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A Linear S-N Curve with Load Dependent Variance and Explicit Failure Probability

Dabiru, Venkata Rambabu and Chatterjee, Anindya (2012) A Linear S-N Curve with Load Dependent Variance and Explicit Failure Probability. In: JOURNAL OF TESTING AND EVALUATION, 40 (4). pp. 557-564.

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Official URL: http://dx.doi.org/10.1520/JTE104419


We reconsider standard uniaxial fatigue test data obtained from handbooks. Many S-N curve fits to such data represent the median life and exclude load-dependent variance in life. Presently available approaches for incorporating probabilistic aspects explicitly within the S-N curves have some shortcomings, which we discuss. We propose a new linear S-N fit with a prespecified failure probability, load-dependent variance, and reasonable behavior at extreme loads. We fit our parameters using maximum likelihood, show the reasonableness of the fit using Q-Q plots, and obtain standard error estimates via Monte Carlo simulations. The proposed fitting method may be used for obtaining S-N curves from the same data as already available, with the same mathematical form, but in cases in which the failure probability is smaller, say, 10 % instead of 50 %, and in which the fitted line is not parallel to the 50 % (median) line.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the AMER SOC TESTING MATERIALS (ASTM)
Keywords: fatigue;S-N curve;load dependent variance;heteroscedasticity; survival analysis
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Depositing User: Francis Jayakanth
Date Deposited: 17 Sep 2012 10:34
Last Modified: 17 Sep 2012 10:34
URI: http://eprints.iisc.ac.in/id/eprint/45068

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