Statistical investigation of surface fatigue cracks in large-sized turbine rotor shaft steel

✍ Scribed by S.K. Sasaki; Y. Ochi; A. Ishii

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 862 KB
• Volume: 28
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(87)90068-3

✦ Synopsis

Distribution properties of an initiation life Ni and a propagation life NP of surface cracks, statistical characteristics of a crack growth rate dl/dN, and a relationship between a scatter of the distributions and a gradient a of S-log N curves in rotating bending fatigue tests were investigated for Ni-Cr-Mo-V steel, using for a large-sized turbine rotor shaft. The distributions of Ni and NP were expressed as Weibull distributions, and the scatter of them for smooth specimens and for lower stress amplitude cr. tests were larger than those for notched ones and for higher o. tests, respectively. The statistical properties of crack propagation rate were almost similar in both smooth and notched specimens. The relationship between the a and a coefficient of variation TJ for the distributions of Ni, NP and a final fracture life N, was expressed as r) = ~(a)-~, where c and 6 are constants.