高温构件蠕变损伤与裂纹扩展预测研究新进展

Advances in Predictions of Creep Damage and Crack Growth in Components under High Temperatures

精准的寿命预测是高温构件设计制造与运行维护的关键,但多轴应力和裂纹等缺陷的存在使得寿命预测的难度大大增加。综述了笔者近年来在高温蠕变损伤模型和蠕变裂纹扩展仿真方面的研究工作,主要包括:讨论了应力水平和应力状态对蠕变断裂应变的影响规律;基于幂律蠕变控制孔洞长大理论,提出了新的多轴蠕变延性模型;采用基于应变的损伤力学模型,预测了多种含缺陷结构中蠕变裂纹的扩展行为,并分析了蠕变条件下多个表面裂纹干涉、扩展及合并的全过程;发展了基于晶界孔洞化损伤机制的裂纹扩展分析方法,实现了蠕变疲劳裂纹扩展仿真和蠕变疲劳氧化裂纹扩展仿真。这些工作为建立考虑多轴应力影响的含缺陷高温构件寿命预测方法提供了有力支持。

An accurate prediction of the lifetime of components operating at high temperatures is the key to design,manufacture,operation and maintenance of them. However,the presence of multiaxial stress and defects,such as cracks,makes the difficulty of its life prediction increased significantly. In the paper,the recent work of the author on high-temperature creep damage models and creep crack growth simulations was reviewed,which mainly includes the following aspects: the influence rules of stress level and stress state on creep rupture strain were discussed;a new multiaxial creep ductility model was proposed based on the power-law creep governed cavity growth theory;creep crack growth behavior in several structures was predicted,and the interaction,propagation and combination of multiple surface cracks under creep conditions were analyzed using the strain-based damage mechanics models. Furthermore,an analysis technique for crack growth based on grain boundary cavitation damage mechanism was developed and applied to simulate creep-fatigue and creep-fatigue oxidation crack growths. The work provides useful support for establishing the lifetime prediction method for high-temperature components considering the effect of multiaxial stress and cracks.