SYNOPSIS A reliability assessment method was presented based on the probabilistic damage tolerance theory to predict the failure probability induced b y fatigue damage for the aero-engine turbine disk. Failure is considered to occur when the crack exceeds the residual strength required crack length and the structure would never endure the ope rational loads. This paper was devoted to the condition that a turbine disk embedded a crack in the lower slot. A two-dimensional finite element 1/64 disk model was established to determin e the most likely site for crack initiation and the crack growth direction. And then, a three-d imensional finite element 3/64 disk model with a crack locating in the most likely initiation site was employed to get the stress intensity factor (SIF) expressions, which is suitable for ana lytical computations. A random variable model was adopted to characterize the crack growth procedure. The distribution of the crack size at a specified service time can be obtained, a nd the same for obtaining the distribution of the service time to reach any given crack size. Th erefore, the failure probability could be
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