【作者】 刘巍；

【导师】 贾振元； 张永顺；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2007， 博士

【摘要】 作为一种新型的功能材料，超磁致伸缩薄膜具有强磁致伸缩效应、高机电耦合系数、较高的响应速度、非接触式驱动及良好的结构性能等优点而倍受关注，在微传感器和微驱动器等领域显示出良好的应用前景。超磁致伸缩薄膜的静动态磁机耦合特性及模型是采用超磁致伸缩薄膜设计开发微器件的重要基础。但由于薄膜的磁机耦合关系具有强的非线性和滞回性，使得薄膜的特性建模十分困难。目前所建立的静态磁机耦合模型存在参数过多、计算复杂等问题，而动态磁机耦合模型的研究尚未见报道。以上这些问题严重阻碍了超磁致伸缩薄膜及其器件的发展。本论文以这种新型的功能材料为基础，以该类材料的静动态磁机耦合特性及模型为研究对象，同时应用超磁致伸缩薄膜拟研制一种能在液体微管道内泳动的微型机器人，为超磁致伸缩薄膜的静动态磁机耦合特性及其微传感器和微执行器的研究提供一个新的途径和思路。本论文从薄膜磁致伸缩现象的产生机理出发，分析论述了超磁致伸缩薄膜的磁致伸缩特性。同时，较为系统地分析研究了材料成分、薄膜内应力和热处理等因素对超磁致伸缩薄膜低磁场下磁致伸缩性能的影响规律。在此基础上，采用射频磁控溅射法，研制出了铽镝铁-聚酰亚胺-钐铁和铽镝铁-铜-钐铁两种双层超磁致伸缩薄膜，该薄膜具有较好的表面质量和较小的滞回性。采用赫姆霍茨线圈作为超磁致伸缩薄膜的驱动线圈，并结合激光微位移传感器作为位移量的检测单元，构成一个超磁致伸缩薄膜静动态磁机耦合特性的实验系统。对驱动线圈产生的磁场进行了有限元分析和实验研究，结果表明：驱动线圈产生磁场强度的大小和均匀度都满足了薄膜的驱动要求。针对超磁致伸缩薄膜的磁机耦合特性“力非线性”的特点，从唯象的角度和工程应用的角度分析了超磁致伸缩薄膜低磁场下的巨磁特性、软磁特性和预应力状态下的滞回特性。提出了一个低磁场下超磁致伸缩薄膜非线性耦合模型。该模型包括改进的瑞利模型和“蝴蝶曲线”模型。采用研制出的双层超磁致伸缩薄膜实验数据验证了所提出的模型。结果显示：模型可较好的预测超磁致伸缩薄膜低磁场磁极化回线和磁致伸缩回线，特别是描述应变回线的“蝴蝶曲线”模型，可较精确地预测超磁致伸缩薄膜低磁场下磁致伸缩回线。利用前人研制出的超磁致伸缩薄膜的实验结果同样验证了模型的正确性。针对超磁致伸缩薄膜的几何非线性变形特性，对研制出的聚酰亚胺基片和铜基片超磁致伸缩薄膜悬臂梁进行实验研究，发现其端部偏移量分别达到其厚度的2倍和0.5倍。同时，结合非线性弹性理论，建立了双层超磁致伸缩薄膜的几何非线性变形模型。采用所研制出的双层超磁致伸缩薄膜悬臂梁变形的试验结果验证了模型的合理性。低磁场下超磁致伸缩薄膜非线性耦合模型和几何非线性变形模型为有效地研制准静态超磁致伸缩薄膜微器件提供了重要的理论依据。在交变的磁场中，超磁致伸缩薄膜会展现出更强的非线性特性。根据哈密顿原理，采用分离变量法和摄动法建立了超磁致伸缩薄膜非线性振动模型。将超磁致伸缩薄膜超谐波共振的实验结果与所提出的模型进行了分析比较，结果表明：非线性振动模型可较好地解释双层超磁致伸缩薄膜的主共振和超谐波共振现象。同时，对双层超磁致伸缩薄膜的驱动特性进行系统的研究，发现两种双层超磁致伸缩薄膜具有十阶超谐波共振的特性，给出并分析了直流偏置磁场和交流磁场对超磁致伸缩薄膜共振频率、振动幅值的影响规律。超磁致伸缩薄膜的非线性振动模型和动态特性的实验研究结论可提高动态超磁致伸缩薄膜微器件的设计效率和控制精度。最后，探索性地将超磁致伸缩薄膜应用于微型泳动机器人的设计研究，设计研制出了一个能在液体微管道内游动的微型机器人。当超磁致伸缩薄膜的驱动频率为5阶超谐波共振频率时，微机器人实现了向前游动。根据流体动力学原理，建立了微型泳动机器人的动力学模型。针对液体粘度、机器人本体的质量和刚度、超磁致伸缩薄膜尾鳍的质量和刚度对泳动性能的影响进行了试验研究。采用聚酰亚胺基双层超磁致伸缩薄膜制作的微型机器人在汽油中的最大泳动速度可达2.86mm／s。更多还原

【Abstract】 As a new functional material, giant magnetostrictive thin film (GMF) exhibits vastpotential in the field of microactuator and microsensor, which can benefit from the largeMagnetostrictive strains, high energy density, short response time, non-contact driving, andrelatively simple integration. The static and dynamic characteristics and models ofmagnetomechanical coupling of GMF are the basis for developing and designing GMF microdevices. However, it is very difficult to model the characteristics of GMF, due to thenonlinearity and hysteresis of the magnetomechanical coupling relations. The static model ofGMF proposed by researchers with much variables and complex computation can notdescribe the hysteresis characteristic of GMF, and the dynamic characteristic model of GMFis not presented now, which hinder the development of GMF and its devices. Therefore, basedon this new functional material, in this paper, a new way is provided to study themagnetomechanical coupling relations of GMF and microactuator and microsensor, withsome new principles and methods.According to the principle of magnetostriction, the magnetostrictive characteristic ofGMF is introduced, firstly. Then, the effects of material composition, internal stress andheating treatment on the magnetostrictive characteristic of GMF at low magnetic fields areanalyzed. Two kinds of bimorph GMF with good surface quality and small magnetizationhysteresis, TbDyFe-PI-SmFe and TbDyFe-Cu-SmFe, are developed by the magnetronsputtering method. Then, an experiment system for the static and dynamic characteristics ofGMF is established, which consists of a Helmholtz coil and a laser triangulation sensor. Themagnetic field amplitude and uniformity of coil are simulated by ANSYS software andtestified by experimental data. The results indicate that the magnetic field produced by thecoil match the need of magnetic field amplitude and uniformity for driving the GMF.For the "force nonlinearity" of magnetomechanical coupling characteristic of GMF,through analyzing the large magnetostriction, the soft magnetization and the hysteresis underthe prestress, a nonlinear coupling model of GMF at low magnetic fields, which is composedof the modified Rayleigh model and the "butterfly curve" model, is proposed. Experiments onTbDyFe-Polyimide(PI)-SmFe and TbDyFe-Cu-SmFe are conducted, respectively, to verifythe proposed model. Results indicate that the model curve coincides well with theexperimental results of the magnetic polarization and the magnetostriction forTbDyFe-PI-SmFe and TbDyFe-Cu-SmFe at low magnetic fields, especially well with the magnetostriction hysteresis. Besides, the proposed model is also in good conformity with thepublished experimental data of other GMFs.For the geometric nonlinear deformation of GMF, experiments on PI substrate GMF andCu substrate GMF cantilever are conformed, and the results show that the deflection ofcantilever end of is two times, and 0.5 times of these thickness, respectively. Meanwhile, withcombining the nonlinear elastic theory, a nonlinear deformation model and flexure lineequation of bimorph GMF is established. The rationality of deformation model is verified bythe bimorph GMF cantilever data. The nonlinear coupling model and nonlinear deformationmodel will provide a theoretical basis for fabricating effective quasi-static micro devices withGMF.Under quasi-static magnetic field, GMF exhibits the "force nonlinearity" and geometricnonlinearity, while, under the alternative magnetic field, GMF shows bigger nonlinearity.Thus, based on the Hamilton principle, by virtue of the method of separation of variables andthe perturbation method, the nonlinear vibration model is presented. Thereafter, thecomparison of the proposed model with the experimental data indicates that the nonlinearmodel can explain well the main resonance and super harmonic vibration. Then, the drivingproperty of bimorph GMF is measured and analyzed. The experimental data shows that twokinds of bimorph GMF exhibits tenth order superharmonic resonance. Moreover, the effect ofdirect current magnetic field and alternative magnetic field on the resonant frequency and thevibration amplitude is given and analyzed. The nonlinear vibration model and theexperimental conclusion of vibration characteristics can improve the design efficiency andcontrol precision of GMF devices.At last, GMF is employed to design a micro swimming robot for the first time. Accordingto the fish propulsion principle, a swimming micro robot in pipe is developed, whose caudalfin is fabricated by the GMF micro actuator. Experiments on the swimming characteristics ofthis micro robot show that this robot can swim in gasoline, when the driving frequency isclose to the fifth superharmonic resonant frequency of GMF beam. Moreover, the dynamicmodel of the swimming robot is given on the basis of fluid dynamics principle. The effects ofliquid viscosity, mass and rigidity of main body and of the GMF caudal fin on the swimmingperformance are studied with the experiments. The PI substrate GMF micro robot can swim ata maximum velocity of 2.86mm/s.更多还原