Residual stress evaluation by measuring barkhausen signals for high efficiency motors

The Barkhausen signal was used for the nondestructive evaluation methods in order to evaluate residual stress levels in ferromagnetic materials. However, it cannot be said that this technique has been established completely because the evaluation is usually not done under controlled magnetic flux conditions. When the magnetic field is applied into the materials by the exciting coil, material characteristics will change, therefore, controlling the magnetic flux condition is required for the precise evaluation of magnetic materials. Some results of the residual stress level evaluation using Barkhausen signals under the controlled magnetic flux condition measured from different tensile stressed specimens are shown and discussed them for high efficiency motors in this paper.