CAREER: Controlling Nonlinear Wave Propagation in Metastructures with Contact Interfaces

该学院早期职业发展（CAREER）奖将进行基础研究，以揭示超结构中界面的机械响应与非线性机械波传播之间的关系。亚结构是一种工程介质，可以控制机械能如何通过材料传播。目前的亚结构在工程材料中的应用有限，因为它们要么只控制小振幅波，要么需要顺应性成分或复杂的约束系统。 如何控制和引导工程材料中更真实的高振幅机械波的知识可能会导致飞机，汽车和能源基础设施中的安全，有效运行和持久的组件，这仍然是社会的迫切需求之一。该奖项将通过回答与非线性波动现象力学相关的基本科学问题来促进科学进步。该奖项还将通过引入和实施一项外展计划来支持教育，该计划通过将音乐和STEM相结合来整合研究和教育。该计划将丰富青年夏季音乐营与模块，将音乐与声学。此外，还将发展一个全校范围的声学社区，与外展计划相结合，并扩大外展计划，为本科生和研究生提供独特的指导经验。通过对超结构的研究，发现了新的波现象，超结构是周期性工程材料，可以控制声波的频率和空间特性。然而，它是不很好地理解如何不同的形式和变化，在当地的非线性关系到全球非线性波反应的元结构，也没有一个广泛的非线性可以物理实现。虽然现有的工作已经显示出有益的非线性波响应，由于赫兹接触颗粒介质，这项工作将建立在不同的长度尺度接触界面几何形状之间的联系，他们的非线性力学响应，和紧急的全球非线性波现象，从这些接触的周期性配置的结果。这将通过测量、分析模型和有限元模拟的紧密结合来完成。频率相关的非线性反射和透射系数将从具有多个长度尺度的工程几何形状的接触界面进行测量，这些几何形状是用金属3D打印制造的。然后，将引入分析模型来描述这些接口的非线性响应。混合分析有限元模型将被引入到表征非线性波传播通过各种周期性安排在1D和2D的研究接触界面。这些响应将通过全波场测量进行验证。这一新的知识将被用来确定物理上可实现的局部力学非线性和整体波在元结构中传播之间的关系。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

This Faculty Early Career Development (CAREER) award will conduct fundamental research to uncover the relationship between the mechanical response of interfaces in metastructures and nonlinear mechanical wave propagation. Metastructures are engineered media that can control how mechanical energy propagates through materials. Current metastructures find limited use in engineering materials as they either only control small-amplitude waves or require compliant constituents or complex constraining systems. Knowledge of how to control and steer more realistic high-amplitude mechanical waves in engineering materials may result in safe, efficiently operating, and long-lasting components in aircraft, automotive, and energy infrastructure, which remains as one of society's pressing needs. This award will promote the progress of science by answering fundamental scientific questions related to the mechanics of nonlinear wave phenomena. This award will also support education by introducing and implementing an outreach program that integrates research and education by combining music and STEM. The program will enrich youth summer music camps with modules that relate music to acoustics. Further, a university-wide acoustics community will be developed that integrates with and broadens the outreach program, to provide a unique mentoring experience for both undergraduate and graduate students.New wave phenomena have been uncovered through the study of metastructures, which are periodically engineered materials that control frequency and spatial properties of acoustic waves. However, it is not well understood how different forms and variations in local nonlinearity relate to global nonlinear wave responses in metastructures, nor how a broad range of nonlinearities can be physically realized. While existing work has shown beneficial nonlinear wave responses due to Hertzian contact in granular media, this work will instead establish links between contact interface geometry at various length scales, their nonlinear mechanical response, and emergent global nonlinear wave phenomena that results from periodic configurations of these contacts. This will be done using a close integration of measurements, analytical models, and finite element simulations. The frequency-dependent nonlinear reflection and transmission coefficients will be measured from contact interfaces with engineered geometries on multiple length scales, fabricated with metal 3D printing. Then, analytical models will be introduced to describe the nonlinear response of these interfaces. Hybrid analytical-finite element models will be introduced to characterize nonlinear wave propagation through various periodic arrangements in 1D and 2D of the studied contact interfaces. These responses will be validated by full wave field measurements. This new knowledge will be used to determine relationships between physically realizable local mechanical nonlinearities and global wave propagation in metastructures.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.