【作者】 周连群；

【导师】 宣明；

【作者基本信息】 中国科学院研究生院（长春光学精密机械与物理研究所） ， 机械制造及其自动化， 2010， 博士

【摘要】 微型Lamb波传感器具有高灵敏度、低损耗、多模式特性,是研究薄膜-流体的界面相互作用最有力的工具之一,尤其在交叉学科且尚未探讨的领域,如气体传感、空气动力学、多参数解耦等领域。本论文从理论上和实验上,系统地探讨了微型Lamb波传感器在薄膜-流体（气体和液体）界面相互作用中的应用。主要研究内容如下:?采用势能函数结合边界耦合模型,分析Lamb波传播过程中的薄膜-流体界面相互作用,重点计算了色散特性曲线、分子位移、应力、坡印廷矢量、群速度、能量速度等。针对微型Lamb波传感器的薄膜纵向长度的有限性,建立相应的简化模型,直观、准确地揭示了微型Lamb波的模式分布,突破和拓宽了以往对微型Lamb波传感器的模式分布的认识,为研究薄膜-流体的界面相互作用奠定了基础。?从理论上和实验上研究了薄膜-气体界面处的消逝波和漏波对气体的响应。结果显示:当气体变化时,低频下的A0模式（消逝波）仅表现为相对频率的移动,且变化曲线呈现“U”型;高频下的A0模式（漏波）表现为的Q值（品质因数）的变化,即Q值随着Lamb波的相位速度接近气体的声速而快速降低。S₀模式对气体的变化不敏感,故S₀模式是作为参考模式的理想选择?利用薄膜-气体界面处的声场（消逝波和漏波）与气体的流动边界层的相互作用,给出流动气体的相关参数。对于消逝波,气流的边界层厚度和消逝波的穿透深度决定着灵敏度的大小。当Lamb的相位速度接近于气体的声速时,气流的速度和方向明显影响消逝波的声场分布。对于漏波,气流对Lamb波的传播几乎没有任何影响。?利用Lamb波的多个模式在薄膜-液体界面处的特性不同,对液体的多个物理参数进行解耦（密度、声速、粘度等）,从而定量地给出液体的成分和组分。结合A01模式（低频A0模式的基模）和A03模式（A0模式的3次谐振模式）可分别解耦出液体的密度和声速。密度确定后,通过测量S₀模式的幅值响应,解耦出液体的粘度。更多还原

【Abstract】 Micro Lamb wave sensor is one of useful tools to study the membrane-fluid interaction, especially in interdisciplinary and not yet explored areas, such as gas sensing, aerodynamics, the multi-parameters decoupling and so on. This is because micro Lamb wave sensor holds high sensitivity, low losses and multi-modes. This thesis deals with the membrane-fluid interaction with micro Lamb wave sensor theoretically and experimentally. The details are described as follows:In theory, combinations of the potential function method and the boundary conditions at all interfaces are used to analyze the membrane-fluid interaction. There are several aspects of this problem can addressed, including the displacement, the stress, velocity dispersion curve, Poynting vector, group velocity, energy velocity and so on. In the case of micro Lamb wave sensor, the resonant modes can be excited and worked simultaneously with the traveling modes, as the membrane is width limited and not large enough comparing with the wavelength of Lamb waves. The established model can reveal the mode distributions in micro Lamb wave device clearly and accurately. These works provide insight into the understandings of the modes in micro Lamb wave device, which is useful for further experiments.The gases effects on the evanescent wave and leaky wave near the membrane-gas interface are studied. The relative frequency shifts in the low frequency range of the A0 mode (evanescent wave, EW) is rather important and the shape of the curve looks like‘U’shape. In the high frequency range of this mode (leaky Lamb wave, LLW), the quality factor decreases rapidly when the Lamb wave phase velocity approaches the gas sound velocity. The S0 mode shows immune to gas loading, which can be used as reference mode. This provides theoretical and experimental works for related fields in gas sensing. The application of membrane-gas interaction in aerodynamics is investigated theoretically and experimentally. The interaction between the gas flow boundary layer and the acoustic sound field (EW and LLW) at the membrane-gas interface can give out the parameter in the gas flow. In the EW case, the thickness of the gas flow boundary layer and the penetration depth of the evanescent wave are the two factors determining the sensitivity. When the Lamb wave phase velocity approaches the gas sound velocity, the gas flow effect is clearly observed. In the LLW case, it is shown experimentally that the gas flow has not evident effects on Lamb wave’s propagations.At the membrane-liquid interface, the effects of different physical parameters (density, sound velocity, viscosity, etc) on the modes’propagations are studied. The liquid ingredients and components can be indentified quantitatively. Combination of the relative frequency shifts of the A01 mode (low frequency of A0 mode) and the A03 mode (the third harmonic wave of the A01 mode), the density and the sound velocity of the liquid can be decoupled. With the determined density, the amplitude in the S0 mode can decouple the viscosity of the liquid.更多还原