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基于晶体塑性本构理论,利用多晶代表性单元从细观尺度研究了ZSGH4169合金在650℃条件下考虑双轴应力状态的循环应力应变行为.计算结果表明:该合金在双轴拉伸应力控制下存在与低周疲劳试验常用的单轴应力状态一致的棘轮效应.对两种应力状态下的结果进行对比发现,在1 150MPa应力单轴循环载荷下初始循环残余应变比双轴应力状态高出3倍,且双轴应力状态下最终循环稳定,残余应变约为1.2%,但在单轴应力状态下是不稳定的.对应力和塑性应变累积不均匀性的分析表明:单轴和双轴拉伸状态下,虽然应力和应变分布的不均匀性都随着循环数的增加而增加,但单轴拉伸状态下平均应力随循环数增加,而双轴拉伸状态下几乎为常数.
Based on the crystal plastic constitutive theory, the cyclic stress-strain behavior of ZSGH4169 alloy at 650 ℃ under biaxial stress was studied by means of the representative units of polycrystalline. The calculated results show that the biaxial tensile stress control Under the condition of uniaxial stress, the ratcheting effect is consistent with the uniaxial stress state commonly used in low-cycle fatigue test.Comparing the results of two kinds of stress states, the residual stress of initial cycle under 1 150MPa stress uniaxial cyclic stress is higher than that of biaxial stress 3 times, and the final cycle of the biaxial stress state stability, the residual strain of about 1.2%, but uniaxial stress state is unstable.Calculation of stress and plastic strain cumulative inhomogeneities show that: uniaxial and biaxial In the tensile state, although the stress and strain distribution inhomogeneities increase with the number of cycles, the average stress increases with the number of cycles under uniaxial tension and almost constant under biaxial tension.