CAREER: Modeling the Unsaturated Flow During Fiber Wetting in the Manufacture of Composite Materials

PI提出发展和验证纤维双尺度多孔介质中反应性非等温流动的新理论。研究计划将从研究用于制造复合材料的定向垫的条件开始，在这种条件下，定向垫表现得像双尺度多孔介质。在此基础上，进一步发展了基于延迟浸渍原理的双尺度介质反应流动的“沉”理论。利用数学上严格的相平均技术，提出了一套新的温度和固化方程，通过附加的汇项来解释树脂的吸收和保留。通过涉及反应物温度和浓度的一维流动实验，将在双尺度介质中测量稳态饱和流动中这些对流扩散方程中的关键电导率和分散性张量。然后将这些张量外推到非饱和流动中，通过双尺度纤维垫的单元胞内的流动模拟来估计速度场和温度场的波动。然后，将进行涉及反应性树脂的1-D充模验证实验，其中不饱和流动状态下的测量温度将与新方程集的预测进行比较。采用有限元/控制体积方案，以迭代的方式同时求解间隙区和拖曳区方程。研究意义：除了通过期刊和会议出版物传播研究成果外，PI还将与美国领先的模具填充模拟公司Moldflow合作，升级其代码的物理特性。该研究将通过加强PI实验室的设施和培训复合材料加工领域的研究生和本科生，促进研究基础设施的发展。后来，PI计划将不饱和流动现象与气泡的形成和迁移结合起来，气泡是复合材料中性能退化的主要原因，从而创建一个能够预测气泡迁移和流动变量的统一理论。聚合物复合材料中lcm的不饱和流动理论也将用于开发金属基和陶瓷基复合材料中lcm的类似物理。教育：PI建议制定一项多管齐下的战略，以促进塑料和聚合物复合材料的教育。首先，他计划在他的职业发展计划中开发最近引入的这一领域的课程，如基于实验室的选修课程“塑料加工”，以及两门研究生课程“材料流动”（基于聚合物流变学）和“多孔介质运输”（重点是复合材料制造）。PI还将通过在聚合物复合材料研究的高科技领域进行令人兴奋的新实验，促进大学生参与塑料研究。

The PI proposes to develop and validate a new theory for reactive nonisothermal flows in fibrous dual-scale porous media. The research plan will begin with and investigation of the conditions under which the directional mats, used in the manufacture of composite materials, behave like a dual-scale porous medium. Then the "sink'' theory, based on the principle of delayed tow impregnation, will be developed further for the reactive flows in dual-scale media. Using the mathematically rigorous phase-averaging technique, a new set of temperature and cure equations are proposed to account for the absorption and retention of resin by the tows through additional sink terms. The crucial conductivity and dispersivity tensors in these convection-diffusion equations will be measured for steady-state saturated flows in dual-scale media through 1-D flow experiments involving the temperature and concentration of reactants. Later these tensors will be extrapolated to the unsaturated flows through flow simulations in the unit-cells of the dual-scale fiber mats to estimate fluctuations in the velocity and temperature fields. Then a 1-D mold-filling validation experiment involving a reactive resin will be carried out where the measured temperatures in the unsaturated flow regime will be compared with the prediction of the new equation-set. The equations for both the gap and tow regions will be solved simultaneously using the finite element/control volume scheme in an iterative manner. Implication of research: Apart from disseminating research findings through journal and conference publications, the PI will be collaborating with Moldflow, a leading American mold-filling simulation company, to upgrade the physics of their code. The research will lead to the development of research infrastructure through facility enhancement at the PI's lab and training of graduate and undergraduate students in the area of composites processing. Later the PI plans to couple the unsaturated flow phenomena with the formation and migration of bubbles, a leading cause of property-degrading voids in composites, and thus create a unified theory capable of predicting both bubble migration and flow variables. The unsaturated flow theory developed for LCMs in polymer composites will also be used for developing similar physics for LCMs in metal-matrix and ceramic-matrix composites. Education: The PI proposes to develop a multi-pronged strategy to promote education in plastics and polymer composites. First, he plans to develop recently introduced courses in this area under his Career Development Plan such as a lab-based elective, "Processing of Plastics", and two graduate courses, "Flow of Materials" (based on polymer rheology) and "Transport in Porous Media" (with emphasis in composites manufacturing). The PI will also promote undergraduate participation in plastics research through exciting new experiments in the high-tech areas of polymer composites research.