Mechanics of Dynamic Discontinuities

动态不连续性的力学

• 批准号: 1462501
• 负责人: James Hanna
• 金额: $ 28.02万
• 依托单位: Virginia Polytechnic Institute and State University
• 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: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1462501&HistoricalAwards=false
• 关键词: Mechanics; Dynamic; Discontinuities

As flexible objects move, they often develop discontinuities in their shapes. Discontinuities of interest are features such as sharp folds, contacts with obstacles and guides, or tears. This work seeks to understand the mechanics and dynamics of these discontinuities and investigates how they move, and how they affect the motion of the flexible object as a whole. Fundamental engineering science outcomes may eventually be applied to many different technology domains. Thin, flexible structures like strings, cables, sheets, and plates are important components of many engineered systems, including, among other things, energy harvesting technologies, sensors, marine and aerospace structures. Manufacturing technologies such as transfer printing and textile processing also involve the dynamical behavior of thin, flexible structures and their contact discontinuities. Mechanical metamaterials and morphing devices rely on the manipulation and response of thin plates or strips linked by hinges or other sharp features. The project will also provide opportunities for outreach and education on topics in mechanics, through demonstration of exciting phenomena insightful to the general public. The dynamical behavior of discontinuities is a fundamental topic in analytical mechanics. The work will apply a new unifying variational framework for non-material discontinuities in materials and structures, including kinks and folds, moving contacts and impacts, and peeling and tearing fronts. The approach is new in that it treats all of these objects as time-dependent boundaries. The work is organized around three projects, each representing a different class of discontinuity: 1) Pickup, impact, and peeling of cables and tapes, 2) Propagating folds in membranes, plates, and shells, and 3) Cracking, tearing, and cutting of sheets. The work will generate novel theoretical results on momentum and energy balances in these systems, and analytical solutions for motions of discontinuities. Tabletop experiments with chains will provide experimental data on discontinuous dynamic contacts.

当柔性物体移动时，它们的形状通常会出现不连续。感兴趣的不连续是指尖锐的褶皱、与障碍物和导轨接触或撕裂等特征。这项工作试图了解这些不连续的力学和动力学，并研究它们如何移动，以及它们如何影响柔性对象作为一个整体的运动。基础工程科学成果最终可能应用于许多不同的技术领域。细而灵活的结构，如弦、索、片和板，是许多工程系统的重要组件，其中包括能量收集技术、传感器、海洋和航空航天结构等。转印和纺织品加工等制造技术还涉及薄型柔性结构的动态行为及其接触不连续性。机械超材料和变形设备依赖于通过铰链或其他尖锐特征连接的薄板或条的操纵和响应。该项目还将通过向公众展示具有洞察力的令人兴奋的现象，提供关于力学主题的外联和教育机会。不连续面的动力学行为是分析力学中的一个基本问题。这项工作将应用一个新的统一变分框架来处理材料和结构中的非物质不连续，包括扭结和折叠、移动接触和碰撞以及剥落和撕裂锋面。这种方法是新的，因为它将所有这些对象视为与时间相关的边界。这项工作围绕三个项目组织，每个项目代表不同类别的不连续：1)电缆和磁带的拾取、冲击和剥离；2)薄膜、板材和外壳中的传播折叠；以及3)板材的破裂、撕裂和切割。这项工作将产生关于这些系统中动量和能量平衡的新的理论结果，以及不连续运动的解析解。链的桌面实验将提供关于不连续动态接触的实验数据。