Dependence Map-Based Flow Control to Reduce Void Content in Liquid Composite Molding

Prohibitive costs are preventing liquid composite molding processes, such as resin transfer molding, from gaining greater popularity. The high costs are mainly due to lack of automation and repeatability. Variations inherent in the preform cutting and placement process lead to unpredictable resin infusion patterns that sometimes form regions devoid of resin. This compromises the structural integrity of the composite and the part is rejected as scrap. Control during the filling stage of liquid composite molding processes have been shown to redirect the flow towards regions difficult to impregnate, providing a greater percentage of acceptable manufactured composite parts. However, many of the current techniques have various limitations. Many off-line control approaches depend on anticipation of problems, and on-line approaches are geometrically limited and can be computationally intensive if executed during manufacturing. The present work combines off-line and on-line approaches to infuse and fill the mold containing fabrics in an attempt to eliminate their shortcomings and reduce the limitations. First, off-line computationally intensive control algorithms based on the specific part geometry and locations for the sensors and injection gates are created. Next, on-line control is initiated with the off-line parameter guidelines. The approach will be presented and illustrated with several case studies to demonstrate geometrical independence in a simulation environment. Comparison will be made between part success rate using no control, other control techniques, and the proposed control approach. Validation in a laboratory environment is also conducted.