Experimental investigation of structural damping of laminated stacks of electrical machine rotors

Abstract

Rotor vibrations in electrical machines depend on structural damping and stiffness properties of the laminated cores. Structural damping determines torsional and transversal vibration amplitudes at resonances. Therefore, it is very important to know the structural damping and stiffness of the laminated cores to carry out structural dynamic simulations. In this paper, a measurement set-up is presented to determine the structural damping and direction-dependent stiffness for laminated cores and stacks. The dissipated damping energy is examined as a result of harmonic excitation of different excitation amplitudes, frequencies and axial prestressing conditions. Thereby, the measured structural damping factor is compared to the material damping factor from tables. To allow a conclusion for the reproducibility of the evaluated damping parameters, repeated measurements are carried out and the results are statistically analyzed using the Weibull distribution.