A novel insight into fatigue damage mechanism of plain-woven composites using 3D-DIC

Composite materials are known for their excellent mechanical properties, but their fatigue damage behavior is complex and challenging to characterize. In order to investigate the fatigue behavior of carbon fiber/epoxy plain-woven composites, a novel testing method is proposed by integrating low-frequency cycles into regular fatigue cycles, enabling precise capture of strain field evolution during fatigue by 3D digital image correlation (3D-DIC). Quantitative characterization methods for typical damage modes are established by combining displacement and strain data from 3D-DIC. The results of fatigue experiments reveal the fatigue damage process for the first time of plain-woven composites, which consists of five stages: initial weft yarn cracking, warp-weft separation, interlayer delamination, reduced load transfer, and final failure. These findings enhance the understanding of fatigue behavior in woven composites, and are of great significance for their anti-fatigue design.