复杂型腔内三维注塑成型的数值模拟研究

Injection molding is one of the most widely employed methods in polymer processing. Since plastic products usually have complex shapes, and physical conditions have a significant impact on product properties, so it is of great theoretical and realistic significance to study numerically the injection molding and corresponding physical phenomena in the complex mold cavity. In this project, firstly the viscoelastic two-phase flow model will be established to describe polymer melt flows. Secondly, the coupled Immersed Boundary and Level Set method is used to deal with complicated boundary problems on the Cartesian grid, and the three dimensional injection molding process in the complex mold cavity is numerical simulated in which the Level Set method is employed to trace the moving interfaces. Lastly, the three dimensional weldlines in injection molding process are dynamically traced, and the effects of processing conditions on the weldlines and their positions are studied.

注塑成型是聚合物加工成型的主要方式之一。而塑料制品往往具有复杂的形状，成型的物理条件对制品性能有显著影响，因此，研究复杂型腔中的注塑成型过程及相应的物理现象具有重要的理论和现实意义。本项目首先建立描述聚合物熔体流动的三维粘弹性两相流模型；其次，在笛卡尔直角网格背景下，采用Level Set函数耦合浸入边界法处理复杂边界问题，并运用Level Set方法追踪运动界面，对复杂型腔内三维注塑成型过程进行数值模拟研究；最后对注塑成型中的三维熔接痕进行追踪和动态显示，并讨论成型条件对熔接痕形成及其位置的影响。

本项目对三维注塑成型进行数值模拟研究，主要研究结果包括以下三方面内容：1.基于XPP(eXtended Pom-Pom)本构方程模型，建立了三维粘弹性两相流模型；2. 在笛卡尔网格背景下，构造形状Level Set函数来描述和刻画复杂型腔，采用浸入边界有限体积法求解熔体流动控制方程，其中采用CLSVOF(Coupled Level Set and Volume of Fluid)方法追踪前沿界面；3. 基于上述模型及算法，对三维复杂型腔内充模及气辅注射成型中气体首次穿透过程进行了模拟，研究了跑道效应、裹气、熔接行为的动态过程，以及气辅注射成型中转角效应和气体穿透不对称等重要物理现象。该项研究为优化型腔设计和指导注塑成型工艺提供了可靠的理论依据。