蠕变与疲劳交互作用下裂纹扩展速率的探讨  

THE RESEARCH ON THE CRACK GROWTH RATE UNDER FATIGUE-CREEP COMBINED LOADING

作　　者：于强[1] 

机构地区：[1]四川理工学院理学院,四川自贡643000

出　　处：《机械强度》2013年第5期674-683,共10页Journal of Mechanical Strength

摘　　要：指出疲劳与蠕变交互作用的过程可以看作是蠕变与疲劳叠加作用的过程,其蠕变应变规律应由疲劳蠕变曲线描述,并根据静蠕变与疲劳蠕变时间百分比寿命曲线基本重合的实验结果,导出了静蠕变应变与疲劳蠕变应变之间的关系式。经过对疲劳与蠕变交互作用下的应力-应变迟滞回线的分析,导出了在一个周期内蠕变应变能密度增量的计算式。还指出在疲劳与蠕变交互作用下应变能密度增量是一个综合性的损伤变量,应变能密度增量应等于疲劳应变能密度增量与蠕变应变能密度增量之和。然后参照纯疲劳的研究过程,导出了基于能量密度增量的在疲劳与蠕变交互作用下的裂纹扩展速率表达式,该表达式得到了316L钢在400℃下梯形应力波加载实验数据的支持。Cyclic creep and fatigue interaction can be regarded as the process of creep and fatigue superposition in this paper. The law of strain and time can be shown by Fatigue-creep strain curve. The Static creep and fatigue-creep equation can be derived by an experiment result of curve Static creep and fatigue creep superposition in terms of normalized time life. The formula of fatigue-creep strain energy density increment in a cycle can be derived by the analysis of Hystersis loop under stress by cyclic creep and fatigue interaction. It can be pointed out that fatigue-creep strain energy density increment is a comprehensive damage variable, and it equals the total of Fatigue strain energy density increment and that of creep. Referred to the study on fatigue loading, the formula of the crack growth rate under cyclic creep and fatigue interaction loading based on stain energy density increment can be derived. It is supported by experiment data, crack growth rate under stress with trapezoidal waveform of 316L steel at 400℃.

关 键 词：疲劳蠕变 迟滞回线 应变能密度 裂纹扩展速率 

分 类 号：O346.2[理学—固体力学]