ABSTRACT The electro-mechanical impedance (EMI) method has been accepted as an effective technique for detecting damages in the Structural health monitoring (SHM). EMI at any point of the structure depends on material properties, geometry and boundary conditions that all appears in dynamic stiffness of the structure. In spite of the expensive experimental methods for measuring the mechanical impedance, or the cheaper one electromechanical impedance, of structures, various analytical methods could be substitutions for them. In this paper, an analytical method is developed to obtain the EMI response of L-shaped beams through calculating the dynamic stiffness of the structure. To verify the model, an experimental setup with an embedded piezoelectric wafer active sensor (PWAS) is carried out. The results have shown that EMI and its real part, extracted by the current analytical method, are with good agreement of the experimental results. Also, the dynamic stiffness of the structure directly depends on the mode shapes of the structure and its natural frequencies in terms of the excitation frequency. The peaks of the real part of the EMI results related to the coincidence between agitation frequency value and natural frequencies of the structure.

中文翻译：

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L型梁框架结构机电阻抗响应分析模型

摘要 机电阻抗 (EMI) 方法已被公认为检测结构健康监测 (SHM) 中损坏的有效技术。结构任何一点的 EMI 取决于材料特性、几何形状和边界条件，这些都出现在结构的动态刚度中。尽管测量机械阻抗的实验方法昂贵，或者结构的机电阻抗更便宜，但各种分析方法可以替代它们。在本文中，开发了一种分析方法，通过计算结构的动态刚度来获得 L 形梁的 EMI 响应。为了验证模型，进行了带有嵌入式压电晶片有源传感器 (PWAS) 的实验装置。结果表明，EMI及其实部，用目前的分析方法提取，与实验结果吻合良好。此外，结构的动态刚度直接取决于结构的振型及其在激励频率方面的固有频率。EMI 结果的实部峰值与搅拌频率值和结构固有频率之间的重合有关。