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Filling of a complex‐shaped mold with a viscoelastic polymer. Part I: The mathematical model
Author(s) -
Papathanasiou Thanasis D.,
Kamal M. R.
Publication year - 1993
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760330705
Subject(s) - materials science , viscoelasticity , mechanics , curvilinear coordinates , isothermal process , flow (mathematics) , rectangle , boundary value problem , thermal , mold , composite material , geometry , thermodynamics , mathematics , mathematical analysis , physics
A model for the filling stage of injection molding of viscoelastic thermoplastics in cavities of complex shape is presented. The model considers two‐dimensional melt flow, with converging and diverging flow patterns induced by complex boundary shape and by the presence of an obstacle. The model is non‐isothermal (with the melt loosing heat to the mold walls as it travels into the cavity) and handles a viscoelastic (following the White‐Metzner model) material with properties that vary with temperature, shear rate, and pressure. The numerical method is based on finite differences, with boundary fitted curvilinear coordinates used in the mapping of the flow field (which has an arbitrary shape that evolves with time) into a time invariant rectangle. The numerical results reveal geometry‐induced asymmetries in the flow and thermal fields as well as the effect of various process parameters on the pressure and temperature profiles in the cavity. The model admits variable cavity thickness, thus allowing for a treatment of the cavity thickness as a process parameter in the simulations.