Plastic dissipation accompanies fatigue crack growth in ductile materials. Previous studies presented a relation between plastic dissipation (dW/dN) and the fatigue crack growth rate (da/dN), where some researchers assumed a linear relation between both to enable crack growth predictions. To study the validity of this assumption, this paper reports an experimental study on fatigue crack growth in 7075-T6, an alloy widely used in aerospace. The experimental results suggest, however, a nonlinear relation between dW/dN and da/dN in 7075-T6. The value of dW/da, indicating the plastic dissipation per unit fatigue crack growth, is not constant. Hence for 7075-T6 it is concluded that dW/dN cannot be used directly to predict da/dN.

塑性耗散伴随着韧性材料中疲劳裂纹的增长。先前的研究提出了塑性耗散（dW / dN）与疲劳裂纹扩展速率（da / dN）之间的关系，其中一些研究人员假设两者之间存在线性关系，以进行裂纹扩展预测。为了研究该假设的有效性，本文报道了一项在7075-T6中疲劳裂纹扩展的实验研究，该合金是航空航天中广泛使用的合金。然而，实验结果表明，在7075-T6中dW / dN和da / dN之间存在非线性关系。表示每单位疲劳裂纹扩展的塑性耗散的dW / da值不是恒定的。因此，对于7075-T6，得出的结论是dW / dN无法直接用于预测da / dN。