Eddy current testing of small radius conductive cylinders with the employment of an I-core sensor

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This paper presents a practical way of using the method of evaluating the metrological properties of eddy current sensors. The idea of the proposed approach consists of employing a mathematical model of an ideal filamentary coil to determine equivalent parameters of the sensor and sensitivity coefficients of tested physical quantities. These parameters were determined on the basis of the measured value of the real sensor’s impedance. The measurements were carried out with an air-core sensor and an I-core sensor while they were positioned at different distances from the surface of tested copper and bronze plates. An analysis of the influence of the coil’s position in relation to the I core on the equivalent parameters was also carried out, and the interpretation of the results obtained for various sensor configurations was presented in a graphical form. When equivalent parameters and sensitivity coefficients of examined physical quantities are known, it is possible to compare even very different sensors with the employment of one measure. The proposed approach makes it possible to make a significant simplification of the mechanisms of calibration of conductometers and defectoscopes, computer simulation of eddy current tests, creating the scale of a measuring device, and designing sensors.

Section: Introductionmentioning

confidence: 99%

Evaluation of the Properties of Eddy Current Sensors Based on Their Equivalent Parameters

Dziczkowski

Tytko

2023

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“…In typical AMB levitated high-speed machine applications, the displacement of the rotor in the mechanical air gap is measured with commercially available eddy-current-based displacement sensors [ 16 , 17 , 19 , 20 , 21 , 22 ]. In recent years, these sensors have gained increasing scientific attention [ 23 , 24 , 25 , 26 , 27 , 28 ] due their wide range of applications in health [ 29 ], aerospace [ 30 ] and automotive [ 31 ] fields. Additionally, improving sensor operational parameters for AMB systems has become an actual challenge for development [ 32 , 33 , 34 , 35 ].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Magnetic Field of AMB on Eddy-Current Sensor Operation

Kurnyta-Mazurek

Kurnyta

2023

This paper presents laboratory results on the influence of the magnetic field of an active magnetic bearing (AMB) on the eddy-current sensor operation. The magnetic suspension technology enables continuous diagnostics and monitoring of a rotary machine and eliminates drawbacks of classical bearing properties. The magnetic bearing system usually consists of two radial and one axial magnetic bearing. It is combined with a control unit, amplifiers and sensors for measuring the instantaneous position of the shaft. For this purpose, eddy-current sensors are frequently used. They operate in close proximity to the electromechanical actuators; therefore, the question arises whether the actuators do not interfere with the correct operation of these sensors. In the paper, the test rig and research plan prepared for that investigation are delivered. Measurement signals were registered from four control channels for different configurations of power supplies for system elements, e.g., with sensors and AMBs turned off, with sensors turn on and at normal work. Recorded time courses are presented and discussed in the paper. For the prepared test rig and AMB/eddy-current sensor configuration, no significant influence of the generated magnetic field from the support is found for the eddy-current sensor output.

“…What poses a real challenge is the determination of complex eigenvalues when the region under consideration consists of several sub-regions (containing conductive material or air). Such a situation occurs when modeling disks [ 8 , 9 , 10 , 11 ], tubes [ 12 , 13 , 14 , 15 , 16 ], rods [ 17 , 18 ], materials with a defect [ 19 , 20 , 21 , 22 , 23 , 24 ], and wherever there are edges [ 25 , 26 , 27 , 28 , 29 ] or discontinuities [ 30 , 31 , 32 ] ( Figure 1 ). Determination of the eigenvalues then boils down to finding complex roots of the appropriate complex function.…”

Section: Introductionmentioning

confidence: 99%

Computation of Eigenvalues and Eigenfunctions in the Solution of Eddy Current Problems

Theodoulidis

Skarlatos

Tytko

2023

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The solution of the eigenvalue problem in bounded domains with planar and cylindrical stratification is a necessary preliminary task for the construction of modal solutions to canonical problems with discontinuities. The computation of the complex eigenvalue spectrum must be very accurate since losing or misplacing one of the thereto linked modes will have an important impact on the field solution. The approach followed in a number of previous works is to construct the corresponding transcendental equation and locate its roots in the complex plane using the Newton–Raphson method or Cauchy-integral-based techniques. Nevertheless, this approach is cumbersome, and its numerical stability decreases dramatically with the number of layers. An alternative, approach consists in the numerical evaluation of the matrix eigenvalues for the weak formulation for the respective 1D Sturm–Liouville problem using linear algebra tools. An arbitrary number of layers can thus be easily and robustly treated, with continuous material gradients being a limiting case. Although this approach is often used in high frequency studies involving wave propagation, this is the first time that has been used for the induction problem arising in an eddy current inspection situation. The developed method is implemented in Matlab and is used to deal with the following problems: magnetic material with a hole, a magnetic cylinder, and a magnetic ring. In all the conducted tests, the results are obtained in a very short time, without missing a single eigenvalue.