航空铝合金弹塑性短疲劳裂纹扩展表征分析

Elastic-plastic Fatigue Short Crack Propagation Analysis of Aero-aluminum Alloy

铝合金短裂纹扩展行为与长裂纹扩展行为差别很大,而在铝合金结构中短裂纹阶段占据构件疲劳寿命的90%以上。通过对线弹性裂纹扩展模型进行修正,得到了改进后的弹塑性短裂纹模型,并利用LY12CZ铝合金材料进行验证性实验。结果表明:改进后的模型能够统一表征弹塑性短裂纹和线弹性长裂纹的扩展行为。这拓展了裂纹扩展行为的预测范围,对于铝合金构件的寿命预测和损伤容限评估具有重要的参考价值。

Short crack propagation behavior is significantly different from relatively long crack, which takes more than 90% of the whole structure fatigue life. The thesis proposed a modified elastic-plastic short crack propagation characterization model based on the traditional LEFM model, which is verified by experimental results on LY12CZ aluminum alloy. Results indicate that the modified model is able to characterize both short and long crack propagation behavior, expanding the region to be precisely predicted, which is remarkably important for fatigue life prediction and damage tolerant analysis of aluminum structure.