Modeling of Reactive Filling in Complex Cavities***

Abstract

The flow of reacting monomers into thin planar cavities of irregular geometry is analyzed. The Hele-Shaw approximations are used to simplify the momentum and mass balances. At each time step, the flow domain is mapped onto a rectangular domain using elliptic expressions. The transformed governing equations are solved using finite-differences. The transient three-dimensional energy and species balances are solved using an explicit marching scheme coupled to the flow. Viscosity is modeled as a function of temperature and extent of reaction. Castro's model is used to compare several fountain flow approximations. A simplified algorithm was found to capture the essence of the fountain flow kinematics. The fountain flow approximations described here can also be used in thermoplastic injection molding modeling. Results for a rectangular end gated mold and for an irregular mold geometry are presented.

Kinetic analysis of two DSC peaks in the curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate

“…For an isothermal reaction, a nth order equation predicts the maximum of reaction rate at zero time, which is not the case for autocatalytic cure processes. However, for most of the nonisothermal cure systems, the efficiency of this model has been postulated by some workers [29][30][31][32][33][34][35]. This is why this model also deserves to be taken into consideration.…”

A methodology to determine permeability distribution of a preform in resin transfer molding process

“…With reference to the iterative scheme in solving Equation (3), Voller and Chen have theoretically shown existence and uniqueness of the solution, 11 that is, for any given time step, there is one and only one filled fraction field F and pressure field P that satisfies Equation (3) subjected to the conditions in Equation (4). In addition to the existence of this unique feature, Voller and Chen have also shown that under the assumption of time invariant boundary conditions, 11 predictions of the filled fraction field are independent of the employed time step size, that is, the prediction of the filled fraction using one large time step is identical to the prediction obtained by using many smaller time steps.…”

“…These predictions could suggest appropriate conditions for inlets and vents such that the aforementioned problems could be avoided. However, accurate and meaningful numerical predictions resulting from the available RTM simulation tools such as mold filling simulations, [1][2][3][4][5][6][7][8][9] filling time, and vent location predictions require the specification of the correct permeability distribution of the preform. [10][11][12] This poses the need for the identification or measurement of the permeability distribution of the preform in order to provide RTM simulation tools with proper process information, thus improving the process design capability.…”

Theoretical analysis on extrusion die flow of electronic packaging materials

“…On the other hand, the flow in the slot section basically follows the 2-D Hele᎐Shaw model, as in the case of reaction Ž . injection molding Garcia et al, 1991 . The following assumptions are also necessary for the mathematical model:…”