RTM中纤维结构对树脂浸渍影响的数值模拟

Numerical Simulation of the Influence of Fibrous Structure on Resin Filling in RTM Process

在树脂传递模塑成型(RTM)中,缩减充模时间以及降低气泡含量是该工艺不断完善的两个关键。本文以牛顿流体为基础,结合Navier-Stokes方程组,构建了二维双尺度气液两相流模型。采用有限体积法(FVM)求解计算域流场物理量,并利用流体体积(VOF)界面追踪技术实现了等温充模阶段的模拟。综合分析了充模阶段流场物理量的变化情况,研究了纤维结构以及树脂黏度对充模时间以及气泡形成与排除的影响,并与分析结果和实验结果进行对照,吻合度较高。数值计算结果表明,二维双尺度模型能准确反映树脂的充模过程。对于低黏度熔体,编织纤维的横纵向孔隙宽度均有一个最佳尺寸,此外,树脂黏度的增加会影响气泡在纤维中的形成以及排除过程,从而影响最终的充模时间。

Reducing mold filling time and bubble content are the two key issues in Resin Transfer Molding （RTM）. The two-phase flow model was built in this paper based on Newtonian fluid and Navier- Stokes equations. Combining the FVM with volume of fluid approach,a successful numerical simulation of isothermal filling stage was achieved. The changes of physical parameters in the filling stage, the influence of the fibrous structure and viscosity of the resin on mold filling time and the formation and exclusion of voids were analyzed. Moreover, there is a good agreement between numerical results and the analytical solutions as well as experimental results. The numerical results show that the model can accurately reflect the process of resin filling. For low viscous melt, pore width of woven fiber has the best horizontal and vertical size. In addition,increase of the viscosity of resin will affect the formation and the removal process of air bubbles in the fiber,thus influence the final mold filling time.