One of the prevalent industrial methods for manufacturing composite structures is fiber winding, a technique extensively employed for producing axis-symmetric parts. This method has gained considerable popularity due to its capability to create lightweight yet durable structures, making it particularly valuable in industries such as aerospace and automotive. The lightweight nature of these composites allows for enhanced fuel efficiency and performance, which are critical factors in these sectors. However, one of the most common damage mechanisms encountered in these composite structures is delamination, which can occur under various loading conditions, such as tension, compression, and shear. This phenomenon can lead to a significant reduction in both the performance and lifespan of the structures, posing challenges in their application.

In this study, we investigated the mechanical behavior and propagation of the initial mode I crack in carbon/epoxy curved beams fabricated using the fiber winding (FW) method, employing the acoustic emission (AE) technique for analysis. To achieve this, a composite tube was first manufactured with an artificial interlaminar separation, from which beam samples were cut along its longitudinal direction. In the initial phase of the research, the initiation of failures was identified using the AE method, which allows for real-time monitoring of crack propagation. Subsequently, the growth and propagation of interlaminar delamination were evaluated through the energy of AE signals and the centroid function. By determining the velocity of AE waves and implementing a filtering method to remove unwanted signals, we were able to predict the instantaneous position of the delamination tip during its growth.

The results indicated that the fiber bridging phenomenon was a result of the interpenetration of two adjacent regions at the delamination interface. Notably, the length of the fiber bridging zone had a significant impact on the mode I fracture toughness of the delamination. Furthermore, as the fiber bridging area increased, the fracture toughness also exhibited an increase. A strong correlation was observed between the fracture toughness values obtained from the AE method and those derived from the ASTM D5528 standard, highlighting the reliability of the AE technique in assessing composite material performance. These findings can significantly contribute to the improved design of composite structures and enhance the ability to predict their behavior under real-world loading conditions, ultimately leading to safer and more efficient applications in various industries.