Non-destructive testing process for ferromagnetic samples - using cyclical loading and monitoring of Barkhausen effect to observe resistance of sample to fatigue

摘要

The non-destructive testing process includes loading a sample with a cyclically varying load of increasing amplitude. This creates in the sample, an arrangement of faults in the dominant crystalline network, in the plane of the irreversible magnetisation changes. The changes in the effective value, the frequency, the width distribution, and the average value of Barkhausen effect mechanical noise pulses are simultaneously measured. The load is reduced to zero, and then cyclically re-applied. The maximum points of the above quantities are measured, and the size of the load at which these occur is taken to be the fatigue resistance equal to the limit of the endurance of the sample.