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Laser Doppler vibrometer for efficient structural health monitoring.

机译：激光多普勒振动计可进行有效的结构健康监测。

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The research effort in this thesis is devoted to develop techniques to accurately and rapidly identify the location, orientation, and magnitude of the defects by using structural health monitoring concepts that use Laser Doppler Vibrometer as a non-contact sensor with multi-point sensing capability. The first research area addresses the formulation and validation of an innovative Damage Measure that is based on the ratios of the strain energy distributions of the damaged and undamaged structure. The innovations include use of a single set of actuator/sensor pair to excite and detect the responses of a structure for low frequency vibrations as well as guided wave propagation studies. A second new capability is the estimation of the Damage Measure without requiring any knowledge of the undamaged baseline structure. This method is made possible because of the development of these new technologies: Spatial Decimation and Wavenumber/Frequency filtering. The third contribution is to develop analytical models for the structural dynamics of damaged structure and seek solutions that use perturbation methods to detect damage in a plate structure. The fourth contribution is the development of a comprehensive damage detection technique over a wide frequency dynamic range. The fifth topic of research involves automation in Structural Health Monitoring based on the comprehensive Damage Measure formulation. Under the control of software the Scanning Laser Doppler Vibrometer is used to acquire the low frequency vibration mode data for a coarse identification of all the suspect regions of damage using a threshold criterion on the Damage Measure. Each suspect region of damage is further investigated using the high frequency elastic wave propagation to clearly identify the location, orientation, and extent of the damage. The computer control of the Laser Doppler Vibrometer and a quantitative assessment of the damage provide the enabling technologies for the automation proof of concept. Finally the developed techniques of damage detection are successfully demonstrated on practical structures such as a turbine blade in the laboratory and an F-15 vertical tail in field maintenance conditions.
机译：本论文的研究工作致力于通过使用结构健康监测概念来准确，快速地识别缺陷的位置，方向和大小的技术，该概念将激光多普勒振动计用作具有多点感应功能的非接触式传感器。第一个研究领域是基于损坏和未损坏结构的应变能分布之比，提出创新性的损坏量度的制定和验证方法。这些创新包括使用单个致动器/传感器对来激发和检测结构对低频振动的响应以及导波传播研究。第二项新功能是无需对未损坏的基线结构有任何了解的情况下，即可估算损坏程度。由于以下新技术的发展，使该方法成为可能：空间抽取和波数/频率滤波。第三个贡献是为受损结构的结构动力学开发分析模型，并寻求使用微扰方法检测板结构中损坏的解决方案。第四个贡献是在广泛的频率动态范围内开发了一种全面的损伤检测技术。研究的第五个主题涉及基于综合损伤度量公式的结构健康监测自动化。在软件的控制下，使用“激光扫描多普勒振动计”获取低频振动模式数据，以使用“损伤度量”上的阈值标准粗略地识别所有可疑的损伤区域。使用高频弹性波传播进一步调查每个可疑的损坏区域，以清楚地识别损坏的位置，方向和程度。激光多普勒振动计的计算机控制和损伤的定量评估为自动化概念验证提供了使能技术。最后，在实际结构上，例如在实验室中的涡轮叶片和在现场维护条件下的F-15垂直尾翼上，成功地证明了开发的损伤检测技术。

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