纤维增强聚合物熔体的纤维取向和流场应力分析

针对纤维增强聚合物基复合材料的成型流动过程, 基于宏观流场、 介观纤维取向和微观聚合物大分子链三尺度信息耦合的多尺度模型, 使用有限体积法和有限差分法相结合的数值算法, 分析了纤维增强聚合物熔体在收缩流腔中的流动行为, 得到了其纤维取向和应力分布, 并讨论了纤维存在对聚合物熔体流场应力的影响。结果表明: 当剪切运动占优时, 纤维呈现周期旋转取向; 而拉伸运动占优时, 纤维沿单轴拉伸取向。同时, 由于纤维的周期旋转, 纤维增强聚合物熔体法向应力差的空间分布呈现出随时间逐步发展的拟序涡结构。 

Fiber orientation and stress analysis for fiber reinforced polymeric melt

In the molding process of fiber reinforced polymeric material, the flow residual stress caused by fibers impacts the performance of material seriously. The analysis of flow residual stress depends on the proper model which must include information of different scales. Here, a multi-scale model was used, in which the macro-flow, the mesoscopic fiber orientation and the microscopic polymer molecular chains were coupled together. In a contraction cavity, using the SIMPLER-FDMS (Semi-implicit method for pressure linked equations revised and finite difference method on source term) method, the fiber orientation and stress distribution of the fiber reinforced polymeric melt were analyzed. And the normal stress difference and shear stress of polymeric melt coupled with fibers or not were discussed. The results show that the fibers rotate periodically in the zone where the shearing motion is dominant, and the fibers orientate along a single axis in the stretched zone; as the fibers rotate periodically, the normal stress difference distribution of fiber reinforced polymeric melt appears unsteady coherent vortex configuration.