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Govt. of India Trust : E/11049/Rajkot
Income tax of India 80G : AADTK8161HF20221
Income tax of India 12A : AADTK8161HE20217

Volume 4 – Issue 2 – 2023

Original Research Article

Modeling of Fatigue Damage

K. Sadananda1, D. Kujawski2, N. Iyyer1, M. Nani Babu3

1Technical Data Analysis, Inc., Falls Church, VA, (USA)
2Department of Mechanical and Aerospace Engineering, Western Michigan University, Kalamazoo, MI 49008-5343, (USA)
3Metallurgy and Material Group, Indira Gandhi Center for Atomic Energy, HBNI, Kalpakkam, 603 102, (INDIA)

PAGE NO: 079-088


We have shown before that representation of the fatigue damage for all materials requires two load parameters Dσ and σmax for S-N fatigue, and DK and Kmax for fatigue crack growth. The intrinsic two-parametric nature of S-N fatigue is traditionally known in terms of mean stress effects. The two-parametric nature is ignored for fatigue crack growth since Elber, by considering the load-ratio effects due to an extrinsic factor called crack closure. When represented in terms of the two parameters, both S-N data and crack growth rate data show a hyperbolic behavior for all materials. In this paper, the Microsoft Excel program is used to solve and arrive at limiting values Dσ* and σmax* for the selected number of cycles for failure, NF, and DK* and Kmax* for selected crack growth rates, da/dN. The approach is valid for characterizing fatigue damage for any material. The predictions based on optimization using the Excel program correlate well with the experimental data. The procedure is considered a step towards developing predictive codes for both S-N fatigue and fatigue crack growth in structural materials in service.