磁致伸缩/压电层叠复合材料磁电效应分析

采用有限元分析软件COMSOL5.0建立了三维悬臂梁模型,分析了磁致伸缩/压电/磁致伸缩叠层复合材料的磁电系数α_(ME),并就几何参数对复合结构磁电系数的影响进行了优化分析.首先,利用稳态求解器研究了磁电层状复合结构内部的应力、应变、位移以及电势分布情况,利用瞬态求解分析了磁电复合结构各变量动态分布规律;其次,应用小信号频域分析研究了该结构的谐振频率以及在不同偏置磁场对输出电压的影响,结果表明,随着直流偏置磁场的增加,输出电压逐渐减小.改变复合材料不同层的厚度,分析了磁电层与压电层厚度比t_m/t_p对磁电系数的影响,结果表明,随着厚度比增加,α_(ME)逐渐增大,其增加速率逐渐减小;最后,分析了磁电系数α_(ME)随复合结构面积、长宽比的变化情况.分析表明,α_(ME)随磁电复合结构面积的增加逐渐增加,其增加速率逐渐减小;当磁电复合结构面积恒定时,其磁电系数随长宽比L/W增加表现出先增加后减小的趋势,存在最优值.

Magnetoelectric effect analysis of magnetostrictive/piezoelectric laminated composites

Based on the finite element analysis software COMSOL5.0,a three-dimensional (3D) model of cantilever beam composed of magnetostrictive/piezoelectric/magnetostrictive laminated composites is established using the piezoelectric module and magnetic field module.The magneto electro coupling coefficient α_ME of the composite is analyzed.The effect of geometrical parameter on magnetoelectric coefficient is studied,and the geometrical parameters are optimized. Firstly,the stress,strain,displacement and potential distributions of the magnetoelectric layered structure are analyzed by the steady-state solver.The stress and strain concentrate on the fixed terminal while the maximum displacement exists in the free end of the structure.As a result,the potential appears between the upper and lower surface of the piezoelectric layer and the voltage distribution is not uniform.The output voltage in the fixed terminal is larger than that in the free end,which is about 49 V compared with 42 V in the free end.And the dynamic distributions of various variables in magnetoelectric composite structure are analyzed by transient solution.Secondly,the resonance frequency of the structure and the influence of the bias magnetic field on the output voltage are studied by small signal analysis in frequency domain.The results show that the output voltage decreases with the increase of H_dc.Also,the maximum output voltage is about 3.36 V at the second-order resonance frequency,which is far higher than the voltage at the first-order resonant frequency in the condition of bias magnetic fields H_dc=200 Oe and alternating magnetic fields H_ac=1 Oe.The reason is that the composite structure has a larger deformation at the second-order resonance frequency.Furthermore,the effect of thickness ratio between magnetostrictive and piezoelectric layers t_m/t_p on coupling coefficient is analyzed by changing the thickness of magnetostrictive layer and piezoelectric layer,respectively.The results show that the magnetoelectric coefficient increases with the augment of the thickness ratio,but the increasing rate decreases gradually.The research also shows that it has a greater influence on magnetoelectric coefficient to change t_p rather than t_m.Finally,the variations of magnetoelectric coefficient with the area of composite structure and the aspect ratio are analyzed.The results show that the magnetoelectric coefficient increases gradually with the augment of magnetoelectric composite area,but the increasing rate declines gradually.With the constant composite area,the magnetoelectric coefficient first increases and then drops with the increase of aspect ratio L/W,demonstrating the existence of an optimized value.Besides,the width W acts more importantly than length L because strain concentrates on the fixed terminal along