Experimental Characterization and Numerical Simulation of Voids in CFRP Components Processed by HP-RTM

Abstract

The long cycle of manufacturing continuous carbon fiber-reinforced composite has significantly limited its application in mass vehicle production. High-pressure resin transfer molding (HP-RTM) is the process with the ability to manufacture composites in a relatively short forming cycle (<5 min) using fast reactive resin. The present study aims to investigate the influence of HP-RTM process variables including fiber volume fraction and resin injection flow rate on void characteristics, and flexural properties of manufactured CFRP components based on experiments and numerical simulations. An ultrasonic scanning system and optical microscope were selected to analyze defects, especially void characteristics. Quasi-static bending experiments were implemented for the CFRP specimens with different void contents to find their correlation with material’s flexural properties. The results showed that there was also a close correlation between void content and the flexural strength of manufactured laminates, as the flexural strength decreased by around 8% when the void content increased by ~0.5%. In most cases, the void size was smaller than 50 μm. The number of voids substantially increased with the increase in resin injection flow rate, while the potential effect of resin injection flow rate was far greater than the effect of fiber volume fraction on void contents. To form complicated CFRP components with better mechanical performance, resin injection flow rate should be carefully decided through simulations or preliminary experiments.

Effect of the subsidiary materials of the manufacturing process on the microstructure of the composite laminate

“…[21] Most of the research on the removal and moving of the formed voids mainly focused on the RTM process. [22,23] Many studies on resin flow and voids have been conducted in various processes based on OoA. [24][25][26] However, the effect of resin behavior and void movement depending on the type of subsidiary material in the composite laminate manufacturing process applying the bagging process based on OoA was not addressed.…”