Simulation Of The Reaction Injection Mold Filling Process For Thin Non Planar Parts

Author : Erwin Wen-Ti Liang
Publisher :
ISBN 13 :
Total Pages : 314 pages
Book Rating : 4.:/5 (269 download)

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Download or read book Compression Mold Filling Simulation for Thick, Non-planar Parts written by Erwin Wen-Ti Liang and published by . This book was released on 1991 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.