Stress intensity factors for a pipe-plate welded joint

Abstract

A major component of any linear elastic fracture mechanics model for fatigue crack growth is the calculation of the crack tip stress intensity factor. This is particularly difficult for welded joints due to the complex geometry. While some data are available for cracks in welded T-plate joints, there is relatively little data available for larger cracks in more complex tubular joints. Such cracks are of significant interest since the most practical application of fracture mechanics models is the prediction of remaining life for cracks discovered in service. A pipe-plate joint has been developed as a simplified model of tubular joint geometries for fatigue studies. Two such specimens have been tested in air, with detailed monitoring of crack growth behaviour using potential drop techniques. These data were used to obtain crack growth rate data from which estimates of stress intensity factors were made. Separately, finite element analyses for various discrete crack configurations were performed. The results of these analyses are presented and discussed, with particular emphasis on the accuracy of the results and the implications for fracture mechanics modelling.