单向石墨纤维增强铝合金复合材料轴向压缩损伤演化与断裂力学行为研究

Research on damage evolution and fracture mechanical behavior of unidirectional graphite fiber reinforced aluminum alloy composites subjected to axial compression loading

针对单向石墨纤维增强铝合金复合材料(CF/Al复合材料),采用细观力学数值模拟与准静态压缩试验相结合的方法研究了其轴向压缩渐进损伤与断裂力学行为,并分析了纤维体积分数对CF/Al复合材料压缩力学性能的影响。结果表明,基于纤维正六边形排布RVE建立的细观力学有限元模型对CF/Al复合材料轴向准静态压缩变形力学行为的计算结果与实验结果吻合良好。复合材料轴向压缩时首先在界面处发生损伤,界面损伤的累积随后引起局部界面失效并诱发基体合金的损伤,变形后期纤维发生失效并导致复合材料产生轴向45°压缩破坏,压缩断口呈现出界面脱粘和局部纤维断裂共存的微观形貌,表明界面脱粘及其导致的纤维断裂是诱发复合材料轴向压缩失效的主要机理。轴向压缩载荷作用下基体合金塑性变形损伤后不易发生失效,纤维性能是决定复合材料轴向压缩力学性能的主要因素,增加纤维体积分数有利于提高复合材料的轴向压缩弹性模量和极限强度。

The progressive damage and fracture mechanical behavior of unidirectional graphite fiber reinforced aluminum alloy composites( CF/Al composites) were investigated by combination method of micromechanical numerical simulation and quasi-static compression test,and the influence of fiber volume fraction on the compression mechanical properties of CF/Al composites was also analyzed. The results show that the axial quasi-static compression deformation mechanical behavior of CF/Al composites calculated by the micromechanical finite element model based on hexagonal fiber array is in good agreement with the experimental results. In axial compression,the damage initiates on the interface first,and then the accumulation of interfacial damage induces the local interface failure and matrix damage. At the later stage of deformation,the fiber failures and results in axial compression failure at 45° of the composites. The microstructure of the compression fracture shows the coexistence of interfacial debonding and local fiber fracture,which indicates that the main mechanism of inducing the axial compression failure of composites is the interfacial debonding and the fiber fracture caused by the interfacial debonding.The failure of the matrix alloy is not easy to occur after plastic deformation and damage under the axial compression load. The fiber properties are the main factors that determine the mechanical properties of composites under axial compression. Increasing the fiber volume fraction is beneficial to increase the axial compression elastic modulus and ultimate the strength of composites.