A Breakthrough Additive Manufacturing Method for High-Strength Lightweight 3D Micro-Architectured Materials

设计和制造具有优异机械性能（如高强度）的轻质材料是科学家和工程师面临的主要挑战之一。目前最先进的材料在重量和强度之间进行了激烈的权衡，而多孔轻质材料的制造策略则受到材料结构控制不力和材料选择有限的影响。该项目研究了一种新型的增材制造（AM）方法，该方法使用纳米颗粒打印来制造一种新型的三维（3D）微结构材料，这种材料将具有低重量和高强度的理想特性。该研究还将纳入多尺度力学模型，考虑AM特有的微观结构和长度尺度的影响。该研究成果将通过使用定制架构和材料快速制造3D结构来推进增材制造领域，这些结构和材料具有广泛的应用，包括生物医学植入物，多孔膜，组织工程和能量存储。将招募少数民族和女性本科生和研究生研究人员参与该项目，并将开展旨在吸引K-12学生进入制造业研究专业的定期活动。该研究的重点是研究一种新的增材制造方法，该方法包括将金属纳米颗粒分散到溶剂中打印，然后将纳米颗粒烧结，以实现高度复杂和可控的3D金属结构，并且重量轻，强度高。该项目的第一个目标是研究控制印刷过程的科学原理。将开发模型，以确定液滴冷凝，溶剂蒸发和系统动力学在3D结构形成中的作用。这些模型将指导实验，包括将银、镍或铝纳米颗粒分散到乙二醇等溶剂中，并使用气溶胶喷射3D打印机打印3D结构。本工作的第二个目标是确定控制金属三维结构力学行为的微纳米级变形机制。复杂的3D晶格（孔隙率高达94%）和微柱将通过打印制造，并在压缩和弯曲下进行测试。将开发考虑位错运动、应力和应变梯度以及微观结构变化的多尺度力学模型。这些模型将预测出最优的3D设计，从而显著提高强度重量比，并将通过力学测试进行验证。该项目的结果将是一个新的增材制造平台，可以创建具有超过五个数量级长度（几十纳米到几毫米）的建筑控制的坚固轻质结构，并将潜在地开辟3D结构制造和增材制造零件机械行为建模方法的新研究领域。

The design and manufacture of lightweight materials having superior mechanical properties such as high strength is one of the key challenges for scientists and engineers. Current state-of-the-art materials show a drastic tradeoff between weight and strength, while manufacturing strategies for porous lightweight materials suffer from poor control over material architecture and limited material choices. This project investigates a novel additive manufacturing (AM) method that uses printing of nanoparticles to fabricate a new class of three-dimensional (3D) micro-architectured materials, which will possess the desired characteristics of low weight and high strength. The research will also incorporate multi-scale mechanical models that consider the effect of microstructures and length scales specific to AM. The research results will advance the field of AM by enabling rapid fabrication of 3D structures with custom architectures and materials that have a wide range of applications, including biomedical implants, porous membranes, tissue engineering, and energy storage. Minority and women undergraduate and graduate researchers will be recruited to work on the project and periodic activities will be carried out targeted to attract K-12 students into the manufacturing research profession. The research focuses on the investigation of a novel additive manufacturing method that involves printing of metal nanoparticles dispersed into a solvent, followed by nanoparticle sintering to realize highly intricate and controlled 3D metal architectures that are lightweight and strong. The first objective of the project is to investigate the scientific principles governing the printing process. Models will be developed that identify the role of droplet condensation, solvent evaporation, and system dynamics in the formation of the 3D architectures. The models will guide experiments that will involve printing of 3D architectures from silver, nickel, or aluminum nanoparticles dispersed into a solvent such as ethylene glycol, and using an Aerosol Jet 3D printer. The second objective of this work is to identify the micro and nanoscale deformation mechanisms governing the mechanical behavior of the metallic 3D structures. Complex 3D lattices (with up to 94% porosity) and micro-pillars will be fabricated by printing, and tested under compression and bending. Multi-scale mechanical models will be developed that consider dislocation motion, stress and strain gradients, and variability in the microstructure. The models will predict optimal 3D designs that improve strength-to-weight ratio dramatically, which will be verified through mechanical tests. The result of this project will be a novel additive manufacturing platform that can create strong lightweight structures with architectural control of over five orders of magnitudes in length scale (tens of nanometers to several millimeters), and will potentially open up new research areas in the manufacturing of 3D architectures and modeling methods for mechanical behavior of additively manufactured parts.