Under the influence of external forces, stresses may develop inside the mechanical components of
ferromagnetic material in
service, and cause distortion and deformation of mechanical components and result in
fatigue failure. The detection of stresses and fatigue in ferromagnetic mechanical components has been a difficult problem for a very long time. Therefore a method for testing the magnitude and distribution of residual and fatigue lives of mechanical components inside ferromagnetic components without testing their strains is urgently needed. And this method must be able to be used in the field conditions. When a
ferromagnetic material is magnetized by an alternating magnetic field, the abrupt irreversible motion of magnetic domain walls inside the material will induce Magnetic Barkhausen Noise (MBN). Due to its sensitivity to the microstructure and stress state of the material, MBN can be used to test fatigue and residual stresses inside ferromagnetic materials. In this paper, the principle of this technique and the measurement of fatigue failure in a plate component are introduced.