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

作者：Dabiru Venkata Rambabu; Chatterjee Anindya^*

来源：Journal of Testing and Evaluation, 2012, 40(4): 557-564.

DOI：10.1520/JTE104419

• fatigue
• S-N curve
• load dependent variance
• heteroscedasticity
• survival analysis

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.

• 出版日期2012-7