Collaborative Research: Dynamics of Surface Instability Propagation in Soft Materials

合作研究：软材料表面不稳定性传播动力学

• 批准号: 1538137
• 负责人: Shengqiang Cai
• 金额: $ 16.25万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1538137&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamics; Surface; Instability

When soft materials are compressed, their surface often spontaneously forms wrinkles, creases, ridges, or folds with periodic patterns. These patterns are called 'surface instabilities'. Over the past several years, there has been significant interest in understanding how surface instabilities form, as they are ubiquitous in biological systems and have found wide use in engineering applications ranging from microfabrication to soft robotics. However, nearly all of the past studies have focused on understanding how surface instabilities form under very slow compression, or have neglected the dynamics leading to this event. This award will investigate how surface instabilities form and propagate across the surface of the material as a result of fast compression or impacts. The speed of the event causing the instability is critical as it yields fundamentally unique phenomena, which are prevalent in most physical systems, but still not well understood. The improved understanding gained as part of this fundamental research will impact a broad range of applications. For example, because of the role of surface instabilities in friction, this research will positively affect engineering applications with moving soft materials in contact. It will also lead to improved understanding of the dynamics of sandwich beam composites, and to improved impact absorbers, shock protective systems, and novel soft electronics devices. In addition to the research goals, this project has a significant education and outreach component that will positively affect students from K-12 through graduate levels, and will increase the involvement of underrepresented students in STEM fields.The research objective of this multidisciplinary, collaborative project is to investigate the initiation and propagation of surface instabilities in soft materials under dynamic loading, using a combined theoretical, computational, and experimental approach. Experimental characterization will be conducted using a combination of drop tower, high-speed video, and laser ultrasonic test methods. Dynamic surface instability propagation will be modeled analytically, and computationally using nonlinear finite element techniques. This project will provide significant intellectual contribution by answering open questions including: What are the conditions for initiating the propagation of surface instabilities, and how do they propagate? How does the propagation of surface instabilities lead to material failure? And how can the propagation of surface instabilities be manipulated? More generally, as there have been almost no investigations into the dynamics of propagating surface instabilities, this investigation will open a new class of instability-based surface waves and provide an improved understanding of dynamic phenomena in soft materials.

当软材料被压缩时，其表面通常会自发地形成具有周期性图案的皱纹、折痕、脊或折叠。这些模式称为“表面不稳定性”。在过去的几年里，人们对了解表面不稳定性如何形成产生了浓厚的兴趣，因为它们在生物系统中无处不在，并且在从微加工到软机器人等工程应用中得到了广泛的应用。然而，过去几乎所有的研究都集中在理解在非常慢的压缩下表面不稳定性是如何形成的，或者忽略了导致这一事件的动力学。该奖项将研究表面不稳定性如何因快速压缩或冲击而在材料表面形成和传播。导致不稳定的事件的速度至关重要，因为它会产生根本上独特的现象，这些现象在大多数物理系统中都很普遍，但仍然没有得到很好的理解。作为这项基础研究的一部分所获得的加深理解将影响广泛的应用。例如，由于表面不稳定性在摩擦中的作用，这项研究将对移动软材料接触的工程应用产生积极影响。它还将提高对夹层梁复合材料动力学的理解，并改进冲击吸收器、冲击防护系统和新型软电子设备。除了研究目标外，该项目还具有重要的教育和推广内容，将对 K-12 到研究生阶段的学生产生积极影响，并将增加代表性不足的学生对 STEM 领域的参与。这个多学科合作项目的研究目标旨在利用理论、计算和实验相结合的方法，研究动态载荷下软材料表面不稳定性的引发和传播。实验表征将结合落塔、高速视频和激光超声测试方法进行。动态表面不稳定性传播将使用非线性有限元技术进行分析和计算建模。该项目将通过回答开放性问题提供重要的智力贡献，包括：启动表面不稳定性传播的条件是什么，以及它们如何传播？表面不稳定性的传播如何导致材料失效？如何控制表面不稳定性的传播？更一般地说，由于几乎没有对传播表面不稳定性的动力学进行研究，这项研究将开辟一类新的基于不稳定性的表面波，并提供对软材料动态现象的更好的理解。