Residual Stresses, Notch Stresses, and Stress Intensities at Welds: An UnifiedAssessment Procedure with Self-Consistency

摘要

Over the last decade, as more in-depth understanding of weld residual stresses is being achieved, particularly of theirrncharacteristic distributions in pressure vessel and piping components, their effects on stress intensities at welds have beenrnbetter understood. In this paper, some of the important residual stress characteristics are first identified in the form of eitherrn"bending" dominated or "self-equilibrating" dominated types for girth welds. The applicability in other joint configurationsrnin welded structures is then discussed, with a collection of validated residual stress distributions. The characterization ofrnboth "bending" and "self-equilibrating" types in residual stress distributions provides a consistent framework for stressrnintensity factor considerations in either fracture and fatigue assessment. The contribution of "bending" type residual stressesrnto stress intensities at welds is shown to be in the form of remote loading, rather than secondary stress effects, asrnconventionally believed. The contribution of "self-equilibrating type residual stresses to stress intensities is shown to be inrnthe form of notch stress effects, being limited to a finite characteristics crack depth, beyond which, negligible residual stressrneffects can be seen. Finally, a simple and robust calculation procedure for evaluating stress intensities for both types ofrnresidual stress distributions and notch stresses is presented for fracture and fatigue assessments of welded joints