The paper contains an original comprehensive review of finite element analysis (FEA) applied by researchers to calibrate and improve existing and developing electromagnetic non-destructive testing and evaluation techniques, including but not limited to magnetic flux leakage (MFL), eddy current testing, electromagnetic-acoustic transducers (EMATs). Premium is put on the detection and modelling of magnetic field, as the vast majority of ENDT involves magnetic induction, either as a primary variable MFL or a complementary phenomenon (EC, EMATs). FEA is shown as a fit-for-purpose tool to design, understand and optimise ENDT systems, or a Reference for other modelling algorithms. The review intentionally omits the fundamentals of FEA and detailed principles of NDT. Strain-stress FEA applications in NDT, especially in ultrasonography and hole-drilling methodology, deserve as well a separate study.
The NDT procedure dubbed 'metal magnetic memory' method and the related ISO 24497 standard has found wide industrial acceptance in some countries, mainly in Russia and China. The method has been claimed by some researchers (Roskosz and Bieniek in NDT&E Int 45:55-62, 2012; Wilson et al. in Sens Actuators A 135:381-387, 2007) as having potential for quantitative determination of local residual stress state in engineering structures, at least for some steel grades. This work presents a critical reexamination of a previous important study by Roskosz and Bieniek, who claimed to have found a direct relationship between local residual equivalent stress levels ranging from 0 to 50 MPa, and the stray field gradients in T/P24 steel sample placed in the Earth's ambient magnetic field. We reconstruct their experiment in a magnetic finite element simulation, computing stray magnetic field and its tangential gradients along the axis of the sample. Different combinations of remanent induction and relative magnetic permeability levels have been modeled, and the influence of geometrical discontinuity is quantified. In order to validate magnetic finite element methodology, a new experiment is presented, along with its numerical counterpart. The magnetic finite element method allowed to obtain a good quantitative correlation with well-controlled stray field measurements. It is demonstrated, that the residual stress level of order of 50 MPa is not the only factor, on which the stray field measurement depends. The geometrical discontinuity and the remanent induction contribute to a higher extent to the field amplitudes. Consequently we prove, that a bidirectional correlation between B Marek Augustyniak maugustyniak@mif.pg.gda.pl 1 Gdansk University of Technology, 80233 Gdansk, Poland 2 DES ART Ltd, 81366 Gdynia, Poland the magnetic field gradient and local stress levels cannot be determined because of at least three concurrent inseparable factors on which the measured stray field and its spatial gradient depends.
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
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.