Iranian Journal of Chemical Engineering (IJChE)
Scientific Journal

Comparative Stress-Strain Field Assessment of BLISK and Fir-Tree Turbine Blade Roots in Ti-6Al-4V Alloy as a Prerequisite for Fatigue Life Prediction

Articles in Press

Document Type : Regular Article

Authors

Alireza Sharifi Nezhad 1
Armin Sabetghadam-Isfahani 2
Yegane Davoodbeygi 3
Seyed Mahmood Latifi 4
Abdolhossein Barzin 2

1 National Iranian Gas Company, Tehran, Iran

2 Safety and Inspection Engineering Department, University of Hormozgan, Bandar-Abbas, Iran

3 Chemical Engineering Department, University of Hormozgan, Bandar-Abbas, Iran

4 Corrosion Engineering and Material Protection Department, Amirkabir University of Technology, Bandar-Abbas, Iran

10.22034/ijche.2026.579155.1588
Abstract
Modern steam turbines employ extended low-pressure blades, subjecting root connections to severe centrifugal and thermal loads. As a result of these loadings, various and severe dynamic stresses are formed in the structure. Understanding this distribution of stresses and conducting studies on it will greatly help determine the lifespan of items and how to manage them. This study evaluates stress and strain distributions in Ti-6Al-4V turbine roots, specifically comparing BLISK and fir-tree designs under operational conditions. Using nonlinear Finite Element Analysis (FEA) and Local Plastic Stress and Strain Analysis (LPSA), peak von Mises stresses were identified as 890.76 MPa for the BLISK and 390.82 MPa for fir-tree roots. Advanced damage frameworks, including the Modified Mohr-Coulomb and Lemaitre's CDM models, are discussed conceptually to identify critical stress triaxiality states, thereby establishing a reliable baseline for subsequent fracture analyses. The findings establish a reliable baseline for fatigue studies, identifying root-blade transition fillets as critical sites for low- cycle fatigue failure. Understanding material behavior under fatigue loading can help in better determining the scope of application and optimizing the design.

Keywords

Ti-6Al-4V
BLISK
Fir-tree Analysis
Finite Element Analysis (FEA)
Subjects
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Articles in Press, Accepted Manuscript
Available Online from 08 August 2026

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