【作者】 王福吉；

【导师】 贾振元；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2005， 博士

【摘要】 微系统技术日益广泛地用于医学、生物学、半导体等许多科技和工业领域中,发挥了重要作用。传感和驱动功能是微系统技术的核心,微系统技术的发展要求其材料能对外界信号做出灵敏的响应或输出较大的应力和应变。稀土超磁致伸缩薄膜材料是近年来发展起来的一种新型的功能材料,具有磁致伸缩应变大、响应速度快、能量密度高、各向异性值低,软磁特性好、无涡流损耗和高频驱动等优点,易于实现微型化、智能化和集成化。在微驱动器件中应用时,具有很高的响应速度和较大的输出应力,从而在微系统器件(如悬臂梁驱动器、原子力显微镜探针、超声微马达和微泵等)中处于重要地位。超磁致伸缩薄膜作为一种新兴的功能薄膜材料,特别是正负超磁致伸缩复合薄膜,其有利于开发成微型驱动器件的性能特点还不完全被人们所认知。在国家自然科学基金资助下,本论文以这种新型的薄膜功能材料为基础,以超磁致伸缩薄膜悬臂梁为研究对象,采用理论分析与实验研究相结合的方法,对薄膜的磁致伸缩机理、静动态特性及控制方法进行研究,理论与实验研究结果为推广超磁致伸缩薄膜微型器件在微系统中的应用奠定基础。 本论文从微观磁致伸缩机理入手,利用弹性小变形理论和微观量子理论建立了薄膜静、动态微观磁致伸缩方程。制备了性能稳定、磁致伸缩应变大、能量密度高、响应速度快的正负超磁致伸缩复合薄膜,超磁致伸缩复合薄膜的基片有两种,分别为聚酰亚胺薄片和铜薄片。研究分析了制备的超磁致伸缩复合薄膜静态磁化的初始磁化曲线、磁滞回线的变化规律,得到制备薄膜的饱和磁化强度、矫顽力以及退磁场等性能参数与相关物理量之间的关系。 在研究、分析空心圆柱磁场设计方法和计算理论的基础上,针对超磁致伸缩薄膜驱动要求,以磁场强度大小、均匀度分布为目标,对无铁芯、有铁芯两种赫姆霍兹组合线圈的结构尺寸、最优磁场效率系数等进行了设计计算。对设计线圈产生的磁场,以及在这两种磁场作用下,磁致伸缩过程中超磁致伸缩薄膜内部磁场的大小及分布均匀度等方面进行了研究分析。实验结果表明:所研制的两种驱动线圈产生磁场强度的大小足以使超磁致伸缩薄膜产生大的磁致伸缩;线圈产生磁场的均匀度高,能够保证超磁致伸缩薄膜受到一个相对均匀的磁场作用。磁致伸缩过程中,超磁致伸缩薄膜内部磁化磁场的分布非常均匀,大小与薄膜外围磁场强度大小基本一致,方向与薄膜外围磁场方向相反。进一步证明了在薄膜磁-机械耦合模型建立和求解过程中,用超磁致伸缩薄膜外围磁场强度替代薄膜内部磁化磁感应强度的方法是切实可行的。 根据薄膜磁致伸缩能计算理论,从热力学第一定律出发,建立和求解超磁致伸缩薄膜的磁-机械耦合模型。在超磁致伸缩薄膜梁的磁致伸缩测量原理和方法研究的基础上,结合研制的赫姆霍兹线圈结构形式,完善了正负超磁致伸缩复合薄膜梁磁致伸缩的测量系统。通过对正负超磁致伸缩复合薄膜梁磁致伸缩受力状态的分析研究,从理论上推导出薄膜梁磁致伸缩的挠曲线方程,并对通过实验测得薄膜梁上各个位置偏移量方法得出的薄膜梁挠曲线与利用理论方程得出的挠曲线进行对比分析,结果表明实验挠曲线与理论挠曲线基本吻合。提出了正负超磁致伸缩复合薄膜梁固有频率的计算方法及振动方程,并通过实验对薄膜梁的振动波形进行研究,得出了超磁致伸缩薄更多还原

【Abstract】 Micro-systems are more and more widely applied in iatrology, biology, semiconductor, and other science and technology fields having played an important role. The functions of micro actuation and micro sensing are the core of the micro-systems technology. The material of the micro-systems is required to produce sensitive response to an outside signal and to output a greater stress and strain. Thulium giant magnetostrictive thin film(GMF) is a new smart material developed recently, which shows many advantages such as large magnetostriction, short response time, high energy density, low anisotropy, soft magnetization and high frequency driving, etc., being able to realize microminiaturization, intellectualization and integration. So, GMF has become a potential material for micro-systems, such as the cantilever driver, the probe of the atomic force microscope, the ultrasonic micro motor. and the micro pump. However, the performance of GMF as a new smart material, especially that of the positive/negative GMF specially suitable for making micro driver, is not yet completely cognized. In this paper, the magnetostriction mechanism, the static and dynamic characteristics and control techniques are studied by combining theoretical analysis with experimental verification. The project is funded by the National Natural Science Foundation of China and the theoretical and experimental achievement will provide a basis for advancing application of GMFs in micro-systems area.Firstly, based on the theory of small elastic deformation and microcosmic quantum mechanics, the static and dynamic magnetostrictive equations are established, and the positive/negative GMF with steady performance, great magnetostrictive strain, high energy density and fast response is formulated. There are two kinds of substrates for positive/negative GMFs made of polyimide (PI) and Cu, respectively. The initial magnetization curve, the magnetic hysteresis loop, the saturation magnetization intensity, the coercive force and the demagnetizing field are measured and analyzed, with the relationship among the performance parameters and relevant physical quantities such as the saturated magnetization intensity, the coercive force and the recessional magnetization, etc. for making positive/negative GMF are obtained.Then, based on the research and analysis of the calculation theory and design method for hollow cylindrical magnetic field, aiming at the requirement for driving, with the intensity of magnetic field and the uniformity of distribution as the objective, two kinds ofHelmholtz combined coils with and without iron core are designed. The internal magnetic field and the uniformity of distribution in these two magnetic fields are studied and analyzed. The measured results show that, the exciting magnetic filed of the two magnetic fields is strong enough to drive GMFs for large magnetostriction; the uniformity of the exciting magnetic field is high enough to make GMFs under a relatively uniform magnetic field. During the magnetostriction, the internal magnetic field of GMFs is very uniform, with identical magnitude but opposite direction with the exciting magnetic field. As a result, in the process of establishing and solution of the magnetomechanical coupling model, it is feasible and applicable that the internal magnetic field of GMFs is substituted by the external exciting one.According to the magnetoelastic energy theory and the first thermodynamic law, the magneto- mechanical coupling model of GMFs is established and solved. Hence, the measurement system of positive/negative GMFs cantilever is established based on the measurement principle and method of GMFs beam. Through the force analysis of positive/negative GMFs, the flexibility curve equation of GMFs cantilever is deduced. The theoretical flexibility curve is compared with the experimental observations and the results show that the former basically coincide with the latter. Furthermore, based on the static equation, the calculation method for resonant frequency and the vibration equation of positive/negative GMFs are proposed. After studying the vibrating waves of GMFs cantilever, it can be concluded that the vibration equation of GMFs cantilever agrees basically with the harmonic equation of the exciting magnetic field. Finally, with the designed measurement system, the static and dynamic characteristics of the two kinds of GMFs with PI and Cu substrate, respectively, are measured, and the influences of Young modulus of the substrate, the exciting magnetic field and the sizes of GMFs on the static and dynamic characteristics are studied.For the study of control theory and method of GMFs, the control model of GMFs based on Preisach hysteresis model is constituted and the adaptive control arithmetic based on PID controller is also proposed. The static and dynamic control variables are chosen among the exciting current and the magnetic flux density. The experimental results show that, in comparison with the control method based on the exciting current, the control method based on the magnetic flux density exhibits lower magnetic hysteresis and nonlinearity, higher control precision, better repeatability and independence of the change of magnetic field for both static deflection and dynamic vibration magnitude. In order to satisfy the need for short response time, the control theory and method of GMFs based on the vibration frequency are presented. The experimental observations illustrate that with the control methods based on frequency, the vibration responds fast with a higher control precision, which is suitable for control of the vibration response velocity near the resonance frequency of the GMFs micro feed system.Finally, systemic experiments on the magnetostriction of positive/negative. GMFs cantilever and the static-dynamic response properties of two kinds of experimental system更多还原