A finite element simulation, based on Barone and Caulk's model, is developed to study the compression mold filling over three-dimensional curved surfaces. The effects of charge thickness and surface curvature on the pressure and velocity distributions are examined. In solving the velocity-pressure type equation, an element-based penalty method is implemented into the simulation. This approach shows great accuracy and efficiency as compared with the mixed formulation and a iteration scheme. The full Barone and Caulk model gives accurate predictions of filling patterns for thick charges. In thin charges, a special numerical treatment of the full Barone and Caulk model is developed by adding artificial elongational viscosity. Finite element results show that this model produces better accuracy in velocity as well as velocity gradient compared with the Hele-Shaw formulation, which is used by most molding simulations. A new technique is developed for tracking the moving flow front, using a fixed finite element mesh which models the part geometry. For each time step, temporary elements and temporary nodes are generated within the filled region of any element intersected by the flow front. This scheme allows a smooth representation of the flow front and the imposition of exact boundary conditions on the flow front. Other advantages of this scheme are flexibility in mesh generation and the local mesh refinement. This simulation accurately predicts the flow patterns and knit line locations. The formation and motion of knit lines can easily be tracked by this scheme. A three dimensional shell-like mold cavity is mapped from the physical domain to a planar cavity of uniform thickness in a transformed domain. Two-dimensional flow equations are formulated in the curvilinear coordinate system associated with the mid-surface. The mold filling simulation is performed in the transformed space, as metric tensors and Cristoffel symbols for the surface are provided. The solutions can be mapped back onto the three-dimensional physical space, since all the quantities in the two domains has a one-to-one correspondence.

Master's Thesis from the year 2007 in the subject Engineering - Mechanical Engineering, language: English, abstract: (Thesis in pdf available here: http: //goo.gl/EZzlT6 and here: http: //hdl.handle.net/10773/2419) Commonly used methods for injection moulding simulation involve a considerable number of simplifications, leading to a significant reduction of the computational effort but, in some cases also to limitations. In this work, Reaction Injection Moulding (RIM) simulations are performed with a minimum of simplifications, by using the general purpose CFD software package Ansys CFX, designed for numerical simulation of fluid flow and heat and mass transfer. The Ansys CFX's homogeneous multiphase flow model, which is generally considered to be the appropriate choice for modelling free surface flows where the phases are completely stratified and the interface is well defined, is shown to be unable to model the filling process correctly. This problem is overcome through the implementation of the inhomogeneous model in combination with the free-slip boundary condition for the air phase. The cure reaction is implemented in the code as a transport equation for an additional scalar variable, with a source term. Various transient and advection schemes are tested to determine which ones produce the most accurate results. Finally, the mass conservation, momentum, cure and energy equations are implemented all together to simulate the simultaneous filling and curing processes present in the RIM process. The obtained numerical results show a good global accuracy when compared with other available numerical and experimental results, though considerably long computation times are required to perform the simulations.