短纤维增强熔体三维充模模拟及制品性能预测

基于气-液-固三相模型,给出了适用于三维流场的纤维质心虚拟速度、纤维平动与取向、动量交换源项的求解公式,建立了描述短纤维增强聚合物熔体充模过程的三维模型。采用同位网格有限体积法和Level Set界面追踪技术,实现了充模过程的三维动态模拟。并且,根据模拟计算出的平均取向角,提出了三维取向短纤维增强复合材料力学性能参数计算的一种简化模型。数值结果表明:三维模拟技术可有效反映注塑成型充模的流动过程和喷泉效应;纤维取向分析可量化显示纤维在型腔中的表层-芯层结构取向;弹性模量计算结果与实验结果吻合较好。

3D simulation of filling process for short fiber reinforced melts and prediction of composite properties

Based on the gas-liquid-solid three-phase model,the concerned equations suitable for the 3D flow field were derived for calculating virtual velocity and motion of fiber,and momentum exchange source term.A 3D model of the filling process for short fiber reinforced polymer melts was developed accordingly.3D dynamic simulation was performed by using the finite volume method on non-staggered grids and the Level Set method of capturing melts interface.On this basis,a new model was presented to calculate the mechanical properties parameters of 3D oriented short fiber reinforced composites according to the simulated oriented angle of fibers.Numerical results showed that 3D technology could be used to simulate effectively the flow process with the fountain effect of melts and fibers in injection molding.The fiber orientation analysis showed quantifiably the skin-core-skin structure,namely,the fibers in the skin region had a tendency to align along the melts flow direction,while the ones in the core region were randomly oriented.The calculated elastic modulus were in good agreement with the experimental values,which further demonstrated that the proposed gas-liquid-solid three-phase model and the relative algorithms could be used as a base for predicting composite properties.