Collaborative Research: Conformal Gradient-Index Lenses for Ultrasonic Wave Amplification and Improved Diagnostics

合作研究：用于超声波放大和改进诊断的共形梯度折射率透镜

基本信息

批准号：
1914583
负责人：
Serife Tol
金额：
$ 36.85万
依托单位：
Regents of the University of Michigan - Ann Arbor
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-06-15 至 2023-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1914583&HistoricalAwards=false
关键词：
Collaborative Research Conformal Gradient Index

项目摘要

Current structural systems are made of homogenous materials such as cast iron, wrought iron, bare steel, and brittle plastic, which are highly susceptible to failure and therefore require accelerated inspection and repair. Ultrasonics is a nondestructive evaluation method based on propagating elastic waves in structures, which are affected by defects in the structure and can therefore be used for damage diagnostics. However, in conventional structures, the amplitude of elastic waves decays with distance due to spreading/scattering, which limits the detectability of critical defects. In this research, new structural systems will be designed with an embedded or externally added lens so that ultrasonic signals can be focused and amplified as they propagate in the structure. In this way, ultrasonic wave energy can be transmitted and preserved over long distances. The research will allow detecting defects at their earliest stage and preventing unexpected failures. The target application will be pipeline systems due to their high susceptibility to failure. Therefore, results from this research will benefit the U.S. economy and society. This multi-disciplinary research encompasses metamaterials, sensors, additive manufacturing, structural monitoring, and design. The project features a synergistic educational component that integrates the strengths of two institutions in recruiting students who are underrepresented in engineering. In particular, female undergraduate and graduate students at both institutions will be connected via mutual workshops and the Society of Women Engineers (SWE).This research will introduce a conformal gradient-index (GRIN) metamaterial lens as part of a structural system such that elastic waves will be amplified as they propagate through the non-planar structure. With the GRIN lens, different ultrasonic wave modes (i.e., longitudinal, flexural, or torsional) will be focused and transmitted such that higher frequencies (50-200 kHz) will be able to propagate with the increased sensitivity to structural damage. The GRIN lens will be designed by varying the refractive index of unit cells, and the existing model of the GRIN lens for flat surfaces will be modified for conformal surfaces. The metamaterial lens layer will be created with 3D printing, which will allow more practical and light weight structures to be easily integrated into the host structure. Additionally, a novel composite pipe structure, produced with multi-material additive manufacturing technologies, will be designed with the embedded metamaterial lens to address the highest risk of major incidents from the conventional materials used in pipelines.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.

当前的结构系统由铸铁、锻铁、裸钢和脆性塑料等均质材料制成，非常容易发生故障，因此需要加速检查和维修。超声波是一种基于在结构中传播弹性波的无损评估方法，弹性波会受到结构缺陷的影响，因此可用于损伤诊断。然而，在传统结构中，由于传播/散射，弹性波的振幅随着距离的增加而衰减，这限制了关键缺陷的可检测性。在这项研究中，新的结构系统将设计有嵌入式或外部添加的透镜，以便超声波信号在结构中传播时可以被聚焦和放大。这样，超声波能量就可以长距离传输和保存。该研究将能够在最早阶段发现缺陷并防止意外故障。目标应用将是管道系统，因为它们很容易发生故障。因此，这项研究的结果将有利于美国经济和社会。这项多学科研究涵盖超材料、传感器、增材制造、结构监测和设计。该项目具有协同教育成分，整合了两个机构在招收工程领域代表性不足的学生方面的优势。特别是，两个机构的女本科生和研究生将通过相互研讨会和女工程师协会（SWE）建立联系。这项研究将引入共形梯度折射率（GRIN）超材料透镜作为结构系统的一部分，使得弹性波在非平面结构中传播时会被放大。使用 GRIN 透镜，不同的超声波模式（即纵向、弯曲或扭转）将被聚焦和传输，以便更高的频率（50-200 kHz）能够传播，同时对结构损坏的敏感性增加。 GRIN 透镜将通过改变晶胞的折射率来设计，并且现有的平面 GRIN 透镜模型将针对共形表面进行修改。超材料透镜层将通过 3D 打印创建，这将使更实用、更轻量的结构能够轻松集成到主体结构中。此外，采用多材料增材制造技术生产的新型复合管道结构将采用嵌入式超材料透镜进行设计，以解决管道中使用的传统材料造成重大事故的最高风险。该奖项反映了 NSF 的法定使命，并已被通过使用基金会的智力优点和更广泛的影响审查标准进行评估，认为值得支持。