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通过新型铝合金2B06轧制薄板材料的金相分析和疲劳断口的扫描电镜分析知,其疲劳裂纹萌生机理与材料微观结构有着紧密的联系,该型铝合金轧制薄板光滑试件的疲劳裂纹一般倾向于尺寸较大的S相(Al2CuMg)粒子处萌生。经统计分析获得S相粒子尺寸的分布规律;将S相粒子当量假设为表面裂纹,运用概率断裂力学,建立涵盖“材料微观结构→短裂纹扩展→长裂纹扩展→断裂”失效过程的全寿命概率模拟理论模型,通过不同应力水平和不同应力比的多组疲劳试验对模型进行验证。结果表明,提出的全寿命概率模拟方法是合理的、可行的。
Through the metallographic analysis of the new aluminum alloy 2B06 rolled sheet and the scanning electron microscope analysis of the fatigue fracture, the mechanism of fatigue crack initiation is closely linked with the microstructure of the material. The fatigue crack of the smooth specimen of the rolled aluminum alloy plate is generally Tend to the size of S phase (Al2CuMg) particles at the initiation. The distribution rule of S-phase particle size is obtained through statistical analysis. The S-phase particle equivalent is assumed to be surface crack. By using the probability fracture mechanics, the whole process of failure process covering “material microstructure → short crack propagation → long crack propagation → fracture” Life probability simulation theoretical model, the model is verified by a series of fatigue tests with different stress levels and different stress ratios. The results show that the proposed whole life probability simulation method is reasonable and feasible.