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针对2024-T62铝合金薄板系统地开展了腐蚀预损伤对材料疲劳SN曲线、小裂纹萌生行为、长短疲劳裂纹扩展及物理小裂纹门槛值扩展行为的影响等试验研究。结果表明:腐蚀预损伤对材料疲劳S-N曲线及材料疲劳小裂纹萌生行为有明显的影响,但对材料长短裂纹扩展及物理小裂纹门槛值扩展行为没有明显的影响。通过假定腐蚀预损伤为初始小裂纹,基于断裂力学理论,利用FASTRAN3.9软件预测了含腐蚀预损伤材料的疲劳S-N曲线。研究发现,预测与试验结果吻合较好。当材料含有较大尺寸的腐蚀预损伤时,对其进行寿命预测可以不考虑小裂纹效应的复杂影响。
In the light of the 2024-T62 aluminum alloy sheet system, experimental studies on the effects of corrosion pre-damage on the SN curve of fatigue, the initiation of small cracks, the propagation of long and short fatigue cracks, and the expansion of thresholds of physical small cracks have been carried out. The results show that the corrosion pre-damage has a significant effect on the S-N curve of fatigue and the fatigue crack initiation behavior of the material, but has no obvious effect on the material crack growth and the threshold expansion of the physical crack. Based on the theory of fracture mechanics, FASTRAN3.9 software is used to predict the fatigue S-N curve of pre-damaged materials with corrosion. The study found that the prediction is in good agreement with the experimental results. When the material contains a larger size of corrosion pre-damage, its life prediction can not consider the small cracks effect of the complex effects.