Burst speed prediction and reliability assessment of turbine disks: Experiments and probabilistic aspects

Under harsh and stochastic environmental conditions, turbine disks may exceed their maximum allowable speed and then burst. Aeroengine certification requires demonstrating its integrity at higher rotation speeds than the designed steady-state speed. In particular, testing the burst speed of turbine disk is an essential part of this procedure. In this work, based on the average stress approach, a novel model for turbine disk burst speed assessment is proposed, in which the notch strength ratio and the stress triaxiality parameter are introduced to characterize the inhomoge-neous stress field and multiaxial stress state, respectively. Disk overspeed test data are utilized for model validation and comparison, and results show that the proposed model matches the experimental evidences well. Furthermore, a probabilistic framework is built to characterize the influence of material property dispersion on burst speed, and the proposed model is extended to a probabilistic one. Finally, the relationship between the safety margin and the reliability index is established, which provides a reference for reliability-based design and evaluation of turbine disk.