Acoustic analysis of an induction motor with viscoelastic bearing supports

The demand for silent bearing applications has resulted in the development of an effective damping layer between the outer ring of a rolling bearing and the surrounding structure. By means of numerical modeling using both FEM and BEM techniques an induction motor for household appliances is analyzed. A hybrid modeling approach combining measured structural velocities with a BEM formulation is used to validate the acoustic model. The numerical results are compared with results obtained from sound intensity measurements estimating the radiated sound power level for a running electric motor. It is found that a relatively simple boundary element model is capable of predicting the radiated sound power in a wide frequency range. By using BEM in combination with the radiation modes formulation it is found that a properly designed viscoelastic layer in the vicinity of the bearing is theoretically capable of reducing a fair amount of sound emitted by the motor.