Analytical modeling and in situ measurement of void formation in liquid composite molding processes

Abstract

Liquid composite molding processes are widely accepted in the aeronautic industry to manufacture large and complex structural parts. In spite of their cost-effectiveness, void defects created during the manufacturing process are a major issue of these processing techniques because they have detrimental effects on the mechanical performance. The reliable modeling is still a difficult task and experimental observations are usually adopted for the analysis of void formation mechanism, however, because many different physics are simultaneously involved during the mold filling process and the resin curing process. The complexity of the void formation physics implies the need for an in situ measurement of void formation not in the final part but in the mold filling procedure during the manufacturing process to better understand the void mechanism. In this regard, we present a sensor system measuring the electric conductivity for the in situ monitoring of void formation during the mold filling process. We also propose a theoretical model to predict void formation in a quantitative way with the properties of the resin and the fiber reinforcement. The model prediction is compared with the experimental data obtained by the sensor system to validate the model.

Keywords:

• liquid composite molding processes
• void defects
• in situ measurement
• theoretical model
• electric conductivity

Acknowledgements

This work has been performed in collaboration with SAFRAN/Aircelle under the research program of ‘RTM Structural’. The authors also would like to acknowledge the financial support from the French Ministry of Economy, Finance and Industry.