Abstract
Aiming to design magnetostrictive/piezoelectric asymmetric bilayer laminate structure that is commonly used in magnetoelectric (ME) sensor, a bilayer static nonlinear magneto-mechanical- electro-thermal coupled theoretical model which is about calculating ME coefficient and sensitivity is established. This model is based on the mechanical-electric linear constitutive relation of piezoelectric layer and one-dimension nonlinear thermal-magneto-mechanical constitutive relation of giant magnetostrictive material (GMM), in which the bending deformation caused by asymmetric structure has also been considered. The model shows universal applicability in the magnetostrictive/piezoelectric bilayer ME structure. In order to verify the validity of the model, magnetostrictive Terfenol-D and piezoelectric PZT are selected to constitute bilayer asymmetric ME composite structure sample, whose static ME coefficient is measured under different temperatures and bias magnetic fields. The model is degenerated to the ME coefficient model without stress, which shows a good predicted result being qualitatively and quantitatively consistent with experimental result confirming the validity of the model. Therefore, the nonlinear effects of pre-stress, bias magnetic field and environmental temperature, thickness ratio, as well as different piezoelectric materials on the ME coefficient and sensitivity were systematically investigated with our established model. The predicted result provides a roadway to improve static ME coefficient and sensitivity of devices by selecting different physic fields, materials, and thickness ratio for designing future ME sensors.
Highlights
The magnetic field sensor has very important application value in many fields, for instance, magnetoencephalography (MEG) and magnetocardiography (MCG) in biomedical applications which require weak magnetic field sensor with high precision and sensitivity.[1,2,3] Currently, the magnetic field sensor widely used in biomedical imaging is the superconducting quantum interference device (SQUID) sensor
The above-mentioned Terfenol-D/PZT bilayer magnetoelectric composite structure was selected to analyze the influence of temperature, bias magnetic field and pre-stress, as well as the influence of different piezoelectric materials and different thickness ratios on the magnetoelectric coefficient and sensitivity
In other words, when pre-stress changes from compressive stress to tensile stress under low magnetic field, magnetoelectric coefficient monotonically increases, while it monotonically decreases under high magnetic field
Summary
The magnetic field sensor has very important application value in many fields, for instance, magnetoencephalography (MEG) and magnetocardiography (MCG) in biomedical applications which require weak magnetic field sensor with high precision and sensitivity.[1,2,3] Currently, the magnetic field sensor widely used in biomedical imaging is the superconducting quantum interference device (SQUID) sensor. The composite ME material has the following advantages: simple structure, low price, high accuracy and ability to operate at room temperature It has huge potential in application of weak magnetic field sensor.[4,5,6,7,8,9,10,11]. Zhou et al.[20,21,22] established the tri-layer symmetry magnetoelectric structure and the equivalent circuit model of nonlinear magneto-mechanical-electro-thermal coupling under static and dynamic resonance based on the nonlinear magnetostrictive constitutive model, which can well describe the nonlinear magnetoelectric coupling effect under bias magnetic field, pre-stress and environmental temperature. The predictions through stress and environmental temperature systematically control the magnetoelectric coupling effect through stress engineering or environmental temperature, achieve high magnetoelectric coupling coefficient and high sensitivity, so as to provide a theoretical basis for the design and application of the ME magnetic field sensor
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