DMREF: Predictive Multiscale Modeling of the Mechanical Properties of Polymers 3D Printed Using Fused Filament Fabrication

这项“设计材料以彻底改变和设计我们的未来”(DMREF) 资助将为熔丝制造 (FFF) 工艺及其对 3D 打印聚合物的基本分子结构和性能的影响提供新的科学认识。 3D 打印正在推动日常生活和高科技应用中物体设计和制造的范式转变。与计算机辅助设计的集成允许快速且廉价地定制打印部件，以满足独特的规格并提供新的功能。 FFF 是使用最广泛、增长最快的 3D 工艺，在打印机结构成本低廉、相对简单以及原料材料的广泛可用性的推动下，FFF 打印机在不断增长的桌面 3D 打印市场中占据主导地位。尽管广泛使用，但 FFF 印刷材料的应用受到适度的强度和韧性以及材料性能的较大变化的限制。该奖项支持基础研究，以了解打印条件如何影响 FFF 打印的聚合物的材料性能。需要这些基础知识来推进 FFF 在结构关键组件中的应用，提供计算工具来加速 FFF 打印零件的设计，并开发下一代聚合物 3D 打印技术。 因此，该项目的成果将有利于美国经济。 该项目还将为本科生和研究生提供参与多学科研究的机会，其中涉及与国家实验室和产品设计研究人员的密切互动，并为 K-12 开展有关 3D 打印科学和工程的创新外展活动。 该项目的研究目标是揭示重要的打印参数和原料材料特性以及打印材料的各向异性、强度和韧性之间的关系。我们将开发一种综合研究方法，在多个长度尺度上通过打印、建模和实验之间的迭代反馈来研究：1）挤出纤维的分子取向，2）退火纤维的非平衡结构和各向异性粘塑性行为，3）纤维-纤维焊缝的缠结结构、强度和韧性，4）光栅结构的各向异性粘塑性和损伤行为，以及5）热历史和残余打印部分的应力。最后，我们将应用经过实验验证的多尺度建模框架来设计原料材料的性能和打印参数，以提高打印部件的强度和韧性。

This Designing Materials to Revolutionize and Engineer Our Future (DMREF) grant will provide new scientific understanding of the Fused Filament Fabrication (FFF) process and its effect on the underlying molecular structure and properties of 3D-printed polymers. 3D-printing is driving a paradigm shift in the design and manufacturing of objects both in every day life and in high-tech applications. The integration with computer-aided design allows printed parts to be customized quickly and inexpensively to meet unique specifications and provide new functionalities. FFF is the most widely used and fastest growing 3D process and FFF printers dominate the growing desktop 3D printing market, driven by the low cost and relative simplicity of the printer construction and wide availability of feedstock materials. Although widely used, applications of FFF printed materials are limited by modest strength and toughness and large variability in material properties. This award supports fundamental research to understand how the printing conditions affect the materials properties of polymers printed by FFF. This fundamental knowledge is needed to advance the application of FFF to structure-critical components, provide computational tools to accelerate the design of FFF printed parts, and develop the next generation 3D-printing technology for polymers. Thus, the outcomes of this project will benefit the US economy. This project will also provide opportunities for undergraduate and graduate students to participate in multidisciplinary research that involves close interactions with national laboratories and product design researchers, and create innovative outreach actives for K-12 on the science and engineering of 3D-printing. The research objective of this project is to uncover the relationships between important printing parameters and feedstock material properties and the anisotropy, strength, and toughness of the printed material. We will develop an integrative research approach with iterative feedback between printing, modeling, and experiments at multiple length scales to investigate: 1) the molecular orientation of the extruded fiber, 2) the nonequilibrium structure and anisotropic, viscoplastic behavior of the annealed fiber, 3) the entanglement structure, strength and toughness of the fiber-fiber weld, 4) the anisotropic viscoplastic and damage behavior of the raster structure, and 5) the thermal history and residual stresses in the printed part. Finally, we will apply the experimentally-validated multi-scale modeling framework to design the properties of feedstock material and printing parameters to improve the strength and toughness of the printed part.