A new method for predicting stress intensity factors in cracked welded tubular joints

Fracture mechanics is an important tool for the analysis of cracked bodies. It has been established for use in a range of industries including the power generation and the aircraft industry. Fracture mechanics provides the basis for fatigue life prediction, steel selection and tolerance setting on allowable weld imperfections. It can also be used during the operational stage of a structure to make important decisions on inspection scheduling and repair strategies and as a tool for establishing limits on operational conditions. The stress intensity factor is a very important fracture mechanics parameter. Linear elastic fracture mechanics relies on the use of the stress intensity factor concept. Therefore the accuracy of any fracture mechanics model for the prediction of fatigue crack growth will depend very much on the accuracy of the stress intensity factor solution used. It is known that some factors are important in this process. One of these is the crack aspect ratio, which represents a major source of uncertainty in fatigue crack growth prediction. This paper presents a new approach for the prediction of stress intensity Y correction factors for welded tubular joints. The proposed method accounts for crack aspect ratio evolution during crack propagation. The method is based on a statistical model used to quantify and account for the deviation of experimental results from previous semi-empirical solutions and the modified Newman and Raju flat plate solution.