湿热环境下碳纤维层合板拉伸疲劳性能

The hygrothermal environment is one of the main factors affecting the mechanical properties of composite laminates. To maintain the safety of the flight structures, it is crucial to study how hygrothermal conditions affect composite structures.The tensile fatigue properties of carbon fiber composite laminates (CFRP) in room temperature and dry (RTD) condition, cool temperature and dry (CTD) condition and elevated temperature and wet (ETW) condition were experimentally studied, then the S-N curves and fatigue damage modes of CFRP laminates in three different environments were obtained. This served as the foundation for the development of the laminate finite element analysis model, the study of laminate fatigue performance, the analysis and discussion of the effects of temperature and humidity on laminate fatigue performance, and the development of a method for determining the environmental factors influencing the fatigue life of laminates. The results show that the tensile fatigue properties of orthometric laminates are greatly affected by the environment of ETW condition. Compared with the RTD condition, the fatigue strength of orthometric laminates decreases by 2.76% in CTD condition when the fatigue life equates to 10⁶, while the fatigue strength of orthometric laminates decreases by 23.77% ETW condition. The damage modes in RTD condition and in ETW condition are mainly fiber fracture and delamination, while the damage mode in CTD condition is almost fiber fracture. The S-N curve includes two stages of rapid and slow reduction for fatigue strength. The influence of temperature on fatigue performance is obviously stronger than that of humidity. When the temperature exceeds 45 ℃, the influence of humidity on fatigue performance enters the strong influence zone.