Choice of the Distance between the Pole-Pieces of the Electromagnet Yoke in a Magnetic Method of Material Testing

With magnetic methods of testing, a magnetic field is induced inside the object being tested and any resulting changes of magnetic flux in the region of interest are observed. In this paper we consider the magnetic field excitation by using an electromagnet yoke, operated by DC and with adjustable distance between the pole‐pieces of the yoke. The sensitivity of detection for any portion of a component being tested varies with the distance between the pole pieces and, hence, the choice of the distance is of great importance. Simplified theoretical analysis as well as results of measurements for steel plates are given.