2D and 3D SPH simulations of transient non-isothermal viscoelastic injection molding process with complex-shaped cavities

Abstract

In the present work, we introduce a smoothed particle hydrodynamics (SPH) method for simulating both 2D and 3D transient non-isothermal viscoelastic injection molding process with complex-shaped cavities. To delineate the viscoelastic properties of the polymer melt, the non-isothermal Oldroyd-B constitutive equation is considered based on the time–temperature superposition principle. To discretize the governing equations, the improved SPH scheme presented by Xu and Jiang, J. Non-Newtonian Fluid Mech. 309 (2022) pp. 104,905 is employed. To model the wall boundaries of complex shapes, an enhanced treatment technique of wall boundaries that utilizes a level-set based pre-processing algorithm is introduced. Initially, the method is applied to simulate a 2D non-isothermal viscoelastic injection molding process involving a circular disc with an irregular insert. The convergence of the method is validated by three different particle sizes. Results on the velocity, temperature, and the first normal stress difference during the injection molding process are presented. The influences of the Péclet, Reynolds, Weissenberg numbers, and viscosity ratio on the process are analyzed. The method is then extended to handle challenging 3D non-isothermal viscoelastic injection molding problems, including cavities of a hexagon screw and a car rim. Change in rheological information at various time points is reported. All the results demonstrate that the proposed SPH method is a robust computation tool for simulations of both 2D and 3D transient non-isothermal viscoelastic injection molding processes, even with highly complex-shaped cavities.