• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.2
• /
• pp.393-398
• /
• 1990

A method is proposed which can be used to obtain the fibesr content distribution of compression molded long fiber-reinforced thermoplastic sheet for nonisothermal state. The fiber is modelled to be a sphere. Once the one-dimensional unsteady state heat conduction equation in solved, the mean temperature in defined across the thickness direction. The viscosity of matrix is determined with the mean temperature. Using the obtained viscosity, two-dimensional sheet0like part compression molding is simulated with the finite element method. Comparison with experiments shows that the method accurately predicts the distribution.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.5
• /
• pp.1150-1160
• /
• 1993

The behavior of polystyrene in the strip cavity during the packing and cooling stages for an injection molding process is examined numerically. The mathematical model is based on the unified post-filling model and finite element/finite difference methods are used to solve simultaneously the continuity, momentum and energy equations coupled to an equation of state. Simulated results show that the density of the molded parts is lower in the core than at the skin, and that the hotter the melt or the higher the packing pressure, the higher the density in the core. The density variation during the packing stage comes up to 50% compared with the total density variation. Also, the density variation after gate sealing and the effect of cooling rate on the equation of state are negligible.