粉末冶金涡轮盘裂纹扩展寿命可靠性敏度分析

Sensitivity Analysis on Reliability for the Crack Growth Life of Powder Metallurgy Turbine Disk

结合粉末冶金材料含有非金属夹杂裂纹的特点,以裂纹扩展寿命可靠性分析的剩余强度模型与寿命干涉模型为基础,建立了多夹杂裂纹扩展的可靠性敏度分析模型。此模型首先给出了多个失效模式系统失效概率敏度与单夹杂裂纹扩展寿命失效概率敏度之间的关系;采用一次二阶矩敏度分析方法求出系统失效概率对综合随机变量分布参数与部分基本随机变量分布参数的敏度;通过回归分析与综合随机变量数字特征的性质,得到综合随机变量分布参数对相关基本随机变量分布参数的敏度,最终得到系统失效概率对所有基本随机变量分布参数的敏度。采用所建敏度模型计算了某型发动机粉末冶金涡轮盘裂纹扩展寿命失效概率对基本变量分布参数的敏度,通过对计算结果的分析,得到了在给定参数情况下影响粉末冶金涡轮盘系统失效概率的最主要因素,指出了模型与参数之间的本质联系。剩余强度模型与寿命干涉模型可靠性敏度计算结果一致性,以及定量计算与定性分析结果的一致性,说明了本研究方法是合理可行的。

Based on residual strength interference model and life interference model, a sensitivity analysis method on reliability was proposed for the fatigue crack growth life of powder metallurgy materials. The characteristics were considered on the multiple inclusions in the powder metallurgy materials, especially on the sensitivity analysis method. The relationship of sensitivity for the system failure probability was firstly constructed between multiple failure modes and single failure mode. The advanced method of first order and second moment was employed to calculate the partial derivatives of the system failure probability for the distribution parameters of the process variables and some basic variables. Then by use of regression analysis and numerical property of process variables, the sensitivities of parameters were derived for the process variables and basic variables. Finally, the sensitivities of system failure probability to the distribution parameters of the total basic variables were obtained. Then the proposed reliability sensitivity model was applied to a powder metallurgy turbine disk. The reliability sensitivity results show that the system failure probability of the turbine disk is significantly influenced by the crack growth coefficient c1 of Paris law at a given condition, and the essential relationship is clarified between the model and the distribution parameters. It is proved that the model might supply guidance to the design of powder metallurgy turbine disks. The calculated results were consistent each other with the residual strength interference model and the life interference model, and showed the feasibility of the proposed analysis method from the good agreement between the quantity calculation and the quality analysis.