Experimental investigation and utilization of a CFD-based multiphase simulation to predict the flow behavior of complex suspensions in the plastic injection molding process using a mineral-filled polyamide

• Applicant: Professor Dr.-Ing. Reinhard Schiffers
• Subject Area: Plastics Engineering
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441824520

The aim of this research project is to further develop a simulation methodology that can already map the essential properties of a complex suspension of plastic melt and filler particles. Such a simulation methodology is necessary because commercially available injection molding simulation software only assumes simplified continuum material properties for such multiphase plastics. This means that no information about the component morphology, such as particle distribution and its orientation, can be taken into account or mapped. Preliminary tests in the first funding period, however, showed an influence of the process parameters on the formation of boundary layers. The research project therefore focuses on the development of a simulation methodology that maps these properties, through micromechanical and flow-related interactions, and thus contributes to an improved understanding of the process. To this end, the boundary layer surface of mineral-filled polyamide 6 components, some of which have passed through the electroplating process chain, will also be characterized using confocal and scanning electron microscopy. Peel tests are carried out in accordance with DIN EN ISO 2819 to quantifiy the quality of the electroplating process. In this way, simulation results can be successfully linked to component quality. The existing simulation methodology is first extended by the Ansys Rocky solver and then optimized for faster computation times. This allows the complexity of the model to be increased and simplifications, such as the neglect of temperature and viscosity changes, to be reduced. Thus, influencing factors are taken into account in the second funding period that were not included in the first funding period. The newly integrated solver Ansys Rocky offers the possibility to adjust the particle shape and to calculate its orientation accordingly. Therefore, the newly emerging interactions of the particles with each other and with the component wall are integrated into the model and the discretization of the flow domain is optimized. To extend the database, further surface characterizations are performed by confocal and scanning electron microscopy for relevant process parameters and new observation positions. The simulation model will then be applied to this new and enlarged study area. An evaluation of the further developed simulation methodology is performed on new components. For this purpose, test specimens with a new geometry are manufactured, galvanized and surface characterized and the methodology is applied to this new geometry. Finally, the results obtained from experiments and simulations are analysed and the simulation methodology is verified and validated on the basis of previously established working hypotheses.

• DFG Programme: Research Grants