可控流场中纤维聚集态结构动力学演变过程的群体平衡模拟

The manufacture process of fiber reinforced polymer composites is a typical multiphase flow. This process involves dynamic evolution of fiber-fractal aggregates, which determines the formation of composites' meso-scale structure. This project is intended to combine experimental methods and numerical simulation, to capture and analyze time-space evolution regularity of the fiber-fractal aggregates in Taylor-Couette flow, which is used as controlled shear flow, construct aggregate and breakage kernel function, establish population balance model and couple it with two-fluid model. The research will investigate the interactive effect between continuous phase and discrete phase, and study key factors affecting formation and transformation of fiber-fractal aggregation structure.Besides, synergy relationship between macro controllable factors and fiber-fractal structure will be established. The results will be beneficial to prediction, optimization and regulation of the structure of fiber reinforced polymer composites as well as its manufacturing process. Moreover, the results will also provide theoretical support for manufacturing of thermoplastic polymer composites with high performance and high stability.

纤维增强聚合物基复合材料加工过程为典型的多相系统，其中涉及一系列纤维聚集态结构的动力学演变过程，对复合材料介尺度结构的形成起决定性作用。本项目拟采用实验研究和数值计算，以Taylor-Couette流场作为可控剪切流场，捕捉、分析剪切流场中纤维聚集态结构的时空演变规律；以此构建描述纤维聚集态结构聚并、破碎过程的核函数，建立群体平衡模型，并与双流体模型耦合，研究连续相与离散相之间相互作用机理，考察影响纤维聚集态结构形成、转变的关键因素，建立宏观可控因素及纤维聚集态结构之间的协同关系。研究结果将用于预测、优化、调控纤维填充聚合物基复合材料结构及其制备过程，为制备高性能、高稳定性的热塑性聚合物基复合材料奠定理论基础。

纤维填充聚合物基复合材料的性能不仅取决于纤维及聚合物自身性能，还与纤维聚集态的存在形式密不可分，其制备过程的流场特性对其形成过程起决定性作用。本项目针对纤维增强聚合物基复合材料加工过程中纤维聚集态结构的动力学演变过程，结合实验和数值模拟，通过构建可控Taylor-Couette流场，观测了纤维束在剪切流场中的分散过程，定量表征了纤维分散程度，提出了一种测试纤维束内聚力的方法；在此基础上，构建了考虑纤维聚集体结构动力学演变的数学模型，定量表征湍流场对纤维分散过程的影响；考虑到纤维聚集体在运动过程中存在复杂的几何演变，尝试建立了普适性更强的MRT格子Boltzmann方法，提供一种可用于模拟聚合物复合材料制备过程的介尺度数值计算方法；进一步，将研究结果应用于对流态化玻纤毡增强热塑性树脂基复合片材制备工艺的改进，获得了性能更为均匀、稳定的热塑性复合片材，可满足工程领域对高性能片材的要求。