ASTM E3498-26

1.1 This guide covers methodological options to analyze experimental fatigue data for the estimation of fatigue life, fatigue strength, or both.

1.2 These techniques enable the use of nonlinear fatigue-life (S-N) relationships.

1.3 These techniques are applicable to S-N fatigue data containing run-outs (also known as right-censored observations). This guide uses maximum likelihood (ML) statistical inference because it is the most well-accepted method for analyzing data containing run-outs. Least squares and Bayesian techniques are not covered.

1.4 In this guide, several analysis options are presented from which users may choose. It provides a procedure for the implementation of these method options, but it does not establish a standard practice to follow in all cases.

1.5 It is intended that users of this guide will implement the portions of the guide that are found relevant without any implication or necessity of adhering to the entirety of the content.

1.6 In this guide, a general framework for fatigue data analysis is provided. It contains commonly used S-N relationships and statistical distributions. The framework is applicable to other relationships and statistical distributions, which may be substituted as justified.

1.7 Experimental methods, sample size selection and choice of test levels are beyond the scope of this guide.

1.8 The analysis of data for variable amplitude cycling and variable mean stress/strain is not covered.

1.9 The methods in this guide assume that the data points being analyzed all belong to the same underlying statistical population. This guide does not cover the subject of pooling data from substantially different experiments.

1.10 Extrapolation—Caution should be used when estimating fatigue life and fatigue strength beyond the life and amplitude ranges of the collected data, as it may lead to non-conservative estimates.

1.11 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.

1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.13 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.