The Strain-based Approach to Predict the Initiation and Propagation of the Crack for the Vintage Pipeline Materials Using the Extended Finite Element Method (XFEM)

• Author / Creator

  Elyasi, Nahid

• Vintage pipelines are widely used in the transmission of gas and oil in North America. They are subject to varieties of loading conditions, especially in aggressive environments in arctic region. Displacement-controlled loads lead to severe longitudinal plastic strain and consequently failure in pipelines. Strain-based design (SBD) can be an effective and economical method in designing pipelines under severe plastic strain. The goal of the current study was to investigate the efficiency of strain-based damage criteria using the extended finite element method (XFEM) to predict the initiation and propagation of the crack in two specific grades of vintage pipelines. First, the damage criteria, maximum principal strain (Maxpe), and fracture energy (G_c) were obtained for the X52 vintage pipeline under internal pressure and eccentric tension loading using XFEM analysis in the ABAQUS software. Then, the predicted XFEM results were validated with previously published eight full-scale experimental tests, and tensile strain capacity (TSC) for each model was calculated. In the second step, to investigate the capability of the strain-based XFEM analysis in the prediction of small-scale tests as well, the initiation and propagation of the crack in the single edge notched tension (SENT) test was simulated. The strain-based damage parameters were applied in the SENT model of vintage X42 grade of pipeline and XFEM results were validated with experiments. The current research investigated the reliability of strain-based damage parameters in the prediction of fracture response in X42 and X52 grades of the vintage pipeline using XFEM. The results showed the capability of the XFEM tool to predict the damage response in both full-scale and small-scale models for these grades of the vintage pipeline.

• Subjects / Keywords

  • XFEM
  • Tensile strain capacity
  • Vintage pipeline materials

• Graduation date

  Fall 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-z7a8-np36

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.