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

• 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; Collaborative; Research; Conformal; Gradient; Index

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.

当前的结构系统由均质材料（例如铸铁，锻铁，裸钢和脆性塑料）制成，它们非常容易失效，因此需要加速检查和修复。超声检查是一种基于结构中传播弹性波的无损评估方法，该方法受结构缺陷的影响，因此可用于损害诊断。但是，在常规结构中，由于扩散/散射，弹性波的幅度随距离衰减，这限制了临界缺陷的可检测性。在这项研究中，新的结构系统将采用嵌入式或外部添加的镜头设计，以便在结构中传播时可以集中和放大超声信号。这样，可以在长距离内传输和保存超声波能量。这项研究将允许在最早的阶段发现缺陷并防止意外失败。由于其对故障的敏感性高，目标应用将是管道系统。因此，这项研究的结果将使美国经济和社会受益。这项多学科研究包括超材料，传感器，添加剂制造，结构监测和设计。该项目具有协同的教育组成部分，该项目将两个机构的优势整合在招募工程中人数不足的学生方面的优势。特别是，这两个机构的女性本科生和研究生将通过共同的研讨会和女性工程师协会（SWE）联系起来。这项研究将引入一个结构性的梯度指数（GRIN）变质镜头，作为结构系统的一部分，以使弹性波会通过非植物结构传播而受到弹性波的扩张。使用笑容的镜头，将集中和传播不同的超声波模式（即纵向，弯曲或扭转），以使较高的频率（50-200 kHz）能够随着对结构损害的敏感性的提高而传播。咧着嘴镜头将通过改变晶胞的折射率来设计，而平面表面的笑镜的现有模型将用于保形表面。超材料镜头层将使用3D打印创建，这将使更实用和轻巧的结构轻松地集成到主机结构中。此外，由多物质添加剂制造技术生产的一种新型的复合管结构将采用嵌入式的超材料镜头设计，以解决管道中使用的常规材料中发生的重大事件的最高风险。该奖项反映了NSF的立法任务，并被认为是通过基金会的智力优质概述的评估来评估的，并且值得通过评估来进行评估。