ABSTRACT

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.

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