CAREER: Multiscale Optimization of Additively Manufacturable Spatially Varying Cellular Microstructures

蜂窝结构依赖于固体材料和空隙的图案来实现高强度、轻重量和其他特性的期望组合。这方面的一个众所周知的例子是蜂窝图案，但通常蜂窝结构可以由具有不同形状、大小和取向的单元组成。蜂窝结构在许多应用中是重要的，包括轻质航空航天结构、生物医学装置、能量吸收器、热交换器和隔音。然而，用于优化设计细胞结构的一般技术仍然是一个挑战。该学院早期职业发展计划（CAREER）奖支持基础研究，以创建优化设计细胞结构的新技术，从而为特定的工程应用实现无与伦比的性能。该设计方法将允许细胞形状和大小在整个结构中优化变化，并将在优化过程中纳入与3D打印技术相关的制造约束。两个应用程序被确定为评估的方法，并证明其对社会的好处：改善骨科植入物和轻型飞机机翼结构，提高能源效率。这个CAREER项目将通过动手演示，视觉工具，概念图和细胞设计计算机应用程序将细胞结构设计和制造概念整合到互动学习计划中。针对从K-12到普通大众的受众，特别强调各种代表性不足的群体，教育计划包括四个部分：（1）教育者培训，（2）学生课外活动，（3）课程开发，以及（4）这个CAREER奖的理论和实验基础将允许从优化宏观结构的拓扑结构转变为细胞微观结构的拓扑结构和形态学扩展设计。灵活性，而不会对计算资源提出过多要求。该项目提供了对异常特征的新的基本理解，例如优化的细胞微结构中的断开和制造的优化设计中的均匀性水平。研究的创新方面包括利用谐波分解，这是适应不同的细胞类型，代表细胞的配置在优化过程中，并实施细胞的大小和长度尺度的限制，以确保制造的可行性。通过数值模拟和实验测试，研究了优化后的蜂窝几何形状与力学性能和结构性能之间的关系。优化的微结构将被3D打印，并将针对不同的细胞类型和长度尺度研究各种可制造性特征，如变形和粉末捕获。为了研究新的优化框架对不同设计要求的有效性，将进行应用研究，以优化骨科植入物的刚度和强度，具有八角桁架内部支撑结构的蜂窝机翼蒙皮的学科设计优化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力价值和更广泛的影响进行评估，被认为是值得支持的审查标准。

Cellular structures rely on patterns of solid materials and voids to achieve desirable combinations of high strength, light weight and other properties. A well-known example of this is the honeycomb pattern, but in general a cellular structure can consist of cells with varying shape, size and orientation. Cellular structures are important in many applications, including light-weight aerospace structures, biomedical devices, energy absorbers, heat exchangers, and acoustic insulation. However, general techniques for optimally designing cellular structures remain a challenge. This Faculty Early Career Development Program (CAREER) award supports fundamental research to create new techniques for optimally designing cellular structures to achieve unrivaled performance for specific engineering applications. The design approach will permit cellular shape and size to vary optimally throughout the structure and will incorporate manufacturing constraints associated with 3D printing techniques in the optimization process. Two applications are identified to evaluate the methodology and demonstrate its benefit to society: improved orthopedic implants and lightweight aircraft wing structures for improved energy efficiency. This CAREER project will integrate cellular structure design and fabrication concepts into interactive learning plans through hands-on demonstrations, visual tools, concept-mapping, and a cellular design computer app. Aimed at audiences from K-12 to the general public, with specific emphasis on diverse underrepresented groups, the educational plan consists of four components: (1) educator training, (2) student extracurricular activities, (3) curriculum development, and (4) public outreach.The theoretical and experimental foundations of this CAREER award will allow a shift from optimizing the topology of macrostructures to topology and morphology of cellular microstructures expanding design flexibility without placing excessive demands on computational resources. This project provides new fundamental understanding of abnormal features such as disconnectivity in optimized cellular microstructures and the level of homogeneity in the fabricated optimized designs. Innovative aspects of the research include utilizing a harmonics decomposition that is adaptable to different cell types to represent the cellular configurations in the optimization process and implementing cell size and length scale constraints in the methodology to ensure fabrication feasibility. The relationships between the optimized cellular geometries and mechanical properties and structural performance are studied through simulation and experimental testing. The optimized microstructures will be 3D printed and various manufacturability characteristics such as deformation and powder trapping will be studied for different cell types and length scales. To investigate the effectiveness of the novel optimization framework for different design requirements, application studies will be performed on optimizing an orthopedic implant for stiffness and strength and multi-disciplinary design optimization of a honeycomb wing skin with octet truss internal support structures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.