Study on the Magnetoelectric Performances of Magnetostrictive/Piezoelectric Laminate Composite

Study on the Magnetoelectric Performances of Magnetostrictive/Piezoelectric Laminate Composite
　　The magnetoelectric (ME) effect of magnetostrictive/piezoelectric (MP) laminate composite is realized by the“product property”, i.e., in a magnetic field, mechanical stresses arise in the magnetostrictive (M) layer due to magnetostriction and are transferred to the piezoelectric (P) layer, where it produces an electric field due to the inverse piezoelectric effect. As such, the ME effect provides a transduction method between magnetic and electric field signals. Important applications of such materials are magnetic field sensors and magnetoelectric transducers, with the main advantage being that they require no external power to operate.Firstly, the theoretical analysis of low frequency magnetoelectric performances in Longitude-Transverse type MP laminate composite is presented. Block neodymium magnet  The magnetostrictive laminate layers are designated to be magnetized in their longitudinal direction, while the piezoelectric layer is designated to be polarized in its thickness direction. The equivalent circuit of the composite is developed based on the constitutive equations of magnetostrictive and piezoelectric effects using the motion equation and circuit status equation. In terms of the equivalent circuit, it is straightforward to obtain the magnetoelectric response of the laminate composite, which is dependent on various parameters of magnetostrictive and piezoelectric materials. According to the theory, a discussion about the affect factors of ME response and a numerical calculation of Terfenol-D/PZT/Terfenol-D laminate composite are given out.
　　The MP laminate composite has dramatically enhanced ME effect when driven near resonance. A theory of the resonant ME effect is investigated using equivalent circuit method, in which the eddy current loss, the mechanical loss and the dielectric http://www.chinamagnets.biz/ loss are all taken into consideration. The results indicate that, when the laminate composite works at resonance, the mechanical loss plays a key role in the dissipation while a strong bias magnetic field is essential to restrain eddy current loss to improve the ME conversion efficiency. In addition, Terfenol-D/PZT-8 shall be more competitive in ME energy conversion near resonance than Terfenol-D/PZT-5.To verify the theoretical results, a ME response measure system is built up. The making procedure of Terfenol-D/PZT-5H sample and the cautions to the test system are introduced respectively. The experiments are processed by the active method and the ME performances are measured. The experimental results indicate, the theoretical value is about 5~8 times as much as the experimental one at low frequency when the losses aren’t taken into account, while the two values are close to each other at resonance in consideration of losses; and the bias magnetic field should be carefully selected to restrain the eddy current loss and adjust the resonant frequency of the composite. 更多还原