Collaborative Research: Enabling Non-contact Structural Dynamic Identification with Focused Ultrasound Radiation Force

本研究项目的目的是了解如何利用非接触式超声辐射力激励来充分表征结构的动力学特性。虽然在过去的三十年里，模态分析已经非常成熟，但现有的经验方法并不能有效地解决超声频率范围(高于~20 kHz)的问题，这阻碍了数值结构模型的定量验证。这尤其适用于小型结构，如发动机涡轮叶片，这些结构具有非常高的、紧密间隔的共振频率，不能通过物理连接适当地激励。该项目将解决将超声辐射力激发从定性实验室技术转变为工程界可广泛采用的方法所需的几个关键需求。其中之一是利用干涉测量方法和创新的光纤压力传感器对所施加的力进行校准和实时监测。另一项主要任务涉及在空气中激发的结构和在水或其他流体中激发的相同结构的共振频率的关联。这项任务所需的联合测量和建模非常重要，因为水中超声辐射力激励的更高强度将允许更短的测试时间、更高的信噪比，以及具有足够的力来识别用于损伤检测的非线性的驱动结构的可能性。这项研究将在广泛的应用中产生广泛的影响，因为它将能够非接触地、高频地表征使用传统技术无法充分表征的小部件的结构动力学。超声辐射力激励技术将有助于了解涡轮叶片的动力学；这对于帮助减少高周疲劳失效至关重要，这与航空和发电行业的公司相关。所展示的技术还将应用于硬盘驱动器悬架、海军推进组件以及类似的应用，这些应用将受益于无需物理接触的激励。参与这项研究的研究生和本科生都将接触到对行业至关重要的技术和非技术问题。将利用计划中的示威活动，开展强有力的外联活动，以激励妇女、K-12学生和代表性不足的少数群体对科学和工程感兴趣。修读通识教育课程的音乐本科生将接触到研究成果，并有机会学习乐器的振动。原理调查人员将开发一系列视频和相应的课程指南，这些视频将发布在YouTube和相关网站上，展示乐器、运动设备和其他常见物体的振动。外展还将延伸到国家实验室和公司，这些公司可能受益于了解新的测量方法和分析方法，以及地方、区域和国家媒体，以便有效地激发普通公众的想象力。

The goal of this research project is to obtain an understanding of how to fully characterize the dynamics of structures by using non-contacting ultrasonic radiation force excitation. Although modal analysis has matured significantly in the last three decades, existing empirical approaches do not effectively address the ultrasonic frequency range (above ~20kHz) which hinders quantitative validation of numerical structural models. This holds particularly true for small structures, such as engine turbine blades, that have very high, closely spaced, resonant frequencies and cannot be appropriately excited by using physical attachment. The project will address several critical needs that are required to move ultrasound radiation force excitation from being a qualitative laboratory technique into a methodology that can be widely adopted by the engineering community. One of these involves calibration and real-time monitoring of the imparted force by utilizing interferometric methods and innovative fiber-optic pressure sensors. Another major task involves correlation of resonant frequencies for structures excited in air and the same structures in water or other fluids. The combined measurement and modeling required for this task are important since the higher intensity available for the ultrasound radiation force excitation in water would allow shorter testing times, improved signal to noise ratios, and the possibility of driving structures with sufficient force to identify non-linearities for damage detection.The research will have a broad impact in a wide range of applications since it will enable non-contact, high-frequency characterization of structural dynamics of small components that cannot be adequately characterized using conventional techniques. Ultrasound radiation force excitation techniques will aid in understanding the dynamics of turbine blades; this is of critical importance to help reduce high cycle fatigue failure, which has relevance to companies in the aviation and power generation industries. The techniques demonstrated will also be applied to hard-drive suspensions, naval propulsive components, and similar applications that would benefit from excitation without physical contact. Both graduate and undergraduate students involved in the research will be exposed to technical and nontechnical problems crucial to industry. A strong outreach effort will be implemented using planned demonstrations to motivate women, K-12 students, and underrepresented minority groups to become interested in science and engineering. Undergraduate music students, taking a general education course, will be exposed to the research results and have the opportunity to study vibrations of their instruments. The Principle Investigators will be developing a collection of videos, and corresponding curriculum guides, that will be posted on YouTube and related sites showing vibration of musical instruments, sporting equipment and other common objects. Outreach will also extend to national laboratories and companies that may benefit from understanding the new measurement approaches and analytical methods created, as well as local, regional, and national media so as to effectively capture the imagination of the general public.