基于粘弹本构模型的注射成型充填过程模拟研究

为反映聚合物粘弹属性对注塑产品质量的影响,基于粘弹本构模型,对三维薄壁制件的注射成型充填过程进行了数值模拟研究。针对三维薄壁件,经合理简化假设,建立了其充填成型过程的数学模型,采用不可压缩Leonov粘弹本构模型。采用有限元/有限差分法来求解压力场和温度场,采用控制体积法来实现前沿界面跟踪,采用4阶龙格-库塔方法求解弹性应变张量。以一薄壁圆盘为例,对其注射充填过程中的充填时间及压力、剪切应力和第一法向应力差分布进行了数值模拟。模拟结果与前人的实验结果吻合较好,说明了本文建立的模型和数值方法的有效性及可靠性。

Numerical Simulation of Mold Filling in Injection Molding of Viscoelastic Polymers

Numerical simulation of the filling stage of thin cavity injection molding is carried out with viscoelastic fluid model to discover the effect of viscoelastic properties of polymer on the quality of injection molding parts.Based on some reasonable hypotheses and simplification,governing equations in the thin cavity are set up with the Leonov viscoelastic fluid model.The pressure field is solved using finite element method,and hybrid finite element and finite difference method is adopted to calculate the temperature field.The governing equation of elastic strain tensor is solved by a four-order Runge-Kutta algorithm.The result is used as an input to the residual stress calculations.Taking a center-gated disk as an example,we carry out numerical simulation of its filling time as well as the distribution of pressure,shear stress and first normal stress difference.The result of numerical simulation of filling time is in good agreement with the experimental result presented in the literature.It indicates that the mathematic model,numerical methods and developed code are effective and reliable.