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本文通过初始切口有较大变化范围的LY12R板材疲劳扩展试验,分析了影响形成疲劳裂纹寿命N_i的因素,得到了N_i的关系式lnN_i=a+b△K_c。对LY12R及三种钢和一种钛合金的实验数据进行了分析,分析表明,在所研究的范围内,疲劳裂纹的形状变化规律对材料、试件尺寸、载荷大小不敏感,且上述平板构件中表面裂纹的深度a均可用同一经验关系式△a=f(△c)来估计,估计值与实测值符合很好。分析还表明,直至σ_(N,max)/σ_y=0.9时,表面裂纹的扩展仍为应力强度因子幅值△K所控制。
In this paper, the fatigue crack propagation of LY12R sheet with larger initial change of notch is analyzed, and the factors that affect the fatigue life of the cracked crack are analyzed. The relation of N_i is lnN_i = a + bΔK_c. The experimental data of LY12R, three kinds of steels and one kind of titanium alloy were analyzed. The analysis shows that the change rule of the shape of the fatigue crack is not sensitive to the size of the material, the size of the specimen and the size of the load in the studied range, The surface crack depth a can be estimated by the same empirical relation Δa = f (Δc), which is in good agreement with the measured values. The analysis also shows that until σ_ (N, max) /σ_y = 0.9, the surface crack propagation is still controlled by the magnitude of stress intensity factor △ K.