Simulation Of Fiber Orientation In The Process Of Injection Molding

During the filling stage of injection molding, Melt flow patterns are complex in the mold cavity, which made the fiber in the flow oriented in a certain direction.Fiber orientation has a great impact on mechanics, physical properties etc, which either made parts anisotropic property or warp, thus affecting the product life and scope of application.So, fiber orientation prediction is very important.At present, when predicting fiber orientation, we usually use two methods. The first one is based on using a fiber distribution function, which is easy to understand, but the shortcomings are computationally intensive. the other one is based on using orientation tensor, This approach requires a closure model because the equation involves an unclosed fourth order tensor, in this way, the uniqueness of solution can't resolved, and the introduction of the smallest error model is a very big challenge.In this thesis, the co-rotational system is introduced to simplify Jeffery's single Fiber Dynsmics.In this way, we can obtain a very simple equation of fiber dynamics, this new method provides a feasible and effective way for the analysis of fiber orientation distribution in complicated flow. Meantime, fiber orientation time is introduced to describe fiber orientation distribution in the plat-panel.Through the study, the theory that the fiber has a strong orientation in the surface of products, but week in the center layer was proved. But, we found that this phenomenon wasn't absolutely.Because fiber orientation by the duel affected of flow field and orientation time. The main conclusions as follows:1. In the most regions of products, in particular,in the sub-surface layer, the fiber has a better orientation distribution, but this phenomenon became weakened along the center layer.2. At the end of products or some regions where melt flow is very slowly, because of the orientation time is very short, the orientation in the surface layer is worse then in the center layer. 3. The fiber orientation distribution is random in center layer. But in the region near the center layer, if the orientation time is long enough, the fiber tend to arrange like the direction of flow field.