OICC Press Journal of Theoretical and Applied Physics 2251-7235 19 3 2025 06 30 Low Frequency domain analysis of alternating magnetic flux leakage method 10.57647/j.jtap.2025.1903.33 EN Hamid Eftekhari Department of physics, SR.C, Islamic Azad University, Tehran, Iran Mohammad Mehdi Tehranchi Laser and Plasma Research Institute, Shahid Beheshti University, Tehran, Iran Journal Article 2025 06 30 Alternating Magnetic Flux Leakage method was used to investigate the relation between the leaked magnetic field and crack dimension by changing the frequency of the magnetic field induced in the specimen. In this way, the alternating magnetic field with frequency in range of 1-100 Hz was induced into a defective ferromagnetic steel plate and the magnetic field over the surface was measured. Then, two sensors in differential modes were used to extract the effect of frequency on the relative Magnetic Flux Leakage signal. The results indicated that the frequency of minimum of the relative Magnetic Flux Leakage increases linearly by increasing the crack depth. The experimental results were verified by numerical finite element simulation method.