Magnetoelectric doubling and mixing of electric and magnetic field frequencies in a layered multiferroic heterostructure

Nonlinear magnetoelectric effects in a disk-like heterostructure composed of a layer of amorphous ferromagnet (FeBSiC) mechanically coupled to a layer of piezoelectric ceramics (lead zirconate titanate) were studied both experimentally and theoretically. The structure was excited by alternating electrical and magnetic fields far from its acoustic resonance frequency. This induced changes in the magnetic induction within the heterostructure which were recorded using an electromagnetic coil. The experiments were performed for excitations with electric and magnetic fields up to 250 V/cm and 6 Oe, respectively, and bias permanent magnetic fields up to 60 Oe. For large excitation fields, a generation of the second harmonic and harmonics corresponding to the sum and difference frequencies were observed. The coefficient of the frequency doubling for the converse magnetoelectric effect and the coefficient of mixing of electrical and magnetic field frequencies were found to be 4.6∙10 −6 G cm 2/V 2 and ∼1∙10 −2 G cm/(Oe∙V), respectively. A simple theoretical model qualitatively describing the experimental findings was proposed. It was shown that the nonlinearity in the converse magnetoelectric effect arises due to the nonlinear dependence of magnetic induction in the ferromagnetic layer on mechanical stress. </p

Exploring the contraction actuation of magnetically functionalized electrospun tubes

Recently, magnetically functionalized polymer tubes (MFPTs) have been fabricated through a multistep electrospinning process. These innovative MFPTs can serve as ducts suitable for microfluidic components and biomedical devices. Considering these applications, it is crucial to investigate the effectiveness of inducing oscillating contractions at low frequencies. For this purpose, we designed an experimental setup to study the cross-sectional contraction of these smart tubes when subjected to a magnetic field produced by the oscillation of a small permanent magnet. A magnetoelastic wave resonator placed near the MFPT section detects the induced contraction, enabling the calculation of both its magnitude and response times. The results demonstrate that oscillating contractions, resulting in a maximum reduction of duct radius by approximately 43%, can be achieved with an oscillating magnetic induction field of amplitude around 10 mT, at a low frequency not exceeding 1/2 Hz. These findings highlight the potential of such innovative MFPTs, particularly in the fields of surgery and endoscopy

Magnetic Response of Nano/Microparticles into Elastomeric Electrospun Fibers

Combining magnetic nanoparticles (MNPs) with high-voltage processes to produce ultrathin magnetic nanofibers (MNFs) fosters the development of next-generation technologies. In this study, polycarbonate urethane nanofibers incorporating magnetic particles were produced via the electrospinning technique. Two distinct types of magnetic payload were used: (a) iron oxide nanoparticles (IONPs) with an average size and polydispersity index of 7.2 nm and 3.3%, respectively; (b) nickel particles (NiPs) exhibiting a bimodal size distribution with average sizes of 129 nanometers and 600 nanometers, respectively, and corresponding polydispersity indexes of 27.8% and 3.9%. Due to varying particle sizes, significant differences were observed in their aggregation and distribution within the nanofibers. Further, the magnetic response of the IONP and/or NiP-loaded fiber mats was consistent with their morphology and polydispersity index. In the case of IONPs, the remanence ratio (Mr/Ms) and the coercive field (Hc) were found to be zero, which agrees with their superparamagnetic behavior when the average size is smaller than 20–30 nm. However, the NiPs show Mr/Ms = 22% with a coercive field of 0.2 kOeas expected for particles in a single or pseudo-single domain state interacting with each other via dipolar interaction. We conclude that magnetic properties can be modulated by controlling the average size and polydispersity index of the magnetic particles embedded in fiber mats to design magneto-active systems suitable for different applications (i.e., wound healing and drug delivery)

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Magnetomechanical Effects in the Elastic Polymer Composites Containing Ferromagnetic Powder Particles

In the present work, a detailed thermodynamic consideration for the magnetic free energy of the composite material consisting of the ferromagnetic powder particles embedded into a polymer matrix is given. We estimate their magnetostatic interaction energy and its dependence on the microscopic distribution of the magnetization and the magnetic field in the composite material. We also define the hydrostatic component of the mechanical force developed in a composite and the volume change effect caused by the magnetostatic interactions in such composites.В данной работе даётся детальный термодинамический анализ магнитной свободной энергии композитного материала, который состоит из ферромагнитных порошковых частиц, внедрённых в упругую полимерную матрицу. Мы даём оценку их энергии магнитного взаимодействия и её зависимости от микроскопического распределения намагниченности и магнитного поля внутри композитного материала. Мы также определяем гидростатическую компоненту механических напряжений, которые развиваются в композите, и эффект изменения объёма, обусловленный магнитостатическими взаимодействиями порошковых частиц в таких композитах.В даній роботі дається детальна термодинамічна аналіза магнетної вільної енергії композитного матеріялу, що складається з феромагнетних порошкових частинок, втілених у пружню полімерну матрицю. Ми даємо оцінку їхньої енергії магнетної взаємодії та її залежність від мікроскопічного розподілу намагнетованости та магнетного поля всередині композитного матеріялу. Ми також визначаємо гідростатичну компоненту механічних напружень, що розвиваються у композиті, та ефект зміни об’єму, зумовлений магнетостатичною взаємодією порошкових частинок у таких композитах

APPLICATION OF THE MODIFIED MAGNETOELASTIC METHOD AND AN ANALYSIS OF THE MAGNETIC FIELD

In the technical praxis there is very often a need of axial force determination in the important structural elements of a building during its construction or operational state. The paper presents practical application of the new approach based on the magnetoelastic principle, especially aimed on experimental evaluation of the axial forces in the prestressed reinforcement on prestressed concrete structures. Described approach is usable not only for newly built structures but in particular for existing ones. The experiment was realized on a prestressed concrete beam dismantled from a bridge that was put out of operation. The influence of a simulated defect of the reinforcement on its magnetoelastic properties has also been investigated. During result evaluation, the knowledge based on the theoretical analysis of the electromagnetic field was used

Torsional oscillation monitoring by means of a magnetoelastic resonator: modeling and experimental functionalization to measure viscosity of liquids

A new application of a high sensitivity magnetoelastic resonator able to measure period and dampingconstant of low frequency torsional oscillation is described and validated by experimental tests. Thesensitive parameter is the amplitude of resonant magnetoelastic waves in the soft ferromagnetic core(Fe62.5Co6Ni7.5Zr6Cu1Nb2B15amorphous ribbon). The theoretical model of the device has been developed,correlating torsional oscillations to the friction force applied by the fluid in which they occur. Thus,an accurate indirect evaluation of fluid viscosity has been demonstrated. The main prerogative of theproposed sensor is to work without contact with the oscillating mechanism. As experimental validation,viscosity of UHT milk was measured versus different fat content. The experimental comparison with astandard rheometer demonstrates the new device competitiveness in the measure of low viscosity fluidsat low share rate. Moreover, the detected behaviors at increasing temperature are in agreement withprevious literature. In perspective, the new magnetoelastic resonators application can be very ductileand effective in on-line monitoring of viscosity change with time to control composition, degradation orcontamination of liquids