Fundamental study on remaining life evaluation of CFRP structures under cyclic loading using remaining life indicator

抄録

Carbon Fiber Reinforced Plastic (CFRP) consists of carbon fibers and resin, and the presence of various damage modes—such as resin cracking, delamination, and fiber breakage—makes it challenging to predict the remaining service life of the structure. Under cyclic loading, damage initiates after a certain number of cycles and gradually accumulates. The timing of damage occurrence varies depending on the type of damage. In many structures, the final damage mode to occur is fiber breakage, which typically occurs near the end of the structure's lifespan. The objective of this study is to investigate the feasibility of a system that incorporates a material into the CFRP, which fractures slightly earlier than the fiber breakage. The fracture of this material is detected through Acoustic Emission (AE) testing, enabling recognition that the structure is nearing the end of its service life. The study also aims to determine whether the failure of the marker material could be detected through AE testing and to assess the impact of the marker on the mechanical properties of the structure. In this paper, tensile tests were performed on specimens containing the marker material to assess its performance and observe the AE generated during the marker's fracture. Fatigue tests were also conducted on these specimens. The results confirmed that incorporating the marker material does not significantly affect the strength of the base material. Furthermore, AE signals generated by the fracture of the marker material were successfully detected.