Collaborative Research: Computational Design of Programmable Lattice Material Systems

通过设计和制造，控制一种或多种基础材料在比块状材料更小的尺寸尺度上的空间排列，可以使晶格材料表现出所需的块状特性。可编程材料是那些可以实时改变其空间结构的材料，从而提供了实现不是一种而是多种预期行为的可能性。本研究考虑的代理可编程材料系统由一个桁架晶格组成，该桁架晶格具有可通过电磁接缝进行启闭的支撑结构。为了获得多种期望的特性，需要确定晶格设计，包括支柱的大小和位置，以及与每个特性相对应的程序，包括节点的开/闭状态。然而，这种努力涉及到大量的设计参数，因此一般来说，仅仅凭直觉设计和编程这些材料是不可能的，依靠计算也不可行，更不用说实验试错了。该工程材料系统设计（dem）奖支持基础研究，为这些晶格材料系统的系统设计和编程制定第一个计算框架。这项研究的结果具有潜在的深远应用，例如在恶劣环境中运行的适应性远程基础设施，根据入射冲击方向调整响应的避难所，根据入射地震波的方向和频率做出响应以避免共振的建筑基础，或适应飞行状态以减少阻力和提高燃油效率的飞机机翼结构。为这个项目招募代表性不足的本科生和研究生将增加他们在计算材料设计领域的参与。这项研究的多学科性质将使他们能够在一个高度协作的环境中进行研究，并最终扩大他们的职业机会。设计框架的基础是将点阵梁的解析几何表示投影到固定的有限元网格上进行分析和拓扑优化。本研究的智力贡献在于能够将具有电磁接头的梁投影，以获得精度足以满足设计的分析模型，将几何要求与强度相结合，稳定性和连通性约束，以确保晶格可以制造并且不失去其指定的功能，同时设计晶格并确定实现多个功能所需的程序，通过解决双级优化问题。

Lattice materials can be engineered to exhibit desired bulk properties by controlling, through design and fabrication, the spatial arrangement of one or more base materials at smaller dimensional scales than the bulk material. Programmable materials are those that can change their spatial configuration in real-time, thereby offering the possibility of attaining not one but a number of desired behaviors. The proxy programmable material system considered in this research consists of a truss lattice with struts that can be opened and closed by means of electromagnetic joints. To attain multiple desired properties, it is necessary to determine both the lattice design, consisting of the size and position of the struts, and a program corresponding to each property consisting of the open/closed state of the joints. This effort, however, involves a large number of design parameters, hence it is not possible in general to design and program these materials by mere intuition, nor is it feasible to resort to computational, let alone experimental trial-and-error. This Design of Engineering Material Systems (DEMS) award supports fundamental research to formulate the first computational framework for the systematic design and programming of these lattice material systems. Results of this research have potentially far reaching applications, such as adaptable remote infrastructure operating in inhospitable environments, shelters that adapt their response to the direction of an incoming impact, building foundations that respond to the direction and frequency of an incoming seismic wave to avoid resonance, or aircraft wing structures that adapt to the flight regime to decrease drag and increase fuel efficiency. A concerted effort to recruit underrepresented undergraduate and graduate students for this project will increase their participation in the field of computational materials design. The multidisciplinary nature of this research will allow them to conduct research in a highly collaborative environment and ultimately widen their career opportunities.The foundation of the design framework is the projection of an analytical geometry representation of the lattice beams onto a fixed finite element grid for analysis and topology optimization. The intellectual contributions of this research lie in the ability to project the beams with electromagnetic joints to obtain an analysis model whose accuracy is adequate for the design, combine geometric requirements with strength, stability and connectivity constraints to ensure the lattice can be fabricated and does not lose its specified functions and simultaneously design the lattice and determine the programs necessary to attain multiple functions by solving a bi-level optimization problem.