Experimental investigations on the stators of electrical machines in relation to vibration and noise problems

All mechanical structures including electrical machine stators and rotors have many built-in mechanisms for dissipating the vibrational energy. Often damping prevents extraneously excited vibrations from being noticed, and the importance and need for damping is not recognised. As advances are made towards building efficient light-weight structures, some of the damping that was present in the structure is inadvertently eliminated. Hence the damping mechanisms need to be studied and efforts be made to incorporate more damping in these re-designed structures in a more reliable and cost-effective way. The authors describe an experimental method to achieve this using modal analysis. The distributed EM forces, and stator models are discussed. The vibration amplitudes at the resonances of two stator models and damping ratios at various resonances are also discussed.