Regardless of the industry, predicting the vibration behaviour of the electric motors by conducting numerical simulation is a critical task, since the consequences in case of structural failure due to resonance in the operating range of the machine could be catastrophic.

First, we will tackle the base of every dynamic assessment, which is the modal analysis at assembled machine level, with the goal of determining the modal parameters (resonant frequencies, natural vibration modes, participant masses), data that can be used to see whether the electric motor has any resonant frequencies in the operating range and how the design can be improved to avoid this phenomenon at low frequency.

Then, we will show how these results are exploited further as input data for future frequency response analyses (response spectrum analysis to mechanical shock loads, random vibration, harmonic vibrations), where predefined standardized spectra or experimentally measured spectra are used as external excitation.

Last, we will focus on probably the most important aspect in vibration simulation of electric motors, which is the rotor-dynamics simulation. We will discuss aspects like finding the critical speeds (Campbell diagrams), rotor unbalance assessment (static and dynamic eccentricity) and the impact of bearings’ stiffness of the rotor dynamics, by taking a deep look at bearing selection, arrangements, and axial preloading.