Determination of Magnetisation Conditions in a Double-Core Barkhausen Noise Measurement Set-up

Abstract

The magnetic Barkhausen effect is useful for assessing 1D and 2D stress states of ferromagnetic steel objects. However, its extension to technically important materials, such as duplex anisotropic steels, remains challenging. The determination of magnetisation inside the studied object and the electromagnet for various geometries, materials and magnetisation angles is a key issue. Three-dimensional, dynamic finite element analysis has been applied to reproduce time-varying fields inside and outside the prototype of a double-core magnetising setup. Useful relationships between characteristics (peak height and location) and magnetic induction vector have been proposed. The qualitative plausibility of simulation has been validated with an experiment and an analytic formula of skin depth. The angular anisotropy of magnetic Barkhausen effect (MBN) in an isotropic sample has been shown in simulation and confirmed experimentally. The numerical model, despite some limitations, seems to be an efficient tool for calibrating stress/MBN relationships at least in isotropic structural steel components.Keywords Electromagnetic finite element method · Dynamic magnetisation of bulk volume · Eddy currents · Magnetic Barkhausen effect (MBN) B Marek Augustyniak

Barkhausen Noise Probes and Modelling: A Review

“…In addition, Patel et al [29] utilized two pickup coils to record BN: one coil to obtain flux density and one H-coil to obtain the magnetic field, whereas the so-called tetrapole probes utilize two electromagnetic yokes and two pickups [19]. Augustyniak et al [30] used a double-core set-up, where all four coils were wrapped on two perpendicular C-cores. In some specific geometries (rotational symmetry) the pickup coil can be wound around the sample as demonstrated in [8] or in [17,28].…”

“…Vengrinovich and Tsukerman have mainly studied stresses and created so-called directional diagrams (DD) of BN [19]. Augustyniak et al [30] utilized a double-core magnetizing set-up, which used four coils that were wrapped around two perpendicular C-cores: called the X-core and Y-core referring to the measurement direction. The tetrapole BN probe has also been studied by Refs.…”

“…Augustinyak et al [30] studied the magnetization of a double core set-up using ANSYS, which included tetrapole magnetizing coils with time-dependent density loading. Pal'a et al [49] studied the effect of an air gap from 50 to 200 µm between the probe and the sample, investigating the reproducibility of the measuring conditions.…”

Finite Element Method Applied in Electromagnetic NDTE: A Review

“…FEA plays an irreplaceable role in a comprehensive description of a time-and space-distribution of the magnetic induction within a studied object (plate, tube), which is impossible with any available analytical or experimental method. The FE solution of a magnetic field distribution inside a bulk ferromagnetic object is complicated by the fact, that excitation frequencies as low as 1 Hz generate a skin effect, which significantly disturbs the static field patterns [55][56][57]. Additional, special degrees of freedom (D.O.F.s) such as time-integrated electric potential may be necessary.…”

“…A recent work [57] presents a detailed analysis of a timeand space-distribution of the nonlinear magnetic field inside a steel plate magnetized with a double-core electromagnet with a separate control of AC excitation currents on both branches. These results, obtained with transient electromagnetic FEA are complementary to the previous research by Nagata [60], who applied the method of boundary elements for calculation of magnetic fields and eddy currents induced by a pair of orthogonal C-cores.…”