Simulation of Compression Effect on Filling Process in Compression Resin Transfer Molding

Abstract

The compression resin transfer molding (CRTM) filling process involves two stages: the injection phase and the compression phase. Two injection modes are considered -constant volumetric flow rate and constant pressure -while the constant compression velocity is utilized in this study. Three typical cases are used to investigate the compression initiation effects on the filling process. When the inlet condition is a constant flow rate, the numerical results show that the compression has both increase and decrease effects on the inlet pressure. Thus, a discontinuity in the inlet pressure is present at the onset or the end of compression. Among three CRTM cases, the process with a simultaneous injection and compression end maximally reduces the inlet pressure by 80% but increases the mold filling time by 65% compared with the resin transfer molding (RTM). For the inlet condition being a constant pressure, the resin may flow out of the mold cavity through the inlet when an excessively low injection pressure and high compression speed are applied concurrently. Compared with RTM, the CRTM processes reduce the mold filling time by 68-76% but cannot ensure a reduction in inlet pressure.

Experimental analysis of mold filling in vacuum assisted compression resin transfer molding

“…An exact position of the flow front versus filling time can be derived in polar coordinates. 6,7,9 For instance, the radius of the theoretical front is 78.5 mm at the injection time of 2 s and K being equal to 1.59 × 10 –9 m 2 , 28 while the average radius of the experimental front is about 74.6 mm. The deviation may result from the pressure loss in the pipelines.…”

“…[5][6][7][8][9][10][11][12][13] Han et al 5 reported that injection/compression liquid composite molding (LCM) process could lead to more regular filling pattern and reduce the molding pressure. Chang 6 investigated the compression initiation effects on the CRTM filling process. Pham and Trochu 7 studied the effect of compression on the filling of a composite part for different compression speeds and injection pressures.…”

Fabrication of continuous carbon fiber reinforced polypropylene composites by injection compression molding with self‐resistance electric heating

“…According to above study, injection compression molding has received extensive attention because it is superior to standard injection molding. [25] Specifically, injection compression molding allows lower injection pressure, shortens impregnation time due to smaller flow lengths [26,27] and reduces distortion of the fabric during injection.…”