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

本研究的目的是了解如何充分表征结构的动力学，通过使用非接触超声辐射力激励。虽然模态分析在过去的三十年中已经显着成熟，现有的经验方法不能有效地解决超声波频率范围（高于~ 20 kHz），这阻碍了定量验证的数值结构模型。这对于小型结构尤其如此，例如发动机涡轮机叶片，其具有非常高的、紧密间隔的共振频率，并且不能通过使用物理附接来适当地激励。该项目将解决几个关键的需求，需要将超声辐射力激励从定性实验室技术转变为可被工程界广泛采用的方法。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的共振频率与在水或其他流体中激发的相同结构的共振频率的相关性。该任务所需的组合测量和建模是重要的，因为水中超声辐射力激发的更高强度将允许更短的测试时间，改善的信噪比，以及用足够的力驱动结构以识别损伤检测的非线性的可能性。该研究将在广泛的应用中产生广泛的影响，因为它将实现非接触，高频表征小部件的结构动力学特性，而传统技术无法对其进行充分表征。超声辐射力激励技术将有助于了解涡轮机叶片的动力学;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。所展示的技术也将应用于硬驱动悬架、海军推进组件以及类似的应用，这些应用将受益于无物理接触的激励。参与研究的研究生和本科生都将接触到对工业至关重要的技术和非技术问题。一个强大的推广工作将实施使用计划的演示，以激励妇女，K-12学生，和代表性不足的少数群体成为科学和工程感兴趣。本科音乐学生，采取通识教育课程，将接触到的研究成果，并有机会研究他们的乐器的振动。主要研究人员将开发一系列视频和相应的课程指南，这些视频和课程指南将发布在YouTube和相关网站上，展示乐器，体育器材和其他常见物体的振动。外联活动还将扩大到国家实验室和公司，这些公司可能会从了解新的测量方法和分析方法中受益，此外还将扩大到地方、区域和国家媒体，以便有效地抓住公众的想象力。

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.