Assessment of stress intensity factors for load-carrying fillet welded cruciform joints using a digital camera

This paper presents an experimental method to determine the stress intensity factors (SIFs) of load-carrying fillet welded cruciform joints. This experimental method measured the crack opening displacements (CODs) of the cruciform joint detail by a common digital camera, and utilized the acquired COD data to derive the SIF for the joint detail by a suggested least-squares procedure. A total of fifteen fillet welded cruciform joint specimens were tested and analyzed in this study. The test results were compared with the SIF formula provided in British Standard 7910, and showed that the demonstrated experimental method is able to give satisfactory SIF evaluation for fillet welded cruciform joints. In fact, this method can be applied to determine the SIF of any detail with surface crack where the Irwin’s series solution for crack tip displacement fields is valid. Moreover, the simplicity and portability of this method make the field measurement of SIF possible and provide a good means to acquire SIFs directly from details at the site. This is very useful for fatigue evaluation of details in structures, such as steel bridges or offshore structures.