Collaborative Research: Three-Dimensional Continuously Scanning Laser Vibrometry with Application to Structural Damage Detection

激光测振仪是一种用于表征结构振动的最先进仪器。这一信息对于评估经常经历振动的结构的设计的正确性、在故障发生之前确定这些结构的维护和修理的关注区域以及在故障前补救措施没有采取或不足的情况下查明结构故障的位置和模式是重要的。 然而，这种技术，是非常繁琐和耗时的测量结构与复杂的配置。 这些可能包括大型结构，例如，承受来自风、流水或稳定交通流的持续载荷。 本项目旨在开发一种连续扫描激光振动测量方法，用于精确和快速表征具有复杂构型的结构的振动。这项研究的最终应用将通过提供对结构维护和修理需求或关键结构故障发生的早期预警来促进国家繁荣和国防。 这可以减少潜在的经济和人类损失，以及推进测量科学领域的知识。 该项目的成果也将在暑期教育计划中展示给缺乏服务的高中学生，以激发他们对科学和工程的兴趣。该项目的总体目标是研究全场三维连续扫描激光振动测量法，并将其应用于非基于模型的结构损伤检测。激光测振仪可以测量具有曲面和时变位置和方向的结构的三维振动，并估计其振动形状，可用于结构在环境激励下的损伤检测。三个激光光斑的扫描轨迹需要同步，这需要推导规定的扫描轨迹与每个激光光斑之间的运动学关系。将开发非基于图像和基于图像的方法来获得它们。对于环境激励下的结构，将开发新的仅输出振型测量方法。一个强大的和有效的非基于模型的损伤检测方法，使用不同类型的激光测振测量的振动形状将被开发。该损伤检测方法具有稳健性、实用性和通用性，并且不需要结构的任何基线信息，如其尺寸和边界条件，以及相应未受损结构的振动形状。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The laser vibrometer is a state-of-art-art instrument used to characterize vibration of a structure. This information is important to evaluate the correctness of design of structures that routinely experience vibration; to identify areas of concern for maintenance and repairs of those structures before failure occurs; and to pinpoint the location and mode of failure of the structures, if pre-failure remediation is not undertaken or is insufficient. This technique, however, is very tedious and time-consuming for measurement of structures with complex configurations. These may include large structures subject, for example, to ongoing loading from wind, or flowing water, or the steady flow of traffic. This project aims to develop a continuously scanning laser vibrometry method for accurate and rapid characterization of vibrations of structures with complex configurations. The ultimate application of this research will advance the national prosperity and defense by providing early warnings of the need for maintenance and repair of structures, or of the onset of failures of critical structures. This can reduce potential economic and human losses, in addition to advancing knowledge in the field of measurement science. Outcomes of this project will also be demonstrated to underserved high school students in a summer educational program to spark their interest in science and engineering.The overarching objectives of this project are to investigate full-field three-dimensional continuously scanning laser vibrometry and apply it to non-model-based structural damage detection. Laser vibrometry can measure three-dimensional vibrations of structures with curved surfaces and time-varying positions and orientations, and estimate their vibration shapes that can be used for damage detection when structures are under ambient excitation. Scan trajectories of three laser spots need to be synchronized, which requires derivation of kinematic relations between a prescribed scan trajectory and each laser spot. Non-image-based and image-based methods will be developed to obtain them. New output-only vibration shape measurement methods will be developed for structures under ambient excitation. A robust and efficient non-model-based damage detection method that uses different types of vibration shapes measured by laser vibrometry will be developed. The damage detection method is robust, practical and versatile, and does not require any baseline information of structures, such as their dimensions and boundary conditions, and vibration shapes of corresponding undamaged structures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.