Eddy current testing of metallic sheets with defects using force measurements

Brauer, Hartmut; Ziółkowski, Marek

doi:10.2298/sjee0801011b

Cited by 32 publications

(12 citation statements)

References 15 publications

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“…The lift-off distance is used to design magnet systems better adapted to the applications. This work is a preparation for the characterization of a solid state body bar that is moving in the vicinity of a magnetic field and can be used for the validation of the results in [1].…”

Section: Resultsmentioning

confidence: 99%

Lorentz force eddy current testing: force dependency in respect to the lift-off distance computation & validation

Uhlig

Zec

Brauer

2011

IET 8th International Conference on Computation in Electromagnetics (CEM 2011)

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Lorentz force eddy current testing is a new nondestructive testing technique that enables its user to detect and localize defects deeply inside a conductive nonmagnetic solid state body. Since the magnet flux density B of a permanent magnet is decaying fast in space it is necessary to validate the known model of a point-like dipole by using finite sized magnets. The paper is comparing the dipole model above an infinite plane with the numerical model of finite shaped magnets and validation experiments. Using the obtained results design criteria for measurement setups can be derived.

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Section: Resultsmentioning

confidence: 99%

Lorentz force eddy current testing: force dependency in respect to the lift-off distance computation & validation

Uhlig

Zec

Brauer

2011

IET 8th International Conference on Computation in Electromagnetics (CEM 2011)

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“…The obtained electromagnetic field distribution is used to calculate the volumetric Joule losses Q (Pantelyat and Shulzhenko, 2006) and local force density f (Ren, 1994;Kumbhar et al, 2007;Brauer and Ziolkowski, 2008) in the structure under consideration:…”

Section: Problem Solutionmentioning

confidence: 99%

Transient electromagnetic field, losses and forces in a synchronous turbogenerator rotor

Pantelyat

Bíró

Stermecki

2013

COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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Purpose -The paper seeks to present a methodology of computer simulation of 3D transient electromagnetic fields, losses and forces due to negative sequence currents in fragments of large synchronous turbogenerator rotors. The methodology allows for the preparation of initial data for further computations of thermal and mechanical behaviour of rotors. Design/methodology/approach -The governing equations for 3D negative sequence transient electromagnetic fields with the Coulomb gauge using magnetic vector potential and scalar electric potential A, V -A are solved by the nodal finite element method in a Cartesian coordinate system moving synchronously with the rotor. Findings -The presented methodology of 3D transient electromagnetic phenomena computation seems to be effective because the electromagnetic field in the rotor of a synchronous generator is generally three dimensional, and therefore 2D field-computation approaches and software are not able to simulate intrinsically 3D electromagnetic processes in turbogenerator rotors. Research limitations/implications -Currently it is difficult to carry out accurate numerical simulation of 3D transient electromagnetic fields and therefore losses and forces within the whole structure of the rotor because of the resulting huge computational expenses. This paper is devoted to the finite element analysis of electromagnetic fields, losses and forces in separate structural parts of the rotor. As an example of practical utilization of the developed technique, the computer simulation of electromagnetic phenomena in junctions of nonmagnetic rotor slot wedges of a 300 MVA class synchronous turbogenerator is carried out. Practical implications -The methodology can successfully be used during the design process of modern large synchronous turbogenerators. Originality/value -This paper presents numerical analysis of intrinsically 3D transient electromagnetic phenomena in large turbogenerator rotors.

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“…The basic principle of Lorentz force eddy current testing (LET) was introduced in 2008 by Brauer and Ziolkowski (2008) and is shown in Fig. 1a.…”

Section: Introductionmentioning

confidence: 99%

Comparison of defect detection limits in Lorentz force eddy current testing and classical eddy current testing

Otterbach

Schmidt

Brauer

et al. 2018

J. Sens. Sens. Syst.

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Abstract. Lorentz force eddy current testing (LET) is a motion-induced eddy current testing method in the framework of nondestructive testing. In this study, we address the question of how this method is classified in comparison with a commercial eddy current testing (ECT) measurement device ELOTEST N300 in combination with the probe PKA48 from Rohmann GmbH. Therefore, measurements using both methods are performed and evaluated. Based on the measurement results, the corresponding defect detection limits, i.e., up to which depth the defect can be detected, are determined and discussed. For that reason, the excitation frequency spectrum of the induced eddy currents in the case of LET is considered.

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Eddy current testing of metallic sheets with defects using force measurements

Cited by 32 publications

References 15 publications

Lorentz force eddy current testing: force dependency in respect to the lift-off distance computation & validation

Lorentz force eddy current testing: force dependency in respect to the lift-off distance computation & validation

Transient electromagnetic field, losses and forces in a synchronous turbogenerator rotor

Comparison of defect detection limits in Lorentz force eddy current testing and classical eddy current testing

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