Lorentz force sigmometry: A contactless method for electrical conductivity measurements

Uhlig, Robert P.; Zec, Mladen; Ziółkowski, Marek; Brauer, Hartmut; Thess, André

doi:10.1063/1.4716005

Cited by 24 publications

(12 citation statements)

References 13 publications

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“…The phase and amplitude of the drag and lift forces provide information about the material properties of the conductor. Oscillating magnet systems could be applied within the context of Lorentz force eddy current testing [49] as an alternative to constant rectilinear motion.…”

Section: Discussionmentioning

confidence: 99%

Oscillatory Motion of Permanent Magnets Above a Conducting Slab

et al. 2015

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This paper provides the 3-D time-dependent analytical solution of the electromagnetic fields and forces emerging if a coil or a permanent magnet moves with a sinusoidal velocity profile relative to a conducting slab of finite thickness. The results can be readily used in application scenarios related to electromagnetic damping, eddy current braking, energy harvesting, or nondestructive testing in order to efficiently analyze diffusion and advection processes in case of harmonic motion. This paper is performed for rectangular and circular coils as well as for cuboidal and cylindrical permanent magnets. The back reaction of the conductor and therewith associated inductive effects are considered. The solutions of the governing equations and the integral expressions for the time-dependent drag and lift force are provided. The analytical results are verified by a comparison with numerical simulations obtained by the finite-element method. The relative difference between the analytically and numerically evaluated force profiles was <0.1%. Exemplary calculations show that the waveforms of both force components strongly depend on the level of constant nominal velocity v 0 , the magnitude of the velocity oscillation amplitude v 1 , and the underlying oscillation frequency f v .Index Terms-Analytical models, boundary value problems, eddy currents, harmonic analysis, permanent magnets. 0018-9464

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Section: Discussionmentioning

confidence: 99%

Oscillatory Motion of Permanent Magnets Above a Conducting Slab

et al. 2015

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“…Conductivity and thickness of metal sheets are two important variables that play an essential role in product quality, process control, and cost control in many industries [1][2][3][4]. Currently, there are various methods available to measure them, such as ultrasonic, thermal, eddy current and four-point methods.…”

Section: Introductionmentioning

confidence: 99%

Elimination of liftoff effect using a model-based method for eddy current characterization of a plate

Fan

Cao

Yang

et al. 2015

NDT & E International

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“…The interaction of the induced magnetic field within the copper plate and the magnetic field of the PM causes a braking force opposing the motion of the PM (Amjadian and Agrawal, 2016, 2017; Knoepfel, 2000). This braking force is proportional to the velocity of the PM that resembles the viscous force in a linear fluid damper (Uhlig et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Planar arrangement of permanent magnets in design of a magneto-solid damper by finite element method

Amjadian

Agrawal

2020

Journal of Intelligent Material Systems and Structures

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This article studies the energy dissipation mechanism of a proposed magneto-solid damper using a three-dimensional finite element model developed in COMSOL Multiphysics software. The energy dissipation mechanism of the magneto-solid damper dissipates energy through combined actions of friction and eddy current damping. The key components of the magneto-solid damper are a steel plate, two copper plates placed on two sides of the steel plate in parallel, and two planar arrays of permanent magnets each one placed between the steel plate and one of the copper plates. These arrays are kept away from the steel and copper plates through narrow gaps; the gaps between them and the steel plate are filled with thin friction pads made of non-magnetic materials. The attractive magnetic interaction between the permanent magnet arrays and the steel plate provides the normal force for the friction developed between the friction pads and the steel plate when the permanent magnet arrays move relative to the steel plate. The motion of the permanent magnet arrays relative to the copper plates, on the other hand, provides the eddy current damping. The main contribution of this article is to optimize the pole arrangement of the permanent magnets and demonstrate that how the optimum pole arrangement can affect the energy dissipation capacity of the magneto-solid damper. The analysis results show that, for a given number and size of the permanent magnets, alternate arrangement of the poles of permanent magnets along the direction of their motion is the most optimal case resulting in large and smooth hysteresis force–displacement loops. This pole arrangement has also been used to find the optimum size of the steel and copper plates by addressing edge and skin effects in the design of the damper.

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Lorentz force sigmometry: A contactless method for electrical conductivity measurements

Cited by 24 publications

References 13 publications

Oscillatory Motion of Permanent Magnets Above a Conducting Slab

Oscillatory Motion of Permanent Magnets Above a Conducting Slab

Elimination of liftoff effect using a model-based method for eddy current characterization of a plate

Planar arrangement of permanent magnets in design of a magneto-solid damper by finite element method

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