A microstructure‐based homogenization model is proposed for simulating the cyclic plasticity and predicting the low‐cycle fatigue (LCF) crack initiation life of GH4169 superalloy. Classical crystal plastic model (CPM) with a simple softening model is used at the grain level. Then, the transition from grain level to polycrystal level is based on the conservation of virtual work between the two levels. The Eshelby's formulation is applied in the model. Especially, local influences of grain interactions are considered by introducing the external Eshelby's tensor. Relatively precise macroresults and microresults as the finite element method can be provided by the present model with less computational cost. Grain volume averaged fatigue indicator parameters (FIPs) with considering the effect of inclusions are formed to predict the LCF crack initiation life, and a fold‐line fitting model is proposed to substitute for the cycle‐by‐cycle simulation. Predicted lives fit well with the experimental data for both the strain loading and stress loading simulations. Scatter of the life can also be predicted by the model and overwhelming influences of the incubation stage on the variability of LCF initiation life can be captured. It is shown that the inclusions and the inhomogeneous plastic strain are responsible for the scatter of the incubation stage.

中文翻译：

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基于微观结构的均质模型，用于预测GH4169合金的低周疲劳起始寿命

提出了一种基于微观结构的均质化模型，用于模拟GH4169高温合金的循环塑性和预测其低周疲劳（LCF）裂纹萌生寿命。在晶粒级别使用具有简单软化模型的经典晶体塑料模型（CPM）。然后，从晶粒能级到多晶能级的转变是基于两个能级之间虚拟功的守恒。该模型采用了埃舍尔比的公式。特别是，通过引入外部Eshelby张量来考虑晶粒相互作用的局部影响。本模型可以提供比较精确的宏观结果和微观结果作为有限元方法，且计算量较小。考虑夹杂物影响的晶粒平均疲劳指标参数（FIPs）的形成可预测LCF裂纹的起始寿命，并提出了折线拟合模型来代替逐周期模拟。预测寿命与用于应变载荷和应力载荷模拟的实验数据非常吻合。该模型还可以预测寿命的分散，并且可以捕获孵化阶段对LCF起始寿命变异性的压倒性影响。结果表明，夹杂物和不均匀的塑性应变是温育阶段散布的原因。预测寿命与用于应变载荷和应力载荷模拟的实验数据非常吻合。该模型还可以预测寿命的分散，并且可以捕获孵化阶段对LCF起始寿命变异性的压倒性影响。结果表明，夹杂物和不均匀的塑性应变是温育阶段散布的原因。预测寿命与用于应变载荷和应力载荷模拟的实验数据非常吻合。该模型还可以预测寿命的分散，并且可以捕获孵化阶段对LCF起始寿命变异性的压倒性影响。结果表明，夹杂物和不均匀的塑性应变是温育阶段散布的原因。