A crystal plasticity finite element (CPFE) simulation framework has been proposed in this study for the prediction of combined detrimental effect of mean stress and defects on the fatigue behavior of aluminum alloy. Experimental data for mean-stress effect on fatigue life and crack growth behavior was obtained on metal inter gas (MIG) welded joints of Al-5083/Al-5.8%Mg alloy plates and has been detailed in authors’ previous work, referred later. The present study focuses on its prediction using computational framework only. A 2D representative model for material’s microstructure was used for the simulations, generated using an anisotropic tessellation algorithm using the EBSD measurements data. A total of 10 different microstructure models were generated for each loading condition using six-node plane strain type quadratic triangular (CPE6) elements of mesh size 6 $\mathrm{\mu }$m. Two different types of cases were investigated: one without defect and other with a semi-circular surface defect. The simulated loadings at different stress ranges and stress ratios (R-ratio) were similar to the experimental conditions for the better comparison of the results. Significant heterogeneity in the distribution of R-ratios and the far-field applied R-ratio was observed. When defect was not considered, a clear deviation in the predicted fatigue lives from the experimental data was observed at different R-ratios: the predicted fatigue lives were higher than the experimentally observed fatigue lives. This was probably because of not considering the detrimental effect of defects on fatigue lives. But, when the defects were considered, the predicted results for different R-ratios was consistent with the experimental fatigue lives. The proposed CPFE simulation framework not only predicted well the effect of defects and mean stress on the fatigue lives, but also the scatter induced in them due to the defects.

本研究提出了一种晶体可塑性有限元（CPFE）模拟框架，用于预测平均应力和缺陷对铝合金疲劳行为的综合有害影响。在Al-5083 / Al-5.8％Mg合金板的金属间气体（MIG）焊接接头上获得了平均应力对疲劳寿命和裂纹扩展行为的实验数据，该数据已在作者先前的工作中详细介绍，稍后再进行介绍。本研究仅专注于使用计算框架的预测。模拟使用材料的微观结构的2D代表模型，该模型是使用EBSD测量数据通过各向异性细分算法生成的。$\mathrm{\mu }$米 研究了两种不同类型的情况：一种没有缺陷，另一种有半圆形表面缺陷。为了更好地比较结果，在不同应力范围和应力比（R比率）下的模拟载荷与实验条件相似。观察到R比值的分布和远场应用的R比值存在明显的异质性。当不考虑缺陷时，在不同的R比率下观察到的预测疲劳寿命与实验数据存在明显偏差：预测的疲劳寿命高于实验观察到的疲劳寿命。这可能是因为未考虑缺陷对疲劳寿命的有害影响。但是，当考虑缺陷时，不同R比率的预测结果与实验疲劳寿命是一致的。