石墨烯及碳化硅增强铝基复合材料的冲击力学行为

采用微机控制电子万能实验机和分离式霍普金森压杆(SHPB)对石墨烯增强的铝基复合材料和碳化硅增强的铝基复合材料进行准静态压缩实验和动态冲击实验,研究石墨烯增强铝基复合材料在不同应变率下的冲击力学性能,采用SEM扫描电镜研究石墨烯增强的铝基复合材料和碳化硅增强的铝基复合材料的形貌特征。结果表明:在各个应变率载荷下,添加石墨烯和添加碳化硅都增强了铝合金的屈服强度,其中,添加石墨烯对铝合金的屈服强度提升更加明显,但不影响材料的应变硬化率;相较于在材料中添加碳化硅,添加石墨烯弱化了材料的应变率效应,在高应变率条件下,添加石墨烯降低了材料的强度极限;选取部分实验数据,拟合确定了添加石墨烯和添加碳化硅两种复合材料的J-C和Z-A本构方程的参数,并比较了两种本构模型的预测能力,对于本工作所研究的复合材料,J-C模型的预测能力更好。

Mechanical behavior of graphene or SiC reinforced aluminum matrix composites under dynamic loading

Quasi-static compression experiments on graphene-reinforced aluminum matrix composites were carried out by means of microcomputer controlled electronic universal testing machine, while dynamic behavior of the composites at various high strain rates was determined by split hopkinson pressure bar (SHPB). In addition, scanning electron microscopy (SEM) was employed to examine the morphological feature of aluminum matrix composites reinforced respectively by grapheme and SiC. The results show that at all strain rate, the yield strength of aluminum is improved both with addition of graphene and SiC, by incorporation of graphene, the yield strength of aluminum is improved more significantly, but without affecting the strain hardening rate of the material. In comparison with SiC as reinforcements, use of graphene undermines strain rate sensitivity of the composites, and meanwhile results in a decline in ultimate strength. J-C and Z-A constitutive models were fitted respectively to the experimental results to obtain relative parameters. Comparison between the two models suggests that J-C model is more accurate in terms of describing stress-strain behavior of both composites reinforced respectively by graphene and SiC.