Distinguishing Stress Concentration or Cracking in Ferromagnetic Material Using Abnormal Magnetic Signals

Abstract

In the geomagnetic field, spontaneous magnetic signals in ferromagnetic materials can be induced by stress, which can be potentially applied to estimate the damage degree. In this research, a method of distinguishing stress concentration or cracking in ferromagnetic material was proposed. The normal component of magnetic field, H_p(y), was measured on the surfaces of ferromagnetic specimens with notch. The results indicated that the shapes of H_p(y) curves of stress concentration and cracking were different, there was abnormal magnetic peak in the H_p(y) curve of cracking. Meanwhile, the effect of lift-off on abnormal magnetic peak was studied, and the optimal lift-off value was also presented.