A study on preventing deterioration of fatigue durability when molding GFRP parts for automobiles using HP-RTM process.

The automobile industry is exploring the use of HP-RTM (high-pressure resin transfer molding) for mass-producing glass fiber-reinforced plastic (GFRP) chassis parts to achieve weight reduction. In this process, dry fabric is used as a material. However, the fatigue endurance performance of these parts deteriorates due to the bobbin threads in the dry fabric. This study aims to propose a laminating method to prevent the deterioration of the durability of GFRP chassis parts with bobbin threads. Specimens were fabricated with different fiber volume fractions (Vf) and bobbin thread positions. After manufacturing, static properties were evaluated to compare the physical properties of each specimen, and the stress for fatigue durability evaluation was determined based on these static properties. Finally, fatigue endurance performance evaluations were conducted to determine the optimal lamination conditions for GFRP chassis parts. The results showed that for the three laminating methods applied in this study, an increase in Vf not only enhanced the static properties but also reduced waviness, as confirmed through OM images and changes in the slope of the stress–strain curve. Additionally, fatigue endurance tests revealed that, along with the improvement in waviness, adjusting the position of the bobbin threads—which negatively impact durability—resulted in an increase in fatigue endurance performance from approximately 67,000 cycles to about 870,000 cycles, an improvement of approximately twelve times. [ABSTRACT FROM AUTHOR]