火箭发动机涡轮叶片疲劳寿命可靠性分析

由于生产加工和使用过程中材料属性、结构尺寸以及工作载荷等的随机性,疲劳寿命通常存在较大的分散性。考虑结构几何参数、材料属性、工作载荷等变量的随机性,采用Monte Carlo模拟法与响应面法相结合,对液体火箭发动机涡轮叶片进行概率疲劳寿命分析,确定了涡轮叶片疲劳寿命可靠度模型,并分析了疲劳寿命对各随机变量的敏感度,以及变量分散度对疲劳寿命的影响。结果表明:疲劳寿命呈偏态分布;涡轮入口温度对叶片疲劳寿命影响最大,材料的低周疲劳性能参数对寿命影响较大,转速及热膨胀系数对寿命有一定影响,而其他参数对寿命的影响小;控制变量分散度是提高叶片安全寿命的有效途径,对单变量而言,控制涡轮入口温度分散度效果最显著。

Reliability analysis of fatigue life for rocket engine turbine blade

Due to the randomness of material properties,structural dimensions and working loads during the process of production and use,fatigue life usually has great dispersion.Based on Monte Carlo simulation combined with response surface method(RSM),probabilistic fatigue life and reliability analysis were conducted for some rocket engine turbine blades,considering the randomness of structural geometric parameter,material property and working load.The sensitivity of blade life to those random factors and the influence of variable dispersion on fatigue life were analyzed.The results show that the fatigue life has a skewed distribution.Turbine inlet temperature has the greatest impact on blade fatigue life,followed by low-cycle fatigue(LCF)properties.The rotating speed and thermal expansion coefficient have some effect on blade life.Controlling the variable dispersion is approved to be an effective way to increase the safe life of turbine blade.For a single variable,the effect of controlling the temperature dispersion of turbine inlet is most significant.