双尺度纤维织物二维非饱和流动的数值模拟与实验

Numerical simulation and experiment of 2D unsaturated flow of dual-scale fiber mat

液体模塑成型工艺(LCM)中非饱和流动的填充模拟对于在虚拟空间中快速、高效地优化工艺参数具有重要意义。采用了一种模拟双尺度纤维织物在等温条件下非饱和流动的双尺度计算模型,通过引入沉浸函数求解宏观-微观流动控制方程组,同时考虑了在微观浸渍中毛细压力的影响,在有限元/控制体积算法中实现了对非饱和流动的数值模拟。随后对三向缝合纤维织物进行了二维径向填充实验,将实验结果与数值模拟的预测值对比。结果表明,该计算模型可以较精确地模拟双尺度纤维织物中的非饱和流动。在此计算模型的基础上,讨论了流体黏度、注射流量及纤维束孔隙率对非饱和填充浸润的影响。结果表明,不同流体黏度、注射流量及纤维束孔隙率对纤维织物填充过程中非饱和区域长度、入口压力曲线及填充时间影响不同。研究结果可以对合理预测纤维织物的浸润及树脂填充过程中入口压力提供指导。

Mold-filling simulation of unsaturated flows in liquid composite molding(LCM) is important for optimizing process parameters quickly and cost-effectively in the virtual space. A dual-scale computational model for simulating unsaturated flow of dual-scale fiber mat under isothermal conditions was presented. The macro-micro flow control equations were solved by introducing the sink function, and the influence of capillary pressure in microscopic immersion was considered. The numerical simulation of unsaturated flow was realized in the finite element/control volume algorithm. The 2-dimensional radial filling experiment was carried out on the triaxial stitched fiber mat. The experimental results were compared with the numerical simulation predictions and the results show that the method can accurately simulate the unsaturated flow in the dual-scale fiber mat. Based on this calculation model, the effects of fluid viscosity, injection flow rate and the tow porosity on the unsaturated filling process were discussed. The results show that different fluid viscosity, injection flow rate and tow porosity have different effects on the length of unsaturated region, the inlet-pressure history and the filling time during filling process. The research results can provide guidance for reasonably prediction of filling process and the inlet-pressure history.