Hi everyone,

I am running a frequency analysis in Abaqus CAE on a base structure with a boundary condition where the bottom is fixed to the ground. The structure supports four motors on top, but for the FEA model, I removed the motors and instead included their masses in the analysis to better represent the real system. My goal is to extract 30 modes and analyze their natural frequencies.

How can I evaluate the risk of resonance by comparing these natural frequencies with the operating speeds of the motors? Should I also consider higher harmonics of the motor frequencies?


Furthermore, after running the resonance analysis, I checked the Effective Mass Ratio in the X direction, and it is around 81%. Does this indicate that I have captured a sufficient number of modes, or should I extract more modes to ensure an accurate analysis? Is there a recommended threshold for the Effective Mass Ratio to determine mode sufficiency?

Thanks in advance,