Probability analysis for the low cycle fatigue life of a turbine disk

The standard deviation of fatigue life increases with reduction of elasticity and plasticity strain components. A standard normal random variable μ and linear standard deviations σ_e and σ_p were introduced into Manson-Coffin equation, so the probabilistic model of fatigue life was established, in which four parameters were expressed as the functions of μ. The parameters of the probabilistic model were obtained by the heteroscedastic regression analysis method based on the low cycle fatigue (LCF) test data, the fatigue life probability analysis for the pinhole of a disk was achieved by this model, and the distribution of the fatigue life of the pinhole was obtained. The results show that the life with the reliability of 0.9987 is well consistent with the technical life of the disk based on test evaluation. This model is suitable for engineering application with its good precision.