纵向极化与磁化的压电/磁伸材料磁电效应理论及实验

Theoretical and experimental study on magnetoelectric effect in longitudinal polarized and magnetized piezoelectric/magnetostrictive laminate materials

将磁致伸缩材料及压电材料的本构方程与运动方程相结合,考虑到压电材料具有高输出阻抗特点及测试仪器的有限输入阻抗和传输信号引线电容对磁电效应输出电压的影响,给出了纵向极化压电材料与纵向磁化的Terfenol-D巨磁伸材料形成的磁电元件的磁电效应理论.研制了由六根一维磁伸材料构成的磁电元件并对其磁电效应性能进行了测试.与前人的理论结果比较可见考虑测试系统有限输入阻抗及电缆电容后建立的磁电效应理论与实验结果更吻合.传输信号的电缆电容及测试仪器输入阻抗对检测结果产生很大的影响,它可用于解释实际中检测到的电压远小于开路电压理论结果的原因.开路下纵向极化磁电元件磁灵敏度的理论值达6V/Oe(1Oe=79.6A/m),而仪器实际检测到的磁灵敏度(电压转换系数)仅为数百毫伏每奥.

Combining the constitutive equations of longitudinal polarized piezoelectric materials and the longitudinal magnetized magnetostrictive materials with an equation of motion for the whole magnetoelectric element, and considering the high impedance characteristics of the piezoelectric materials, the finite input impedance of the measuring instrument and the cable capacitance, the theory describing the magnetoelectric effect was derived. The performance of the magnetoelectric element consisting of six slender magnetostrictive bars was tested. The theoretical results are in better agreement with the experimental results compared with the one previously reported. It is pointed out that the output voltage of magnetoelectric element can be greatly influenced by the cable capacitance and the input impedance of the measuring instrument. The theory can be used to explain why very large output voltage predicted by the former theoretic results has never been observed by measuring instrument. The theoretical voltage value of the magnetoelectric element for open-circuit condition can reach 6 V/Oe, but the measured output voltage is only hundreds of mV per Oe.