全湿热场下碳纤维/环氧树脂复合材料弯曲性能及寿命预测

Flexural properties and life-time estimation of carbon fiber/epoxy composite under hygrothermal conditions

以碳纤维/环氧树脂(T700/TR1219B)复合材料为研究对象,采用湿度场和温度场单一及耦合的方式,研究了不同湿热环境下其弯曲性能的变化,通过断口形貌和表面粗糙度表征,分析其湿热损伤机制。结果表明:T700/TR1219B复合材料的弯曲性能受湿度场和温度场影响明显,当吸湿率达到2%时,弯曲强度从干态的1 440.60MPa下降到1 081.07MPa;随温度的升高弯曲性能呈下降趋势,且在玻璃化转变温度Tg所在温度区间发生陡降,当环境温度为180℃时,弯曲模量和弯曲强度分别下降了71.18%和93.32%;高温高湿环境下弯曲性能陡降的温度区间前移,且性能衰减并非单一湿度场和温度场下衰减量的简单叠加。通过微观形貌分析发现,湿度场主要导致树脂水解脱黏,温度场下树脂形态破坏严重,而湿热耦合场对纤维与树脂均产生较大程度的损伤。考虑湿度场和温度及湿热耦合相关项,建立并验证了全湿热场下剩余弯曲强度模型,结合湿热老化时间、环境当量等参数提出T700/TR1219B复合材料的寿命预测模型。

The flexural properties of carbon fiber/epoxy(T700/TR1219 B)composite were investigated under different hygrothermal conditions,including single moisture,temperature and coupled moisture-temperature conditions.Combined with fracture morphology and surface roughness,the degradation mechanism was analyzed.The experimental results show that the flexural properties decrease significantly under hygrothermal conditions.With the moisture absorption rate of 2%,the flexural strength decreases sharply from 1 440.60 MPa to 1 081.07 MPa due to the interfacial debonding caused by water absorption.The flexural properties decrease with temperature increasing and exhibit a steep fall in the range of glass transition temperature Tg.The flexural modulus and flexural strength decrease by 71.18%and 93.32%at 180℃,respectively,caused by resin degradation under high temperature.The coupled moisture-temperature condition results in the steep fall of properties at lower temperature range.The residual strength model is established and verified concerning the effects of hygrothermal conditions.The life-time estimation of T700/TR1219 Bcomposite is realized by introducing the aging time and environmental equivalence.