Probabilistic failure risk assessment for structural fatigue

A probabilistic methodology for evaluating failure risk, assessing service life, and establishing design parameters for structures subject to fatigue failure has been developed. In this methodology, engineering analysis is combined with experience from tests and service to quanti& failure risk. The methodology is particularly valuable when information on which to base design analysis or failure prediction is sparse, uncertain, or approximate and is expensive or difficult to acquire. Sensitivity analyses conducted as a part of the probabilistic methodology can be used to evaluate alternative measures to control risk, such as design changes, testing, or inspections, thereby enabling limited program resources to be allocated more effectively. The probabilistic methodology and an example application to fatigue crack growth in a heat exchanger tube are presented.