RELIABLE NONDESTRUCTIVE EVALUATION OF DAMAGE IN INFRASTRUCTURE AND SOIL DYNAMIC CHARACTERIZATION USING NOVEL LASER TECHNOLOGY

如果我们要最大限度地延长民用基础设施（如学校、桥梁、电力线路、管道）的使用寿命，就必须开发更好、更经济有效的方法来识别内部结构损伤和表征基础土壤。我已经开发了一种基于激光技术的新系统，这使得它第一次能够真正看到和量化换能器和它们激发的材料中的超声波场。这项创新技术有可能揭示超声波是如何产生、传播和衰减的基本知识，从而可以可靠地检测内部损伤，并更好地表征基础土壤。我的研究计划有三个主要的长期目标：1)利用最先进的技术、实验室和现场测试以及数值模拟，提高对超声波产生、传播和衰减的基本理解；2)利用这一新认识开发可靠的无损评估方法（NDE），以延长现有民用基础设施的使用寿命和安全性；3)将这些新的无损检验方法的应用扩展到基础土壤的动力特性，以提高新基础设施在地震、风或机器振动下的安全性。因此，我的研究计划的短期目标是旨在解决目前缺乏可靠性的超声波检测。我们将从问题的根源开始：超声波传感器的适当表征。为了完成这项任务，我们将在实验项目中使用两个新的协同发展：激光系统和透明颗粒材料。通过首次看到试样内部的超声波场，我们将能够测量真实的超声输入和输出位移。从实际位移，我们将获得基本的了解超声波的产生，传播和相互作用的缺陷在试样内。

If we are to maximize the service life of civil infrastructure (e.g. schools, bridges, power lines, pipelines), it is imperative to develop better and more cost effective methods to identify internal structural damage and characterize foundation soils. I have developed a novel system based on laser technology that makes it possible, for the first time, to actually see and quantify the ultrasonic wave field in the transducers and the materials they excite. This innovative technology has the potential to reveal fundamental understanding of how ultrasonic waves are generated, propagated, and attenuated so that internal damage can be reliably detected and foundation soils can be better characterized. The three main long-term goals of my research program are to 1) advance the fundamental understanding of ultrasonic wave generation, propagation, and attenuation using state-of-the art technology, laboratory and field testing, and numerical simulations; 2) use this new understanding to develop reliable nondestructive evaluation methods (NDE) to extend the service-life and safety of existing civil infrastructure; and 3) extend the application of these new NDE methods to the dynamic characterization of foundation soils to increase the safety of new infrastructure subjected to earthquake, wind, or machine vibrations. Consequently, the short-term goals of my research program are aimed at addressing the current lack of reliability of ultrasonic testing. We will start at the root of the problem: proper characterization of the ultrasonic sensors. For this task, we will use two new synergetic developments in our experimental program: the laser system and transparent particulate materials. By seeing for the first time the ultrasonic wave field inside the specimens, we will be able to measure the real input and output ultrasonic displacements. From the real displacements, we will gain fundamental understanding of the ultrasonic wave generation, propagation, and interaction of defects inside specimens. This research program will generate new and reliable methods that will make the Canadian industry more competitive. Our solutions will be based on robust analytical, experimental, and numerical programs. My research team has been doing pioneering work in NDE and soil dynamics for more than 15 years; as demonstrated by our publication record and the leadership roles that my graduate students have in the private and public sectors. This fact recognizes the need of nondestructive techniques for the extension of the service life of civil infrastructure - a multimillion-dollar task. The proposed research program provides fundamental knowledge that supports and complements a multi-faceted program that includes 5 PhD, 1 MSc, and 6 undergraduate students.