恒幅载荷16MnR钢疲劳裂纹扩展统计特性分析

通过21个紧凑拉伸试件的疲劳试验，进行16MnR钢疲劳裂纹扩展统计特性研究。研究给定裂纹尺寸条件下疲劳寿命的分布规律，给定寿命条件下裂纹尺寸的分布规律，给定裂纹尺寸下疲劳裂纹扩展速率的分布规律；为16MnR钢疲劳可靠性评估提供基础数据。

STATISTICAL NATURE OF FATIGUE CRACK GROWTH FOR CHINESE STEEL 16MnR

From a microscopic, a metallic material is micro-structural heterogeneous, the scatter generally observed in fatigue test arises precisely because it is not a homogeneous continuum. The stochastic nature of the fatigue crack growth phenomena has to be considered in practical engineering failure analysis. In this paper, a new sets of experimental data was obtained by replicate constant-amplitude fatigue crack propagation tests on the specimens of Chinese steel 16MnR. Twenty-one pre-cracked specimens obtained from the same sheet of Chinese steel 16MnR were subjected to identical load and environmental conditions. The tests were strictly conducted following ASTM standards E647-93. Non-line regression technique and incremental polynomial method were used in data process. From the experimental data, the distribution of the crack size at any given number of cumulative load cycles, and the distribution of the number of load cycles to reach any given crack size, were determined using probability paper. The statistical distribution of the crack growth rate at any given crack size was discussed. The statistical investigation method proposed by this paper is also suitable for other materials.