PROBABILISTIC LIFE ESTIMATION OF TURBINE SHAFT BOLTED JOINTS CONSIDERING THE EFFECT OF NONLINEAR STRESS GRADIENTS ON CRACK GROWTH RATES


Tümergin Ö., Ertekin Ş., Kara A., Giz A. S., Topak E. K., Ozturk U. E., ...More

ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition, GT 2023, Massachusetts, United States Of America, 26 - 30 June 2023, vol.11B identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 11B
  • Doi Number: 10.1115/gt2023-101771
  • City: Massachusetts
  • Country: United States Of America
  • Keywords: crack propagation, probabilistic analysis, Turbines
  • Istanbul Technical University Affiliated: Yes

Abstract

Crack growth in mechanical components is determined by initial crack size and fracture toughness that have probabilistic distributions. With a focus on a turbine shaft bolted joint made of Inconel 718, fracture damage was examined during a test cycle while crack size and fracture toughness were random variables. A finite element model of a turbine was created to calculate the stress field in turbine components. Following, stress distribution around the potential crack zones was included in calculating the crack growth. Proposed approach was verified by making comparisons with the results of Nasgro. Probabilistic distribution of crack depth and length, expected life and probability of detecting a crack was included in crack growth analyses. Probability of failure of the stub shaft was calculated via Monte-Carlo simulations. Comparisons were made with the crack growth results of Nasgro to verify the developed methodology. Effect of inspection period on probability of detecting the cracks before failure was determined.