弯曲载荷下碳纤维/双马复合材料湿热特性实验研究

研究了碳纤维/双马复合材料单向层板在三点弯曲载荷作用下70℃水浸的湿热特性，测试分析了层板的吸湿量、玻璃化转变温度、弯曲性能及其破坏模式随湿热时间的变化，通过对比研究弯曲载荷作用和无外载荷条件下层板湿热性能的差异，探讨了应力对复合材料湿热行为的作用规律。结果表明：弯曲载荷作用下试样整体的吸湿规律、剩余弯曲性能等方面与未加载情况相比没有显著差异，但弯曲加载试样吸湿饱和前相同吸湿率时玻璃化转变温度下降更多；弯曲加载试样受压应力部分吸湿速度小于受拉应力部分，同时弯曲断口的扫描电镜照片显示，与未加载情况相比弯曲加载试样受拉应力部分树脂与纤维粘结较弱，说明应力会对复合材料湿热性能产生影响，并且不同方向应力的作用规律不同。

Hygrothermal behavior of carbon fiber/bismaleimide resin composite under flexural load

Hygrothermal behavior of unidirectional carbon fiber reinforced BMI matrix composite laminates was investigated，which were subjected to three-point flexural load in the distilled water at 70℃ for different times. Compared with the unstressed specimens，there are no significant differences in apparent moisture absorption，as the glass transition temperature and residual flexural properties were observed for flexural-stressed specimens. However，the flexural-stressed specimens show a greater decrease in glass transition temperature before saturation. The tensile-stressed section absorbs water faster than the compressive-stressed section for the flexural -stressed specimens. The SEM of the flexural fracture surface shows that the adhesion property of the fiber and matrix in the tensile-fracture section of the stressed specimens suffers more severe deterioration than that of the unstressed specimens. It indicates that the stress has significant influence on the hygrothermal property of the composite，which depends on the direction of the stress.