Into on Rotordynamic Phenomena of Rotors, e-Motors

A summary on the basic simulations to be performed are:


  • steady state siimulations
  • transient simulations


Rotordynamic analysis has the following main parameters:

  • rotating speed
  • bearings
  • mass distribution
  • rotor inertia
  • motor mounting


The rotor inertia is the sum of the core, shaft  and bearings inertia. The rotor core and the shaft makes the rotor assembly. The rotor assembly critical speed is an important factor to determine resonances of the rotating machine.

Simplifying the complex dynamic problem we can say that it consists of the following main matrices:


  • Stiffness matrix
  • Mass matrix
  • Damping matrix


Special attention should be given when the frequency of the vibrating force is equal to the natural frequency of the system and this is where resonance occurs.


The loads on the rotor assembly are mainly  mechanical and electromagnetic loads. Hence, any unbalance creates unbalances both on mechanical and electromagnetic domain. In addition, these extra unbalanced forces are passing through the bearing configuration causing significant deterioration on the bearings.