高周疲劳裂纹萌生的非线性微观力学模型  

An Nonlinear Micromechanics Models of the Fatigue Crack Initiation under High Cycles

作　　者：李玉春[1] 姚卫星[1] 

机构地区：[1]南京航空航天大学飞行器系

出　　处：《南京航空航天大学学报》1998年第3期261-267,共7页Journal of Nanjing University of Aeronautics & Astronautics

基　　金：国家自然科学基金

摘　　要：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 micromechanics models of fatigue crack initiation under high cycles are briefly reviewed, i.e., the slip band extrusion intrusion model, dislocation blocking mo del and dislocation reaction model. Most of these models show that shear stress within the fatigue failure zone controls the initiation of fatigue cracks. Among these models, the most typical model is the linear dislocation dipole model of the slip band extrusion intrusion model, which shows that the dislocation number in the crystalline grains increases li nearly with the fatigue loads. By the fatigue experiment and micro metallographic analysis, it is found that the dislocation number in the crystalline grains increases nonlinearly with the fatigue loads and an improved nonlinear dislocation dipole model is put forward based on the linear dislocation dipole model. By the contrast between the experiment and the simulated calculation, it is found that this model is more coincidental with the experimental results.

关 键 词：疲劳裂纹 位错反应 金属疲劳 微观力学模型 

分 类 号：TG111[金属学及工艺—物理冶金]