Sensing and Control of Photopolymerization-based Additive Manufacturing Processes

该奖项的研究目标是测试以下假设：1)基于干涉仪的传感器可以监测基于光聚合的增材制造过程的整个辐照区域的聚合程度，2)传感器将能够测量固化部件的尺寸，以及3)传感器将能够对过程进行反馈控制。大多数增材制造过程以开环方式运行。相反，研究了一种新的基于干涉测量的传感器来实时监测光聚合过程。该传感器将与研究曝光控制投影光刻系统集成，以实现零件制造。使用该传感器，可以对聚合样品进行高分辨率的询问，从而了解聚合速率和固化程度的时空分布作为过程变量的函数。将测试一种新的光聚合模型，该模型包含聚合速率、抑制剂的存在和扩散以及收缩。该模型将用于开发工艺规划和预测固化零件尺寸和形状的新方法。反馈控制能力将开发，使调整光聚合程度，以提高工艺精度和可重复性。如果成功，这项研究可以通过制造传统工艺无法经济制造的精密微光学器件而造福社会。这些设备可以应用于医学成像、便携式能源、摄影和计量等行业。本项目将招募来自代表性不足群体的研究生和本科生。这项工作将通过开发和维护光聚合传感和控制实验以及零件制造的设施，加强研究和教育的基础设施。通过加强研究成果的课程、大学生研究机会、积极的工业参与、在工程论坛上的论文和演讲，以及一个报告结果和提供已开发的增材制造传感和控制系统的网站，将实现广泛传播。

The research objective of this award is to test the hypotheses that 1) an interferometery-based sensor can monitor the extent of polymerization throughout the irradiation area of a photopolymerization-based additive manufacturing process, 2) the sensor will enable measurement of cured part size, and 3) the sensor will enable feedback control of the process. Most additive manufacturing processes operate in an open-loop manner. In contrast, a novel interferometry-based sensor is investigated to monitor photopolymerization processes in real-time. The sensor will be integrated with a research Exposure Controlled Projection Lithography system to enable part fabrication. With this sensor, high resolution interrogation of polymerizing samples can be performed, enabling an understanding of the spatial and temporal distribution of polymerization rate and degree of cure as a function of process variables. A new model of photopolymerization will be tested that incorporates polymerization rate, inhibitor presence and diffusion, and shrinkage. The model will be used in the development of a new approach to process planning and to predict cured part size and shape. Feedback control capability will be developed that enables adjustments of photopolymerization extents in order to improve process precision and repeatability. If successful, this research could benefit society by enabling the manufacture of precision micro-optics devices that could not be fabricated economically by conventional processes. These devices could have applications in medical imaging, portable energy, photography, and metrology industries, among others. Graduate and undergraduate students from under-represented groups will be recruited for this project. The work will enhance the infrastructure for research and education by developing and maintaining facilities for photopolymerization sensing and control experiments and for part fabrication. Broad dissemination will be achieved through courses enhanced with research results, undergraduate research opportunities, active industry involvement, papers and presentations in engineering forums, and a web-site to report results and provide access to the developed additive manufacturing sensing and control system.