Damage detection and structural health monitoring using the electromechanical impedance method has been accepted as an effective technique between various approaches of nondestructive evaluation. Many efforts have been made on experimental methods for obtaining the impedance of structures. However, expensive experimental methods encourage researchers to develop theoretical models. In this paper, a new theoretical model is developed for damage detection of L-shaped beams, which are basic components in frame structures, with an embedded piezoelectric wafer active sensor. For this purpose, a chirp signal of voltage is used to activate a piezoelectric patch for inducing local strains that lead to lateral forces and bending moments on the structure, emerging resonance and anti-resonance vibration behavior of the structure in a wide frequency range. Considering these induced loads, the impedance at each point of the structure is determined by calculating the dynamic stiffness of structures. The model results verified by experiments. The estimated impedance spectrum for both pristine and damaged structure has shown an acceptable agreement, particularly, around the structural resonances. The results show that electromechanical impedance responses of the structure depend on excitation and natural frequencies of the structure which emerge as resonance frequencies in the impedance spectrum. Finally, damage detection is performed using statistical algorithms including root-mean-square deviation and cross-correlation by comparing pristine and damaged L-shaped beams and accordance between experiment and model results demonstrates the efficacy of predicted spectra.

中文翻译：

---

通过机电阻抗响应检测带有裂纹的 L 形梁结构的损伤：分析方法和实验验证

使用机电阻抗方法进行损伤检测和结构健康监测已被公认为各种无损评估方法之间的有效技术。已经在获得结构阻抗的实验方法上做出了许多努力。然而，昂贵的实验方法鼓励研究人员开发理论模型。在本文中，开发了一种新的理论模型，用于 L 形梁的损伤检测，L 形梁是框架结构的基本组件，带有嵌入式压电晶片有源传感器。为此，使用电压的啁啾信号来激活压电贴片，以引起局部应变，从而导致结构上的侧向力和弯矩，在宽频率范围内出现结构的共振和反共振振动行为。考虑到这些感应载荷，结构每个点的阻抗是通过计算结构的动态刚度来确定的。模型结果经实验验证。原始和损坏结构的估计阻抗谱显示出可接受的一致性，特别是在结构共振周围。结果表明，结构的机电阻抗响应取决于结构的激励频率和固有频率，这些频率在阻抗谱中表现为共振频率。最后，通过比较原始和损坏的 L 形光束，使用包括均方根偏差和互相关在内的统计算法进行损坏检测，实验和模型结果之间的一致性证明了预测光谱的有效性。结构每个点的阻抗是通过计算结构的动态刚度来确定的。模型结果经实验验证。原始和损坏结构的估计阻抗谱显示出可接受的一致性，特别是在结构共振周围。结果表明，结构的机电阻抗响应取决于结构的激励频率和固有频率，这些频率在阻抗谱中表现为共振频率。最后，通过比较原始和损坏的 L 形光束，使用包括均方根偏差和互相关在内的统计算法进行损坏检测，实验和模型结果之间的一致性证明了预测光谱的有效性。结构每个点的阻抗是通过计算结构的动态刚度来确定的。模型结果经实验验证。原始和损坏结构的估计阻抗谱显示出可接受的一致性，特别是在结构共振周围。结果表明，结构的机电阻抗响应取决于结构的激励频率和固有频率，这些频率在阻抗谱中表现为共振频率。最后，通过比较原始和损坏的 L 形光束，使用包括均方根偏差和互相关在内的统计算法进行损坏检测，实验和模型结果之间的一致性证明了预测光谱的有效性。