Verification and Validation of openInjMoldSim, an Open-Source Solver to Model the Filling Stage of Thermoplastic Injection Molding

Abstract

In the present study, the simulation of the three-dimensional (3D) non-isothermal, non-Newtonian fluid flow of polymer melts is investigated. In particular, the filling stage of thermoplastic injection molding is numerically studied with a solver implemented in the open-source computational library O p e n F O A M ® . The numerical method is based on a compressible two-phase flow model, developed following a cell-centered unstructured finite volume discretization scheme, combined with a volume-of-fluid (VOF) technique for the interface capturing. Additionally, the Cross-WLF (Williams–Landel–Ferry) model is used to characterize the rheological behavior of the polymer melts, and the modified Tait equation is used as the equation of state. To verify the numerical implementation, the code predictions are first compared with analytical solutions, for a Newtonian fluid flowing through a cylindrical channel. Subsequently, the melt filling process of a non-Newtonian fluid (Cross-WLF) in a rectangular cavity with a cylindrical insert and in a tensile test specimen are studied. The predicted melt flow front interface and fields (pressure, velocity, and temperature) contours are found to be in good agreement with the reference solutions, obtained with the proprietary software M o l d e x 3 D ® . Additionally, the computational effort, measured by the elapsed wall-time of the simulations, is analyzed for both the open-source and proprietary software, and both are found to be similar for the same level of accuracy, when the parallelization capabilities of O p e n F O A M ® are employed.

Application of Selective Induction Heating for Improvement of Mechanical Properties of Elastic Hinges

“…The injection molding simulations were performed with Autodesk Moldflow Insight 2019 (Autodesk, San Rafael, CA, USA) software, which uses a Cross-WLF thermorheological model to describe the behavior of polymer melt during the filling of the cavity (it is the material model that is widely used for injection molding simulations [ 36 ]). The mesh size in the whole part was set to 0.5 mm, whereas the dense mesh was created at the elastic hinges (mesh size of 0.1 mm and the number of layers was increased from 10 to 20) to obtain more accurate results.…”

New boundary conditions for simulating the filling stage of the injection molding process

“…This will be explained along the text. Additionally, the readers are referred to Pedro et al (2020) for the numerical validation of the current algorithm.…”

Non-Isothermal Free-Surface Viscous Flow of Polymer Melts in Pipe Extrusion Using an Open-Source Interface Tracking Finite Volume Method

“…The polymer production process is mainly non-isothermal in nature, including heat transfer phenomena such as heating and cooling, e.g., in the injection molding [3,4] or extrusion [5][6][7][8] processes. Since the flow properties are strongly dependent on rheology and temperature, it is of great interest to understand and predict this type of heat transfer phenomenon.…”