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

基本信息

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

项目摘要

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.

这项探索性研究（急切）项目的早期概念赠款将进行基本的实验和数值研究，以阐明超材料中波浪方向，应变定位和故障负荷路径等特性。结构晶格为设计机械超材料设计的框架提供了指导，转向和衰减机械波的能力，这与诸如振动隔离，吸收噪声和压力波缓解等应用有关。这些特性是设计用于波浪管理和影响保护的新型机械超材料的关键。成功实现项目目标将为广泛的工程材料以及多孔，自然发生或以生物为灵感的架构材料的特征打开许多可能性。该项目的发现将影响设计方法，用于吸收防弹衣，车辆保护和保护层用于运输，运动和军事用途的头盔的保护层。因此，该项目支持基本调查，这些调查将使致力于缓解头部受伤和脑震荡的影响或爆炸作用的研究受益。此外，部分项目发现将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新的机械表征方法。将通过新颖的全场测量技术以及基于数字图像相关的新型机制以及数字分析的动态分析，通过新颖的全场测量技术来调查大型变形的结构晶格的动态行为。当前可用的数字图像相关技术不适合估计高度多孔的结构中的位移和菌株，即，空隙的体积大大超过了材料所占据的体积。此外，这些技术在动态事件中跟踪大型运动的能力受到限制。该项目将通过制定图像跟踪程序来应对这些挑战，从而利用晶格的连通性，以及用于运动跟踪的拉格朗日框架，该框架从实验流体动力学中使用的粒子图像速度计汲取灵感。实验技术的配方和实施将使波动运动能够研究，最值得注意的是不稳定性的发作，不均匀的变形和潜在崩溃。实验测量将为数值模型提供信息和验证，然后将其用于估计波动，应变定位和不稳定性的方向。