湿热环境对T700/MTM46复合材料层合板拉-拉疲劳性能和疲劳可靠寿命的影响（英文）

Effect of hygrothermal environment on the tension–tension fatigue performance and reliable fatigue life of T700/MTM46 composite laminates

目的:碳纤维复合材料的疲劳特性对航空结构的安全性和可靠性有很大的影响,而湿热环境对复合材料性能的退化作用较大.本文针对湿热环境对碳纤维复合材料层合板的拉-拉疲劳性能和疲劳可靠寿命的影响进行研究,为碳纤维复合材料在实际湿热环境中的应用提供参考.创新点:1.通过实验分析得到碳纤维复合材料层合板在吸湿过程中的损伤演化过程;2.采用实验和理论分析的方法,研究湿热环境对碳纤维复合材料层合板拉-拉疲劳性能和疲劳可靠寿命的影响.方法:1.通过吸湿实验,观测分析得到碳纤维复合材料层合板在湿热老化过程中的损伤演化过程;2.通过疲劳试验,研究湿热环境下碳纤维复合材料的疲劳损伤演化过程、刚度退化规律和损伤失效模式;3.通过理论分析,采用疲劳可靠寿命预测模型,得到湿热环境下碳纤维复合材料的疲劳可靠寿命.结论:1.T700/MTM46复合材料层合板在吸湿过程中,出现了微孔和微脱层等损伤,但比疲劳过程中产生的损伤要小得多;2.与常温环境相比,湿热环境下实验件的刚度退化曲线的变化趋势保持一致,但刚度下降幅度增大;3.与常温环境相比,湿热环境下实验件的疲劳极限降低约6%,疲劳损伤模式相似,但在相同疲劳循环数下的损伤程度加剧;4.在湿热环境作用下,实验件的疲劳可靠寿命大大降低.

The tension–tension fatigue performance of T700/MTM46 composite laminates after hygrothermal aging was investigated and compared with those of virgin T700/MTM46 laminates. The most significant failure mode of the moisture-saturated fatigue specimens is still severe delamination, and the stiffness degradation of moisture-saturated fatigue specimens can be divided into two distinct stages. However, the hygrothermal conditions will aggravate the stiffness degradation of the composite laminates during fatigue. damage evolution was studied by the edge view of the specimens. The degree of damage of the saturated specimens is more serious than that of the virgin specimens at the same percentage of fatigue life during the fatigue process, especially in the initial stage. The distribution of fatigue life in each stress level was determined. The p-γ;-S-N surfaces were established to predict a reliable fatigue life. The results show that the reliable fatigue life of the moisture-saturated specimens is much lower than that of the virgin specimens under the same conditions. Although the hygrothermal environment does not show a significant effect on the static tensile properties of the T700/MTM46 composite laminates, the fatigue performance is significantly degenerated.