Rheo-Control 3D Printing: Tuning Suspension Viscosity for Fabricating Functional Materials with Gradient Properties

该补助金支持将贡献与增材制造过程相关的新知识的研究，促进科学进步和促进国家繁荣。增材制造，通常称为3D打印，在快速设计和制造技术设备方面发挥着关键作用，而无需昂贵的工具和较长的周转时间。然而，功能设备的高性能3D打印，如能量吸收材料，可穿戴电子产品和变形结构，仍然是一个重大挑战。这种性能上的限制很大程度上归因于挤出高功能油墨和主动控制其性能的困难。该奖项支持基础研究，为开发3D打印工艺提供知识，该工艺可挤出具有可调特性的高性能油墨。新的打印技术将提高当前3D打印设备的性能，并在材料制造、生物制造和可定制的电子产品生产中开启新的设计。因此，这项研究的成果将大大有利于美国的经济和社会。这项研究涉及多个学科，包括流体力学，微细加工和材料科学。这种跨学科的方法将有助于扩大代表性不足的群体在研究中的参与，并促进工程教育的公平和包容性。3D打印中的功能性油墨通常由于所需的高填料含量而非常粘稠，并且它们经常表现出导致灾难性喷嘴堵塞的剪切堵塞。此外，不能改变油墨性质，例如刚性、导电性和热响应，限制了制造，从而抑制了实现许多新设计的潜力。为了应对这一挑战，本研究将发展一种理解和策略，通过超声波声场在挤出过程中控制功能性油墨的性能。该假设建立在增稠悬浮液的最新进展基础上，其中高频扰动可用于操纵粘性流体的微观结构并大幅降低其流动阻力。具体来说，这个项目将研究基于颗粒的模型墨水的机械性能和墨水的声学改变的微观结构之间的关系。这些研究结果的整合将导致设计原则和扰动协议的发展，用于构建打印平台。该项目将探索两种扰动方法：第一，将压电元件简单地连接到打印喷嘴上，第二，设计一种精确控制油墨微观结构的声学图案形成装置。总的来说，这些实验将为开发印刷功能设备的油墨性能主动控制提供基础。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This grant supports research that will contribute new knowledge related to an additive manufacturing process, promoting both the progress of science and advancing national prosperity. Additive manufacturing, often called 3D printing, plays a pivotal role in the rapid design and fabrication of technological devices without the need for expensive tooling and long turnaround times. However, high-performance 3D printing of functional devices, such as energy-absorbing materials, wearable electronics, and morphing structures, remains a major challenge. Such limitations in performance are largely attributed to the difficulty in extruding highly functional inks and actively controlling their properties. This award supports fundamental research to provide knowledge for developing a 3D printing process that extrudes high-performance inks with tunable properties. The new printing technology will improve the performance of current 3D-printed devices and unlock new designs in material fabrication, bio-manufacturing, and customizable electronic production. Therefore, results from this research will greatly benefit the U.S. economy and society. This research involves multiple disciplines including fluid mechanics, microfabrication, and materials science. This transdisciplinary approach will help broaden participation of underrepresented groups in research and promote equity and inclusion in engineering education.Functional inks in 3D printing are often extremely viscous due to the required high filler content, and they often exhibit shear jamming that leads to catastrophic nozzle clogging. Moreover, the inability to alter ink properties, such as rigidity, conductivity, and thermal response, constrains manufacturing and thus inhibits the potential of realizing many new designs. To address such a challenge, this research will develop an understanding of and strategies for controlling functional ink properties via ultrasonic acoustic fields during extrusion. The hypothesis builds upon recent advances in thickening suspensions, in which high-frequency perturbations can be used to manipulate the microstructure of viscous fluids and substantially reduce their flow resistance. Specifically, this project will investigate the relationship between the mechanical properties of a particle-based model ink and the ink’s acoustically altered microstructure. The integration of these findings will lead to the development of design principles and perturbation protocols for building printing platforms. The project will explore two perturbation approaches: first, the simple attachment of a piezoelectric to a printing nozzle, and second, the engineering of an acoustic patterning device that precisely controls the ink microstructure. Collectively, these experiments will provide a foundation for developing active control of ink properties for printing functional devices.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.