树脂浸润天然纤维织物的双渗漏流动机理的研究

Growing low-carbon economy has aroused a woldwide interest in the use of natural fiber composites manufactured by the low-cost process of Liquid Composite Molding (LCM). Based on a combination of theoretical analysis, numerical simulation and experimental demonstration, this project will focus on the study of resin twin-sink flow mechanism in natural fiber fabrics. A multiscale twin-sink model is developed to accurately describe the coupled macro-micro flow of resin in liquid absorbing and swelling natural fiber media. Governing equations with moving boundary for the coupled flow can be sovled using the stabilized high-precision finite element /control volume method in a multiscale framework, thus realizing the multiscale modeling of resin flow in natural fiber preform of LCM. Experiments will also be conducted to measure the twin-sink effect and the relation between swelling deformation, porosity and permeability. The exploration of twin-sink flow theory in natrual fiber fabrics will directly benefit the theoretical foundation for the manufacturing of natural fiber composites by LCM, and derive guidelines for process control, optimal design and quality control. It will also be helpful for the development of percolation theory in swelling porous media and computational fluid dynamics.

低碳经济的发展使得低成本复合材料液体模塑成型（LCM）制备天然纤维复合材料的研究在国际上倍受关注。本项目拟采用理论分析、数值模拟和实验研究相结合的方法，开展LCM过程中树脂浸润天然纤维织物渗流机理的研究。重点建立较为真实反映树脂浸润天然纤维织物时发生的宏微观耦合流动和纤维吸收流体膨胀现象的多尺度双渗漏数学模型，采用两套网格体系以及高分辨率的稳定有限元算法结合控制体技术，对带有移动边界的宏微观流耦合控制方程进行数值求解，实现LCM过程中树脂浸润天然纤维织物的多尺度数值模拟；并开展实验研究表征树脂的双渗漏流动行为，分析天然纤维膨胀变形-孔隙率-渗透率与时间的关系，揭示树脂在天然纤维织物中的双渗漏流动机理，为LCM制备天然纤维复合材料奠定理论基础，为成型过程控制、工艺参数优化和制品质量控制提供依据，对发展可膨胀变形多孔介质的渗流理论和计算流体力学理论也具有重要意义。

低碳经济的发展使得低成本复合材料液体模塑成型（LCM）制备天然纤维复合材料的研究在国际上倍受关注。本项目采用理论分析、数值模拟和实验研究相结合的方法，开展了LCM过程中树脂浸润天然纤维织物渗流机理的研究。开展实验研究了天然纤维膨胀变形及其对孔隙率、渗透率的影响规律，采用代表体积单元建立了天然纤维渗透率、膨胀变形与时间的关系，掌握了影响天然纤维渗透率的关键因素；建立了树脂浸润天然纤维织物时发生的宏微观耦合流动和纤维吸收流体膨胀现象的多尺度双渗漏数学模型，采用整体和局部两套网格体系以及高分辨率的稳定有限元算法结合控制体技术，对带有移动边界的宏微观流耦合控制方程进行数值求解，通过对天然纤维织物LCM充模实验与其充模过程的数值模拟结果进行了对比分析，发现流动前沿的预测值与实验值吻合较好，实现了对充模过程的仿真预测，为成型过程控制、工艺参数优化和制品质量控制提供依据。