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在含缩松缺陷的材料疲劳试验的基础上,对缩松结构的疲劳寿命的表征方法和疲劳寿命的预估进行了研究。综合考虑缺陷面积、位置和外加载荷的影响,使用扫描电镜分析计算得到了缩松缺陷的应力强度因子变化值。建立了应力强度因子和缺陷结构疲劳寿命之间的相互关系。结果表明,缩松的应力强度因子变化值可表征其疲劳寿命,二者成幂指数函数关系。反推得到了缩松缺陷的当量初始裂纹长度,建立了缺陷应力强度因子变化与当量初始裂纹之间的关系。进一步建立了基于应力强度因子变化的疲劳寿命预测方法,为含缩松缺陷结构的疲劳寿命预估提供依据。
Based on the fatigue test of the material with shrinkage defects, the characterization of the fatigue life of the shrinkage structure and the estimation of the fatigue life are studied. Considering the influence of defect area, location and applied load, the change of stress intensity factor of shrinkage defect was calculated and analyzed by SEM. The relationship between the stress intensity factor and the fatigue life of the defect structure is established. The results show that the change of stress intensity factor of shrinkage can be used to characterize the fatigue life of the product, and the relationship between the two is an exponential function. The equivalent initial crack length of the shrinkage defect is deduced and the relationship between the change of the stress intensity factor and the equivalent initial crack is established. The fatigue life prediction method based on the change of stress intensity factor is further established, which provides the basis for estimating the fatigue life of the structure with shrinkage defects.