Jetty Bhimesh, Wittemann Florian, Kärger Luise
Department of Lightweight Engineering, Karlsruhe Institute of Technology (KIT), Rintheimer-Querallee 2, 76131 Karlsruhe, Germany.
Polymers (Basel). 2024 Aug 7;16(16):2245. doi: 10.3390/polym16162245.
Recycling production waste in the reactive injection molding (RIM) process is a step towards sustainability and efficient material usage. The recycled thermoset composite (RTC) material obtained by shredding the production waste is reused with a virgin thermoset composite (VTC). This study presents a mold-filling simulation approach considering this polydisperse suspension of RTC and VTC. Mold-filling simulations can assist in predicting processability and assessing the impact of reinforced RTC on the final part of production. State-of-the-art mold-filling simulations use the Cross-Castro-Macosko (CCM) model or anisotropic fiber-orientation-dependent viscosity models. The rheological parameters are determined either for the VTC or neat resin. However, these models do not account for changes in viscosity due to the reinforcing of fillers such as RTC. An effective viscosity model is developed by extending the CCM model using the stress-strain amplification approach to overcome this gap. This model is implemented in the computational fluid dynamics code OpenFOAM, and simulations are performed using an extended multiphase solver. To validate the simulations, experimental trials were executed using a two-cavity mold equipped with pressure sensors. Molding compounds with different compositions of VTC and RTC were injected at different speeds. Reinforcing VTC with RTC increases the viscosity. Results demonstrate that RTC-reinforced compounds require higher injection pressure for mold filling than VTC alone. The qualitative agreement of pressure profiles from simulations and experiments for different proportions of reinforcing RTC and different injection speeds shows that the implemented viscosity model can reproduce the experimental mold-filling behavior.
在反应注射成型（RIM）工艺中回收生产废料是迈向可持续发展和高效材料利用的重要一步。通过粉碎生产废料获得的再生热固性复合材料（RTC）与原始热固性复合材料（VTC）一起重新使用。本研究提出了一种考虑RTC和VTC这种多分散悬浮液的充模模拟方法。充模模拟有助于预测加工性能并评估增强型RTC对最终生产部件的影响。目前先进的充模模拟使用Cross-Castro-Macosko（CCM）模型或与各向异性纤维取向相关的粘度模型。流变参数是针对VTC或纯树脂确定的。然而，这些模型没有考虑到诸如RTC等填料增强导致的粘度变化。通过使用应力-应变放大方法扩展CCM模型，开发了一种有效的粘度模型来弥补这一差距。该模型在计算流体动力学代码OpenFOAM中实现，并使用扩展的多相求解器进行模拟。为了验证模拟结果，使用配备压力传感器的双腔模具进行了实验试验。以不同速度注射具有不同VTC和RTC组成的模塑料。用RTC增强VTC会增加粘度。结果表明，与单独使用VTC相比，RTC增强的模塑料在充模时需要更高的注射压力。对于不同比例的增强RTC和不同注射速度，模拟和实验得到的压力曲线的定性一致性表明，所实施的粘度模型可以再现实验充模行为。
