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为探讨单向纤维增强复合材料中纤维损伤与材料热阻变化之间的关系,建立了由纤维断裂引起热阻变化的细观理论模型,并利用该模型对热阻变化率进行了定性分析。针对纵向传热与垂直传热两种情形下的热阻进行分析,结合Weibull纤维强度分布模型,引入纤维失效长度作为纤维链段的最小长度,获得了纤维断裂引起的复合材料纵向和沿厚度方向热阻变化率的解析函数。采用Monte-Carlo随机方法对外加应力作用下复合材料热阻随着纤维断裂而发生变化的过程进行模拟。研究结果表明:无论是纵向热阻还是厚度方向的热阻,热阻变化率均随纤维断点数目的增大而线性递增;纤维体积组分越大,热阻变化率越大。纵向热阻变化率随着纤维/基体导热系数比β的增大而迅速增大,但当β>10时增大的幅度逐渐减弱;而厚度方向的热阻变化率则随着β的增大先急剧增大而后递减,当纤维与基体的导热系数相当时(在β=1附近)达到最大值。
In order to investigate the relationship between the fiber damage and the change of thermal resistance in unidirectional fiber-reinforced composites, a mesoscopic model based on the change of thermal resistance caused by fiber breakage was established. The thermal resistance change rate was qualitatively analyzed by the model. The thermal resistance under longitudinal and vertical heat transfer was analyzed. According to the Weibull fiber strength distribution model, the fiber failure length was introduced as the minimum length of the fiber chain segment, and the longitudinal direction and thickness direction Analytic function of thermal resistance change rate. The Monte-Carlo method was used to simulate the thermal resistance of composites with the change of fiber fracture under the applied stress. The results show that the thermal resistance changes linearly with the increase of the number of fiber breakpoints, no matter in the longitudinal thermal resistance or in the thickness direction. The larger the fiber volume fraction, the greater the thermal resistance change rate. The change rate of longitudinal thermal resistance increases rapidly with the increase of fiber / matrix thermal conductivity ratio β, but increases gradually with the increase of β> 10, while the change rate of thermal resistance in the thickness direction increases with the increase of β The first sharp increase and then decrease, when the fiber and the substrate thermal conductivity is equivalent (in the vicinity of β = 1) to reach the maximum value.