Flexural properties and life-time estimation of carbon fiber/epoxy composite under hygrothermal conditions
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摘要: 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1 440.60 MPa下降到1 081.07 MPa；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。Abstract: The flexural properties of carbon fiber/epoxy (T700/TR1219B) 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/TR1219B composite is realized by introducing the aging time and environmental equivalence.
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Keywords:
- carbon fiber /
- epoxy /
- composite /
- hygrothermal effect /
- flexural properties /
- residual strength /
- life-time estimation
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