This study conducts tensile-tensile fatigue tests of plain-woven carbon fiber-reinforced plastic (CFRP), observing progressive damage under cyclic loading using the replica method. The tests reveal two fatigue damage modes characterized by differing crack growth patterns: high-cycle (HCF) and low-cycle (LCF) fatigue. Due to their complex woven structure, damage mechanisms such as interface debonding and transverse cracks interact, complicating damage prediction of plain-woven CFRP. To improve the reliability of woven CFRP structural components designed for long-term use under repeated loading, elucidating their fatigue damage characteristics of this material is essential. The study performs tensile-tensile fatigue tests on plain-woven CFRP laminates to evaluate their fatigue damage characteristics under cyclic loading. Observations made at specific cycle intervals clarify the damage initiation and progression of damage in plane-woven CFRP as the number of cycles increases. The two damage modes identified in the study exhibit different growth patterns of interface debonding. Notably, these damage modes emerge at the same stress level, leading to significant variability in fatigue fracture cycles.
