Structural integrity of pipelines: T-stress by line-spring
The elastic T-stress is an important constraint parameter for characterizing elastic–plastic crack-tip fields and in fracture assessment procedures. However, many of the methods reported in the literature for estimating T-stress are not easily suited for surface-cracked pipes because these are three-dimensional in nature. Here, the line-spring method is demonstrated to be an efficient and accurate tool for the constraint estimation in surface-cracked pipes. Detailed three-dimensional analyses are performed to verify the line-spring results. Using the line-spring method, the effects of different crack geometries and diameter-to-thickness ratio on stress-intensity factor (SIF) and T-stress in circumferentially surface-cracked pipes are examined. Further, a compendium of normalised SIF and T-stress values for surface-cracked pipes in remote tension and bending, calculated from a total of 1000 analyses, is tabulated. Finally, the application of an ‘elastic–plastic’ T-stress under large-scale plasticity is explored.
Document Type: Research Article
Affiliations: 1: The Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, N-7491 2: Sintef Material Technology, N-7465 3: LINKftr AS, N-7491, Trondheim, Norway
Publication date: May 1, 2005