Abstract Fatigue crack growth (FCG) is simulated here by node release, which is made when the accumulated plastic strain reaches a critical value. The numerical procedure is very robust, showing a very fast stabilization and independence relatively to the load considered for node release. A critical accumulated plastic strain of 110% was obtained for the 2024-T351 aluminium alloy, comparing the experimental value of da/dN for a crack length of 26.5 mm and a stress ratio of 0.1, with plane strain numerical predictions. This critical value was used to predict da/dN for different crack lengths. The da/dN-ΔK curve was found to be linear in log-log plot with a slope m = 2.4, which is lower than the slope m = 3.6 presented by the experimental results. The difference is attributed to crack tip mechanisms activated at relatively high loads. The variation of stress ratio and stress state did not affect the da/dN-ΔK curves, which indicates that the effect of these parameters is not linked to crack tip plastic deformation. FCG rate was also predicted for the 7050-T6 aluminium alloy and the 18Ni300 maraging steel, and slopes m = 3.09 and 2.70, respectively, were obtained for da/dN-ΔK curves. The predictions obtained for the steel agreed well with experimental results.

中文翻译：

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基于累积塑性应变的疲劳裂纹扩展数值模拟

摘要 这里通过节点释放模拟疲劳裂纹扩展（FCG），当累积塑性应变达到临界值时进行节点释放。数值程序非常稳健，相对于考虑节点释放的负载，显示出非常快的稳定性和独立性。2024-T351 铝合金的临界累积塑性应变为 110%，将裂纹长度为 26.5 mm 和应力比为 0.1 的 da/dN 实验值与平面应变数值预测进行比较。该临界值用于预测不同裂纹长度的 da/dN。发现 da/dN-ΔK 曲线在 log-log 图中呈线性，斜率 m = 2.4，低于实验结果呈现的斜率 m = 3.6。这种差异归因于在相对高的负载下激活的裂纹尖端机制。应力比和应力状态的变化不影响 da/dN-ΔK 曲线，这表明这些参数的影响与裂纹尖端塑性变形无关。还预测了 7050-T6 铝合金和 18Ni300 马氏体时效钢的 FCG 率，并且分别获得了 da/dN-ΔK 曲线的斜率 m = 3.09 和 2.70。对钢获得的预测与实验结果非常吻合。