3-D stress intensity factors due to autofrettage for an inner radial lunular or crescentic crack in a spherical pressure vessel

M. Perl, M. Steiner, J. Perry

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Three dimensional Mode I Stress Intensity Factor (SIF) distributions along the front of an inner radial lunular or crescentic crack emanating from the bore of an autofrettaged spherical pressure vessel are evaluated. The 3-D analysis is performed using the finite element (FE) method employing singular elements along the crack front. A novel realistic autofrettage residual stress field incorporating the Bauschinger effect is applied to the vessel. The residual stress field is simulated in the FE analysis using an equivalent temperature field. SIFs for three vessel geometries (. R0/Ri=. 1.1, 1.2, and 1.7), a wide range of crack depth to wall thickness ratios (. a/t=. 0.01-0.8), various ellipticities (. a/c=. 0.2-1.5), and three levels of autofrettage (. ε=. 50%, 75%, and 100%) are evaluated. In total, about two hundred and seventy different crack configurations are analyzed. A detailed study of the influence of the above parameters on the prevailing SIF is conducted. The results clearly indicate the possible favorable effect of autofrettage in considerably reducing the prevailing effective stress intensity factor i.e., delaying crack initiation, slowing crack growth rate, and thus, substantially prolonging the total fatigue life of the vessel. Furthermore, the results emphasize the importance of properly accounting for the Bauschinger effect including re-yielding, as well as the significance of the three dimensional analysis herein performed.

Original languageEnglish
Pages (from-to)282-295
Number of pages14
JournalEngineering Fracture Mechanics
Volume131
DOIs
StatePublished - 1 Nov 2014

Keywords

  • Autofrettage
  • Crescentic crack
  • Lunular crack
  • Spherical pressure vessels
  • Stress intensity factors

ASJC Scopus subject areas

  • Materials Science (all)
  • Mechanics of Materials
  • Mechanical Engineering

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