Comparing alternative flexible pipe fatigue stress models with focus on the Bflex helix models

Abstract

this thesis deals with the stress and slip behaviour for non-bonded flexible pipe of three different models (itcode0, itcode1 and fullfe), comparisons are made among these three models. Besides, pipes with different cross sections are analysed, namely 4 inch, 6 inch, 7.5 inch, 8 inch, and 16 inch pipe cases. In addition to the two tensile layers pipe construction for all the pipe size cases, the 7.5 inch pipe with four tensile layers case is also included. The main advantage of this thesis is the application of the new developed beam elements in Bflex2010, namely HSHEAR353, HSHEAR363 and HCONT463, implemented in the new model FullFE. For HSHEAR353 element, the transverse degrees of freedom of the helix are included, while for HSHEAR363 element, the radial degree of freedom of the plastic layer is introduced, which means that the new model FullFE simulates the most realistic situation for design and operation.