Sensitivity analysis on reliability for the crack growth life of powder metallurgy turbine disk

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 c\ 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.