Stress intensity factors for inclined external surface cracks in pressurized pipes

Guoyang Fu, Chun Qing Li, Wei Yang, Sujeeva Setunge, Annan Zhou

Research output: Contribution to journalConference articleOther

Abstract

Inclined surface cracks may occur in pressurized pipes due to corrosion, poor manufacturing quality, complex loading systems or a combination of these factors. However, very few studies have been conducted on the stress intensity factors for inclined cracks in pipes. Due to the high failure rate of pipes with brittle failure, it is essential to thoroughly examine the causes of pipe failures. This paper is intended to study the stress intensity factors with mixed modes (Modes I, II and III) for inclined external surface cracks in pressurized pipes. A three dimensional finite element model meshed with mixed quadratic tetrahedron and hexahedron elements is employed. After verification of the finite element model, the influence coefficients of the stress intensity factors for a wide range of inclined external cracks in a pressurized pipe are obtained. Based on the numerical results, it was found that the influence coefficients of both mode I and equivalent stress intensity factors are symmetric with respect to the deepest point and decrease along the whole crack front with the increase of the inclination angle. In contrast, those of mode II and mode III reach the maximum when the inclination angle is 45 ° and decrease when the angle increases or decreases from 45 ° . It was also observed that, the maximum mode I stress intensity factors of semi-elliptical cracks with high aspect ratios for different inclination angles all appear near the free surface, which is different from the semi-elliptical cracks with low aspect ratio. In addition, for given wall thickness to internal radius ratio and aspect ratio, the influence coefficients of all three modes stress intensity factors along the whole crack front for all inclination angles, increase with the increase of the relative depth.

Original languageEnglish
JournalSustainable Construction Materials and Technologies
Volume2016-August
Publication statusPublished - 1 Jan 2016
Externally publishedYes
EventInternational Conference on Sustainable Construction Materials and Technologies 2016 - Las Vegas, United States of America
Duration: 7 Aug 201611 Aug 2016
Conference number: 4th

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