Collaborative Research: Design of Negative Stiffness Metamaterials

合作研究：负刚度超材料的设计

• 批准号: 1435548
• 负责人: Carolyn Seepersad
• 金额: $ 43万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-11-01 至 2018-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1435548&HistoricalAwards=false
• 关键词: Collaborative; Research; Design; Negative; Stiffness

Engineers frequently face a critical selection decision between materials with high structural stiffness and materials with superior damping capabilities. Existing materials cannot provide both capabilities simultaneously. This award supports fundamental research to break this tradeoff by designing negative stiffness (NS) metamaterials. These materials gain their properties from their internal structure, which includes micro-scale structures that snap back and forth to absorb energy - a phenomenon called negative stiffness. Novel top-down design strategies developed in this project will allow engineers to quickly identify the material designs that meet performance goals as closely as possible. Negative stiffness metamaterials will benefit a variety of applications of great interest to society, such as stiff, low-vibration wind turbine blades and rotors and sonar mounts for submarines. The research involves graduate and undergraduate students, educational outreach activities, and a minority-serving institution, which will help broaden the participation of underrepresented groups and positively impact engineering education. The research team will design these materials with a novel, top-down design exploration strategy for quickly and efficiently back-propagating application-specific, system-level performance requirements to the characteristics of the micro-scale material structure. This top-down strategy contrasts with trial-and-error, bottom-up strategies that cycle through multiple material structures in search of satisfactory system-level performance. The top-down design exploration strategy utilizes Bayesian network classifiers for mapping structure-property relationships at each level of the multi-level design problem in such a way that the maps can be intersected across levels to identify good multi-level designs and also efficiently guide the search for better designs. The design exploration strategy is coupled with three levels of material models, ranging from (a) the micro-scale level on which the geometry and fabrication route for the snap-through inclusions must be designed to provide negative stiffness behavior to (b) the meso-scale level on which the distribution of inclusions in a ductile matrix must be designed to provide targeted effective material properties to (c) the macro-scale level of a component, which must be designed along with the metamaterial to provide targeted structural stiffness and damping. Materials design and modeling efforts will be validated by additively manufacturing micro-scale inclusions using microstereolithography, embedding them in a matrix material, and testing the resulting composite to determine the overall dynamic structural stiffness and loss characteristics. A collaboration with an industrial partner will pave the way for applications of the NS metamaterials in challenging military and commercial applications.

工程师经常面临在具有高结构刚度的材料和具有卓越阻尼能力的材料之间做出关键选择的决定。 现有材料无法同时提供这两种功能。 该奖项支持通过设计负刚度（NS）超材料来打破这种权衡的基础研究。 这些材料从其内部结构中获得特性，其中包括来回弹性吸收能量的微观结构，这种现象称为负刚度。 该项目中开发的新颖的自上而下的设计策略将使工程师能够快速识别尽可能满足性能目标的材料设计。 负刚度超材料将有利于社会广泛关注的各种应用，例如刚性、低振动风力涡轮机叶片和转子以及潜艇的声纳支架。 该研究涉及研究生和本科生、教育推广活动和一个为少数族裔服务的机构，这将有助于扩大代表性不足群体的参与并对工程教育产生积极影响。 研究团队将采用新颖的、自上而下的设计探索策略来设计这些材料，以便快速有效地将特定于应用的系统级性能要求反向传播到微尺度材料结构的特征。 这种自上而下的策略与反复试验、自下而上的策略形成鲜明对比，后者循环使用多种材料结构来寻找令人满意的系统级性能。 自顶向下的设计探索策略利用贝叶斯网络分类器来映射多层设计问题的每个级别的结构-属性关系，使得映射可以跨级别相交以识别良好的多层设计并有效地指导寻找更好的设计。 设计探索策略与三个级别的材料模型相结合，从 (a) 微观级别，必须设计弹穿夹杂物的几何形状和制造路线，以提供负刚度行为到 (b) 细观级别- 必须设计延性基体中夹杂物分布的尺度水平，以便为 (c) 组件的宏观尺度水平提供目标有效材料特性，必须与超材料一起设计，以提供目标结构刚度和阻尼。 材料设计和建模工作将通过使用微立体光刻增材制造微型夹杂物、将它们嵌入基体材料中并测试所得复合材料以确定整体动态结构刚度和损耗特性来验证。 与工业合作伙伴的合作将为 NS 超材料在具有挑战性的军事和商业应用中的应用铺平道路。