Eddy Current Principle Research Articles

Effect of Mechanical Alloying Time on Microstructure, Hardness and Electrical Conductivity Properties of Cu-B4C Composites

This study aims to investigate the effect of mechanical alloying time on the microstructure, hardness, and electrical conductivity properties of copper (Cu) matrix boron carbide (B4C) reinforced composites. Cu-B4C composites with 2% B4C by volume were subjected to mechanical alloying processes for 0, 1, 5, 10, and 20 hours. The microstructure and phase formation of the composites were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Hardness measurements of the composites were conducted using the microhardness measurement method, and density values were determined using the Archimedes principle. The electrical conductivity values of the samples were measured in terms of the international annealed copper standard (%IACS) based on the eddy current principle. SEM images revealed a more homogeneous distribution of B4C particles in the Cu matrix as the mechanical alloying time increased. Hardness values showed significant increases with the increasing mechanical alloying time, reaching the highest value in the 20 h milled sample with a 90.86 value. The effect on electrical conductivity values was noteworthy, with a measurement of 63% IACS at 0 hours and 25% IACS at 20 hours of mechanical alloying.

The Influence of Blade Structure Optimization on the Hydraulic Performance of Vane Pump

Vane pump has the problems of low pressure reduction efficiency and easy to be stuck at the bottom of the well. In order to solve this problem, the annular pressure reduction downhole tool of vane pump based on eddy current principle is adopted. On the basis of introducing the principle of eddy current hydraulic pressure reduction technology, this paper studies the influence of blade number, blade outlet angle, blade chord height and blade thickness on tool characteristics. The results show that the tool head increases with the increase of blade number, increases first and then decreases with the increase of blade outlet angle, and decreases first and then stabilizes with the increase of blade wall thickness and chord height. The tool efficiency increases with the increase of blade number, decreases with the increase of blade chord height, and decreases with the increase of blade outlet angle to a certain value, which is less sensitive to blade wall thickness. The research results have important guiding significance for the design and structural optimization of blade annular pressure reducing tools.

Microstructure, wear and corrosion properties of Cu–SiC/WCCo composite coatings on the Cu substrate surface by plasma spray method

In this study, the microstructure, wear and corrosion properties of Cu–SiC/WCCo composite coatings produced on Cu substrates by plasma spray method were investigated. In order to achieve this aim, SiC and WCCo powders were added to copper at different rates such as 5 %, 10 % and 20 % by weight. In order to determine the microstructure properties and phase distribution of the produced coatings, optical microscope, SEM-EDS and XRD analysis were investigated. The reciprocating wear method was used in order to determine the wear properties and the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods was used to determine the corrosion properties. The electrical conductivities of the coating layers were performed according to the eddy current principle. XRD analysis results showed that in both coating types, ceramic particles decomposed in the plasma flame and as a result, binary and ternary metallographic phases were formed. There were significant increases in hardness by adding ceramic particles to Cu, especially with 20 % WCCo additive, the hardness obtained was 82 % higher than the Cu substrate. When the wear properties were examined, both abrasive/adhesive wear types were observed in the copper substrate and coating layers. In all samples, material loss increased as the load increased. Both EIS measurements and Tafel curve results showed that the Cu-5% WCCo coating had the best corrosion resistance among the coatings. When the electrical conductivity results of all samples were compared, the electrical conductivity decreased with increasing rate of carbide in the coating.

Detection, Verification and Analysis of Micro Surface Defects in Steel Filament Using Eddy Current Principles, Scanning Electron Microscopy and Energy-Dispersive Spectroscopy.

In the current industrial revolution, advanced technologies and methods can be effectively utilized for the detection and verification of defects in high-speed steel filament production. This paper introduces an innovative methodology for the precise detection and verification of micro surface defects found in steel filaments through the application of the Eddy current principle. Permanent magnets are employed to generate a magnetic field with a high frequency surrounding a coil of sensors positioned at the filament's output end. The sensor's capacity to detect defects is validated through a meticulous rewinding process, followed by a thorough analysis involving scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Artificial defects were intentionally introduced into a sample, and their amplitudes were monitored to establish a threshold value. The amplitude signal of these created defect was identified at approximately 10% FSH, which corresponds to a crack depth of about 20 µm. In the experimental production of 182 samples covering 38 km, the defect ratio was notably high, standing at 26.37%. These defects appeared randomly along the length of the samples. The verification results underscore the exceptional precision achieved in the detection of micro surface defects within steel filaments. These defects were primarily characterized by longitudinal scratches and inclusions containing physical tungsten carbide.

Automatic Feeder for Hardness Testing Equipment

This paper presents the development of the concept of automating the process of feeding the rocker arm bearing shafts into the hardness testing equipment. The present system used in industry for feeding is a manual feeding of the rocker arm bearing shafts (RABS) into the hardness testing equipment. A labourer feeds each and every component by hand, picking up 10-15 components at a time and then feeds it into the hardness testing equipment one by one. The eddy current principle is used here to check the hardness of the component. Hardness testing of components is done to ensure the rocker arm bearing shafts meet the hardness standard to ensure that it works for the designed purpose without any failure. The proposed system is an automated process. Suitable mechanical and electronic components are used to achieve automation and a finalized concept was generated. The proposed system consists of an automatic vibratory feeder bowl, a pneumatic double acting cylinder and proximity sensors. When the components are placed in the vibratory bowl due to the action of the feeder the components get stacked up then moves through a chute and then it will be pushed into the hardness testing equipment with the help of a double acting cylinder. The sensors are used to monitor and control the feeding process.

Индукционный метод локализации фронта кристаллизации

The paper describes the development and testing of an inductive sensor designed for determining the position of the solidification front of electricallyconductive melts. The operation of the sensor is based on the eddy current transducer principle. We compared induction and ultrasonic methods of localizing the solidification front of a gallium alloy on a model problem of directional solidification of liquid metal in a flat vertical layer. The principles of the induction method are described, its ap-plicability is shown, the measurement error has been found.

Experimental Investigations to Study the Influence of Thickness and Speed of Aluminum Discs on Brake Parameters with Neodymium – Iron – Boron Magnets

In the existing friction brakes there are several problems such as squealing, judder, thermal and mechanical failures, disc distortions etc. Hence, in the current work an effort is made to develop contactless braking system using eddy current principles. Aluminum disc along with Neodymium – Iron – Boron (NdFeB) permanent magnets are used for investigations. Thickness of discs considered are 4, 6 and 8 mm. Speeds of disc rotation are equivalent of 75.39 Km/hr, 113 Km/hr, 150.8 Km/hr and 188.5 Km/hr. Considered brake parameters are percentage of reduction in speed, negative acceleration and time consumed. In lone magnet situation with gradual application, higher percentage of reduction in speed, good negative acceleration and less time consumed were observed in 4 mm disc thickness. Hence is suitable for faster train applications. In lone magnet with rapid application situation, superior negative acceleration and lesser time consumed were found in 4 mm disc thickness. This situation is beneficial for high speed automobile applications.

IMPROVING THE EDDY CURRENT IDENTIFIER OF METALS BASED ON THE CORRELATION APPROACH

Context. The article considers the problem of improving the eddy current device for metal identification on the basis of the correlation approach. This approach is convenient for the accumulation of a database of known leading materials, as well as for the comparison of the signal from an unknown metal object with the available standards in the database. The proposed approach allows to determine the type of metal from which the sample is made, without damaging its surface.
 Objective. The aim of the work is the identification of metals by type on the feedback signals from the eddy current converter, due to the identification of new informative features and the creation of a database of images of metals.
 Method. The paper presents the results of an experimental study of the proposed approach to increase the reliability of identification of metal objects that are detected using an eddy current device. These studies are conducted on the basis of a radio system that operates on the eddy current principle and has low-frequency magnetic loop antennas. The eddy current method allows the identification of metals by type remotely and without damaging their surface, in contrast to X-ray fluorescence, optical emission or chemical methods. A correlation approach for processing the response signal spectrum from a hidden metal object is proposed. The correlation approach allows to increase the reliability of the identification of metals by type when processing the signal in the spectral region based on the Fourier transform. Studies have been conducted on the example of metals that have similar spectral characteristics (silver, gold, lead). The updated approach allowed to increase the percentage difference between the information parameters of signals – responses from 1.87% to 5.02% for silver and gold, from 2.24% to 4.34% for silver and lead and from 0.36% to 0.7% for gold and lead.
 Results. The developed radio system is a laboratory model, which consists of an analog part and a digital one. The analog part is an antenna unit, a signal amplifier and a bandpass filter, a digital part – a microcontroller with an ADC for digitizing and transmitting data to a laptop, which software implements the proposed approaches to signal processing. The paper experimentally confirmed the possibility of using a radio engineering system to solve the problem of metal identification within a subset of nonmagnetic and magnetic materials.
 Conclusions. The development of modern eddy current devices is aimed at increasing the reliability of the identification the hidden metal objects, which is relevant in geophysical exploration, archeology, and law enforcement agencies in the search for hidden non-ferrous metals. The development and improvement of such systems includes both the development the hardware and the discovery new information parameters in the feedback signals from metals. One such direction may be the correlation approach to signal processing in the spectral region.

Development of an Inductive Rain Gauge.

Measuring weather data in an urban environment is an important task on the journey towards smart cities. Heavy rain can cause flooding in cities and prevent emergency services from reaching their destination because roads or underpasses are blocked. In order to provide a high-resolution site-specific overview in urban areas during heavy rainfall, a dense measurement network is necessary. To achieve this, a smart low-cost rain gauge is needed. In this paper, the current status of the development of an inductive rain gauge is presented. The sensor is based on the eddy current principle and evaluates the frequency of an electrical resonant circuit. For this purpose, a coil is placed under a metal plate. When raindrops hit the plate, it starts to oscillate, which changes the distance to the coil accordingly and causes changes in the frequency of the resonant circuit. Since the sensor is cost-effective, operates self-sufficiently in terms of energy and transmits data wirelessly via LoRaWAN, it can be used flexibly. This enables dense, area-wide coverage over the urban area of interest. The first experimental investigations show a correlation between the size of the rain droplets and the frequency change. Small droplets cause a shift of about 8 kHz and larger droplets of up to 40 kHz. The results prove that raindrops can be detected and categorized using this measurement principle. These data will be used as a basis for future work on calculating precipitation.

Development of a Cone-Shaped Pulsed Eddy Current Sensor

Compared with the conventional eddy current, pulsed eddy current (PEC) technology has the characteristic of abundant components in the frequency domain, which is a significant technological advancement. Improvements in the production and performance of PEC sensors are necessary for nondestructive testing. Sensor configuration parameters have significant influence on the development of PEC system. In this study, through finite element simulation and experimental investigation, different optimization methods for PEC sensors are compared and studied. According to the eddy current detection principle, a two-dimensional finite element simulation model was established to study the influence of the shape and size parameters of cone-shaped PEC sensors. Then a cone-shaped PEC sensor was optimized by the orthogonal methodology and the response surface methodology, respectively. To compare the effectiveness of the optimization methods, two optimized sensors were fabricated. It was demonstrated that the combination of finite element method and response surface methodology was superior for improving the detection performance of the PEC sensor compared with the orthogonal methodology. The result also indicated that the developed cone-shaped PEC sensor had a stronger defect detection capability than cylindrical-shaped PEC sensors. The proposed optimization design method provides a feasible reference method for the design of PEC sensors and corresponding parameters.

Study on Adaptive Excitation System of Transmission Line Galloping Based on Electromagnetic Repulsive Mechanism

Due to the uncontrollable weather conditions, it is difficult to carry out the controllable prototype test to study fatigue damage of transmission tower and armour clamp and the effect evaluation of antigalloping device under actual transmission line galloping. Considering the geometric nonlinearity of the transmission line system, this study proposed an adaptive excitation method to establish the controllable transmission line galloping test system based on the Den Hartog vertical oscillation mechanism. It can skip the complicated process of nonlinear aerodynamic force simulation. An electromagnetic repulsion mechanism based on the eddy current principle was designed to provide periodic excitation for the conductor system according to the adaptive excitation method. The finite element model, including conductor, insulator string, and electromagnetic mechanism, was established. Newmark method and fourth-order Runge-Kutta algorithm were used to complete the integrated simulation calculation. By comparing with the measured data record of the actual transmission line galloping test, the results show that the proposed adaptive galloping excitation system can effectively reconstruct the key characteristics of the actual transmission line galloping, such as amplitude, frequency, galloping mode, and dynamic tension, and make the galloping state controllable. Thus, a series of research about transmission line galloping with practical engineering significance can be carried out.

The braking service of the linear induction motors with a compound-equalized magnetic flux for magnetic-levitation transport

In recent years, more and more attention has been paid to the development of new promising high-speed modes of the transport, especially, magnetic and vacuum pipelines. The linear induction motors will be used as traction machines in the early stages of the development of the magnetic-levitation and vacuum transport. The linear induction motors with compound-equalized magnetic flux for lines of the force, which, in addition to traction, can create lateral stabilization forces of high-speed carriages on a magnetic suspension, will be used in a magnetic vehicle in the nearest future. The effective and safe braking issues are of particular importance for high-speed magnetic-levitation transport. To reduce the speed and stop high-speed transport carriages on a magnetic suspension, the linear traction motors can operate as eddy current principle of the brakes. The article discusses the braking modes of a linear induction motor with a compound-equalized magnetic flux for lines based on the equivalent circuit of the machine. The analytical relationships are obtained for the calculation of the braking forces.

Influence of AC magnetic field on the cladding layer during the micro beam plasma welding of austenitic stainless steel

In the process of micro beam plasma welding of thin-walled parts, gravity and surface tension make a molten metal flow downward, sometimes causing a bad formation. To solve this problem, a new external magnetic field-controlled method based on the eddy current principle was proposed. The distribution of the magnetic flux density, the induced current density, and the Lorentz force on a 4 mm stainless steel AISI 304 thin plate was examined using different oscillation frequencies (1, 5, 10 kHz) of the magnetic field with the finite element package COMSOL Multiphysics 5.0. The higher frequency was found to be more helpful to create greater electromagnetic force. This study examined the single-pass and three-layer welding of the 4-mm-thick stainless steel AISI 304 with different magnetic fields (3~12 mT) at 10 kHz. The results show that 7- and 8-mT magnetic fields were effective in suppressing the sagging of the cladding layer.

Eddy current sensor simulation

PurposeThis paper aims to present a simulation concept and an experimental verification of a novel sensor design for the shaft position measurement based on the eddy current principle and the phase-shift measurement. The simulation method for the sensor characteristic determination is presented. Possible application of a new sensor type is theoretically presented, verified in simulation and compared with experimental results.Design/methodology/approachSensor is based on the injection-locking phenomenon between coupled oscillators. Only one sensor per axis is used for position measurement. A pair of the sensing and reference oscillators in the sensor is electrically coupled via the coupling resistor. A change in the inductance for the eddy current sensor is simulated in the finite element method (FEM) software Flux and behavior of the sensor circuit is simulated in the SPICE simulator software LTSpice program. Finally, the simulation results are compared with the measurements conducted on the laboratory test rig.FindingsA novelty in this approach is the usage of only one sensor per axis compared to the well-known differential measurement of the position that uses the opposite pair of the sensing oscillators in the same axis. A methodology for the sensor characteristic determination is presented and experimentally verified.Originality/valueA new variation of a coupled-oscillator eddy current sensor design is introduced. A simulation approach for the characteristic determination of the sensors based on the weakly coupled oscillators and the injection-locking mechanism is presented.

Single-tone and Polyharmonic Eddy Current Metal Detection and Non-Destructive Testing Education Software

This paper describes the design of a measuring chain for polyharmonic metal detectors used for education in laboratory exercises at Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Measurement. The Measuring chain is composed of DDS signal generator, Digitiser and PC with software programmed in Labview. Eddy current principles or more specifically eddy current metal detectors are an important part of nondestructive testing, instrumentations and measurement. A short introduction to the background and principles of eddy current metal detectors are presented. Next part of the article deals with a brief description of the most common methods, as well as, non-traditional polyharmonic methods for eddy current metal detection. The following part contains an implementation of the proposed algorithms in LabVIEW graphical programming language. Finally, the created program for education of eddy current metal detectors and results obtained on the metal detector ATMID are discussed.

Preliminary Investigations of Machine Frame Vibration Damping Using Eddy Current Principle

A novel approach to vibration attenuation, based on the eddy current principle, is described. The combined effects of all magnetic forces acting in the oscillatory system attenuate frame vibrations and, concurrently, decrease the damped natural frequency. A mathematical model of the forces balance in the oscillatory system was derived before. Some experimental results from a mock-up machine frame excited by an asynchronous motor are presented.

The Design of Eddy Current Sensor Based on ANSYS and the Research on Weld Flaw Recognition Method

Eddy current sensor with online non-contact measurement, no coupling medium and high sensitivity etc, is widely used in engineering. In this paper, based on the eddy current testing principle, the eddy current sensor is modeled in ANSYS software to complete the optimization design. The article research on the method of flaw recognition after extracting the detection signal features and analysis the impact of the flaw size on the detection signal, so as to provide a theoretical method of qualitative detection in the practical application.

A Data Standardization and Reconstruction Method for Magnetic Induction Tomography

Magnetic induction tomography (MIT) is a biologic tomography technology, which is to obtain the conductivity distribution by detecting the data on the boundary of the imaging area based on the eddy current principle. The small impedance difference between biological tissues makes the eddy current weak, and it leads to a direct effect on the biological impedance measurement and imaging sensitivity. A measured data standardization method is presented in this paper for enhancing the measured data sensitivity, and combined with the back-projection reconstruction algorithm to get reconstruction image. It is applied to a variety of measurement and the simulation experiment based on the calculation results of finite-element methods. The reconstructed images indicate that the method can improve the image resolution and sensitivity, and which provides an effective data standardization and reconstruction algorithm for the magnetic induction tomography.

Prediction of the Ferrite-Core Probe Performance Using a Neural Network Approach

Physical properties and coating thickness of the materials are measured using the eddy current principles. Most publications on the eddy current method are directed toward air-core coils operated at high frequency. But low-frequency ferrite-core probes provide the advantage of enhanced signal-to-noise ratio and increased resolution for electronic detection. A ferrite-core probe design has several parameters, which includes the selection of ferrite material and the design of the probe structure and core. In this article a total of five variables, which are most influential on probe performance, were considered. A three-layer back-propagation neural network model is used to correlate these variables to probe performance using the data generated based on experimental observations.

Effect of Processing Parameters on the Structural and Mechanical Properties of Micro Arc Oxidized Aluminium Alloy

The micro arc oxidation process (MAO) was applied to a 2024 ingot aluminium alloy by an AC MAO equipment using an alkali based electrolyte. The processing parameters of the process were positive and negative voltage pulse durations. Structural and morphological characterization of the coating were made by a scanning electron microscope (SEM), an X-ray diffractometer (XRD), a surface profilometer and a thickness gage operating according to the Eddy current principle. Cross sectional hardness of the coatings was measured, and reciprocating wear and immersion corrosion tests were performed. XRD analysis showed that an oxide layer comprising - and -Al2O3 phases was produced on the surface, whose thickness and surface roughness varied by the processing parameters applied. Wear and corrosion resistance of the original alloy significantly improved upon the MAO process. Variation of hardness, wear and corrosion resistance with respect to the processing parameters was discussed based on the experimental data obtained.