Three-dimensional mixed-mode stress intensity factors for deflected internal surface cracks in thin and midsize-thick-walled spherical pressure vessels

• Published in: The International journal of pressure vessels and piping 2019-03, Vol.171, p.10-33
• Main Authors: Kurt, Emre, Ayhan, Ali O.
• Format: Article
• Language: English
• Subjects: Fracture mechanics; Mixed mode; Spherical vessels; Stress intensity factor
• ISSN: 0308-0161; 1879-3541
• DOI: 10.1016/j.ijpvp.2019.01.018

In this paper, three-dimensional mixed-mode stress intensity factor solutions are obtained for deflected inner surface cracks contained in thin- and midsize-thick-walled spherical pressure vessels. In an effort to build a library of stress intensity factor solutions for different realistic cases, main parameters affecting the problem, which are crack deflection angle, normalized crack depth and crack shape aspect ratio, are changed systematically to cover all combinations. The results show that as the deflection angle increases, mode-I stress intensity factors decrease and mode-II and mode-III stress intensity factors increase for a given case. It is also observed that as the normalized crack depth increases, stress intensity factors increase along the crack front. The results show that magnitudes of the normalized mixed mode stress intensity factors for midsize-thick-walled vessels are higher than those of thin-walled spherical vessels. Crack deflection angle is shown to have the highest influencing effect among all parameters. It is also observed that especially for higher crack deflection angles, which have higher mode-mixity, crack surfaces may come into contact partially or fully. •Effects of crack deflection angle, normalized crack depth and crack shape aspect ratio are investigated.•As the deflection angle increases, mode-I stress intensity factors decrease, mode-II and -III stress intensity factors increase.•Normalized stress intensity factors for midsize-thick-walled vessels are higher than those of thin-walled spherical vessels.•Crack deflection angle is shown to have the highest influencing effect among all parameters.•Especially for higher crack deflection angles, crack surfaces come into contact partially or fully.