EAGER: Optical Measurement and Analysis of Dynamic Large Deformations of Mechanical Metamaterials

EAGER：机械超材料动态大变形的光学测量和分析

• 批准号: 1719728
• 负责人: Massimo Ruzzene
• 金额: $ 20.43万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1719728&HistoricalAwards=false
• 关键词: EAGER; Optical; Measurement; Analysis; Dynamic

This EArly-concept Grant for Exploratory Research (EAGER) project will perform a fundamental experimental and numerical study to elucidate properties such as wave directionality, strain localization and failure load paths in metamaterials. Structural lattices provide the framework for the design of mechanical metamaterials with the ability to guide, steer and attenuate mechanical waves, which is relevant to applications such as vibration isolation, noise absorption, and stress wave mitigation. These properties are key to the design of novel mechanical metamaterials for wave management and impact protection. Successful achievement of the project objectives will open numerous possibilities for the characterization of a broad class of engineered materials as well as of porous, naturally occurring, or bio-inspired architected materials. The findings of the project will impact design methodologies for energy absorbing structures for body armor design, vehicle protection, and protective layers for helmets for transportation, sport and military use. Thus, the project supports fundamental investigations that will benefit research devoted to the mitigation of the effect of head injuries and concussions, or the effect of blasts. In addition, part of the project findings will be directly transferred to an educational module for an undergraduate laboratory course that will expose students to state-of-the-art mechanical characterization methodologies.The dynamic behavior of structural lattices undergoing large deformations will be investigated through novel full-field measurement techniques based on digital image correlation, along with the numerical analysis of wave properties, dynamic instabilities and collapse mechanisms. Currently available digital image correlation techniques are not suitable for the estimation of displacements and strains in structures that are highly porous, i.e. with volume of voids significantly exceeding the volume occupied by material. Furthermore, these techniques are limited in their ability to track large motion during dynamic events. The project will address these challenges through the formulation of image tracking procedures that exploit the connectivity of lattices, and of a Lagrangian framework for motion tracking that takes inspiration from particle image velocimetry used in experimental fluid dynamics. The formulation and implementation of the experimental technique will enable the study of wave motion and, most notably, of the onset of instabilities, non-uniform deformations and potentially collapse. Experimental measurements will inform and validate numerical models that will then be used to estimate directions of wave motion, strain localizations and instabilities.

这一早期概念探索研究资助项目将进行基本的实验和数值研究，以阐明超材料中的特性，如波的方向性、应变局部化和破坏加载路径。结构晶格为机械超材料的设计提供了框架，具有引导、引导和衰减机械波的能力，这与隔振、吸声和缓解应力波等应用有关。这些特性是设计用于波浪管理和冲击保护的新型机械超材料的关键。项目目标的成功实现将为一大类工程材料的表征以及多孔、自然发生的或受生物启发的建筑材料的表征打开无数可能性。该项目的发现将影响用于防弹衣设计、车辆保护以及交通、运动和军事用头盔防护层的吸能结构的设计方法。因此，该项目支持基础研究，这将有助于致力于减轻头部损伤和脑震荡或爆炸影响的研究。此外，该项目的部分成果将被直接转移到本科实验室课程的教育模块中，该模块将使学生接触到最先进的力学表征方法。将通过基于数字图像相关的新型全场测量技术以及对波浪特性、动态不稳定性和坍塌机制的数值分析来研究结构网格经历大变形的动态行为。目前可用的数字图像相关技术不适用于高度多孔的结构中的位移和应变的估计，即孔洞的体积显著超过材料所占的体积。此外，这些技术在动态事件期间跟踪大型运动的能力受到限制。该项目将通过制定利用晶格连通性的图像跟踪程序，以及从实验流体动力学中使用的粒子图像测速技术获得灵感的拉格朗日运动跟踪框架来解决这些挑战。实验技术的形成和实施将使人们能够研究波动，尤其是不稳定、不均匀变形和潜在坍塌的开始。实验测量将提供并验证数值模型，然后这些模型将被用来估计波动方向、应变局部化和不稳定性。

项目成果

Optical evaluation of the wave filtering properties of graded undulated lattices

• DOI: 10.1063/1.5011369
• 发表时间: 2018-03-07
• 期刊: JOURNAL OF APPLIED PHYSICS
• 影响因子: 3.2
• 作者: Trainiti, G.;Rimoli, J. J.;Ruzzene, M.
• 通讯作者: Ruzzene, M.