Micro- to Nanoscale Granular Contact Dynamics and Nonlinear Granular-Elastic Metamaterials

粒状晶体是弹性颗粒的紧密堆积阵列，并且在定制声波传播方面是有效的。然而，到目前为止，粒状晶体通常是在宏观长度尺度上构造的，并且被设计成影响声频声波。该补助金为微纳米颗粒晶体的非线性接触动力学研究提供资金。将颗粒晶体扩展到微米级和纳米级有可能使基于颗粒的设备能够在兆赫和千兆赫频率下工作。尺寸尺度也很重要，因为在宏观尺度上可以忽略不计的影响，如粘附力，在微观尺度上变得重要。粒状晶体将通过自组装来制造。光声技术将用于研究微米和纳米颗粒的基本接触动力学，以及研究更复杂的微尺度颗粒系统中的非线性波传播。实验结果将使用非线性动力系统，固体力学和声学超材料领域的技术相结合来建模。本项目将探讨局部共振颗粒弹性超材料结构中的非线性问题，因为微纳米级颗粒晶体和局部共振颗粒弹性超材料可能在信号处理、无损评估和粘附特性以及生物医学超声成像和治疗等领域具有潜在的未来应用前景，因此具有重大的社会影响。也可以预期，这个项目将建立非线性波在微尺度颗粒介质中传播的基本理解。研究工作将与重要的教育组成部分相结合，并将在课堂和实验室中为多样化的学生群体提供独特的跨学科教育机会。 拟议的研究将纳入由主要研究者领导的新开发的课程，并将开发相关实验的简化版本，以通过外联活动提高对科学和工程的兴趣。

Granular crystals are close-packed arrays of elastic particles, and are effective at tailoring acoustic wave propagation. However, so far granular crystals are typically constructed at macroscopic length scales and designed to affect sonic frequency acoustic waves. This grant provides funding for the study of the nonlinear contact-based dynamics of micro to nanoscale granular crystals. Extending granular crystals to the microscale and nanoscale has the potential to enable granular-based devices that operate at megahertz and gigahertz frequencies. The size scale is also important, as effects which are negligible at the macroscale, such as adhesion, become significant at microscales. Granular crystal will be manufactured by self-assembly. Photoacoustic techniques will be utilized to study the fundamental contact-based dynamics of micro- and nanoparticles, as well as to study nonlinear wave propagation in more complex microscale granular systems. The experimental findings will be modeled using a combination of techniques drawn from the areas of nonlinear dynamical systems, solid mechanics, and acoustic metamaterials. Nonlinearities in locally-resonant granular-elastic metamaterial configurations will be explored.This project has the potential for significant societal impact, as micro- to nanoscale granular crystals and locally-resonant granular-elastic metamaterials may have potential future applications to areas such as signal processing, non-destructive evaluation and adhesion characterization, and biomedical ultrasound imaging and therapy. It is also anticipated that this project will establish the fundamental understanding of nonlinear wave propagation in microscale granular media. The research efforts will be combined with a significant educational component, and will provide a diverse student group with a unique interdisciplinary educational opportunity in the classroom and the laboratory. The proposed research will be incorporated into a newly developed course led by the PI, and simplified versions of relevant experiments will be developed to generate increased interest in science and engineering through outreach activities.