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Browsing by Author "Hasanyan, Davresh J."

Now showing 1 - 12 of 12
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    Effects of an in-plane axisymmetric magnetic field on the vibration of a thin conductive spinning disk
    Michalek, Arthur J.; Marzocca, Piergiovanni; Moosbrugger, John; Hasanyan, Davresh J. (American Institute of Physics, 2005-05-15)
    This paper details the derivation and solution of the governing equation for linear transverse vibrations of a thin perfectly conducting rotating disk subjected to an axisymmetric in-plane magnetic field having a circumferential flux pattern. Previous works on plates and shells have hypothesized that the application of a magnetic field is capable of increasing the natural frequency of a thin conductive plate. Analytical results show a significant increase in maximum stable operating speed of a thin disk in the presence of a magnetic field. The effect is dependent on both thickness and magnetic field strength. (c) 2005 American Institute of Physics.
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    Flux distraction effect on magnetoelectric laminate sensors and gradiometer
    Shen, Ying; Gao, Junqi; Wang, Yaojin; Hasanyan, Davresh J.; Finkel, Peter; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2013-10-07)
    A magnetic flux distraction effect caused by a nearby metallic material was investigated for Metglas/Pb(Mg1/3Nb2/3)O-3-PbTiO3 laminated magnetoelectric ( ME) sensors. Using flux distraction, a ME sensor can perform an accurate search for metallic targets of different dimensions at various distances. Detection results and simulations were in good agreement. The findings demonstrate an effective means to employ stationary ME sensors and gradiometers for magnetic search applications. (C) 2013 AIP Publishing LLC.
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    Geometry-induced magnetoelectric effect enhancement and noise floor reduction in Metglas/piezofiber sensors
    Wang, Yaojin; Li, Menghui; Hasanyan, Davresh J.; Gao, Junqi; Li, Jiefang; Viehland, Dwight D. (AIP Publishing, 2012-08-01)
    The geometry-dependent magnetoelectric (ME) effect was theoretically and experimentally investigated for multi-push-pull mode Metglas/Pb(Zr,Ti)O-3 sandwich-like laminates. Such structures hold promise for passive sensor applications. A geometry-induced significant enhancement in the ME coefficient and an effective reduction in the equivalent magnetic noise was observed due to an increase in the Metglas width fraction. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737906]
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    Giant converse magnetoelectric effect in multi-push-pull mode Metglas/Pb(Zr,Ti)O-3/Metglas laminates
    Li, Menghui; Wang, Yaojin; Hasanyan, Davresh J.; Li, Jiefang; Viehland, Dwight D. (AIP Publishing, 2012-03-01)
    The converse magnetoelectric (CME) effect was investigated theoretically and experimentally for multi-push-pull mode Metglas/Pb(Zr,Ti)O-3/Metglas laminates. The experimental and theoretical values of the CME coefficient (alpha(B)) exhibited similar trends. A large alpha(B) = 6.94 G/V was observed at 1 kHz under a dc magnetic bias of 11 Oe. At an electromechanical resonance frequency of 29.6 kHz, the laminate exhibited a giant value of alpha(B) = 79.5 G/V. These results show significantly enhanced CME effects in multi-push-pull mode laminates, compared to previously reported ones with different structures and materials. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3698114]
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    Giant resonant magnetoelectric effect in bi-layered Metglas/Pb(Zr,Ti)O-3 composites
    Gao, Junqi; Hasanyan, Davresh J.; Shen, Ying; Wang, Yaojin; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2012-11-15)
    In this paper, giant resonant magnetoelectric (ME) effect in an unsymmetrical bi-layered Metglas/Pb(Zr,Ti)O-3 ME composites with multi-push pull configuration that can be significantly tuned was investigated experimentally and theoretically. The actual measured and predicted results present the similar resonant frequency shifting behaviors for such ME composites: The resonant frequency can be varied from 70 Hz to 220 Hz by tip mass loading, where the ME voltage coefficients were over 250 V/cm-Oe. Moreover, the giant frequency-tunable resonant effect allowed us to design a 60Hz magnetic field energy harvester to be capable of harvesting energy generated by electronic instruments working on a 60Hz ac power supply. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4765724]
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    Magnetic and Elastic Interactions at Cracks and Interfaces in Ferromagnetic Materials
    Harutyunyan, Satenik (Virginia Tech, 2008-09-11)
    In addition to being useful for some nondestructive evaluation techniques, interactions between magnetic fields and defects in solids may also alter material properties. To explore this possibility, Maxwell's equations were coupled with a continuum mechanics model for elastic strain to formulate analytical expressions for the interaction of a magnetic field with several crack geometries. The influence of crack velocity and a realistic (nonlinear) magnetic susceptibility were included into a model of this type for the first time and shown to introduce unexpected trends in the magneto-elastic stress intensity. Singularities magneto-elastic stresses appear at different combinations of magnetic field strength and crack velocity, and the stresses at the crack tip switch sign. In a related study, the interaction of an alternating magnetic field with elastic stress through was explored through a coupling effect known as magneto-acoustic resonance. A model for the phenomena, in which magnetic waves excite elastic waves and vice versa, was formulated and used to explore the spin (magnon) and anti-plane elastic (phonon) interactions in piecewise homogeneous ferromagnetic spaces with two different sets of properties. The model suggests some combinations of magnetic field and frequency can produce a new kind of wave to appear. These new waves, which we call Accompanying Surface Magnetoelastic (ASM) waves, are localized at the interface between the two ferromagnetic media and they accompany reflection and transmission waves. It is shown that the amplitudes of the reflected, transmitted, and ASM waves depend strongly on magnetic field strength, frequency, and the angle of the incident wave, as well as on the physical properties of ferromagnetic media.
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    Magneto-Elastic Interactions in a Cracked Ferromagnetic Body
    Harutyunyan, Satenik (Virginia Tech, 2006-11-30)
    The stress-strain state of ferromagnetic plane with a moving crack has been investigated in this study. The model considers a soft magnetic ferroelastic body and incorporates a realistic (nonlinear) susceptibility. A moving crack is present in the body and is propagating in a direction perpendicular to the magnetic field. Assuming that the processes in the moving coordinates are stationary, a Fourier transform method is used to reduce the mixed boundary value problem to the solutions of a pair of dual integral equations yielding to a closed form solution. As a result of this investigation, the magnetoelastic stress intensity factor is obtained and its dependency upon the crack velocity, material constants and nonlinear law of magnetization are highlighted. It has been shown that stress result around the crack essentially depend on external magnetic field, speed of the moving crack, nonlinear law of magnetization, and other physical parameters. The results presented in this work show that when cracked ferromagnetic structure is under the influence of magnetic field it is necessary to take into account the interaction effects between deformation of the body and magnetic field and that such interaction can bring to a new conditions for strengthening the materials. Closed form solutions for the stress-strain state are obtained, graphical representations are supplied and conclusions and prospects for further developments are outlined.
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    Modeling of resonant magneto-electric effect in a magnetostrictive and piezoelectric laminate composite structure coupled by a bonding material
    Hasanyan, Davresh J.; Wang, Yaojin; Gao, Junqi; Li, Menghui; Shen, Ying; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2012-09-15)
    The harmonic magneto-electro-elastic vibration of a thin laminated composite was considered. A theoretical model, including shear lag and vibration effects was developed for predicting the magneto-electric (ME) effect in a laminate composite consisting of magnetostrictive and piezoelectric layers. To avoid bending, we assumed that the composite was geometrically symmetric. For finite length symmetrically fabricated laminates, we derived the dynamic strain-stress field and ME coefficients, including shear lag and vibration effects for several boundary conditions. Parametric studies are presented to evaluate the influences of material properties and geometries on the strain distribution and the ME coefficient. Analytical expressions indicate that the shear lag and the vibration frequency strongly influence the strain distribution in the laminates and these effects strongly influence the ME coefficients. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752271]
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    Shear-mode magnetostrictive/piezoelectric composite with an enhanced magnetoelectric coefficient
    Wang, Yaojin; Hasanyan, Davresh J.; Li, Jiefang; Viehland, Dwight D.; Luo, Haosu (AIP Publishing, 2012-05-01)
    A magnetoelectric (ME) laminate heterostructure consisting of two shear-mode piezoelectric Pb(Mg1/3Nb2/3)O-3-30PbTiO(3) (PMN-PT) single crystal layers, a longitudinally magnetized magnetostrictive Tb0.3Dy0.7Fe1.92 alloy plate, and a mechanical clamping brass substrate has been demonstrated that has a notably superior ME effect relative to previous laminate configurations of these two materials. A giant ME coefficient of 7.5 V/(cm Oe) at low frequencies under an optimal dc magnetic bias of similar to 400 Oe was found. The superior ME effects originate from the nature of heterostructure design, which allows the PMN-PT single crystals to operate in a shear mode that has maximum electro-mechanical coupling (i.e., d(15) = 6800 pC/N). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4718352]
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    Theoretical and experimental investigation of magnetoelectric effect for bending-tension coupled modes in magnetostrictive-piezoelectric layered composites
    Hasanyan, Davresh J.; Gao, Junqi; Wang, Yaojin; Viswan, Ravindranath; Li, Menghui; Shen, Ying; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2012-07-01)
    In this paper, we discuss a theoretical model with experimental verification for the resonance enhancement of magnetoelectric (ME) interactions at frequencies corresponding to bending-tension oscillations. A dynamic theory of arbitrary laminated magneto-elasto-electric bars was constructed. The model included bending and longitudinal vibration effects for predicting ME coefficients in laminate bar composite structures consisting of magnetostrictive, piezoelectric, and pure elastic layers. The thickness dependence of stress, strain, and magnetic and electric fields within a sample are taken into account, as such the bending deformations should be considered in an applied magnetic or electric field. The frequency dependence of the ME voltage coefficients has obtained by solving electrostatic, magnetostatic, and elastodynamic equations. We consider boundary conditions corresponding to free vibrations at both ends. As a demonstration, our theory for multilayer ME composites was then applied to ferromagnetic-ferroelectric bilayers, specifically Metglas-PZT ones. A theoretical model is presented for static (low-frequency) ME effects in such bilayers. We also performed experiments for these Metglas-PZT bilayers and analyzed the influence of Metglas geometry (length and thickness) and Metglas/PZT volume fraction on the ME coefficient. The frequency dependence of the ME coefficient is also presented for different geometries (length, thickness) of Metglas. The theory shows good agreement with experimental data, even near the resonance frequency. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4732130]
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    Theoretical model for geometry-dependent magnetoelectric effect in magnetostrictive/piezoelectric composites
    Wang, Yaojin; Hasanyan, Davresh J.; Li, Menghui; Gao, Junqi; Li, Jiefang; Viehland, Dwight D.; Luo, Haosu (American Institute of Physics, 2012-06-15)
    A quasistatic theoretical model including geometry effect is presented for predicting the magnetoelectric (ME) coefficients in a ME multilayer composite consisting of magnetostrictive and piezoelectric layers. The model is developed based on average-field method considering the geometry effect. The model characterizes the ME coefficient in terms of not only the parameters of two composite components and the thickness fraction but also the length and width fractions for the piezoelectric or magnetostrictive components. Analytical predictions indicate that the width and length fractions strongly influence the maximum ME coefficient and the corresponding thickness fraction also. Clearly, geometry effects cannot be ignored in predicting ME coefficient. Theoretical ME coefficients are also compared to experimental test data, demonstrating excellent agreement. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729832]
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    Ultralow equivalent magnetic noise in a magnetoelectric Metglas/Mn-doped Pb(Mg1/3Nb2/3)O-3-PbTiO3 heterostructure
    Wang, Yaojin; Gao, Junqi; Li, Menghui; Hasanyan, Davresh J.; Shen, Ying; Li, Jiefang; Viehland, Dwight D.; Luo, Haosu (AIP Publishing, 2012-07-01)
    An ultralow equivalent magnetic noise of 6.2 pT/root Hz at 1 Hz was obtained in a bimorph heterostructure sensor unit consisting of longitudinal-magnetized Metglas layers and a transverse-poled 1 mol. % Mn-doped Pb(Mg1/3Nb2/3)O-3-29PbTiO(3) (PMN-PT) single crystal. Furthermore, the equivalent magnetic noise was <= 1 pT/root Hz at 10 Hz. Compared with previously reported multi-push-pull configuration Metglas/PMN-PT sensor units, the current heterostructure exhibits a higher magnetoelectric coefficient of 61.5 V/(cm x Oe), a similar equivalent magnetic noise at 1 Hz and a lower noise floor at several hertz range. The ultralow equivalent magnetic noise in this sensor unit is due to the low tangent loss and ultrahigh piezoelectric properties of Mn-doped PMN-PT single crystals. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4733963]