注射成型中充填流动对短纤维取向的影响研究

Numerical Prediction of Effect of Filling Flowon Short Fiber Orientation in Injection Molding

在建立聚合物熔体在型腔中流动以及纤维取向的数学模型的基础上，提出一种数值方法，同时进行充填流动的模拟和纤维取向的预测，构造包含结点的体积微元，求解结点处的速度梯度。并且给出两个例子，说明流动对纤维取向的影响，预测的纤维取向分布与Ｌｏｃｋｅｔ的定性预测相符合。

Lockett′s experimental study led him to make a qualitative prediction of short fiber orientation, which exerts remarkable influence on strength properties of fiber reinforced composites. We developed a numerical method for predicting such orientation quantitatively. In quantitative prediction, we did three things: development of a flow simulation model, calculation of nodal velocity gradients, and calculation of fiber orientation field. Eqs.(1) through (4) describe mathematically the flow simulation model we developed. It is based on generalized HeleShaw flow of an inelastic, nonNewtonian fluid under nonisothermal condition. We derived eqs.(12) through (15) with a hybrid finiteelement/finitedifference scheme and used them to calculate nodal velocity gradients. Finally, using FolgarTucker orientation model, we determined the fiber orientation field with finite difference method. We computed two examples(Figs.2 and 3) to show the effect of filling flow on fiber orientation. The calculated prediction of fiber orientation agrees with the test data of Lockett.