中文摘要：

借助扫描电镜（SEM）对2B06铝合金薄板料疲劳断口进行分析,揭示疲劳裂纹萌生机理;借助金相显微镜测量2B06铝合金第二相尺寸,通过统计分析获得最佳分布形式及拟合的概率密度函数;建立基于裂纹萌生微观机理的疲劳寿命的可靠性评估方法,分别计算不同可靠度条件下（90％,95％,99％和99.9％）的理论计算寿命.对比分析理论计算和试验结果,对评估方法进行试验验证.结果表明,基于疲劳微观机制的可靠性评估方法较好地模拟疲劳寿命随机分散性,经验证是合理可行的.

英文摘要：

Using scanning electron microscope （SEM）, the morphology of fatigue fracture of 2B06 aluminum sheet specimen was in- vestigated, and the micro-mechanism of fatigue crack initiation was evaluated. Using optical microscope, the size of the second phase particles was measured, and the best distribution rule and fitting probability distribution functions were obtained using statistical analy- sis. A probabilistic approach to predicting fatigue life based on crack initiating micro-mechanism was put forward in accordance with the probabilistic fracture mechanism. The fatigue life for different reliability （90% , 95% , 99% and 99.9% ） was calculated. By compar- ison between testing fatigue life and calculation, the theoretical model was validated. The results show that the probabilistic method can simulate the variability of fatigue life, and it is feasible and reasonable.