Session: 26-03 Probabilistic Lifing and Damage Tolerance

Submission Number: 178826

On the Application of the IBESS Model As a Deterministic Base for Probabilistic Lifing of Fatigue Cracks in Cast MAR-M247 Considering Shrinkage Pores 

This paper builds on previous work on the application of the so-called IBESS model in quantifying probabilistic crack nucleation life in MAR-M247 cast turbine blades. It is the fourth of a series of publications that presented earlier stages of the work, including the methodology for using the IBESS model. The specimens were extracted from cast gas turbine (GT) blades, either defect-free or with casting shrinkage pores (natural defects). In some defect-free specimens, holes were introduced, either partially or entirely through the thickness (artificial defects). Strain-controlled testing was conducted to support a probabilistic assessment of the material's low-cycle fatigue (LCF) behavior. The defects were characterized by their size and shape on the fracture surfaces of the specimens. Using information from micro-CT scans of the specimens, this work transforms the complex geometry of the casting pores in the IBESS model into geometrically simple shapes via pore-volume-based conversion. Fitting the IBESS model to new fatigue crack growth (FCG) data based on the plasticity-corrected stress intensity factor (SIF) range (∆K_p) significantly improves model performance. For more accurate crack growth predictions, the individual material properties extracted from each specimen's corresponding hysteresis loop, along with the fluctuating stress levels throughout the entire loading, are used as input parameters. Additionally, different model crack geometries are explored to assess their impact on prediction accuracy.

Presenting Author: Malek Al-Ameri Siemens Energy

Presenting Author Biography: Mar 2022 - Present:
Siemens Energy - Doctoral Candidate

May 2021 - Nov 2021:
Tata Steel in Europe - Master Thesis Intern

Sep 2019 - 2021:
Luleå University of Technology - M.Sc. in Materials Engineering

Jun 2017 - Dec 2017:
Lehigh University - Exchange Program, Mechanical Engineering

Aug 2014 - May 2019:
King Fahd University of Petroleum & Minerals - B.Sc. in Mechanical Engineering

Authors:

Malek Al-Ameri Siemens Energy
Christian Amann Siemens Energy
Jan Radners Fraunhofer Institute for Mechanics of Materials IWM
Christoph Schweizer Fraunhofer Institute for Mechanics of Materials IWM
Michael Schlesinger Fraunhofer Institute for Mechanics of Materials IWM
Stefan Eckmann Fraunhofer Institute for Mechanics of Materials IWM
Peter Gumbsch Fraunhofer Institute for Mechanics of Materials IWM | Karlsruhe Institute of Technology KIT
Kai Kadau Siemens Energy Inc.