Study Of Effect Of Stress On Magnetostrictive Properties Of Electrical Steel Sheet

With the growing demand for energy and the improving of the social electrification,motor and transformer and other electrical equipments had deeply introduced in human’s life,due to the need of electricity production and transmission.At the same time,the daily life had been affected by the noise of the motor vibration.The magnetostriction in electrical steel sheet is one of the important causes of the motor vibration noise.In order to optimize the performance of the motor and provide convenience to optimize the design of the motor,it is necessary to measure and analyze the magnetostriction of electrical steel accurately.The manufacture process of the motor stator includes tailoring,stamping,riveting and assembly,which can produce residual stress on electrical steel.This paper analyzed the effect of the stress on electrical steel sheet.The non-oriented electrical steel sheet(50AW600)was selected as the research object.Using the tri-axial strain gauge as the measuring tools,the magnetostrictive measurement platform under applied stress had been set up,which was based on the equipment of meauring the relationship between magnetic property and applied stress.The magnetostriction of non-oriented electrical steel sheet under different conditions were measured.Through the X-ray diffraction system,the residual stress of the stator laminations were obtain and the magnetostriction in the stator core of a permanent magnet motor can be simulated.All of research provide reference for the analysis and inhibition of motor vibration noise.The main research contents are summarized as follows:First of all,the magnetostrictive measurement platform of the electrical steel sheet had been set up.This platform is mainly composed of the equipment of meauring the relationship between magnetic property and applied stress,data acquisition card,strain bridge box,strain amplifier,tri-axial strain gauge.The platform can only measure the magnetostriction under the alternating magnetic field.Through the device of the air compressor and load cell,the stress between-10 MPa and 10 MPa can be applied to the samples,the relationship between applied stress and magnetostriction was obtained.Secondly,on the basis of measurement device,the magnetostriction of the non-oriented electrical steel sheet under different stress and different magnetic flux density were measured.In order to develop the magnetostrictive property along different magnetization directions for a non-oriented steel sheet,the electrical sheet were cut in different directions along with the rolling direction,the magnetostrictive data along different angles are obtained.Due to the existence of 3rd harmonic of the magnetic flux density in actual working conditions.The 3rd harmonic with different percentages and different phase delay has been added into sinusoidal magnetic flux density and the corresponding magnetostriction had been measured.Meanwhile,the effect of 3rd harmonic on the harmonic in magnetostriction was analyzed.Then,cut the samples in different ways,which include laser,wire-cutting,hydraulic plate shear.The magnetostriction of electrical steel sheet under different cutting methods was measured.To analyze the peak to peak value of magnetostriction before and after annealing under different stress,the samples with different cutting ways were annealing.Finally,utilizing the X-ray diffraction system,the residual stress of the tooth and the yoke of the stator laminations was measured.The magnetostriction in the stator core of a permanent magnet motor can be simulated.