三维四向和五向编织复合材料冲击断裂行为的多尺度模拟

为对三维编织复合材料的结构特性进行模拟预测分析,采用一种多尺度和细观结构结合的方法,建立三维编织复合材料的等效拼接组合模型,进一步揭示编织复合材料在微观结构水平下的冲击损伤演化、裂纹扩展和能量吸收。设计制备三维四向和三维五向2种编织结构的碳/环氧树脂三维编织复合材料,根据编织参数建立等效拼接组合模型;通过落锤式冲击试验仪结合高速摄影系统记录2种编织复合材料在低速冲击下的断裂行为,与等效拼接组合模型在有限元数值模拟结果相对比,验证等效拼接组合模型的有效性。模拟结果表明,相同的体积分数下轴纱表现出最高的能量吸收,由于轴纱的存在,三维五向编织复合材料的抗裂性和裂纹扩展性优于三维四向编织复合材料。

Multi-scale simulation of impact failure behavior for 4- and 5-directional 3-D braided composites

In order to simulate and predict the complex mechanical characteristics of 3-D braided composites against impact, a multi-scale meso-structure method was used to establish an equivalent combination model of 3-D braided composites to study impact behavior of braided composites. Impact damage evolution, crack propagation and energy absorption were examined numerically. 4- and 5-directional 3-D braided structures were used to prepare braided composites, and the equivalent combination model was established according to the obtained braid parameters. A drop weight impact tester equipped with a high-speed camera was used to record the fracture behavior of the 4-directional 3-D and 5-directional 3-D braided composites under low-speed impact. The 3-D braided composite equivalent combination models were validated by the fracture behavior obtained from the experiments. The simulation results show that under the same volume fraction, the axial yarn exhibits the highest energy absorption. Due to the presence of axial yarns, the 5-directional 3-D braided composites have better crack resistance and crack propagation than the 4-directional 3-D braided composites.