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简要介绍了高周疲劳裂纹萌生的微观力学模型，如滑移带挤入挤出模型、位错塞积模型和位错反应模型等。通常认为这些模型在疲劳破坏区的剪应力是疲劳裂纹萌生的控制量，其中较为典型的是滑移带挤入挤出的线性位错偶极子模型。该模型理论认为在疲劳加载过程中晶粒内的位错数是线性增加的。作者在疲劳试验及微观金相分析中发现，晶粒内的位错数随着疲劳加载的进行是非线性增加的，并在线性模型的基础上提出了一个改进的滑移带挤入挤出的非线性位错偶极子模型。通过试验观察和模拟计算的对比可知，该模型与实验观察结果相吻合。
The microscopic mechanical models of high-cycle fatigue crack initiation are briefly introduced, such as sliding-zone extrusion-extrusion model, dislocation plugging model and dislocation reaction model. It is generally accepted that the shear stress in fatigue failure zones of these models is the control of fatigue crack initiation, and the slip band is more typical of extruded linear dislocation dipole model. The model theory assumes that the number of dislocations in the grain increases linearly during fatigue loading. In the fatigue test and microstructure analysis, the authors found that the number of dislocations in the grains increases nonlinearly with the fatigue loading. Based on the linear model, an improved slip band extrusion extrusion Nonlinear Dislocation Dipole Model. Through the comparison of experimental observation and simulation calculation, we can see that the model is consistent with the experimental observation.