Magnetic Noise Research Articles

Fatigue Behaviour of Medium Carbon Steel Assessed by the Barkhausen Noise Method

Abstract In this paper, an attempt to estimate the stage of the fatigue process using the Barkhausen noise method is studied. First, microstructural and static tensile tests were carried out and, subsequently, fatigue tests up to failure were conducted. After determination of the material behaviour in the assumed static and dynamic conditions, the interrupted fatigue tests were performed. Each specimen was stressed up to a different number of cycles corresponding to 10%, 30%, 50%, 70% and 90% of fatigue lifetime for the loading conditions considered. In the next step of the experimental programme, the specimens were subjected to the Barkhausen magnetic noise measurements. Various magnetic parameters coming from the rms Barkhausen noise envelopes were determined. The linear relationship betweenthe full-width at half-maximum (FWHM) of the Barkhausen noise envelope and the number of loading cycles to fracture was found. Specimens loaded up to a certain number of cycles were also subjected to a tensile test to assess an influence of fatigue on the fracture features.

Low noise magnetic field compensation based on differential biplanar coils with small coil constant

Magnetic field noise is a key factor limiting the resolution of quantum precise measurement. In active magnetic field compensation systems, the large coil constant and fixed noise of the coil and current source, respectively, cause excessive noise. This study proposes a differential biplanar coils (DBCs) design method by comprehensively optimizing two sets of biplanar coils with differential evolution (DE) algorithm, which can reduce the coil constant by two magnitude orders while ensuring high uniformity. The peak-to-peak magnetic field at the center point is reduced to 0.8 pT, and the magnetic field noise is reduced to 8 fT/Hz, which is a reduction of 94.4%. The low noise active magnetic compensation system based on the differential biplanar coils can improve the accuracy of the magnetic shielding room (MSR) internal magnetic field control and reduce magnetic field noise effectively. The proposed method contributes to generating a near-zero magnetic field environment with low magnetic field noise, which is critical to promoting magnetoencephalography (MEG) measurements.

Fast Prediction and Staged Optimization of Electromagnetic Vibration in Permanent Magnet Synchronous Motor

The most common method to suppress electromagnetic vibration is to weaken the electromagnetic force harmonics (EMFHs), which are the vibration sources. Clearly, vibration is related to some other factors, too. Therefore, in this paper, modal analytical model and transmission function of a permanent magnet synchronous motor (PMSM) are studied, based on which a fast analytical method of predicting the electromagnetic vibration is proposed, so that the vibration can be preliminarily evaluated during the machine electromagnetic design. The time-consuming 3-dimensional finite element method (FEM) is not needed when predicting the vibration. Moreover, using the fast prediction method, a 15-dimensional multi-objective optimization problem for vibration, torque and efficiency performances is solved in stages. After optimization, the vibration is greatly reduced, and the torque performance is improved. The proposed methods are also proved to be applicable for different operating conditions and types of motors with various slot-pole combinations.

Research on Electromagnetic Vibration and Noise Suppression of PMaSynRM with Slotted Stator and Rotor

Research on Electromagnetic Vibration and Noise Suppression of PMaSynRM with Slotted Stator and Rotor

Dynamic Eccentricity Impact on Electromagnetic Vibration and Acoustic Noise of Interior Permanent Magnet Synchronous Motors With Different Numbers of Parallel Branches

Dynamic Eccentricity Impact on Electromagnetic Vibration and Acoustic Noise of Interior Permanent Magnet Synchronous Motors With Different Numbers of Parallel Branches

Measurement of Ambient Magnetic Field Noise for Through-the-Earth (TTE) Communications and Historical Comparisons

Measurement of Ambient Magnetic Field Noise for Through-the-Earth (TTE) Communications and Historical Comparisons

Detection of thermo-mechanical damages by in-process Barkhausen Noise Analysis combined with Grinding Power Evaluation

Grinding of workpieces from hardened steel, especially in case of safety relevant components, usually requires a reliable method for the detection of thermo-mechanical surface damages. Compared to the common post-process methods, in-process detection promises saving of detection time and, particularly, a fast reaction to negative influences on the surface integrity. The present work shows the suitability of magnetic Barkhausen noise (BN) for the in-process detection of thermo-mechanically influenced regions during an outer diameter cylindrical grinding process. Different from other non-destructive inspection methods, BN allows the detection of changes of the residual stress state even before the occurrence of visible tempering zones. However, in case of pronounced tempering or rehardening zones, a single BN value does not enable an unambiguous statement about the surface state. Therefore, additionally the specific grinding power Pc” in dependence of the contact time Δt is considered, which allows to exclude grinding burn starting from light tempering zones. A particular focus of this study is the BN analysis during grinding with different types of grinding wheels.

An Experimental Approach for Correlation of the Magnetic Barkhausen Noise to Microstructural Changes and Residual Stress in Welding Joints

An Experimental Approach for Correlation of the Magnetic Barkhausen Noise to Microstructural Changes and Residual Stress in Welding Joints

Coupling of Magnetic Field Noise in Multilayer Magnetic Shields for Atomic Magnetometer

Coupling of Magnetic Field Noise in Multilayer Magnetic Shields for Atomic Magnetometer

Alginate/GelMA microparticles via oil-free interface shearing for untethered magnetic microbots.

Microrobots hold broad application prospects in the field of precision medicine, such as intravenous drug injection, tumor resection, opening blood vessels and imaging during abdominal surgery. However, the rapid and controllable preparation of biocompatible hydrogel microparticles still poses challenges. This study proposes the one-step direct acquisition of biocompatible sodium alginate and gelatin methacrylate (GelMA) hydrogel microparticles using an oil-free aqueous solution, ensuring production with a controllable generation frequency. An adaptive interface shearing platform is established to fabricate alginate/GelMA microparticles using a mixture of the hydrogel, photoinitiator, and Fe3O4 nanoparticles (NPs). By adjusting the static magnetic field intensity (Bs), vibration frequency, and flow rate (Q) of the dispersed phase, the size and morphology of the hydrogel microparticles can be controlled. These hydrogel microparticle robots exhibit magnetic responsiveness, demonstrating precise rotating and rolling movements under the influence of an externally rotating magnetic field (RMF). Moreover, hydrogel microparticle robots with a specific critical frequency (Cf) can be customized by adjusting the Bs and the concentration of Fe3O4 NPs. The directional in situ untethered motion of the hydrogel microparticle robots can be successfully realized and accurately controlled in the climbing over obstacles and in vitro experiments of animals, respectively. This versatile and fully biodegradable microrobot has the potential to precisely control movement to bone tissue and the natural cavity of the human body, as well as drug delivery.

Hybrid Analytical-Numerical Electromagnetic Vibration Calculation Method for Surface-inserted PMSMs with Skewed Slots

Hybrid Analytical-Numerical Electromagnetic Vibration Calculation Method for Surface-inserted PMSMs with Skewed Slots

Analytical Study and Experimental Verification of Electromagnetic Vibration Sources and Optimization of Rotor Skew in Surface-Mounted Permanent Magnet Synchronous Machines

Analytical Study and Experimental Verification of Electromagnetic Vibration Sources and Optimization of Rotor Skew in Surface-Mounted Permanent Magnet Synchronous Machines

Fast Calculation of Electromagnetic Vibration of Switched Reluctance Machines Considering Magnetic Saturations and Simply Supported Constraints

Fast Calculation of Electromagnetic Vibration of Switched Reluctance Machines Considering Magnetic Saturations and Simply Supported Constraints

Fast Calculation of Electromagnetic Vibration of Surface-Mounted PMSM Considering Teeth Saturation and Tangential Electromagnetic Force

In view of the shortcomings of the existing calculation methods of electromagnetic forces, this paper proposes an analytical method (AM) combining the magnetomotive force (MMF)-permeance method and the improved subdomain method. The amplitude of each force density component considering stator teeth saturation and current harmonics is calculated, and the specific order and frequency components in the radial and tangential electromagnetic force densities are analyzed and sorted out. In modal analysis, the stator core and the casing are regarded as cylindrical shells with axial ribs, the natural frequencies of the stator are obtained based on the energy method, and the accuracy is well verified by the modal test. Finally, the frequency response functions of low-order modes of the stator only related to the stator structure parameters are determined, and the vibration accelerations under different working conditions are obtained based on the linear superposition principle by only updating the electromagnetic forces. Compared with the multi-physical coupling finite element analysis, the total calculation time of the proposed AM is reduced by more than 92%, which facilitates the fast prediction and effective reduction of electromagnetic vibrations in the motor design stage.

Optimization of Yoke Structure in Electromagnetic Vibration Devices

Optimization of Yoke Structure in Electromagnetic Vibration Devices

Optimized Suppression of Multi-Case Electromagnetic Vibration in Electric Vehicle IPMSM

Optimized Suppression of Multi-Case Electromagnetic Vibration in Electric Vehicle IPMSM

Enhancement of magnetoelectric coupling in laminate composites of textured Fe–Ga thin sheet and PZT

Magneto-mechano-electric (MME) generators consisting of piezoelectric and magnetostrictive materials can convert the stray magnetic noise to useful electric energy for the wireless sensor networks utilizing the magnetoelectric coupling effect and magnetic interactions. In this paper, a scalable engineering approach was proposed to fabricate the laminate MME generator composed of a PZT/Fe–Ga/PZT sandwich structure. The Goss-oriented Fe81Ga19 thin sheet with a large magnetostriction of 244 ppm was produced by a simple and low-cost approach, and the commercial polycrystalline piezoelectric ceramic products (PZT-5H) were used as the PZT layers. The effect of grain orientation, device structure, magnetic field amplitude, and resonance frequency on the electrical output of the PZT/Fe–Ga/PZT MME generator was investigated. The electrical output of the MME generator containing the Goss-oriented Fe81Ga19 thin sheet reached an AC voltage of 4.58 V and the ME coefficient of 76.33 V/cm·Oe under a low excitation magnetic field of 26 Oe at a low resonance frequency of 26 Hz. The MME generator with a Goss-oriented Fe–Ga layer shows 4.7 times higher output voltage and ME coupling coefficient than that with the no-oriented polycrystalline Fe–Ga layer, but only 81% of the latter’s resonance frequency. This is related to the significant increase in magnetostriction due to the texture transition after secondary recrystallization annealing at the temperature of 950 °C. This paper provides a very promising solution to meet the self-power supply needs of the Internet of Things utilizing low-value and low-frequency magnetic fields.

Suppression of Magnetic Noise and Field in Cubic Low-Noise Ferrite Magnetic Shields

Suppression of Magnetic Noise and Field in Cubic Low-Noise Ferrite Magnetic Shields

Comparative Non-Destructive Investigations of the Effects of Structural Changes After Heat Treatment of Carbon Steel Samples by Magnetic Noise and Vibration Methods

The microstructure of some components that work for a long time at high temperatures changes, which leads to a reduction in their life cycle. Traditionally, the study of the resulting structures is carried out by mechanical tests and metallographic analysis. The application of non-destructive methods increases the possibilities to monitor the quality of the elements and to prevent destruction. The aim of the study is to detect changes in the microstructure after different heat treatment and ageing heating of materials via magnetic noise and vibration methods. To realize the goal, samples of high-quality medium carbon steel were prepared through targeted heat treatments, quenching and tempering at different temperatures, as well as ageing heating at temperatures of 700 o C for up to 16 hours by vibration and magnetic noise method. The natural frequencies and damping properties of forced longitudinal vibrations of various heat treated steel specimens were obtained and analyzed. Using magnetic noise method, the following parameters were obtained and analyzed: root mean square voltage (RMS), energy and envelope parameters of magnetic noise signals. The comparative application of several non-destructive methods increases the knowledge of methods and materials and makes it possible to establish their sensitivity in studying microstructural characteristics.

Variation of color of magnetic noise in Er3+ molecular magnets contacting metal surface in ferromagnetic composite

Interaction between single molecule magnets (SMMs) and metal surface is a hot topic promising controllable deposition of SMMs, programmable frequency of magnetic relaxation and addressed reading of information. In this paper, we develop strategy of the Er3+ based SMM functionalization by its penetration inside the arrays of Ferromagnetic Micro Particles (FMPs). We show that predictable residual magnetic field of the FMPs arrays is an effective tool for regulation of the frequency maximum of imaginary magnetic susceptibility. We analyzed color of magnetic noise in respect to physical origin of magnetic relaxation. An additional channel for control over spin noise is formation of chemical bonds between SMM and the FMPs surface. Oxidation of an Er complex transforms 20 ± 5 % of the initial 10-coordinated SMM complex to the 9-coordinated complex with reduced relaxation time. Memorized residual magnetization of the composite material allows one to set desirable relaxation frequency in the individual micronized cells to create a sound frequency register. The proposed compaction of SMMs of different types in ferromagnetic composites provides engineering of the chemically designed spin interface on ferromagnetic surface for spintronics and quantum computing.