中文摘要：

建立了混杂复合材料纤维和纤维束两个尺度的三维有限元模型。纤维尺度模型包含了单种纤维和树脂基体,考虑了纤维、基体、纤维/基体界面等微观失效机理,以此得到了单种纤维复合材料（纤维束）的强度参数;纤维束尺度模型包含了不同种类的纤维束,考虑了纤维束自身及相邻纤维束之间界面的失效。模型中各组分材料的损伤和失效均采用粘聚力模型模拟,反映出材料中裂纹的分布和扩展情况。两级模型的计算均采用显式有限元算法,可考虑纤维断裂时释放出的能量对周围材料的冲击效应。两级模型还分别引入了纤维和纤维束强度参数的Weibull分布,考虑了破坏的随机性。用上述模型模拟了不同混杂比例、不同混杂方式的碳/玻纤维混杂复合材料拉伸失效过程。研究发现碳纤维束体积含量小于等于10%时有明显的二次破坏现象,此时夹芯混杂材料的最大伸长率和拉伸强度略高于分散混杂材料;当碳纤维束体积含量大于10%时,二次破坏不明显,且两种混杂方式对材料的强度影响不大。

英文摘要：

Two 3D finite element approaches for unidirectional hybrid composites were built to represent failure process in scales of individual fiber and fiber tow, respectively. The first scale approach was defined as iso-type fibers and epoxy composed fiber tow in which micro damages concerned including failures of individual fiber, matrix and fiber/matrix interface. The second scale approach assembled with different type fiber tows. In this scale, failure regularities of tow and interface between adjacent tows were considered and the former was obtained from first scale model. Cohesive zone model was used to simulate the damage and failure of component materials, this method could reflect the distribution and propagation of the crack in composites. Explicit FEM was used for both the two scale models to characterize the impaction of energy released from the broken fiber or tow. Weibull type distribution was used to describe strengths of fiber and fiber tow in the two scale approaches for charaetering the randomness of failures. The two scale approaches were employed to simulate the progressive failure of carbon/glass fiber hybrid unidirectional composites under tensile load. Two distribution patterns of carbon tow in hybrid composites, i.e. coaxial and dispersed were taken into account, meanwhile for each pattern different volume ratio of carbon fiber and glass fiber was considered. The study reveals that when volume fraction of carbon tows is equal or less than 10% the second damage phenomenon is obvious, meanwhile the critical elongation and strength for coaxial hybrid composited are slightly bigger than those for dispersed one. Otherwise, the two patterns hybrid composites behave in brittle way and little discrepancy between their strengths has been found.