The effects of biaxial stress on Barkhausen noise signals when the magnetic field is noncoaxial with the stress axes

Abstract

The Barkhausen noise amplitude was measured under conditions of biaxial stress in steel pipe for the case of a magnetic field noncoaxial with the stress axes. The stress axes for stresses σ1 and σ2 were orthogonal to each other. In particular, σ1 was the axial stress and σ2 was the hoop stress. Various angles were used for the field direction, along with various stress magnitudes, both compressive and tensile. The stress σ2 was always tensile, but σ1 was both compressive and tensile. A model for this biaxial stress situation, based on the Sablik–Jiles magnetomechanical model, was formulated. Using a model for the Barkhausen noise deriving from the Alessandro et al. model, the Barkhausen noise power maximum amplitude was computed for various field angles and stresses σ1 and σ2. The numerical results from this model calculation agreed qualitatively with many features of the experimental results. Thus, one found both numerically and experimentally that with field direction at small angles from the σ1 axis, the Barkhausen noise amplitude increased as the stress σ1 was increased from negative to positive. At large angles (generally greater than 45°), the reverse was true and the Barkhausen noise amplitude decreased as stress σ1 was increased. Also, the curves for the various angles tended to intersect when σ1 was set equal to σ2. Differences between numerical and experimental results are discussed, and suggestions are made for further improvement of the modeling.