Reliability assessment of high cycle fatigue design of gas turbine blades using the probabilistic Goodman Diagram

A probability-based procedure has been developed to predict the reliability of gas turbine engine blades subjected to high cycle fatigue. The procedure provides a systemic approach for predicting and designing turbomachinery blading reliability against various potential high cycle fatigue problems for all relevant vibratory modes, and taking into account variability in geometry (e.g. dimensional variation, surface smoothness, etc.). The variability in materials (e.g. damage, cracks, degradation, etc.), unsteady aerodynamics, and structural damping can be also considered in this approach. A reliability prediction was performed on gas turbine blades at high frequency modes (e.g. third strip modes) using a probabilistic vibratory stress distribution in conjunction with the modified Goodman Diagrams. The cumulative reliability and risk assessment are then calculated using the fast probability integration (FPI) technique to construct a novel probabilistic Goodman diagram which provides lifetime design guide lines for blades and an optimal maintenance strategy in management, in decision-making relating to the PM/inspection scheduling, replacement, and spare parts requirements. (C) 1999 Elsevier Science Ltd. All rights reserved.