Determination of the resistance of modern structural materials containing cracks to possible fatigue damages is important in evaluating the structures in terms of design and performance and to ensure a safe operation of the materials with cracks. Structures with damage/crack tolerance can be designed by prediction of crack growth lives of materials accurately and precisely. In this study, analytical investigations are performed to study the role of equivalent stress intensity factor range ($\Delta K_{eq}$) equation in the modified Paris’ law on prediction of the crack growth lives of cracked nonhomogeneous materials. The fatigue damage models are examined using the numerical and experimental data from literature reported for inclined cracked steel plates strengthened with carbon fiber reinforced polymer (CFRP) patch and two-phase composite material with slant interface. Results show that the $\Delta K_{eq}$ model plays a remarkable role on prediction of the crack growth lives.

确定含有裂纹的现代结构材料对可能的疲劳损伤的抵抗力对于从设计和性能方面评估结构以及确保有裂纹材料的安全运行非常重要。通过准确、准确地预测材料的裂纹扩展寿命，可以设计具有损伤/裂纹容限的结构。在本研究中，进行了分析研究以研究等效应力强度因子范围（$\Delta {钾}_{情商}$) 方程中的修正巴黎定律预测裂纹非均质材料的裂纹扩展寿命。疲劳损伤模型使用来自文献报道的数值和实验数据来检查，这些数据是用碳纤维增强聚合物 (CFRP) 补片和具有倾斜界面的两相复合材料加固的倾斜裂纹钢板。结果表明，$\Delta {钾}_{情商}$ 模型对裂纹扩展寿命的预测具有显着的作用。