Collaborative Research: Process-Specific Topology Optimization for 3D-Printed Hierarchical Composites and Structures

仔细观察几乎任何生物结构，就会发现一种优雅而复杂的不同长度尺度的材料层次排列，以最少的材料浪费赋予结构所需的机械坚固性和功能。在开发添加制造技术之前，使用工程材料制造具有类似复杂性和层次结构的部件的成本高得令人望而却步，甚至完全不可能。现在，添加剂制造技术，即使用材料的增量沉积从头开始建造材料和结构，已经打开了设计和创造具有前所未有的复杂性、层级和性能的全新结构类别的大门。然而，目前还没有设计工具可以为任何给定的应用程序确定材料、层次和形状的最佳组合，工程师也不能确切地了解层次结构何时、如何以及为什么会带来卓越的性能。这一奖项将提高我们对机械部件的结构层次如何带来卓越性能的理解，并创造一种设计此类结构的新方法。通过生成这些知识，设计工程师将能够更好地决定是否、何时以及如何利用层次结构来制造更强大、更坚固、更轻、更高效的部件，应用范围从植入物、假肢和运动设备，到航运和航空航天。该项目包括教育高中生了解先进制造和将成果直接传播到行业的活动。这项研究将重点放在熔丝制造和直接墨水书写上，因为这些添加剂技术是可获得最广泛的，并且最近在新型高强度、轻质复合材料原料方面发展迅速。该项目的具体范围由一系列耦合的实验/数值研究任务组成。这些任务从在简单、经典的拓扑优化基准问题中评估3D打印和层次结构的效果，到设计、制造和评估利用分级形状和密度的单元格填充的设计。通过将材料挤压添加剂制造产生的独特功能(即周长、填充和材料各向异性)融入到拓扑优化方案中，结构将专门针对原料和所需层次类型的组合进行优化。虽然加法制造技术已经在学校、大学和工业中变得无处不在，但教授“加法制造的设计”的系统方法还需要进一步发展。该项目还将通过实践添加剂制造和拓扑优化演示、行业教育研讨会以及针对未被充分代表的少数民族、妇女和残疾人的外联计划来帮助解决这一国家迫切需要，这些计划将激励下一代科学、技术、工程和数学劳动力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

A close look at almost any biological structure reveals an elegant and complex hierarchical arrangement of materials at different length scales that imparts desirable mechanical robustness and function to the structure with minimal wasted material. Prior to the development of additive manufacturing technologies, the creation of components with analogous complexity and hierarchy using engineering materials has been prohibitively expensive or entirely impossible. Now, additive manufacturing technologies, which build materials and structures from the ground up using incremental deposition of material, have opened the doors to designing and creating entirely new classes of structures with unprecedented complexity, hierarchy, and performance. However, design tools do not currently exist that can identify the optimal combinations of materials, hierarchy, and shape for any given application, nor do engineers yet understand exactly when, how, and why hierarchy leads to superior performance. This award will improve our understanding of how structural hierarchy in mechanical components leads to superior performance and create a novel method for designing such structures. By generating this knowledge, design engineers will be better able to make decisions about if, when, and how to utilize hierarchy to create stronger, stiffer, lighter, more efficient components for applications ranging from implants, prosthetics, and sporting equipment, to shipping and aerospace. The project includes activities to educate high school students about advanced manufacturing and dissemination of results directly to industry.This research will focus on fused filament fabrication and direct-ink writing, since these additive technologies are the most widely accessible and have seen rapid recent development in new high strength, lightweight composite feedstocks. The specific scope of the project is comprised of a series of coupled experimental/numerical research tasks. These tasks build from assessing the effects of 3D printing and hierarchy in simple, classic topology optimization benchmark problems to designing, fabricating, and evaluating designs that utilize cellular infill with graded shape and density. By incorporating the unique features that result from material extrusion additive manufacturing (i.e., perimeter, infill, and material anisotropy) into topology optimization schemes, structures will be optimized specifically for the combination of feedstock material and type of hierarchy desired. While additive manufacturing technology has become ubiquitous in schools, universities, and industry, systematic approaches to teach "design for additive manufacturing" require further development. This project will also help address this national imperative through hands-on additive manufacturing and topology optimization demonstrations, industry educational seminars, and outreach programs for underrepresented minorities, women, and persons with disabilities that will inspire the next generation Science, Technology, Engineering, and Math workforce.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.