湿热环境对碳纤维增强树脂基复合材料力学性能的影响及其损伤机理

Effect of hygrothermal environment on mechanical properties and damage mechanism of CFRP

采用加速吸湿法研究经3种湿热环境(湿度为85%RH,温度分别为25,70,85℃)处理后CFRP层合板的吸湿特性,对吸湿前后的碳纤维增强树脂基复合材料(CFRP)层合板分别进行拉伸、压缩、剪切实验,研究其力学性能变化规律,利用扫描电镜和红外光谱分析湿热环境中CFRP层板的损伤机理,最后采用最小二乘法拟合提出湿热环境下CFRP层合板力学性能的预测公式。结果表明:CFRP层合板的吸湿初期特性符合Fick定律;相同湿度下环境温度越高,CFRP的吸湿速率和平衡吸湿率越大,达到吸湿平衡所需时的间越长;3种湿热环境处理后的CFRP层板的90°拉伸和剪切力学性能下降最明显;经湿热环境处理后水分子通过氢键与环氧树脂发生缔合,但CFRP层合板中的各组分未发生化学结构变化;拟合建立的不同湿热条件下力学性能衰退公式与实验结果基本一致。

The moisture absorption properties of carbon fiber reinforced plastics (CFRP) laminates treated with three kinds of hygrothermal environments (relative humidity 85% RH,temperature 25,70,85℃ respectively) were investigated by accelerated moisture absorption method.Tensile,compressive and shear tests were carried out to study the effect of hygrothermal conditions on the mechanical behavior of CFRP laminates.Meanwhile,the damage mechanism of CFRP laminates in hygrothermal environment was analyzed by scanning electron microscopy and infrared spectroscopy.Finally,a formula which could predict the mechanical properties of CFRP laminates in hygrothermal environments was proposed by least square method.The results show that the moisture absorption characteristics of CFRP laminates in preliminary stage accords with Fick's law well.At the same humidity,the CFRP's moisture absorption speeds,the moisture saturation contents and times are increased with the increment of the environmental temperature.The mechanical properties of CFRP laminates in 90°tensile test and shear test are decreased most obviously.Water molecules are associated with epoxy resin through hydrogen bonds after the treatment in hygrothermal environment,however,there is no chemical structure change in the components of the CFRP laminate.The formula of mechanical performance degradation under different hygrothermal conditions is basically consistent with the experimental results.