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疲劳寿命符合对数正态分布,并且对数寿命的标准差随弹性应变幅和塑性应变幅的减小而增大。采用基于异方差回归分析的整体推断方法在现有低循环疲劳试验数据的基础上,得到了航空发动机涡轮盘材料GH4133在温度250℃下的P-ε-N曲线;利用P--εN曲线对某涡轮盘进行低循环疲劳寿命可靠性分析,得到置信度0.95,可靠度0.998 7的轮盘寿命为1 866次循环,合683飞行小时,与涡轮盘疲劳试验分析得到的技术寿命接近。整体推断得到的P-ε-N曲线精度较高,利用P-ε-N曲线进行轮盘寿命可靠性设计分析具有计算简便、节约试验成本的优点。
The fatigue life accords with the logarithm normal distribution, and the standard deviation of logarithmic life increases with the decrease of elastic strain amplitude and plastic strain amplitude. Based on the existing low cycle fatigue test data, the global inference method based on heteroscedasticity analysis was used to obtain the P-ε-N curve of GH4133 at 250 ℃. The P-ε-N curves The reliability analysis of low cycle fatigue life for a turbine disk obtained a reliability of 0.95 and a reliability of 0.998 7 with a life of 1 866 cycles and a flying time of 683 hours which is close to the technical life of the turbine disk fatigue test. The P-ε-N curve obtained by the overall estimation has high precision. The reliability analysis of the reliability of the disk life using the P-ε-N curve has the advantages of simple calculation and saving test cost.