Stress anisotropy characterisation with the help of Barkhausen effect detector with adjustable magnetic field direction

摘要

In the paper we describe a novel apparatus for the measurement of the Barkhausen noise (BN) angular dependence, which in turn may be indicative of the stress induced anisotropy of magnetic properties. Such dependence can be further used for the stress distribution evaluation. The change of magnetization direction in the material is obtained by varying the magnetic flux density in two perpendicular yokes of the apparatus. We present here, as an example, the application of the apparatus for the determination of the stress distribution in the welded plates. It is to be stressed that, thanks to the very short time of measurements achieved with the presented apparatus, it is very straightforward to obtain the spatial distribution of the stress over relatively big area of the plates in question. The whole measurement process as well as obtained data post processing is computer controlled and a stress distribution (based on 5 x 5 measurement matrix) for a single plate may be determined in less than an hour.