Preisach-based magnetic evaluation of fatigue damage progression

For the evaluation of fatigue damage progression, the application of magnetic hysteresis measurements combined with the Preisach hysteresis model is investigated. Therefore, a stress testing apparatus is built in order to apply cyclic uniaxial mechanical loading with constant stress amplitude to a ferromagnetic sample. Measurements of the quasi-static magnetic behaviour are carried out at predetermined interruptions of the fatigue test. A Lorentzian Preisach distribution function is used in the investigation of the relation between the magnetic characteristics and the mechanical fatigue properties. The Lorentzian distribution parameters appear to be related to the dislocation density, which make these parameters suitable for NDE during the early stages of fatigue.