界面对双向纤维增强复合材料力学性能的影响

基于均匀化理论与有限元方法,针对双向连续纤维增强复合材料(CBFRC),建立了微观代表体积单元(RVE)模型,并预测了界面对CBFRC宏观等效力学性能的影响。在建立的RVE模型中,采用表面内聚力本构关系描述纤维/基体之间的界面。研究结果表明:不同界面刚度下,CBFRC中的基体发生不同形式的初始损伤。与界面断裂能相比,界面刚度和界面强度对CBFRC面外抗拉强度的影响较大,而对CBFRC面内抗拉强度的影响较小,且界面的存在会降低CBFRC整体的抗拉强度。随着纤维体积分数的增加,CBFRC面内的抗拉强度也随之急剧增加,但CBFRC的面外抗拉强度反而有减小的趋势。本文中所提出的方法能够简单有效地对实际复杂的三维纤维增强复合材料进行优化设计。

Interfacial effect on mechanical behaviors of bidirectional-fiber-reinforced composites

A micromechanical representative volume element (RVE)model was developed for analyzing effective mechanical behaviors of continuous bidirectional-fiber-reinforced matrix composites (CBFRCs)by combining the homogenization method and finite element method.In the proposed RVE model,the imperfect interfaces between the fiber and the matrix were taken into account by introducing some cohesive contact surfaces.The results show that an imperfect interface with a different interfacial stiffness may induce different damage onsets in the matrix of CBFRCs.Compared with the interfacial fracture energy,both the interfacial stiffness and strength play a more im-portant role in determining the out-of-plane tensile strength of the CBFRCs,while have slight effect on the in-plane tensile strength.The tensile strength of the CBFRCs will be reduced because of the existence of interface.With an increase in the fiber volume fraction,the in-plane tensile strength increases sharply while the out-of-plane tensile strength decreases slightly.The numerical results indicate that the proposed model is simple and efficient for per-forming realistic optimum design on complex three dimensional fiber-reinforced composites.