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Investigation of Local Buckling in Marine Pipelines under External Pressure

Salahshoor Langroudi, Soheil | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46113 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Fallah Rajabzadeh, Famida; Seef, Mohammad Saeed
  7. Abstract:
  8. To keep up with the growing demands for energy, the oil and gas industry ventures into deeper waters. This increases complexity of offshore projects. Part of this complexity is due to the resistance of a pipeline against local buckling collapse due to external pressure that is more significant in higher pipe laying depth and consequently higher external pressure. Pipeline response to external pressure is an important factor in design of marine pipeline.Local buckling of a pipeline is the buckling behaviour within the pipeline cross section. Other types of buckling behaviour such as upheaval and lateralbuckling are not in the scope of this thesis.In this thesis, the installing pipeline is modeled as an infinetly long thin cylindrical shell and its local buckling bihaviour under hydrostatic pressure is investigated in elastic region. Using infinitely long cylinder assumption makes the effects of boundary conditions disappear. In this analysis, Donnell and Sanders classicalshell theoriesare used.In the analysis based on Donnell shell theory, the governing equations and total potential energy of long cylindrical shell under external pressure are extracted.In Sanders shell theory, just the potential energy of long cylindrical shell under external pressure is derived. In both theoties, the critical pressure is determined using Ritz method and the numerical results are compared with literature and DNV criteria.In order to investigate finite element results in buckling problem, a long thin cylindrical shell is modeled in Abaqus software and its results are compared with the results of semianalytical solution based on mentioned theories. Finally, the influence of different parameters like thickness, radius and length on buckling pressure is investigated
  9. Keywords:
  10. Local Buckling ; Hydrostatic Pressure ; Shell Theory ; Elastic Buckling ; Ritz Method

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