论文部分内容阅读
通过定义考虑拉伸保载效应的CFI因子(creep-fatigue interaction factor),将拉伸蠕变损伤和疲劳损伤进行非线性耦合．根据断裂实验的观察,针对拉伸主导的裂纹萌生、扩展及破坏的多轴疲劳问题,给出了一个基于临界面方法的能量型高温多轴疲劳寿命预测模型．所给出的模型可对不同温度、不同载荷特点、不同保载时间的多轴疲劳寿命进行预测,模型的材料参数不依赖于温度和载荷．并且此方法可以很方便地推广到其它因素主导破坏的高温多轴疲劳寿命预测．通过拟合高温合金Udimet720Li单轴带保持时间的低循环疲劳(low cycle fatigue,LCF)寿命试验数据,得到了材料常数．结合黏塑性有限元分析方法,对高温双轴带保载循环载荷下Cruciform试件的寿命进行了预测,预测结果基本落在2倍分散带内,达到工程的要求,证明了该模型的有效性．
Tensile creep damage and fatigue damage are non-linearly coupled by defining a creep-fatigue interaction factor that takes into account the tensile loading effect. According to the fracture experiment, a multi-axis fatigue life prediction model based on the critical surface method is proposed for the multi-axial fatigue problems of tensile-dominated crack initiation, propagation and failure. The proposed model can predict the multi-axial fatigue life under different temperatures, different load characteristics and different loading time. The material parameters of the model do not depend on the temperature and load. And this method can be easily extended to other factors dominated the destruction of the high temperature multi-axis fatigue life prediction. The material constants were obtained by fitting the low cycle fatigue (LCF) life test data of the superalloy Udimet 720L uniaxial holding time. The viscoelastic finite element analysis method was used to predict the life of Cruciform under high temperature biaxial belt loading. The predicted results are basically within 2 times of the dispersion belt and meet the requirements of engineering. The effectiveness of this model is proved .