Nondestructive evaluation of fatigue in ferromagnetic material using magnetic frequency mixing technology

The magnetic frequency mixing method was investigated for fatigue damage evaluation of medium carbon steel. Two types of magnetic signal, the magnetic flux density and the tangential magnetic field, are detected and analyzed. Two parameters, the magnetic frequency mixing factor and the power law coefficient, are proposed for magnetic frequency mixing effect characterization. On-line and off-line magnetic frequency mixing experiments were performed on specimens with various degrees of fatigue. Experimental results show that the two parameters changed along with the fatigue cycles with monotonic linear regularity and both parameters can be used for fatigue damage evaluation of medium carbon steel.