Magnetic Barkhausen Effect in Steel Under Biaxial Strain/Stress: Influence on Stress Measurement

Abstract

Experimental investigation of bi-axial steel deformation is presented using new equipment for bi-axial loading. Main conclusion obtained from displayed results is the condition of the invariance of Barkhausen noise intensity relative to any changes of spherical (isotropic) strain/stress tensor, the last being influenced only by material microstructure. This conclusion is supported by independent measurement of Barkhausen noise (BN) intensity on cross-shaped specimens of optimized shape using novel biaxial loading equipment, and tubular specimens like pipe and a balloon loaded by means of oil pressure. Finite Element Modeling (FEM) simulation was also investigated. Thus the BN intensity depends only on the deviatoric (shear) stress tensor value. The presence of this symmetric effect yields too many uncertainties in strain/stress evaluation via BN. Further investigation should identify whether this condition is also present in other magnetic parameters, such as coercive force, remanence, permeability, associated with BN.