SOME EXPERIMENTAL RESULTS ABOUT THE CORRELATION BETWEEN BARKHAUSEN NOISE AND THE FATIGUE LIFE OF STEEL SPECIMENS

The results of Barkhausen Noise (BN) measurements during pulsating axial fatigue tests on notched steel specimens are reported. The aim of these measurements was to study the cyclic signal in the first stage of the fatigue process, in order to find a correlation between this magnetic parameter and the fatigue life of the specimens. The hysteresis loop of the BN intensity versus the applied load, during the initial stage of the process up to the crack nucleation, for different load levels has been studied. The loop amplitude is found to change significantly during the life period investigated, according to the load level. This behaviour is connected to the degree of cyclic plastic deformation and reflects the micro-structural settling phenomena that happen during the first stage of the fatigue process. The loop amplitude measured at the first cycle of each specimen has been related to the corresponding failure cycles number, showing a possible way for the prediction of the fatigue life.