Fatigue Analysis in Pressure Vessel Design by Local Strain Approach: Methods and Software Requirements

Abstract

The purpose, methods for the analysis, software requirements, and meaning of the results of the local strain approach for fatigue analysis in pressure vessel design is discussed. Three methods that are consistent with the approach are evaluated, based on the requirement that the calculated stress-strain behavior of a stabilized cycle in a pressure vessel component offers a valid comparison with that of the smooth specimens used to develop the cyclic stress-strain curve of the material. Software that can produce results consistent with the approach is identified. The question of the kind of multiaxial equivalent strain range that should be used in the local strain approach is addressed and answered. The concept of a multiaxial equivalent hysteresis loop, which replaces multiple hysteresis loops between stress and strain components, is developed. Its purpose is to determine the multiaxial equivalent stress and strain ranges that are consistent with the local strain approach.