Presidential Young Investigator Award: Polymer Processing, Modelling and Simulation

该项目将在聚合物加工、复合材料和流变学领域进行研究，特别是对注塑、压缩和树脂传递成型等过程进行建模和模拟。这项研究的成果将有助于设计者通过创新的建模、分析和工艺模拟来控制材料特性和零件质量。将对复合材料的热机械行为进行研究。在设计塑料零件时，尤其是那些由纤维增强复合材料制成的零件，出现的一个主要问题是由于收缩和翘曲而改变零件的形状和尺寸。本研究将对纤维增强复合材料的成型过程进行热力学模拟。另一项研究将确定低粘度聚合物流动过程中的惯性效应。这对于反应注射成型(RIM)过程尤其有趣，在该过程中，只需要几分之一秒的循环时间。目前的模拟不可能预测这种充型过程的流动模式和取向，因为它们都是基于可以忽略不计的惯性项的假设。该项目还将开发板材热成形过程的模拟，特别是树脂传递模塑过程中使用的纤维哑光预制件和用于车身内板的木粉填充聚丙烯板材。重要的是要知道成型后的填充物方向，并检测薄板中会使其不能使用的折叠或撕裂的形成。了解塑料的热机械行为，并能够在零件实际成型之前预测填充图案、填充物取向、收缩、翘曲和表面波纹度，可提高零件质量，并消除在零件和模具设计的早期阶段完成的一些昂贵且耗时的任务。

The project will conduct research in the field of polymer processing, composites and rheology, specifically modeling and simulating processes such as injection, compression and resin transfer molding. The outcome of this research will aid the designer in controlling material properties and part quality through innovative modeling, analysis and process simulation. Research will be done on the thermomechanical behavior of composites. A major problem that arises when designing plastic parts, especially those made of fiber reinforced composites, is the change of the part's shape and dimensions due to shrinkage and warpage. A thermomechanical simulation of the molding process of fiber reinforced composites will result from this research. Another study will determine the inertial effects during flow of low viscosity polymers. This is especially interesting for the reaction injection molding (RIM) process where cycle times of only fractions of a second are sought. It is not possible to predict flow patterns and orientations for this mold filling process using current simulations, since they are all based on the assumption of negligible inertia terms. The project will also develop a simulation of the thermoforming process of sheet materials, specifically, fiber matt preforms used in the resin transfer molding process and wood flour filled polypropylene sheets used for interior body panels. It is important to know the filler orientation after forming and to detect the formation of folds or rips in the sheet which would make it unacceptable for use. Understanding the thermomechanical behavior of plastics and being able to predict filling patterns, filler orientation, shrinkage, warpage and surface waviness before a part is actually molded leads to higher part quality and eliminates some of the expensive and time consuming tasks done in the early stages of part and mold design.