better way to do this?

 

Thanks...

[Ashish Khemka]

Hi, a general joint may be useful to measure rotation: How to retrieve relative rotation between faces in ANSYS Mechanical (ozeninc.com)

Regards,

Ashish Khemka