湿热环境对CCF800/环氧挖补板拉压性能的影响

针对挖补修理后飞行器在服役期间会经历高温高湿环境，进行了湿热环境对挖补修理层合板（以下简称挖补板）拉压性能影响的研究。首先，测试了4种湿热环境下CCF800/环氧挖补板的拉伸和压缩性能；然后，建立了相应的湿热应力有限元模型，探索了不同湿热环境下挖补板内的湿热应力分布；最后，在此基础上建立了湿热环境下挖补板的拉伸和压缩力学模型，研究了湿热环境对CCF800/环氧挖补板力学性能的影响。试验结果显示，湿热环境使挖补板的承压能力降低，承拉能力提高，这与常理不符。经试验观察和机理分析，发现CCF800/环氧铺层中纤维弯曲是导致湿热环境下挖补板拉伸性能不降反升的主要原因。在考虑湿热环境时，制备CCF800纤维复合材料过程中需要格外注意纤维弯曲问题。 

Effect of hygrothermal environment on tensile and compressive properties of CCF800/epoxy scarf-repaired laminates

As the aircrafts after scarf repair may experience hygrothermal environment during its service, the effect of hygrothermal environment on tensile and compressive properties of scarf-repaired laminates was studied in this paper. The tensile and compressive properties of composite CCF800/epoxy scarf-repaired laminates in four hygrothermal environments were firstly tested. Then, corresponding finite element models of hygrothermal stress were established to explore structural hygrothermal stress distribution in different environments. Finally, the tensile and compressive property analysis models of scarf-repaired laminates in the hygrothermal environment were established to explore the effect of the hygrothermal environment on the mechanical properties of the scarf-repaired laminates. The experimental results show that the hygrothermal environment reduces the compressive bearing capacity of scarf-repaired laminates, but improves their tensile bearing capacity, which is inconsistent with the common sense. Through experimental observation and mechanism analysis, it was found that the fiber misalignment in CCF800/epoxy laminates is the main reason that the tensile properties of the scarf-repaired laminates do not decrease but rise in hygrothermal environment. Therefore, with hygrothermal environment considered, the problem of fiber misalignment needs to be paid special attention to in the production of CCF800 fiber composite materials.