Probabilistic High Cycle Fatigue Assessment Process for Integrally Bladed Rotors

Abstract

This paper defines a probabilistic High Cycle Fatigue (HCF) assessment process for a fan or compressor Integrally Bladed Rotor (IBR). It identifies key design variables, how they are statistically modeled, the probabilistic integration technique, and the physics-based modeling process. It defines how previous eigensensitivity based reduced order models cannot be used for IBR assessment and validates an alternate approach. An autoregressive model accounts for correlation between IBR blade-to-blade variabilities. An approach is also defined to combine sector tuned stress variation and mistuning amplifications. Predicted stress variations integrate with a probabilistic Goodman Diagram to allow an IBR risk assessment. The paper concludes by summarizing several remaining areas that are necessary for a practical assessment process. These areas are probabilistic fluid dynamic prediction, probabilistic mission analysis, propagating model error, and the need for an effective validation strategy.