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，它们的形状常常会出现不连续性。感兴趣的不连续性是诸如尖锐的折叠、与障碍物和引导线的接触或撕裂等特征。这项工作旨在了解这些不连续性的力学和动力学，并研究它们如何移动，以及它们如何影响整个柔性物体的运动。基础工程科学成果最终可能会应用于许多不同的技术领域。细绳、电缆、片材和板材等薄型柔性结构是许多工程系统的重要组成部分，其中包括能量收集技术、传感器、海洋和航空航天结构。转移印刷和纺织加工等制造技术还涉及薄型柔性结构及其接触不连续性的动态行为。机械超材料和变形装置依赖于通过铰链或其他尖锐特征连接的薄板或条带的操纵和响应。该项目还将通过向公众展示令人兴奋的现象，提供有关力学主题的推广和教育机会。不连续性的动力学行为是分析力学的一个基本主题。这项工作将为材料和结构中的非材料不连续性应用一个新的统一变分框架，包括扭结和折叠、移动接触和冲击以及剥离和撕裂前沿。该方法的新颖之处在于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进行组织，每个项目代表不同类别的不连续性：1）电缆和胶带的拾取、冲击和剥离，2）在膜、板和壳体中传播折叠，以及 3）破裂、撕裂和切割床单。这项工作将为这些系统中的动量和能量平衡产生新颖的理论结果，以及不连续性运动的分析解决方案。链条桌面实验将提供不连续动态接触的实验数据。