Current models for delamination propagation prediction in fiber-reinforced polymer (FRP) composites exhibit limitations to explain the physics underlying the mechanisms of damage formation in fatigue. In order to contribute in this field, this research focuses on the study of damage development within a single loading cycle of FRP double cantilever beam specimens under different stress ratios (R). The acoustic emission technique was used to investigate damage propagation. Results showed that under high R-ratios, the load cycle spends an increased time above the threshold energy (U_th). This time difference affects the damage distribution within a single loading cycle. Furthermore, the steady-state delamination propagation was influenced by the R-ratio variation due to the modification of the external work applied to the specimen.

当前的纤维增强聚合物（FRP）复合材料中的分层传播预测模型显示出局限性，无法解释造成疲劳损伤的机理。为了在该领域做出贡献，本研究着重研究在不同应力比（R）下FRP双悬臂梁试样在单个加载周期内的损伤发展。声发射技术用于研究损伤的传播。结果表明，在高R比率下，负载周期花费的时间超过阈值能量（U _th）。该时间差会影响单个加载周期内的损坏分布。此外，由于对样品施加的外部功的修改，稳态分层传播受到R比率变化的影响。