ERI: Unraveling Multi-Phase Ink Shear-Thinning Flow Mechanism in Direct Ink Writing Process: Computational Fluid Dynamics Simulation and In-Situ Experimental Verification

直接墨水书写(DIW)是一种能够将功能材料制造成三维结构的灵活的添加剂制造方法。在DIW印刷过程中，多相油墨结合了固体、液体和气相成分，引入了复杂的流体动力学，使零件的制造具有更高的性能。潜在的应用包括电子、航空航天和生物技术。该工程研究启动奖(ERI)支持将DIW工艺参数与油墨性能联系起来的全面研究工作。如果成功，该项目将为用于挤出3D打印的多相油墨的流变性提供新的理解。其影响将超越研究成果，并为科学、技术、工程和数学(STEM)领域的研究生、本科生和代表性不足的群体提供有价值的教育。外展活动将促进更广泛的参与，并激励学生在先进制造业中追求职业生涯。本研究旨在揭示DIW过程中多相油墨的剪切稀化流动机理。目前对多相油墨的认识主要依赖于宏观流变性质，导致宏观认识与微观流体动力学之间存在差距。这项工作试图通过三项研究任务，通过发现油墨剪切稀释流变性与DIW工艺参数之间相互作用的基本知识来填补这一空白。任务1重点是建立和实施多相油墨的计算流体力学(CFD)模拟。任务2使用所建立的模型来评估流变性。如何准确模拟油墨各组分之间的相互作用，预测油墨的流变性是一个亟待解决的关键研究问题。任务3开发用于实验验证的现场传感。模拟模型将使用现场传感和制造后表征进行验证。流体动力学数据，包括流动轨迹、墨水速度和剪切速率，将使用基于粒子成像测速仪(PIV)的设置进行收集。CFD模拟与实验的比较可以为过程控制提供新的见解。从这项研究中发现的新知识将促进DIW技术的更广泛采用，并对其他工程领域产生影响。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。

Direct ink writing (DIW) emerges as an agile additive manufacturing method capable of fabricating functional materials into three-dimensional structures. During the DIW printing process, multi-phase ink, which combines solid-, liquid-, and gas-phase ingredients, introduces complex fluid dynamics to allow for the fabrication of parts with enhanced properties. Potential applications include electronics, aerospace, and biotechnology. This Engineering Research Initiation (ERI) award supports a comprehensive research effort to link the DIW process parameters with ink property. If successful, the project will provide new understanding of the rheological behavior of multi-phase inks used for extrusion-based 3D printing in general. The impact will extend beyond the research outcomes and empower valuable education for graduate, undergraduate, and underrepresented groups in science, technology, engineering, and mathematics (STEM) fields. The outreach activities will promote broader participation and inspire students to pursue careers in advanced manufacturing. This research project aims to unravel the shear-thinning flow mechanism of multi-phase inks in the DIW process. The current understanding of multi-phase ink primarily relies on macroscopic rheological properties, resulting in a gap between macroscopic understanding and microscopic fluid dynamics. The effort seeks to fill in this gap by discovering the fundamental knowledge of the interaction between ink shear-thinning rheological properties and DIW processing parameters via three research tasks. Task 1 focuses on establishing and implementing computational fluid dynamics (CFD) simulation for multi-phase inks. Task 2 uses the established model to evaluate rheology properties. A key research question to be addressed is how to accurately simulate the interactions among various ink components and predict rheological properties. Task 3 develops In-situ sensing for experimental verification. Simulation models will be validated using in-situ sensing and post-manufacturing characterization. The fluid dynamics data, including the flow trajectory, ink velocity, and shear rate, will be collected using a particle imaging velocimetry (PIV)-based setup. The comparison between CFD simulations and experiments could provide new insights into process control. The new knowledge to be discovered from this research will facilitate broader adoption of the DIW technology and impact the other fields of engineering.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.