Second Students Symposium on Engineering Application of Mechanics (SSENAM’2)
The importance of the two-parameter approach in linear elastic fracture mechanics analy-sis is increasingly being recognized for fracture assessments in engineering applications. The consideration of the second parameter, namely, the elastic T-stress, allows estimating the level of constraint at a crack or notch tip. It is important to provide T-stress solutions for practical geometries to employ the constraint-based fracture mechanics methodology. In the present research, T-stress solutions are provided for a V-shaped notch in the case of sur-face defects in a pressurised pipeline. The V-shaped notch is analyzed using the finite ele-ment method by the commercial Castem2000 software to determine the stress distribution ahead of the notch tip. The notch aspect ratio was varied in the following range a/t = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7. The notch-tip radius was fixed for all geometries and equal 0.25 mm. In contrast to a crack, it was found that the T-stress is not constant and depends on distance from the notch tip. To estimate the T-stress in the case of a notch, a novel method, inspired from the volumetric method approach proposed by Pluvinage, has been developed. The method is based on averaging the T-stress over the effective distance ahead of the notch tip. The effective distance corresponds to the point with a minimum of the stress gradient in the fracture process zone. This approach was successfully used to quantify the constraints of notch-tip fields for various geometries and loading conditions. Moreover, the proposed T-stress estimation creates a basis to analyse the crack path under mixed mode loading from viewpoint of the two-parameter fracture mechanics.
Keywords : constraint, T -stress, effective distance, notch, finite element analysis.
Abstracts Submission Deadline: 05 December 2017