## Abstract

Fracture mechanics-based failure theory has been used for analyzing structural integrity in Fitness-for-Service assessments of structures containing cracks. The stress intensity factors (SIFs) along the crack front are the key information in order to assess the remaining service life of a cracked component. In the case of a multiply cracked component, according to Fitness-for-Service (FFS) standards, these cracks must be first identified as to whether they are on the same cross-sectional plane, to be considered aligned cracks, or whether they are on parallel planes and thus be considered non-aligned parallel cracks. Extensive studies have been carried out on the mutual influence of adjacent parallel cracks. However, the scenario of a semi-elliptical surface crack under the influence of a quarter corner circular crack under remote bending has never been addressed. The present analysis addresses this problem by evaluating the effect of a corner circular crack of length a_{2} on the SIF of an adjacent nonaligned parallel semi-elliptical surface crack of length 2a_{1} and depth b_{1}. A parametric study of the effect on the SIF as a function of the horizontal separation (S) and vertical gap (H) distances between the two cracks and the crack length ratio a_{2}/a_{1} is conducted. Mode I SIFs are evaluated for a wide range of the normalized crack gaps of H/a_{2} = 0.4~2, and normalized crack separation distances S/a_{2} = -0.5~2. As in the case of tension, the presence of the corner quarter-circle crack affects the stress intensity factor along the semi-elliptical crack front. The present results clearly indicate that the effect of the corner quarter-circle crack on the surface semi-elliptical crack is weaker in the case of bending, when compared to the tension case. The largest percentage differences (5-22%) occur at the farthest crack tip of the semi-elliptical surface crack from the corner crack. The largest percent differences occur for a_{2}/a_{1} < 1. In general, the deeper the semi-elliptical crack, the lower this percentage difference. When comparing maximal absolute values of the SIF, that normally occurs when b_{2}/a_{2}=1 for the cases undertaken. In general, the maximum values are found at the closest tip of the semi-elliptical crack to the corner quarter-circle crack. When b_{1}/a_{1} is different from 1, then the maximum’s location can depend on the value of H/a_{2} and S/a_{2} irrespective of the ratio a_{2}/a_{1}. In these cases, the absolute maximum can occur in the vicinity of the deepest point or in the vicinity of the farthest crack tip of the semi-elliptical crack. As in the case of tension, in the case of bending the presence of the Corner Quarter-Circle Crack changes the stress intensity factor along the semi-elliptical crack front. The change reaches its maximum at the tip of the semi-elliptical crack closest to the corner crack, and it monotonically decreases moving away from this tip for the case b_{1}/a_{1}=1. For most of the cases b_{1}/a_{1} < 1, the maximum occurs in the vicinity of the midpoint of the semi-elliptical crack and decreases monotonically in both directions from the midpoint.

Original language | English |
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Title of host publication | Computer Technology and Bolted Joints; Design and Analysis |

Publisher | American Society of Mechanical Engineers (ASME) |

ISBN (Electronic) | 9780791887455 |

DOIs | |

State | Published - 1 Jan 2023 |

Event | ASME 2023 Pressure Vessels and Piping Conference, PVP 2023 - Atlanta, United States Duration: 16 Jul 2023 → 21 Jul 2023 |

### Publication series

Name | American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP |
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Volume | 2 |

ISSN (Print) | 0277-027X |

### Conference

Conference | ASME 2023 Pressure Vessels and Piping Conference, PVP 2023 |
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Country/Territory | United States |

City | Atlanta |

Period | 16/07/23 → 21/07/23 |

## Keywords

- Fitness-for-Service
- Non-aligned
- Quarter-Circle Corner Crack
- Semi-elliptical crack
- Stress Intensity Factors

## ASJC Scopus subject areas

- Mechanical Engineering