Calculation of outer crack stress intensity factors for nozzle junctions in cylindrical pressure vessels using FCPAS

Murat Bozkurt, David Nash, Asraf Uzzaman

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

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Abstract

Pressure vessels can be subjected to various external local forces and moments acting in combination with main internal pressure. As a result of the stress system set up, and in the presence of attachment welds, surface cracks can occur on the interior and exterior walls. If these cracks cannot be detected at an early stage, there is a real potential for the vessel to rupture with obvious dangerous consequences. The behavior of fractured or geometric discontinuity structures can be investigated with linear elastic fracture mechanics (LEFM) parameters. The stress intensity factor (SIF) is the leading one, and with correct calculations, it can produce the stress intensity in the crack tip region. In cylinder-cylinder intersections subject to local loads, the maximum stress distribution occurs in and around these opening areas and failure in the system usually occurs in this region. 

Using this approach, the present study develops threedimensional mixed mode stress intensity factor solutions on for external cracks on nozzle joints in cylindrical pressure vessels nozzle junctions for a variety of geometrical configurations. This was undertaken using a finite element approach and employing a bespoke software tool and solver, FCPAS-Fracture and Crack Propagation Analysis System-to create the finite element mesh and propagation characteristics. From this, a parameter study examining the influence of the crack shape, size and position was carried out with a fixed pressure vessel nozzle cylinder intersection geometry configuration and the appropriate stress intensity factors identified and reported. The FCPAS tool is shown to be an effective approach to modelling and characterizing cracks in pressure vessel nozzles.

Original languageEnglish
Title of host publicationProceedings of ASME 2021 Pressure Vessels & Piping Conference
Subtitle of host publicationComputer Technology and Bolted Joints; Design and Analysis
Place of PublicationNew York
PublisherAmerican Society of Mechanical Engineers
Number of pages10
ISBN (Electronic)9780791885321
DOIs
Publication statusPublished - 18 Oct 2021
EventASME 2021 Pressure Vessels and Piping Conference, PVP 2021 - Virtual, Online
Duration: 13 Jul 202115 Jul 2021

Publication series

NameAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Volume2
ISSN (Print)0277-027X

Conference

ConferenceASME 2021 Pressure Vessels and Piping Conference, PVP 2021
CityVirtual, Online
Period13/07/2115/07/21

Keywords

  • crack
  • finite element analysis
  • fracture
  • local loads
  • nozzle intersection
  • pressure vessel
  • stress intensity factor

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