压电复合结构中弹性波传播特性分析及其在高性能声波器件中的应用研究

发布时间：2018-03-14 18:32

  本文选题：声表面波器件　切入点：非理想界面　出处：《西安交通大学》2017年博士论文　论文类型：学位论文

【摘要】：声表面波器件、薄膜体声波谐振器、压电变压器、石英晶体微天平以及质量传感器等电子器件在声学、无损检测、航空航天、电子通讯、医学器械、主动控制等众多领域中应用广泛。本文从弹性力学的基本方程入手,借助于MATLAB计算软件,从电子器件实际工程应用的角度出发,针对这些器件在使用过程中经常遇到的结构之间的弱连接、材料的非均匀分布以及变截面等问题开展了理论分析和数值研究。首先,以剪切-迟滞模型为基础,通过引入弱界面的电学非理想参数、阻尼系数等方式,详细讨论了含非理想界面的压电层合结构中B-G波的传播、电学边界条件的非理想性对压电平板中厚度-扭转波的影响、电激励作用下压电器件中的粘弹性弱界面以及由非理想界面激发出的高频波等四个基本问题。理论分析和数值计算的结果表明,非理想界面显著影响器件的工作性能,主要体现在:非理想界面可以改变声表面波器件中B-G波的存在条件;相对于力学特性而言,界面的电学非理想边界条件对波传播特性影响很小,可以忽略;界面的刚度系数与共振频率直接相关,进而影响输出幅值或输出电压与输入电压的比值、输入导纳、能流密度等性能指标,而阻尼系数对共振频率几乎没有影响,但会显著干扰器件的能量转换效率;非理想界面的出现可以激发出新的厚度-扭转波或厚度-剪切波,这是在界面理想情况下没有出现的新现象。其次,应用波函数展开法和幂级数展开法分别讨论了功能梯度压电压磁半空间中的B-G波和材料参数沿长度方向变化时板中的厚度-扭转波。材料的非均匀分布可以从本质上改变波的传播特性,具体表现为:当功能梯度压电压磁材料的各参数以同一指数规律变化时,在其表面传播的B-G波是频散波;如果压电损伤导致了材料参数沿板长度方向分布不均,那么某些频率范围内的厚度-扭转波将呈现出能陷现象,能量主要集中在压电板的某个区域。这些现象也是当材料均匀分布时没有出现过的。最后,利用Tiersten HF的近似方程和傅里叶级数,通过改变谐振器的横截面、石英晶体微天平中附加质量层的厚度等手段,最终达到了激发能陷的目的。附加质量层的惯性对振动频率起主导作用,振动主要集中在器件较厚的区域,如果将器件设计成中间厚边缘薄的形状,将有利于器件的固定和能陷现象的发生。本研究揭示了弱界面、功能梯度材料、厚度的非均匀变化等因素对波传播特性影响的物理机制,对压电复合材料器件的分析和设计以及具体实验数据的测量具有重要的理论和指导意义。
[Abstract]:Surface acoustic wave devices, thin film bulk acoustic resonators, piezoelectric transformers, quartz crystal microbalance, mass sensors and other electronic devices in acoustics, nondestructive testing, aerospace, electronic communications, medical equipment, Active control is widely used in many fields. This paper starts with the basic equations of elastic mechanics, with the help of MATLAB software, from the point of view of practical engineering application of electronic devices. In this paper, the weak connections between structures, the non-uniform distribution of materials and the variable cross-section are analyzed and numerically studied. Firstly, based on the shear-hysteresis model, the shear hysteresis model is used to solve the problems of the weak connection between the structures, the non-uniform distribution of the material and the variable cross-section. The propagation of B-G wave in piezoelectric laminated structure with non-ideal interface is discussed in detail by introducing electrical nonideal parameters and damping coefficient of weak interface. The influence of non-ideality of electrical boundary condition on thickness torsional wave of piezoelectric plate is discussed in detail. Four basic problems, such as the viscoelastic weak interface and the high frequency wave excited by the non-ideal interface, are discussed in piezoelectric devices under electrical excitation. The theoretical analysis and numerical results show that the non-ideal interface significantly affects the performance of the device. The main results are as follows: the non-ideal interface can change the existence condition of B-G wave in saw devices, compared with the mechanical properties, the electrical nonideal boundary condition of the interface has little effect on the wave propagation characteristics, which can be ignored. The stiffness coefficient of the interface is directly related to the resonance frequency, which affects the output amplitude or the ratio of the output voltage to the input voltage, input admittance, energy flow density, etc., while the damping coefficient has little effect on the resonance frequency. But it can significantly interfere with the energy conversion efficiency of the device. The appearance of the non-ideal interface can excite new thick-torsion wave or thick-shear wave, which is a new phenomenon that does not appear in the ideal condition of the interface. Using the wave function expansion method and the power series expansion method, respectively, the thickness torsion wave in the plate is discussed when the B-G wave and the material parameter change along the length direction in the half-space of the functionally graded voltage-voltage magnetic field. The non-uniform distribution of the material can be obtained from this method. Qualitatively changing the propagation characteristics of waves, The results show that the B-G wave propagating on the surface of the functionally graded voltage-voltage magnetic material is a dispersive wave when the parameters of the material vary with the same exponential law, if the piezoelectric damage results in the uneven distribution of the material parameters along the length of the plate. So the thick-torsion wave in some frequency range will show an energy trapping phenomenon, and the energy will be concentrated in a certain region of the piezoelectric plate. These phenomena will not occur when the material is uniformly distributed. Finally, By using the approximate equation of Tiersten HF and Fourier series, by changing the cross section of the resonator and the thickness of the additional mass layer in the quartz crystal microbalance, The inertia of the additional mass layer plays a leading role in the vibration frequency. The vibration is mainly concentrated in the thicker region of the device. If the device is designed to be a thin shape with a thick middle edge, This study reveals the physical mechanism of the influence of weak interface, functionally graded material and non-uniform thickness on the wave propagation characteristics. It has important theoretical and guiding significance for the analysis and design of piezoelectric composite devices and the measurement of specific experimental data.
【学位授予单位】：西安交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN384
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本文编号：1612445