应变率对Gr/Al金属基复合材料力学性能的影响

EFFECT OF STRAIN RATE ON MECHANICAL BEHAVIOUR OF Gr/Al COMPOSITES

利用自行研制的冲击拉伸实验装置对单向石墨纤维增强铝基复合材料实施了不同应变率下的拉伸实验。获得了材料在００００５～１３００ｓ－１应变率范围内完整的应力应变曲线。结果表明Ｇｒ／Ａｌ的应力应变曲线可分为两个部分：非线性弹脆性变形以及材料失稳后的残余变形。实验结果还表明Ｇｒ／Ａｌ是一种应变率敏感材料，随着应变率的提高，材料的拉伸强度、失稳应变以及剩余应力均相应提高。根据不同应变率下的实验结果，提出了计及应变率强化效应的复合丝束统计本构模型，模型拟合的结果与实验结果吻合得很好。拟合结果还表明，特征纤维统计分布的Ｗｅｉｂｕｌ参数（尺度参数与形状参数）均是与应变率无关的，复合材料的应变率效应主要是由基体的应变率强化效应引起的。

In this paper,the loading and loading unloading tests of Gr/Al metal matrix composite have been carried out by a self designed tensile impact apparatus and the quasi static tensile tests have been performed on the Shimadzu 5000 testing apparatus.The stress strain curves of composites in strain rate range from 0 0005s -1 to 1300s -1 have been obtained.The experimental results show that complete stress strain curves of the material can be divided into two parts:the elastical brittle deformation and residual deformation.The test results also indicate clearly that the Gr/Al composite is a rate sensitive material,namely the strength,failure strain and residual strength of composite are all depend on strain rate.According to the statistical analysis and models,the mechanical parameters for composites and their relationship with strain rate are obtained from experimental results.The simulated stress strain curves from the model are in good agreement with the test data.The test results show that the shape parameter β and the scale parameter σ 0 both are strain rate independent.The constituent,Gr fibers in Gr/Al composites can beragarded as a rate insentive material,and the strain rate effect of Gr/Al composites is mainly caused by the strain rate strengthening effect of Al alloy matrix.