EAGER: Manufacturing USA: Viscoelastic Model for Extrusion-Based 3D Printing of Polymers

University Of Tennessee Knoxville, Knoxville TN

Investigators

Abstract

This EArly-concept Grant for Exploratory Research (EAGER) project presents a much-needed, general framework for 3D printing of extruded polymers and investigates the bounding conditions that determine a successful processing window for a given machine and material combination. Continued development of specialized and high-performance material systems are needed for the application space for extrusion-based 3D printing techniques to grow; these resin materials can be costly, and with deposition rates exceeding 50 kg/h for certain systems, the prospect of trial-and-error based process development is not feasible, and a fundamental scientific understanding of the process is needed. Fundamental printing criteria may be generally applied across multiple printing platforms to guide future process and material development as well as influencing current design decisions for 3D printing approaches. Such research is essential for important industrial sectors such as aerospace, automotive, medical products and defense. Thus, this project directly impacts American economic welfare and national security. The popularity of 3D printing among today's youth (K-12 through college) also makes it the perfect platform to attract and inspire the next generation of engineers, including underrepresented minorities and women, and introduce complex topics such as rheology and composite materials in a tangible, accessible manner with clear implications on resulting component quality and performance. The objective of this research is to identify the fundamental laws of nature that dominate the behavior of extrusion-based 3D printing of polymers. A generalized viscoelastic framework is planned for multiple modes of extrusion-based 3D printing across multiple platforms that incorporates specific pass/fail criteria. For each printing mode, a fundamental bounding equation is planned that dominates the behavior of the system and predicts the success or failure of the printing process under given operating conditions. This project will focus on the first two modes of extrusion-based deposition; namely the pressure-driven extrusion of viscoelastic material through a circular orifice and the formation of a stable geometry. The bounding equations for each mode will be refined by exploring the processing parameter space of several relevant polymer systems in the processing region about the boundary condition. The result of each research task will be a refined and validated boundary equation that may be applied across multiple platforms and material compositions. As the bounding equations for each of the printing modes are refined, they will be combined into a "processing space map" framework that will guide future innovations in material properties and successful 3D printing processes. 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.