COSTANT ANGULAR VELOCITY IN HARMONIC ANALYSIS

edited August 28 in Structures

Hi everyone!

I would like to perform a harmonic analysis on a MEMS gyroscope structure to obtain the frequency response function. In brief, the structure is excited in the x-direction by a harmonic force and when there is an angular rate around the z-direction, the structure starts to move along the y-direction. I attach an image of my very simple structure.

I have performed an initial harmonic analysis with no angular velocity and I had no problem. My results match very well the analytical ones.

The problem starts when I try to apply a constant angular velocity on the structure and perform the harmonic analysis. I summarize the steps which I followed (I am using APDL at the moment but I can use also Workbench):

1) I built the model (the central rectangular plate is meshed with shell181 elements, while the beams suspension system is meshed with beam188 elements);

2) I activate the Coriolis effect using a stationary reference frame;

3) I apply on the central plate the constant angular velocity around the z-axis, using the CMOMEGA command (CMOMEGA, NAME-OF-THE-CENTRAL-PLATE-SELECTION,,,VALUE-OF-VELOCITY);

4) I perform a full harmonic analysis, applying the harmonic force along the x-direction.

My results are completely wrong and they are the same as the case of no velocity applied. I doubt this is related to having applied a constant angular rate.

Any advice?

Thanks for your time.

Best regards,

Francesca



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