In this work, fatigue crack growth (FCG) in the 2024-T351 aluminium alloy is studied using the plastic CTOD range, Δδ_p. Experimental tests were performed on 12 mm thick CT specimens in order to obtain FCG rate and in cylindrical specimens to obtain stress–strain loops. A numerical analysis replicated the experimental work in terms of material, geometry and loading conditions, but assuming pure plane strain state, in order to obtain Δδ_p. The material parameters were fitted using the experimental stress–strain loops. The experimental work showed an increase of FCG rate with the increase of stress ratio from R = 0.1 to R = 0.7 mm, which indicated the existence of the crack closure phenomenon. However, the analysis of the position of the first node behind the crack tip showed that there is no crack closure under plane strain state, while a maximum value of 36% was found for plane stress state. Therefore, the surfaces influence FCG rate even in 12 mm thick specimens. A nearly linear relation was found between da/dN and Δδ_p. The comparison with other aluminium alloys showed that there is a significant influence of material on da/dN-Δδ_p relation. The change from plane strain to plane stress state decreased FCG rate due to crack closure. Under plane strain state there is a minor influence of stress ratio in the range R = 0.1–0.7, also because there is no crack closure. Finally, a comparison was made between plastic CTOD and cumulative plastic strain at the crack tip. Well defined relations were found, showing that both parameters can be used to quantify crack tip deformation.

在这项工作中，使用塑性 CTOD 范围 Δ δ _p研究了 2024-T351 铝合金中的疲劳裂纹扩展 (FCG) 。实验测试在 12 毫米厚的 CT 试样上进行，以获得 FCG 率和圆柱形试样，以获得应力 - 应变环。数值分析复制的实验工作中的材料，几何形状和负载条件的术语，但假设纯平面应变状态下，为了获得Δ δ _p。使用实验应力-应变环拟合材料参数。实验工作表明，随着应力比从R  = 0.1 增加到R，FCG 率增加 = 0.7 mm，表示存在裂纹闭合现象。然而，对裂纹尖端后面第一个节点位置的分析表明，在平面应变状态下没有裂纹闭合，而在平面应力状态下发现最大值为36%。因此，即使在 12 毫米厚的试样中，表面也会影响 FCG 率。在da/dN和 Δ δ _p之间发现了几乎线性的关系。与其他铝合金的比较表明，有材料上的显著影响DA / DN -Δ δ _p的关系。由于裂纹闭合，从平面应变到平面应力状态的变化降低了 FCG 率。在平面应变状态下，应力比的影响很小R  = 0.1–0.7，也是因为没有裂缝闭合。最后，对裂纹尖端的塑性 CTOD 和累积塑性应变进行了比较。发现了明确定义的关系，表明这两个参数均可用于量化裂纹尖端变形。