Journal Published Online: 21 March 2024
Volume 13, Issue 2

Kitagawa-Takahashi Diagram to Support Design for Safe Life and Period between Inspections under Service Load Spectra



A procedure is described to construct Kitagawa-Takahashi (K-T) diagrams to suit a given material and service load spectrum. The diagram serves as a graphic platform to audit permissible design stress level against desired service life and inspection period. It involves numerical analyses leading to a spectrum load S-N curve and residual fatigue crack growth estimates given initial defect size. The required analyses are performed on the Rainflow cycle count table for a given load spectrum. They account for potential load history effects on notch root fatigue crack initiation and near-threshold crack growth with and without crack closure. A key element of residual life estimates is consideration of sensitivity of threshold stress intensity range to load history in the absence of crack closure. The procedure was used to construct K-T diagrams for two aluminum alloys, a titanium alloy and a medium strength low alloy steel, subject to TWIST, HELIX, and TURBISTAN load spectra.

Author Information

Sunder, R.
BISS labs, ITW-India (P) Ltd, Peenya Industrial Area, Bangalore, India
Pages: 26
Price: $25.00
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Stock #: MPC20230122
ISSN: 2379-1365
DOI: 10.1520/MPC20230122