超磁致伸缩薄膜悬臂梁的非线性变形分析及试验

将双层超磁致伸缩薄膜(Giant magnetostrictive thin film，GMF)悬臂梁的磁致伸缩作用等效为分布弯矩作用，以简化磁机耦合模型。在几何非线性弹性变形理论基础上，根据哈密顿原理推导出超磁致伸缩薄膜非线性变形的控制方程，并给出超磁致伸缩薄膜悬臂梁静态几何非线性变形模型、非线性主共振和超谐波共振响应模型。采用悬臂梁式超磁致伸缩双层膜(铽镝铁—聚酰亚胺—钐铁)进行变形特性的试验研究，发现超磁致伸缩双层膜表现出明显的几何非线性变形特征，悬臂梁端部位移量约为厚度的2/3；同时检测到悬臂梁的超谐波共振现象，前三阶超谐波共振的驱动效率与一阶主共振的驱动效率具有可比性。将所提出的静态非线性变形模型和振动响应模型分别与试验结果对比发现，两个模型可较好地说明双层超磁致伸缩薄膜的非线性变形特性，为有效地利用超磁致伸缩薄膜设计开发微驱动器和微传感器提供依据。

NONLINEAR DEFORMATION ANALYSIS AND EXPERIMENT OF GIANT MAGNETOSTRICTIVE THIN FILM CANTILEVER

Through assuming that the magnetostriction effect of bimorph giant magnetostrictive thin film(GMF) cantilever is equivalent to the effect of a uniformly distributed bending moment, a nonlinear deformation governing equation of GMF is proposed, based on the geometrical nonlinear deformation theory and the Hamilton principle. Moreover, a static geometrical nonlinear deformation model, a nonlinear primary resonance and superharmonic resonance model, are presented. Thereafter, experiments on TbDyFe-PI-SmFe cantilever show that the deformation of cantilever end reaches the 0.67 times size of cantilever thickness, and the GMF exhibits clear superharmonic resonance, where the efficiency of superharmonic resonance of order 2, 3 and 4 is comparable with that of the primary resonance. The comparison between the static deformation model and resonance model with the experimental data indicates that the proposed models can describe well the static and dynamic nonlinear deformation of bimorph GMF cantilever. Thus, the proposed model provides the necessary basis for developing and designing effective microactuators and microsensors with GMF.